Albany Thicket Biome

Jan Vlok

Changes in the environment are first observed in changes in the vegetation. Vegetation survey, classification and mapping form the basis on which informed and scientifically defendable decisions on the environment can be taken. The classification and mapping of vegetation is one of the most widely used tools for interpreting complex ecosystems. By identifying different plant communities we are essentially identifying different ecosystems at a particular hierarchical level. Phytosociologists in Europe have been involved in such studies following, in particular, the Braun-Blanquet approach since the early 1900s. In South Africa, such studies were undertaken on a limited basis from the early 1970s and have since then steadily increased. The surveying of the enormous diversity of South African vegetation is one of the objectives of phytosociological studies. The demand for such data has steadily increased over the past few years to guide conservation policies, biodiversity studies and e...

Seepages occurring at high altitudes in the Hottentots Holland Mountains (HHM) (Western Cape Province. South Africa) were subject to a phytosociological survey. Relevé sampling method and classification procedures of the floristic-sociological (Braun-Blanquet) approach as well as numerical data analyses (numerical classification and ordination) were used to reveal syn- taxonomic patterns and characterize the position of the syntaxa along major environmental gradients. Nine plant communities were recognized, three of which were classified as associations, following formal syntaxonomic and nomenclatural rules of the floristic-sociological approach Most of the studied mire communities were dominated by low-growing clonal restios (Restionaceae). whereas some consisted of other types of graminoids. The most important species determining the structure (and function) of the mire communities on sandstones of the HHM include restios Anthochortus crinalis, Chondropetalum deustum.C. mucronatum...

฀ ฀ S % 19 (2006) 10 Albany Thicket Biome David B. Hoare, Ladislav Mucina, Michael C. Rutherford, Jan H.J. Vlok, Doug I.W. Euston-Brown, Anthony R. Palmer, Leslie W. Powrie, Richard G. Lechmere-Oertel, Şerban M. Procheş, Anthony P. Dold and Robert A. Ward Table of Contents 1 Introduction: Delimitation and Global Perspective 2 Major Vegetation Patterns 3 Ecology: Climate, Geology, Soils and Natural Processes 3.1 Climate 3.2 Geology and Soils 3.3 Natural Processes 4 Origins and Biogeography 4.1 Origins of the Albany Thicket Biome 4.2 Biogeography 5 6 7 8 9 10 Land Use History Current Status, Threats and Actions Further Research Descriptions of Vegetation Units Credits References 542 544 544 544 545 546 547 547 548 548 549 550 550 565 565 List of Vegetation Units AT 1 Southern Cape Valley Thicket AT 2 Gamka Thicket AT 3 Groot Thicket AT 4 Gamtoos Thicket AT 5 Sundays Noorsveld AT 6 Sundays Thicket AT 7 Coega Bontveld AT 8 Kowie Thicket AT 9 Albany Coastal Belt AT 10 Great Fish Noorsveld AT 11 Great Fish Thicket AT 12 Buffels Thicket AT 13 Eastern Cape Escarpment Thicket AT 14 Camdebo Escarpment Thicket 550 551 552 553 555 556 557 558 559 560 561 562 563 563 L. Mucina Figure 10.1 AT 8 Kowie Thicket: Kowie River meandering in the Waters Meeting Nature Reserve near Bathurst (Eastern Cape), surrounded by dense thickets dominated by succulent Euphorbia trees (on steep slopes and subkrantz positions) and by dry-forest habitats housing patches of FOz 6 Southern Coastal Forest lower down close to the river. 541 S % 1. Introduction: Delimitation and Global Perspective Following the earlier work of Acocks (1953), the structurally unusual vegetation of the semi-arid river valleys of the eastern seaboard of South Africa was described as Valley Bushveld. This nomenclature probably followed the colloquial term used by the agriculturalists, mainly livestock farmers, who found it a largely impenetrable thicket which had to be ‘opened-up’ to allow access to domestic livestock (cattle and goats). According to Acocks, this comprised ‘a semi-succulent thorny scrub 2–3 metres in height’. Rutherford & Westfall (1986) classiﬁed the biomes of South Africa on the basis of dominant life-form combinations (Raunkiaer 1934, Cain 1950) and climatic features. Therefore, the areas now considered here to be the Albany Thicket Biome were classiﬁed by them as Savanna on the basis of the dominance of phanerophytes associated with, on average, hemicryptophyte co-dominance (Rutherford & Westfall 1986), although they acknowledged the existence of a variety of life-form combinations. This view continued in the work of Scholes (1997), who mapped the vegetation of the discussed region as a part of the broad-leaved Savanna. Following White & Moll (1978) and Cowling (1983), some evidence for its classiﬁcation as a distinct structural and ﬂoristic unit was presented, and this provided justiﬁcation for the later recognition of the Thicket Biome (Low & Rebelo 1996, 1998). Rutherford & Westfall (1986) noted that many parts of the areas classiﬁed here as Thicket Biome, namely Spekboomveld and the Fish River Scrub, Addo Bush and Sundays River Scrub forms of Valley Bushveld (Acocks 1988), had vegetation co-dominated by phanerophytes and chamaephytes. This corresponds to a ‘missing biome’ that they suggested may be recognised in the future. This concept is formally adopted here. Recent analyses, primarily within the STEP project (Cowling et al. 2003), have conﬁrmed that the climatic uniqueness (Robertson & Palmer 2002) and peculiar vegetation structure resulting from a unique combination of constituent growth forms (Vlok & Euston-Brown 2002) as well as ﬂoristic diversity (including high regional endemism) justify its recognition as a biome. The term ‘Albany Thicket’ is a concept recognised by the WWF (Olson et al. 2001, Burgess et al. 2004) where this vegetation type (‘ecoregion’) is listed as a part of the broader category (biome) ‘mediterranean forests, woodlands, and scrubs’, thus, as a part of the Cape Floristic Region—a misplacement that partly reﬂects the transitional nature of the biome. The same WWF categorisation does not recognise a global thicket biome. Various thicket formations in Africa, Madagascar, Asia, Australia and the Americas are spread over four different biomes. In Africa, patches of typical thicket are included in two other ‘biomes’: ‘montane grasslands and shrublands’ (e.g. Jos Plateau forest-grassland mosaic), and ‘tropical and subtropical grasslands, savannas, and shrublands’ (e.g. Somali Acacia– Commiphora bushlands and thickets). Worldwide, other thicket types are classiﬁed as ‘tropical and subtropical dry broadleaf forests’ (see Olson et al. 2001). In terms of vegetation structure and climate at least two other regions qualify as analogous to Albany Thicket. These include the thickets of the Chaco straddling the border areas between Argentina and Paraguay in South America (Lewis 1991, Cábido et al. 1992, 1994) and the Didiereaceae-rich semideciduous thickets (also called dry forests) of southern and southwestern Madagascar (Koechlin et al. 1974, Grubb 2003). Madagascar spiny thickets, largely equivalent in vegetation structure to southern Africa’s Albany Thicket, are classiﬁed under ‘deserts and xeric shrublands’. 542 Albany hicket Biome 19 (2006) Table 10.1 Major correspondence between vegetation units and STEP vegetation types (Vlok & Euston-Brown 2002). Those STEP units are listed which have at least 80% of their area within the vegetation units and do not necessarily constitute a high proportion of the vegetation unit (these proportions are given under the headings in the description of each unit). Only Gouritz Valley Thicket is (much) less than 80%. Vegetation Units STEP AT 1 Southern Cape Valley Thicket Gouritz Valley Thicket AT 2 Gamka Thicket Gamka Arid Spekboomveld Gamka Spekboom Thicket Oudtshoorn Karroid Thicket Baviaans Spekboom Thicket Baviaans Valley Thicket Bethelsdorp Bontveld Groot Arid Spekboomveld Kleinpoort Karroid Thicket Gamtoos Arid Spekboomveld Gamtoos Bontveld Gamtoos Thicket Gamtoos Valley Thicket Kromme Forest Thicket Otterford Forest Thicket Vanstadens Forest Thicket Sundays Noorsveld Elands Forest Thicket Koedoeskloof Karroid Thicket Kremlin Grassland Thicket Motherwell Karroid Thicket Sundays Spekboom Thicket Sundays Spekboomveld Sundays Thicket Sundays Valley Thicket Zuurberg Fynbos Thicket Grass Ridge Bontveld Albany Spekboom Thicket Albany Spekboomveld Albany Thicket Albany Valley Thicket Ecca Bontveld Salem Karroid Thicket Shamwari Grassland Thicket Thorndale Forest Thicket Geluk Grassland Thicket Hamburg Dune Thicket Kiwane Dune Thicket Nanaga Savanna Thicket Paterson Savanna Thicket Zuney Strandveld Fish Noorsveld Crossroads Grassland Thicket Doubledrift Karroid Thicket Fish Spekboom Thicket Fish Thicket Fish Valley Thicket Hartebeest Karroid Thicket Buffels Thicket Buffels Valley Thicket Kei Thicket Mountcoke Grassland Thicket Escarpment Thicket AT 3 Groot Thicket AT 4 Gamtoos Thicket AT 5 Sundays Noorsveld AT 6 Sundays Thicket AT 7 Coega Bontveld AT 8 Kowie Thicket AT 9 Albany Coastal Belt AT10 Great Fish Noorsveld AT11 Great Fish Thicket AT12 Buffels Thicket AT13 Eastern Cape Escarpment Thicket AT14 Camdebo Escarpment Thicket Escarpment Spekboom Thicket S % 19 (2006) Perhaps also the Somali-Masai thickets as described by White (1983), the so-called ‘Vine Thickets’ of Australian Queensland (Webb 1978) and succulent-rich thickets of northern Venezuela and Colombia (Matteuci 1987) could be viewed as part of the global subtropical succulent-rich thickets. the equatorial and tropical regions of Africa, and Addo Bush (Acocks 1953) is similar to certain thickets of the Arid Lowveld (Acocks 1953, 1988) in the Mpumalanga Lowveld, northern KwaZulu-Natal and parts of Swaziland. The Albany Thicket also has a unique phylogenetic and biogeographic origin and is transitional between Nama-Karoo and the subtropical regions of the eastern seaboard of southern Africa. Thicket in the valleys from the other side of the Great Kei River to the Thukela River in KwaZulu-Natal are not recognised here as being part of the Albany Thicket Biome (the Great Kei River Valley does contain some mapped Albany Thicket). In fact, this is a gradual transition from the characteristic bimodal rainfall, with no seasonal period of pronounced drought of the Albany Thicket to the summer-rainfall areas with dry winters typical of the Savanna Biome. Also in terms of species afﬁnities, an increasing number of typical savanna species occur along this gradient towards the northeast. Woody elements of strandveld units to the west, including parts of the west coast, are not regarded as part of the biome despite their recognition as thicket by some authorities (e.g. Cowling 1984). The current delimitation of the Albany Thicket Biome closely follows (in most parts) the set of core (‘solid’) thickets of STEP (Vlok & EustonBrown 2002) (Table 10 1). Much of the area of STEP’s mosaic thickets is not here included in this biome, although small parts of some of them are incorporated where the evidence for belonging to an adjacent biome (Forest, Fynbos, Savanna, Grassland, Nama-Karoo and Succulent Karoo) appeared unwarranted. Valley Bushveld and Spekboomveld (Acocks 1953) of the Eastern Cape are similar in structure to thickets found in L. Mucina L. Mucina Rainfall can occur at any time of the year in Albany Thicket, which occurs in a climatic interface between an all-year rainfall zone in the west and a stronger summer-rainfall zone in the northeast (Schulze 1997). Thicket vegetation is considerably fragmented and displaced by renosterveld and fynbos in the winter-rainfall zone and by grasslands and savanna in the summer-rainfall zone (Vlok & Euston-Brown 2002). The climate in itself is not the primary selective force for this pattern, but rather the ﬁre regimes that are determined by seasonal precipitation. Evidence for this lies in the occurrence of outliers of thicket vegetation in ﬁre refugia in the winter- and summer-rainfall zones. Although it is tempting to think that thicket is also differentiated by occurring mostly on deep soils rich in nutrients, it is not limited to or restricted by any particular soil type (Vlok & Euston-Brown 2002). The clumping of the vegetation is another distinguishing feature and appears to be strongly facilitated by below-ground animal activity (termite mounds, active mole rat colonies, aardvark burrows, earthworm activity). The clumps show elevated levels of C, Ca, K, organic and moisture content when compared with the adjacent soils (Palmer et al. 1988). Figure 10.2 Spekboomveld dominated by Portulacaria afra (Didiereaceae) in the Ecca Pass (north of Grahamstown, Eastern Cape). Figure 10.3 Euphorbia triangularis (Euphorbiaceae) at road from Addo to Zuurberg Inn (Eastern Cape)—a ﬂagship species of the Albany Thicket Biome. Albany hicket Biome 543 S % 2. Major Vegetation Patterns Thicket, according to a dictionary deﬁnition, is a tangle or dense growth of shrubs or trees. This is a physiognomic or structural description of a type of vegetation that may be found in many geographical areas. The term ‘Thicket’ (uppercase ‘T’) refers to the Biome, whereas ‘thicket’ (lowercase ‘t’) refers to a structural type of vegetation. Within several biomes there may be a wide variety of structural vegetation types found which would, through high densities of woody plants, qualify as ‘thicket’ (see for instance chapters on Fynbos and Savanna in this book). The vegetation of the Albany Thicket Biome is described in general as a dense, woody, semisucculent and thorny vegetation type of an average height of 2–3 m (Acocks 1953, Everard 1987), relatively impenetrable in an unaltered condition. During his journey of 1776–1777, Paterson found this vegetation impenetrable except along elephant tracks (Dyer 1937). It comprises a broad spectrum of physiognomic types reﬂecting gradients in climate, geology, soil and herbivory. The Albany Thicket Biome consists of various major vegetation types, and the wide variety of plant communities, with varying structure and species composition, has posed a challenge for researchers attempting to describe it. Acocks (1953, 1988) recognised four vegetation types currently classiﬁed as thicket, namely Valley Bushveld, Noorsveld, Spekboomveld and False Karroid Broken Veld. His thicket also contains small patches of other vegetation types that are embedded within thicket, e.g. Coastal Forest and Thornveld, Alexandria Forest, etc. Acocks also subdivided Valley Bushveld into valley thicket, scrub and Addo Bush. Typical valley thicket may be tall or low and may be composed of different proportions of succulent and nonsucculent plants. Following Acocks (1953), Martin & Noel (1960) described this vegetation as a Succulent Woodland Formation, with two subformations, the taller ‘sub-succulent woodland’ and the ‘low succulent scrub’. In an effort to contextualise the vegetation relative to its origin, White & Moll (1978) included it in their TongalandPondoland Regional Mosaic, as it was part of the vegetation with strong tropical afﬁnity. This afﬁnity was attributed to the presence of genera such as Acacia, Brachylaena, Carissa, Euclea, Grewia, Pappea, Ptaeroxylon, Rhoicissus and Ziziphus, which were able to extend down the coast due to the inﬂuence of the warm Agulhas Current. This led to incorporating the notion of the subtropical origin of the ﬂora into nomenclature. Cowling (1983) recognised the ﬂoristic uniqueness of the regional vegetation and coined the term Subtropical Transitional Thicket, which had two formations, the mesic ‘Kaffrarian Thicket’ and the xeric ‘Kaffrarian Succulent Thicket’. In further ﬂoristic research in the Subtropical Transitional Thicket, Everard (1987) described the Albany region as comprising two formations, the ‘Xeric Succulent Thicket’ formation which could be distinguished from the ‘Mesic Succulent Thicket’ because of its higher proportion of succulents (29% as opposed to 24% for the Mesic Succulent Thicket) and lower proportion of woody taxa (39% as opposed to 48%). The ﬂoristic data collected by these researchers were further supplemented by local-scale research in the Great Fish River Valley (Palmer 1981, Palmer et al. 1988) where gradients in species composition and structure were described. These were further elaborated upon by Evans et al. (1997), providing landscape-scale descriptions of the vegetation units. They described Tall Succulent Thicket (TST), Medium Succulent Thicket (MST) and Short Succulent Thicket (SST) of the Great Fish River Valley (Evans et al. 1997). MST is dominated by the leaf succulent Portulacaria afra, which comprises the most extensive version of the thicket, synonymous with subsucculent woodland of Martin & Noel (1960). SST, characterised by the dominance of Euphorbia x bothae, 544 Albany hicket Biome 19 (2006) is represented by our Great Fish Noorsveld and is structurally similar to our Sundays Noorsveld, being shorter in height (1–2 m) and having a lower standing biomass than the MST. The TST is associated with cooler, moister southern aspects, comprises taller emergent Euphorbia species, and has a greater standing biomass than either the MST or the SST. Noorsveld (Acocks 1953) is a uniform, 1–2 m high scrub dominated by Euphorbia coerulescens, known as noors. Spekboomveld is dominated by Portulacaria afra (spek: Dutch word meaning bacon), thus referring to the apparent delicacy of the plant. Other vegetation found in the Albany Thicket Biome includes mosaics of thicket clumps and grassland, and various secondary vegetation types, including grassland and thornveld. Vlok & Euston-Brown (2002) also point to examples of a gradient of plant species turnover within the biome from the Buffels to the Gamtoos Rivers. There is a wide range of growth forms and a high diversity of plant species, including leaf and stem succulents (Figure 10.2 and 10.3), deciduous and semideciduous woody shrubs and dwarf shrubs, geophytes, annuals, grasses, and a high diversity of plant species (Cowling 1983). The understorey typically hosts a relatively high diversity of dwarf succulent shrubs and forbs (mainly Crassulaceae and Aizoaceae), many of which are locally endemic and rare (Cowling 1983, Johnson et al. 1999, Vlok & Euston-Brown 2002, Vlok et al. 2003). Perennial grasses are often prevalent inside the clumps, with Panicum maximum, P. deustum and numerous Eragrostis species being found. The wide range of growth forms and taxa in Albany Thicket is a reﬂection of the transitional nature of thicket vegetation, being an interface between various types of forest, sclerophyllous shrublands, karoo and grasslands (Cowling 1984, Palmer 1990, Everard 1991, Kerley et al. 1995, Vlok & Euston-Brown 2002). A distinct guild of spinescent woody plants occurs in certain types of thicket, that develop recurved branches once the plants are more than 1 m tall and continue to produce the recurved branches even when mature (deurmekaarbossie; Vlok & EustonBrown 2002). This unusual growth pattern results in an impenetrable barricade of thorny branches, because adjacent plants become entwined as they mature. Seeds of all woody species of this guild are contained within edible fruits and are bird-dispersed. The initial establishment of the woody species of this guild with their spinescent, recurved branches is followed by the growth of vines (often poisonous, wind-dispersed species) within the bush clumps. These often spinescent lianas further become interwoven within the individual bush clumps, to form the impenetrable vegetation so typical of, for example, Sundays Thicket. Once the matrix of shrub, grass and herb species is well established, herbivores play an important role in maintaining growth form richness. There are insufﬁcient data to describe major patterns of alpha, beta and gamma diversity in thicket vegetation fully, but a local study (Birch et al. 1999) gives some indication of alpha diversity in this vegetation. Within the MST, the alpha diversity in the clumps is higher (approx. 28 taxa per plot, range 15–44) than outside the clumps (using data from Birch et al. 1999), but the changes in diversity between clumps are low (total number of species in 58 plots was 195). Clump diversity in SST is 25 taxa per plot. TST contains 30 taxa per 100 m2 plot. 3. Ecology: Climate, Geology, Soils and Natural Processes 3.1 Climate Albany Thicket is found in semi-arid areas of the Eastern and Western Cape, with 200–950 mm MAP (Vlok & Euston-Brown S % 19 (2006) AT 1 Southern Cape Valley Thicket mm AT 2 Gamka Thicket °C 75 399 ^^ >2A 30 2A4G 33 17.1 4 20 >2E 3U >75 10 >2A6 1900 ^^ 0 >2D>D 72 50 25 0 75 25 0 ; 7>2> ; ; 2 D @?5 AT 3 Groot Thicket AT 4 Gamtoos Thicket mm °C 299 ^^ >2A 30 2A4G 35 16.7 4 20 >2E 19 U >75 10 >2A6 2256 ^^ 0 >2D>D 81 75 50 25 0 50 25 0 AT 6 Sundays Thicket mm °C 259 ^^ >2A 30 2A4G 36 18.3 4 20 >2E 5U >75 10 >2A6 2288 ^^ 0 >2D>D 82 75 50 25 0 25 0 AT 8 Kowie Thicket mm °C 75 452 ^^ >2A 30 2A4G 32 17.8 4 20 >2E 3U >75 10 >2A6 1861 ^^ 0 >2D>D 76 50 25 0 25 0 AT 10 Great Fish Noorsveld mm °C 677 ^^ >2A 30 2A4G 27 17.8 4 20 >2E 2U >75 10 >2A6 1730 ^^ 0 >2D>D 72 75 50 25 0 50 25 0 AT 12 Buffels Thicket mm °C 449 ^^ >2A 30 2A4G 32 17.1 4 20 >2E 7U >75 10 >2A6 1916 ^^ 0 >2D>D 77 75 50 25 0 655 ^^ >2A 30 2A4G 27 17.7 4 20 >2E 2U >75 10 >2A6 1695 ^^ 0 >2D>D 74 50 25 0 ; 7>2> ; ; 2 D @?5 AT 13 Eastern Cape Escarpment Thicket AT 14 Camdebo Escarpment Thicket °C °C mm 520 ^^ >2A 30 2A4G 30 16.0 4 20 >2E 16 U >75 10 >2A6 1964 ^^ 0 >2D>D 75 ; 7>2> ; ; 2 D @?5 °C 75 ; 7>2> ; ; 2 D @?5 0 420 ^^ >2A 30 2A4G 32 18.2 4 20 >2E 3U >75 10 >2A6 1859 ^^ 0 >2D>D 78 ; 7>2> ; ; 2 D @?5 AT 11 Great Fish Thicket 25 °C 75 ; 7>2> ; ; 2 D @?5 50 517 ^^ >2A 30 2A4G 30 17.5 4 20 >2E 3U >75 10 >2A6 1843 ^^ 0 >2D>D 75 50 ; 7>2> ; ; 2 D @?5 AT 9 Albany Coastal Belt 75 °C 75 ; 7>2> ; ; 2 D @?5 mm 334 ^^ >2A 30 2A4G 34 17.5 4 20 >2E 8U >75 10 >2A6 2134 ^^ 0 >2D>D 80 50 ; 7>2> ; ; 2 D @?5 AT 7 Coega Bontveld mm °C 75 ; 7>2> ; ; 2 D @?5 mm 460 ^^ >2A 30 2A4G 32 17.1 4 20 >2E 7U >75 10 >2A6 1967 ^^ 0 >2D>D 76 ; 7>2> ; ; 2 D @?5 AT 5 Sundays Noorsveld mm °C 75 ; 7>2> ; ; 2 D @?5 mm 267 ^^ >2A 30 2A4G 36 16.9 4 20 >2E 13 U >75 10 >2A6 2396 ^^ 0 >2D>D 81 50 ; 7>2> ; ; 2 D @?5 mm °C mm 352 ^^ >2A 30 2A4G 34 15.9 4 20 >2E 25 U >75 10 >2A6 2302 ^^ 0 >2D>D 80 75 50 25 0 ; 7>2> ; ; 2 D @?5 Figure 10.4 Climate diagrams of Albany Thicket Biome units. Blue bars show the median monthly precipitation. The upper and lower red lines show the mean daily maximum and minimum temperature respectively. MAP: Mean Annual Precipitation; APCV: Annual Precipitation Coefﬁcient of Variation; MAT: Mean Annual Temperature; MFD: Mean Frost Days (days when screen temperature was below 0°C); MAPE: Mean Annual Potential Evaporation; MASMS: Mean Annual Soil Moisture Stress (% of days when evaporative demand was more than double the soil moisture supply). 2002; see also Figure 10.4). Two prevailing climate systems (allyear rainfall to the southwest and summer rainfall to the northeast) converge in the region, resulting in all-year rainfall, with spring and autumn maxima (Aucamp & Tainton 1984). All the Thicket vegetation units have nonseasonal rainfall, with optima in March and October or November. The increase in summer rainfall to the northeast corresponds with a change in vegetation towards grassland and thorn-tree savanna; the increase in winter rainfall to the southwest corresponds to a gradual replacement by fynbos. In these two zones interannual variations in climate, in combination with different ﬁre regimes and substrate factors, may lead to temporal species turnover and changes in dominance between thicket species and those from adjoining biomes. Rainfall is unreliable, with an average coefﬁcient of variation of 25–36% (as low as 18% at the coast and along the escarpment, and as high as 40% in Gamka Thicket), and droughts of several months are common. There is a 25% chance of not receiving 80% of the mean rainfall in any given year (Aucamp & Tainton 1984). In addition to this unpredictable rainfall regime, the inland region experiences high temperatures in summer (exceeding 40°C on occasion) and low temperatures with frost (0 to 64 days) in winter. The dominant plants in these inland regions reﬂect this harsh climate, with a high degree of succulence and sclerophylly. The larger shrubs and trees are deep-rooted, and plants with storage organs are common. Studies on primary productivity in thicket have shown that the life strategy in most species appears to be one of slow growth (Aucamp & Tainton 1984). Thicket vegetation growing close to the coast experiences less extreme climatic variability due to the inﬂuence of the ocean. Coefﬁcients of variation here are usually lower than 30% and the number of days of frost fewer than 10 per year. There also tends to be a higher annual rainfall, with the vegetation less succulent, and there is a lower degree of leaf sclerophylly and more predictable growth rates. Vlok & Euston-Brown (2002) suggested that fog may be important even in arid thickets, with a high incidence of bark and ground lichens. 3.2 Geology and Soils The dominant geological feature in the region occupied by the Albany Thicket Biome is the east-west trending Cape Fold Belt. These mountain ranges consist mostly of the folded strata of the Cape Supergroup, of which the sandstone and quartzite of the Table Mountain and Witteberg Groups (Ordovician to Silurian and Devonian, respectively) are biogeographically important (Gibbs Albany hicket Biome 545 S % 19 (2006) L. Mucina Russell & Robinson 1981) in that they typically support outlier populations of fynbos and renosterveld within a matrix of thicket. Early Karoo Supergroup sedimentary rocks, namely the Dwyka and Ecca Groups, are also folded in the northern margin of the Belt, where they overly the Cape Supergroup rocks. The main folding event took place around 250 mya. Another signiﬁcant topographical feature is the escarpment which consists mostly of the ﬁne-grained sediments of the Beaufort Group of the Karoo Supergroup. These rocks of Permian and Triassic age are also intruded by Jurassic Karoo Dolerite dykes and sills that formed in association with the break-up of the supercontinent Gondwana. This rifting of South America from Africa also resulted in the formation of halfgraben structures within the Cape Fold Belt that formed the Cretaceous depo- Figure 10.5 AT 6 Sundays Thicket: Spekboomveld (Portulacaria afra) with a herd of last Cape elephants (Loxodonta africana) browsing in the Greater Addo Elephant National Park sitional basins for the Uitenhage Group (Eastern Cape). sediments. This sequence includes Enon conglomerates as well as other ﬁnergrained clastic sediments. During the Tertiary Period, times of nonﬂammable succulent component with a potentially ﬂamrelatively high sea level caused the peneplanation of large areas mable ﬁeld layer (Vlok & Euston-Brown 2002). between the coast and the mountains. As the sea level dropped, Albany Thicket has historically supported a high diversity and the accelerated erosion resulted in the dissection of the plains density of indigenous herbivores, ranging in size from duiker by a series of large river valleys such as the Fish, Sundays and to elephants (Skead 1989). Early accounts of the travellers and Gamtoos. It is these large valleys that gave rise to the name explorers in the region report high numbers of elephant (see ‘Valley Bushveld’, as thicket vegetation is restricted to their references in Stuart-Hill 1992). The high nutrient status of the slopes and ﬂoors. Recent deposits of shallow marine sandstones vegetation and proximity of many perennial rivers suggest that and coastal dunes are present along the coast in many parts as these large herbivores were permanent residents (Stuart-Hill a result of more recent ﬂuctuations in sea level. 1992) and support the hypothesis that herbivory has played an The soils derived from these rocks vary considerably over a important role in shaping vegetation and ecosystem propervariety of scales, closely tracking the underlying geology and ties (Kerley et al. 1999b). The impact of indigenous herbivory topography. The ﬁne-textured rocks of the Karoo Supergroup has been reﬂected in the evolution of the plant species, many typically give rise to deep, well-structured soils. A repeated cat- of which are well defended against browsing (Everard 1987, ena pattern of shallow rocky soils on upper slopes and deep Haschick 2002). Midgley (1991) and Stuart-Hill (1992) describe ﬁne-textured soils in the valley ﬂoors is evident in the series of the potential impacts of large herbivores through herbivory, river valleys through the Eastern Cape. The more coarse-tex- trampling and dunging, and suggest that large mammals were tured rocks of the Witteberg and Table Mountain Groups are the primary patch disturbance agents in Albany Thicket prior to typically found in sharply folded mountain systems, and the their extirpation in the 1800s. combination of steep slopes and the high percentage of quartz Megaherbivores, such as elephants and rhinos, seem to be sand gives rise to coarse, unstructured soils that are shallow important in maintaining the structure of thicket vegetation and nutrient-poor. Much of the ﬁne-scale pattern in the vegeta(Stuart-Hill 1992), although they do impact on the diversity tion is likely to be attributable to the interaction of climate and of the dwarf succulents (Johnson 1998, Johnson et al. 1999, pedology (e.g. Palmer et al. 1988). Cowling & Kerley 2002). Stuart-Hill (1992) demonstrated the role that elephants play in maintaining vegetation structure and 3.3 Natural Processes promoting asexual recruitment of Portulacaria afra in Albany Thicket (Figure 10.5). Elephants encourage coppicing in woody Albany Thicket shows little annual ﬂuctuation in its relatively shrubs and promote the development of a skirt around P. afra high perennial cover or biomass, irrespective of the relatively plants. Sigwela (1999) and Sigwela et al. (2004) showed how high coefﬁcient of variation in mean annual precipitation or signiﬁcantly more seeds are dispersed by indigenous herbivores with droughts that may last months or even years (Aucamp than by goats. There have been several previous studies that & Tainton 1984). This general resistance to drought probably examine the impact of goats and indigenous megaherbivores involves several mechanisms such as below-ground storage on biodiversity and ecological processes. Most of the earlier organs, sclerophylly, CAM photosynthesis and succulence. work was done from an agricultural production perspective, Unlike other semi-arid ecosystems such as savannas and cer- where the vegetation was viewed primarily as a resource for tain Mediterranean-type shrublands, intact Albany Thicket does browsing animals (Aucamp & Tainton 1984). There are two key not support a regular or widespread ﬁre regime (Kerley et al. vegetative traits that contribute to degradation of the Albany 1999a). The combination of the low availability of fuel and the Thicket. Firstly, despite a high standing biomass, Albany Thicket high degree of succulence has largely excluded ﬁre from Albany has a low annual production, thus giving a false impression of Thicket (Kerley et al. 1995). However, the occurrence of ﬁre may the amount of forage available for animal production (Aucamp be increasing in degraded areas due to the replacement of the & Tainton 1984). Another is the very slow recovery periods of 546 Albany hicket Biome S % 19 (2006) the main forage species such as P. afra, which can take up to 18 months to recover from 50% defoliation by goats (Aucamp & Tainton 1984). Also, the feeding behaviour of goats, both as individuals and as herds, differs from that of indigenous herbivores (Danckwerts 1984, Stuart-Hill 1992). Goats are gregarious animals and tend to feed in groups around individual plants and vegetation patches, leading to very high localised impacts. They also damage the structure of bush clumps by browsing from the sides and exposing the interior to the forces of desiccating winds and erosion by water (Stuart-Hill 1992). 4. Origins and Biogeography 4.1 Origins of the Albany Thicket Biome The Albany Thicket Biome is part of a poorly deﬁned global Subtropical Thicket Biome, characterised by subtropical, semixeric conditions. Such conditions became globally important during the Eocene characterised by climate both colder and drier than the usual (Zachos et al. 2001). Hence one can expect that it was this period when most thicket plant lineages originated. In support of this hypothesis, Cowling et al. (2005) have shown that many plant groups characteristic of thicket vegetation (as well as associated insect taxa) are of Eocene age, although both older and more recent taxa currently represent important thicket components. This timing is conﬁrmed by both palynological evidence (Boureau et al 1983, Salard-Cheboldaeff & Dejax 1991) and recent calibration attempts (Davies et al. 2004). Ebenaceae, two clades of Celastraceae, Sapindaceae, Didiereaceae (currently including also Portulacaria) and Cotyledonoideae (Crassulaceae) can be reasonably listed as those families well represented in the Albany Thicket Biome which diversiﬁed most likely in the Eocene (Cowling et al. 2005). Generally, these are taxa endemic to, or most diverse in, semixeric African vegetation. Many other clades will probably be added to this list as more well-dated phylogenies become available. Some of the succulents and geophytes are of more recent origin (Klak et al. 2004, Procheş et al. 2006), presumably dating back to the more pronounced mid- to late Tertiary aridiﬁcation. These are groups that are generally centred in the arid southwest of southern Africa (Nama-Karoo and Succulent Karoo Biomes), but have clades typical of the Albany Thicket Biome, indicating a retrocolonisation of a semixeric environment from fully xeric conditions. Examples are several clades within Aizoaceae and within Asteraceae, specially the tribe Senecioneae (Cowling et al. 2005). The geographic origins of Albany Thicket are poorly understood, and southern African fossil sites of relevant age are few. The fossil woods from Bogenfels (Namibia) indicate an assemblage more similar to present savanna or arid bushveld than to the Albany Thicket (Bamford 2000). Older sites, such as the pollen ﬂora of Banke in Namaqualand (Cretaceous/Early Tertiary, Scholtz 1985) show no clear evidence of thicket elements. The Umzamba site in the Eastern Cape (of similar age) contains a variety of fossil woods, some belonging to the Euphorbiaceae, more likely typical of forest sites (Bamford 2000). The assemblages that can be quite clearly associated with the present-day Albany Thicket taxa come from other parts of the African continent, mainly from East Africa, such as the variety of woody plants of Ebenaceae, Celastraceae and Oleaceae occurring in Eocene to Miocene deposits from Ethiopia, Uganda and Egypt (Laudoueneix-Dupéron & Dupéron 1995). Recently, Schrire et al. (2005) have suggested that those plant forms characteristic of a global ‘succulent biome’ (covering also the parts of global Subtropical Thicket Biome) ﬁrst appeared during the Eocene in the region of the Tethyan Ocean (the Mediterranean Sea being a remnant of the latter), in conjunction with the aridiﬁcation that affected this region more drastically than others. This area is likely to have represented the cradle of the Fabaceae. An early branch that supports this hypothesis is the tribe Detarieae, which includes the southern African endemics Schotia and Umtiza. A northern origin is also supported by the Tertiary records of typical thicket genera such as Ehretia and Rhoicissus from Europe, where they are now extinct (Gottschling et al. 2002, Ingrouille et al. 2002). The above evidence may suggest that the Albany Thicket Biome may represent a relict formation with deep roots in the Eocene. L. Mucina Another set of taxa are likely to represent true Gondwanan relicts, and therefore are of Mesozoic age, although they may have adopted a semixerophytic habit only during the Eocene or later. These are the cycads of the genus Encephalartos as well as Cussonia (Araliaceae) and Strelitzia (Strelitziaceae; Figure 10.6), all having their closest relatives in South America, Madagascar and Australia. Figure 10.6 Strelitzia reginae (Strelitziaceae)—a ﬂagship beauty among South African plants (near Ecca Pass north of Grahamstown, Eastern Cape). Currently, several centres of semixeric and xeric plant diversity can be distinguished on the African continent (including Madagascar), the most important being the Succulent Karoo Region, the thicket vegetation of the Eastern Cape, the KwaZulu-Natal/Limpopo high diversity zone, several smaller centres in East Africa, the Horn of Africa (including the Island of Socotra), the Mediterranean Basin, and southern and southwestern Madagascar. Three of these areas appear to have been most important in harbouring the earliest branches in various semixeric lineages, namely the Succulent Karoo Region, the Eastern Cape and Albany hicket Biome 547 S % western Madagascar. Various groups appear to have colonised large parts of the continent having originated in one of these three areas. The southern African-Madagascan semixeric connection is particularly interesting, given that Madagascar has been separate from the African mainland since the Cretaceous. Nevertheless, the distance was never large enough to prevent multiple crossing events by wind-dispersed as well as bird-dispersed plants (Grubb 2003, Pell 2004). At the same time, temporary aridiﬁcation events during the Tertiary (and recent ones associated with Pleistocene glaciations) may have facilitated exchange events between southern Africa and the Horn of Africa and consequently the entire Mediterranean region along an arid corridor, even in groups with limited dispersal abilities (see Axelrod & Raven 1978). The ﬂoristic uniqueness of the Albany Thicket Biome, marked by a signiﬁcant contingent of local endemics, suggests an uninterrupted existence in its current geographic distribution area. However, variations in size may have been great. The absence of endemic vertebrates—as would be expected given the relatively large area covered by the biome—strongly suggests that thicket vegetation suffered several constrictions in recent times, most likely associated with Pleistocene glacial cycles (see Cowling et al. 1999). Then the Albany patch may not have been much larger than other vegetation patches of similar composition growing under different climatic conditions in ﬁre-free pockets along the eastern escarpment of southern Africa and the Great Rift Valley. The establishment of a relatively large nonseasonal rainfall and ﬁre-protected area in the Eastern Cape may have allowed it to expand to its current extent. Browser pressure and the unreliable arid climate of the region have probably been the driving forces in the evolution of Albany Thicket since the Last Glacial Maximum (LGM), 18 000 to 21 000 years BP (Palmer 1990). Yet, in the face of the impressive array of indigenous herbivores (not even considering arthropods), Albany Thicket appears to show little ﬂuctuation (in recent decades) in standing biomass over short periods of time (Aucamp & Tainton 1984). This feature sets it apart from most of the other herbivore-driven systems, such as savannas (Scholes & Walker 1993) and grasslands (O’Connor & Bredenkamp 1997), where the herbivores (Owen-Smith & Danckwerts 1997), ﬁre, and climate (Schulze 1997) are primary determinants of plant biomass. In Albany Thicket, indigenous herbivores do reduce plant biomass, but the overall patch structure is retained (Cowling & Kerley 2002). In spite of the widespread and varied defences employed by plants, and their apparent resistance to herbivory, the onset of domestic herbivory was the catalyst to degradation of the Albany Thicket ecosystems. 4.2 Biogeography The Eastern Cape ﬂora corresponds with the convergence of ﬁve of White’s (1983) phytochoria (Cowling 1983, Cowling & Campbell 1983), namely the Cape Region, the Karoo-Namib Region (later subdivided; see chapter on Succulent Karoo in this book), the Maputaland-Pondoland Regional Mosaic, the Afromontane Region and the Kalahari-Highveld Regional Transition Zone. As a result, the ﬂora has been described as complex and transitional and the convergence of these phytochoria in the Eastern Cape has led to a huge ‘tension’ zone (Cowling 1983). No less than 21 of 70 national Acocks (1953) Veld Types are represented in the Albany area, which constitutes the core of the Albany Thicket Biome. Subtropical MaputalandPondoland forests enter Albany Thicket from the northeast along the coast, penetrating up the river valleys after the establishment of warmer wetter conditions that followed the LGM (Palmer 1990). The succulent and dwarf shrublands of the 548 Albany hicket Biome 19 (2006) Karoo-Namib phytochorion penetrated down the river valleys from the arid interior and graded into the forest and thicket. Afromontane (afrotemperate) forest elements are found from the sea level forests to the forest pockets in the interior mountains, possible refugia from the LGM. Cape fynbos elements are well represented on the infertile soils derived from the Cape Supergroup rocks (Cowling 1983). The relative distributions of these phytochoria are held in balance by environmental drivers such as climate and, more recently, land use. The result is a mosaic of plant communities with different or mixed chorological afﬁnities (Cowling 1983). The Albany Thicket is the Eastern Cape biome supporting the highest number of endemic taxa. It forms the core of the socalled Albany Centre of Endemism (Van Wyk & Smith 2001). Some authors (e.g. Gibbs Russell & Robinson 1981) consider the Albany region to have relatively low levels of endemism in comparison to the rich centres of endemism elsewhere in southern Africa. Many of the species in the Albany Thicket Biome are considered to have their centres of distribution elsewhere, and it has been suggested that the region does not have a strongly characterised ﬂora (Gibbs Russell & Robinson 1981, Hoffman & Cowling 1991). However, endemism in this region is probably grossly under-estimated (Van Wyk & Smith 2001) and the region represents a centre of endemism for karroid succulents (Hoffman & Cowling 1991, Van Wyk & Smith 2001), most of which are restricted to the thicket vegetation in the region. High percentages of endemism are reported for the families Asclepiadaceae, Crassulaceae, Euphorbiaceae and for several families of the Asparagales (see Smith & Marx 1990). High numbers of local endemics are known to occur and Cowling & Hilton-Taylor (1994) report 51 Red Data taxa, 200 endemics and 2 000 taxa in the Albany hotspot, an area that corresponds broadly with the Albany Centre of Endemism (Van Wyk & Smith 2001). An analysis of threatened species in the Albany Centre of Endemism (Victor & Dold 2003), which includes the Albany Thicket, indicates that 180 (61%) of the species evaluated have a very narrow distribution range. This list does not include all endemic taxa, but is similar to the 200 endemics reported by Cowling & Hilton-Taylor (1994) and 205 by Lubke et al. (1986) that give an overall estimate of 10% endemism for the Albany Centre of Endemism. There are many more near-endemics (with about 90 listed in the descriptions of the vegetation types of the biome). Van Wyk & Smith (2001) report 365 endemic/nearendemic succulents in the Albany Centre of Endemism; inclusion of nonsucculents would expand this list considerably and indicates that 10% endemism is probably an under-estimate. Vlok & Euston-Brown (2002) provide a list of 322 out of 1 588 species (20%) in subtropical thicket that are endemic. The endemics of the region are a mixture of palaeoendemics and neoendemics, with few endemic genera and no endemic families (Van Wyk & Smith 2001). 5. Land Use History Prior to the arrival of colonial settlers in the early 1800s the region was sparsely populated by humans. Most human activity was concentrated along the Sundays River Valley, the principal source of perennial water in the area. Early travellers described the area as an unbroken expanse of dense thicket north of Uitenhage (Skead 1989). Initially, domestic stock was restricted by the high densities of ticks (carrying the fatal heartwater disease) and difﬁcultly of access for the stock associated with the very dense bush, and the limited perennial water (A. Rudman, personal communication). Later, the use of dips and boreholes allowed farmers to increase their stock densities and enter into S % 19 (2006) new areas of thicket. This trend resulted in the opening up of large areas of thicket. More recently, an increasing number of farmers are switching from stock to game farming (Smith & Wilson 2002) as reduced availability of forage and increased variability in forage production make stock farming less proﬁtable and sustainable. Current Status, Threats and Actions The current Albany Thicket vegetation is highly transformed and shows high levels of degradation (Lloyd et al. 2002, Palmer et al. 2004). Of the untransformed Thicket, only 11% is still in pristine condition and 60% is severely degraded (Lloyd et al. 2002). Approximately 7.3% has been transformed. The factors responsible for degradation and obliteration across the biome include cultivation in the moister regions, herbivory by livestock in the drier regions and urban settlement along the coast (Lloyd et al. 2002). The pressure on individual species, likewise, is high. Of the 126 species threatened with extinction in the Albany Centre of Endemism, the major threats, in decreasing order of importance, are illegal collecting, urban residential development, industrial development, alien plants, agriculture (including browsing/grazing), medicinal harvesting and forestry (Victor & Dold 2003). Current land use pressure on thicket vegetation includes primarily urbanisation, agriculture and afforestation/alien trees L. Mucina Considering that thicket has historically been exposed to a range of indigenous herbivores, from duiker to elephants, sometimes in very dense populations (Skead 1989), it is interesting to note why it collapses so rapidly in the face of domestic herbivory. The production potential of Albany Thicket is easily destroyed by domestic herbivory due to a combination of the feeding behaviour of goats (Stuart-Hill & Danckwerts 1988) and the slow growth rate of the plants (Aucamp & Tainton 1984). StuartHill (1992) shows how goats feed into the sides of bush clumps, exposing the interior and reducing essential vegetative recruitment. In comparison, indigenous herbivores that browse from the top of the bush clumps, encourage vegetative recruitment. If damaged by over-utilisation, the woody component of the vegetation does not recover within management time frames (Stuart-Hill 1992). In comparison to other woody and herbaceous systems, such as savannas, removal of the woody component does not necessarily lead to a more produc- 6. J.P.H. Acocks With the arrival of the ﬁrst European settlers in the early 1800s, began the extirpation of megaherbivores (elephant and black rhino) and signiﬁcant reductions in the populations of small (e.g. duiker) and medium-sized (e.g. bushbuck and kudu) herbivores (Kerley et al. 1999b). Since then, the high-quality forage available in intact Albany Thicket has been used to support extensive pastoralism. Goats were the most successful domestic species in the region since they were able to make use of the high biomass of browse. Despite its long history of herbivory, Albany Thicket has not displayed resilience to domestic herbivory and there is much evidence to show that commercial pastoralism has led to ecosystem-level degradation (Aucamp & Tainton 1984, Hoffman & Cowling 1990, Moolman & Cowling 1994, Kerley et al. 1999a, b). Approximately 92% (7 500 km2) of Albany Thicket in the Eastern Cape has been degraded to some degree over the past 200 years (Lloyd et al. 2002). Much of this degradation occurred decades ago when there was little understanding of sustainable stocking levels in Albany Thicket. Anecdotal accounts suggest that government-recommended stocking rates during the 1950s were at least 20-fold those of today. Furthermore, it seems that some thicket farmers deliberately over-stocked goats to open up the dense bush, as much of the biomass was inaccessible to other stock, and high levels of tick-borne heartwater disease were associated with dense bush (A. Rudman, personal communication). Thus, the area is now dominated by grasses and ephemeral forbs, with remnant trees and pockets of thicket (Figure 10.7). tive grass understorey. The herbaceous layer is not a reliable source of forage, as its production closely tracks rainfall patterns (Stuart-Hill 1992). Figure 10.7 AT 3 Groot Thicket: Fence-line effect in the Spekboomveld near Willowmore (Eastern Cape), 13 km south of Beervlei Dam. To the right of fence small trees and shrubs of Euclea undulata, Pappea capensis, Rhigozum obovatum and Lycium oxycarpum are left. Photographed by J.P.H. Acocks in the 1950s (above top) and in 1998 (above). See also Acocks (1979, Figure 8). Albany hicket Biome 549 S % (Cowling et al. 2003). Two urban areas constitute a signiﬁcant pressure on surrounding vegetation, namely the Nelson Mandela Metropole (including Port Elizabeth) and environs and the corridor spanning Buffalo City (East London) and the Amathole range (Cowling et al. 2003). The Nelson Mandela Metropole is considered to constitute a signiﬁcant urbanisation pressure on the surrounding landscape and therefore on biodiversity (Cowling et al. 2003). Coega is a speciﬁc nucleus of urban sprawl due to the development of the Industrial Development Zone that will result in the attraction of large populations of people to the surrounding areas. The Albany Thicket vegetation types from this node most at threat are Coega Bontveld and, to a lesser extent, Sundays Thicket. Further northeastwards, Buffalo City and its extensions towards Bisho constitute a threat to Buffels Thicket, but this vegetation is more widespread in areas removed from this threat. A recent report detailing the effects of climate change on vegetation in South Africa (Rutherford et al. 1999, WWF 2001) did not treat the Albany Thicket as a separate biome. However, according to modelled climatic scenarios over the next 50 to 100 years, the area occupied by Thicket vegetation would undergo a major shift in climate, becoming warmer with fewer days when soil moisture and temperature are suitable for plant growth. Only the extreme western and eastern portions of the biome would be less affected. Fynbos would extend slightly eastwards, suggesting that bimodal climate conditions will also move eastwards shifting Albany Thicket in that direction. On the basis of this type of analysis, it is possible that there might be a signiﬁcant loss in area of the Albany Thicket types that do not occur in the kind of habitat available in these eastern regions, for example steep-sided river valleys. Predictions are that approximately 20% of the area where Portulacaria afra is found, would become unsuitable for this species under modelled scenarios of climate change (Robertson & Palmer 2002). The worst-affected areas are likely to be the coastal region around Algoa Bay, almost at the core of the biome, as well as the Keiskamma River Valley and areas to the south of GraaffReinet (Robertson & Palmer 2002). Climate change effects are, however, more complex, and it is likely that changes in the variability of climate parameters will have as big an inﬂuence on the survival and distribution of species as changes in the mean values of parameters (O’Connor & Roux 1995). A number of megaconservancy networks (MCNs) and expanded parks have been proposed or are in the process of being established within the biome, including the Fish-Kowie MCN, the Gqunube-Amathole MCN, the Kei MCN, the Gouritz-Little Karoo MCN, the Baviaanskloof MCN and the Addo-Camdebo MCN, many of which include existing reserves. Despite the formation of these new conservation areas, conservation of the variety of Thicket vegetation will not be achieved without the establishment of new protected areas that conserve unprotected types of Albany Thicket. One of the major conservation initiatives in the biome area is the expansion of the Addo Elephant National Park, which began in 1997 and is still under way, made possible by funds from the government (DEAT) and foreign donors (primarily the Global Environmental Fund). The park is currently 148 000 hectares in extent (December 2004) and will eventually cover 240 000 hectares to become South Africa’s fourth largest National Park. Large areas of Albany Thicket degraded by overgrazing and invasive alien plants require a substantial restoration effort for the achievement of both pattern and process conservation targets (Cowling et al. 2003). The Working for Water Programme may restore the function and biodiversity of the catchment through the systematic eradication of alien invasive plants. However, 550 Albany hicket Biome 19 (2006) rehabilitation efforts to restore Albany Thicket vegetation are likely to be very labour-intensive and require long-term investment of resources (Todkill 2001). Much of the degraded thicket was Portulacaria afra-dominated and the re-establishment of this species is necessary to begin to restore the vegetation. However, this is costly and unlikely to be undertaken by private land owners. Due to the high carbon-storage ability of Portulacaria afra-dominated thicket (Lechmere-Oertel 2003), the opportunity exists to initiate restoration through the international carbon credit system (Cowling et al. 2003). 7. Further Research The main focus of the research in the Albany Thicket Biome appears to have been on the agricultural potential of these areas and the contribution that Thicket may make towards animal production, both domestic (e.g. Aucamp 1976, 1979, Aucamp & Tainton 1984, Danckwerts 1984) and wild (e.g. Cowling & Kerley 2002), as well as on the inﬂuence of grazing and browsing on thicket structure and function (e.g. LechmereOertel 2003). Two ‘Valley Bushveld Symposia’ (proceedings published in 1991 and 1996) generated much interest and data on the economic and conservation aspects of the Albany Thicket Biome. Earlier studies (Dyer 1937, Story 1952, Acocks 1953, 1988, Archibald 1955, Lubke et al. 1986) were broad in nature, but provided a good ﬁrst approximation of vegetation patterns. Some detailed studies have been undertaken, e.g. Cowling (1984), Everard (1987), Palmer (1988), Birch et al. (1999), Judd (2001), but most of these are concentrated in speciﬁc areas and have been undertaken at different levels of intensity. There is an urgent need for detailed ﬂoristic studies on the different vegetation units within the Albany Thicket Biome to provide baseline information on diversity, structure and species composition, as well as on the distribution of individual species and the relationship between the different parts of the Biome. Two major universities located in the region (the Nelson Mandela Metropolitan University in Port Elizabeth and the Rhodes University in Grahamstown) are the institutions that should take the lead to deal with these challenges. Recently, the Subtropical Thicket Ecosystem Planning Project (STEP) was an important measure in identifying ecologically uniform areas on the basis of remote-sensed data and environmental parameters. The STEP (Cowling et al. 2003, Pierce et al. 2005) identiﬁed a number of research priorities of an ecological nature, including the need to identify dynamics within different Thicket types, how these dynamics compare in intact and degraded forms of Thicket, what the biological indicators of ecosystem health are in different Thicket types, what they mean and how they can be used in monitoring programmes, to what extent different Thicket types are dependent on herbivory by different guilds of indigenous herbivores for the maintenance of biodiversity and ecosystem health, and what processes are essential across all spatial and temporal scales for the long-term maintenance of Thicket biodiversity. 8. Descriptions of Vegetation Units AT 1 Southern Cape Valley Thicket Aloe Scrub (Muir 1929). VT 23 Valley Bushveld (44%), VT 46 Coastal Renosterbosveld (39%) (Acocks 1953). LR 63 South and South-west Coast Renosterveld (86%) (Low & Rebelo 1996, 1998). BHU 93 Gouritz Mesic Succulent Thicket (74%) (Cowling & Heijnis 2001). STEP Gouritz Valley Thicket (63%) (Vlok & Euston-Brown 2002). S % 19 (2006) Distribution Western Cape Province: The core of the distribution is in river valleys of the Goekoe River (between Riversdale and Still Bay) with the largest patch in the Gouritz River Valley (between Herbertsdale and the Gouritzmond) and is found in unmapped smaller patches of the Groot Brak and Klein Brak Rivers as well as the Kaaimans River (here at its easternmost limit). Towards the west this vegetation is found (unmapped) in valleys of the Duiwenhoek and Slang Rivers and reaches its westernmost limits of distribution in the Breede River Valley. Altitude 20–200 m. Vegetation & Landscape Features Steep slopes of deeply incised valleys of rivers ﬂowing mainly in a north-south direction and dissecting the Southern Cape coastal peneplain. Mediumsized to tall (3–5 m), dense thicket composed of sclerophyllous (often spinescent) evergreen shrubs (e.g. Euclea, Grewia, Gymnosporia, Putterlickia, Rhus, Sideroxylon, Tarchonanthus) as well as an important admixture of a microphyllous (partly ericoid) shrub element (Athanasia, Elytropappus, Oedera, Stoebe) and with a prominent (locally also dominant) succulent, rosulate tree, Aloe ferox. The low shrub layer contains a high proportion of succulent shrubs (Aloe, Crassula, Euphorbia, Ruschia). Grasses are abundant in some favoured grazing areas. Geology & Soils Shallow, loamy-clayey soils (mostly Glenrosa and Mispah) derived from siltstone and shales of the Bokkeveld Group in the western part of the area, and Jurassic Enon conglomerates and other clastic sediments of the Uitenhage Group in the eastern part of the area. Where on hard Ordovician Table Mountain sandstone, only on the Aasvogelberg range—on rocky south-facing slopes with organic-rich soils (Rebelo et al. 1991). Fc land type predominates, while Ia is of lesser importance. Climate Nonseasonal rainfall with several slight optima (in March, May, August, October), and with driest summer months December to February. MAP 400 mm, which ranges from about 340 mm in the west (Swellendam) to about 940 mm in the east (Wilderness). Frost is infrequent. MAT falls within warm-temperate range (17°C). Mean monthly maximum and minimum temperatures for the nearby Riversdale weather station are 37.5°C and 0.2°C for February and July, respectively and corresponding values on the coast for Mossel Bay (Cape St Blaize) are 29.6°C and 7.4°C for April and August, respectively. Also see climate diagram for AT 1 Southern Cape Valley Thicket (Figure 10.4). Important Taxa Succulent Tree: Aloe ferox (d). Small Trees: Acacia natalitia, Schotia afra var. afra. Tall Shrubs: Chrysanthemoides monilifera (d), Elytropappus rhinocerotis (d), Olea europaea subsp. africana (d), Carissa bispinosa subsp. bispinosa, Clausena anisata, Euclea undulata, Grewia occidentalis, Gymnosporia buxifolia, Putterlickia pyracantha, Rhus glauca, R. laevigata, R. longispina, R. lucida, Tarchonanthus camphoratus. Low Shrubs: Pteronia incana (d), Anthospermum aethiopicum, A. prostratum, Aspalathus globulosa, Asparagus capensis var. capensis, A. striatus, Athanasia pectinata, Felicia ﬁlifolia, Freylinia undulata, Galenia pubescens, Garuleum latifolium, Gnidia squarrosa, Lauridia tetragona, Leonotis leonurus, Oedera genistifolia, Otholobium hirtum, Pentzia incana, Polygala myrtifolia, P. scabra, Stoebe muirii, Sutera caerulea. Succulent Shrubs: Adromischus triﬂorus, Aloe maculata, Aptenia cordifolia, Cotyledon orbiculata var. orbiculata, C. papillaris, Crassula cultrata, Euphorbia burmannii, E. mauritanica, Lampranthus prominulus, Zygophyllum foetidum. Woody Succulent Climbers: Crassula perforata (d), Sarcostemma viminale. Woody Climbers: Asparagus africanus, A. racemosus. Graminoids: Ehrharta erecta (d), Cynodon dactylon, Ehrharta calycina, Festuca scabra, Karroochloa curva, Merxmuellera stricta, Panicum maximum, Stipa dregeana. Herbaceous Climber: Cynanchum obtusifolium. Succulent Herbs: Anacampseros telephiastrum, Carpobrotus edulis, C. muirii, Crassula muscosa, C. saxifraga, Senecio ﬁcoides. Geophytic Herbs: Bulbine praemorsa, Cheilanthes hirta, C. multiﬁda, Cyanella lutea, Hesperantha acuta, Mohria caffrorum, Nerine humilis, Oxalis bifurca var. angustiloba, O. obtusa, O. pes-caprae. Herbs: Arctotheca calendula, Berkheya heterophylla, Cineraria lobata, Cotula sororia, Erucastrum austroafricanum, Hypoestes aristata, Lepidium africanum, Lotononis calycina, Nemesia fruticans, Sebaea ramosissima, Sisymbrium capense, Stachys aethiopica. Biogeographically Important Taxa ( E Eastern limit, Southeastern limit, W Western limit) Succulent Tree: Aloe speciosaW. Succulent Shrubs: Aloe arborescensW, Euphorbia mammillarisW, Portulacaria afraW. Tall Shrubs: Azima tetracanthaW, Diospyros pallensSE. Low Shrub: Lyperia antirrhinoidesE. Succulent Climber: Crassula lacteaW. Succulent Herb: Gasteria carinataSE. Herb: Senecio muirii (shared with AT 2 Gamka Thicket). Graminoid: Pentaschistis trisetaE. SE Endemic Taxa Succulent Shrub: Cotyledon eliseae. Succulent Herbs: Haworthia chloracantha, H. turgida (all three varieties). Conservation Vulnerable. Target 19%. Very little of unit conserved in Pauline Bohnen Nature Reserve (statutory) and in Langeberg-Oos Reserve (private). 35% transformed by cultivation. Erosion is variable—from very low to high. Near Albertinia the local Aloe ferox has become the subject of a local industry aimed at extracting substances for medicinal and cosmetic use. Remark 1 This is the westernmost thicket type completely embedded within the matrix of the Fynbos Biome (with a minor border with the Succulent Karoo Biome in the upper Gouritz Valley). A number of taxa reach their westernmost limits of distribution here (see above), suggesting a (past) link to the Albany Thicket proper. At least two species (Cotyledon papillaris and Senecio muirii) are shared with Gamka Thicket. Not surprisingly, this thicket type contains the highest number of Fynbos elements of the whole Albany Thicket Biome. Remark 2 The steep, rocky slopes, geomorphology and consequently poor soil development create environmental conditions very different from the surrounding renosterveld vegetation (Fynbos Biome) which typically covers the coastal plateaus of the Southern Cape. The habitats supporting this type of thicket are usually protected from ﬁre that occurs in the neighbouring renosterveld. Grazing by domestic animals was (or in places still is) common. References Muir (1929), Grobler & Marais (1967), Taylor (1970), Acocks (1988), Rebelo et al. (1991), Cowling & Heijnis (2001), Vlok & Euston-Brown (2002), Vlok et al. (2003). AT 2 Gamka Thicket VT 25 Succulent Mountain Scrub (Spekboomveld) (58%) (Acocks 1953). LR 8 Spekboom Succulent Thicket (47%), LR 58 Little Succulent Karoo (20%) (Low & Rebelo 1996, 1998). BHU 97 Spekboom Xeric Succulent Thicket (42%), BHU 89 Oudtshoorn Broken Veld (18%) (Cowling & Heijnis 2001). STEP Gamka Arid Spekboomveld (30%), STEP Kandelaars Karroid Thicket (17%), STEP Mons Ruber Fynbos Thicket (17%) (Vlok & Euston-Brown 2002). Distribution Western and (marginally) Eastern Cape Provinces. Centred around Oudtshoorn in the basin of the Little Karoo between the Groot Swartberg Mountains in the north and the Outeniqua Mountains in the south, where it occurs on the lower mountain slopes and in some river valleys. It extends from the lower Gamka River Valley and the eastern lower ﬂank of Rooiberg and through the Groot Swartberg Mountains (including the enclosed valley of ‘The Hell’), for about 130 km eastwards on lower parts of ridges north of the Groot Swartberg Albany hicket Biome 551 S % 19 (2006) L. Mucina commutata, C. tetragona subsp. acutifolia, Othonna carnosa, Pachypodium succulentum, Sceletium rigidum, Zygophyllum ﬂexuosum, Z. foetidum, Z. fulvum. Low Shrubs: Garuleum latifolium (d), Pteronia incana (d), P. pallens (d), Aptosimum indivisum, Asparagus burchellii, A. mucronatus, A. striatus, Ballota africana, Chrysocoma ciliata, Eriocephalus africanus, Euryops brevipapposus, Felicia filifolia, F. muricata, Galenia africana, Gloveria integrifolia, Helichrysum zeyheri, Limeum aethiopicum, Lycium cinereum, L. oxycarpum, Monechma spartioides, Oedera squarrosa, Polygala myrtifolia, P. scabra, Tetragonia robusta var. psiloptera, Zygophyllum microphyllum. Woody Succulent Climbers: Pelargonium zonale, Sarcostemma viminale. Semiparasitic Epiphytic Shrub: Viscum rotundifolium. Woody Climbers: Asparagus racemoFigure 10.8 AT 2 Gamka Thicket: Spekboomveld (Portulacaria afra) on steep northern slopes of the Huisrivier Pass between Calitzdorp and Ladismith in the Little Karoo (Western Cape). sus, Cissampelos capensis. Herbaceous Climbers: Cynanchum ellipticum, Kedrostis capensis. Graminoids: Cynodon dactylon (d), C. incomas far as the Droëkloofberg Mountains (including the isolated pletus (d), Ehrharta calycina (d), Eragrostis curvula (d), Aristida ridges to the north that include Tierberg) and to the upper adscensionis, Cymbopogon prolixus, Digitaria argyrograpta, D. reaches of the Olifants River Valley south of the Groot Swartberg eriantha, Ehrharta erecta, Eragrostis obtusa, Fingerhuthia afriand north of the Kammanassie Mountains. Altitude varies from about 300–1 000 m. cana, Hyparrhenia poecilotricha, Stipagrostis ciliata var. capensis. Succulent Herbs: Crassula muscosa, Haworthia blackburVegetation & Landscape Features Undulating to steep footniae var. blackburniae. Geophytic Herbs: Oxalis pes-caprae (d), hills and valleys dominated by a low succulent thicket, sometimes Asplenium cordatum, Cheilanthes hirta, Chlorophytum crispum, quite open. In its pristine condition dense stands of spekboom Drimia intricata. Herbs: Arctotheca calendula, Chamaesyce (Portulacaria afra) occur, often with Euclea undulata, Gloveria inaequilatera, Cineraria platycarpa, Conyza scabrida, Emex integrifolia, Pappea capensis and Rhus glauca. Shrubs are also australis, Hermannia pulverata, Lepidium africanum, Pulicaria abundant, stem- and leaf-succulents are often prominent, and scabra, Troglophyton capillaceum. the grass component is poorly developed, with Cenchrus ciliaris, Endemic Taxa Succulent Shrub: Euphorbia gamkensis. Ehrharta calycina, Eragrostis plana and Sporobolus ﬁmbriatus Geophytic Herbs: Eriospermum rhizomatum, Lachenalia occasionally abundant after good rain. haarlemensis. Geology & Soils Mostly restricted to sites where relatively deep (>1 m) loamy-clayey soils occur on Enon Formation conglomer- Conservation Least threatened. Target 19%. About 9% statutorily conserved mainly in Groot Swartberg, Groenefontein and ates (Jurassic), thus often deep beds of gravelly rocky soil. In the Gamkapoort Nature Reserves. About 4% transformed mainly lower Gamka River Valley it occurs on Bokkeveld Group shales by cultivation. The invasive alien, Atriplex lindleyi, is scattered in and north of the Swartberg Mountains it is found on arenites places. Erosion is very low to moderate. Fragmentation of the and shales of the Witteberg, Ecca or Bokkeveld Groups. Land Gamka Thicket has occurred due to frequent ﬁres that sweep types: mostly Ag (almost half of the area), followed by Ic, Ib down from the adjacent fynbos-clad mountains. and Fc. Climate The driest of the thicket types, MAP ranges from about 105 mm on the plains north of the Swartberg to about 540 mm (extremes are 102–545 mm) on the south-facing mountain foothills. The rainfall is nonseasonal with slight optima in March and October/November and lowest rainfall in the summer months of December to February. Frost is fairly frequent. Mean monthly maximum and minimum temperatures for Oudtshoorn are 39.9°C and –0.4°C for February and July, respectively. See also climate diagram for AT 2 Gamka Thicket (Figure 10.4). Important Taxa Succulent Trees: Aloe ferox, A. speciosa. Small Trees: Acacia karroo, Pappea capensis, Schotia afra var. afra. Tall Shrubs: Cadaba aphylla, Carissa bispinosa subsp. bispinosa, Elytropappus rhinocerotis, Dodonaea viscosa var. angustifolia, Euclea undulata, Gymnosporia heterophylla, Melianthus comosus, Nymania capensis, Olea europaea subsp. africana, Putterlickia pyracantha, Rhigozum obovatum, Rhus glauca, R. lancea, R. lucida. Succulent Shrubs: Crassula cultrata (d), Euphorbia mauritanica (d), Portulacaria afra (d), Aloe microstigma, Cotyledon orbiculata var. orbiculata, C. papillaris, Crassula lanceolata, C. nudicaulis, C. ovata, C. rupestris subsp. 552 Albany hicket Biome Remarks The vegetation has complex ﬂoristic and spatial links to Nama-Karoo and Succulent Karoo as well as to the Fynbos Biome vegetation demonstrated by the synonymy with a number of previously described vegetation units (see above). It is particularly in this area that Acocks (1953) characteristically positioned his Spekboomveld (thicket) in a vegetation sequence between the lower lying karoo and higher positioned renosterveld. References Acocks (1953, 1988), Lloyd et al. (2002), Vlok & Euston-Brown (2002), Vlok et al. (2003), Cleaver et al. (2005). AT 3 Groot Thicket VT 25 Succulent Mountain Scrub (Spekboomveld) (43%), VT 26 Karroid Broken Veld (27%) (Acocks 1953). LR 8 Spekboom Succulent Thicket (33%), LR 54 Central Lower Nama Karoo (29%) (Low & Rebelo 1996, 1998). BHU 98 Willowmore Xeric Succulent Thicket (23%), BHU 92 Steytlerville Broken Veld (13%), BHU 73 Baviaanskloof Mountain Fynbos Complex (10%), BHU 99 Addo Xeric Succulent Thicket (9%) (Cowling & Heijnis 2001). STEP Groot Arid Spekboomveld (43%), STEP Baviaans Spekboom Thicket (21%) (Vlok & Euston-Brown 2002). S % 19 (2006) Distribution Eastern Cape Province: Lower slopes and ridges from Willowmore/Perdepoort in the west to the Klein Winterhoek/Zuurberg Mountains (northwest of Kirkwood) in the east including some narrow northern edges of the Baviaanskloof and Groot Winterhoek Mountains as well as the thicket of the central and upper Baviaanskloof (also narrow tributaries, for example, the Kouga River). Altitude ranges from about 200–1 100 m. Vegetation & Landscape Features Moderate to steep slopes on the ridges of the mountain ranges dominated by a low succulent thicket, usually fairly dense and closed. Under favourable conditions spekboom (Portulacaria afra) is abundant amongst sometimes dense stands of other low woody shrubs. Stem- and leaf-succulents are present and may be prominent, and the grass component is usually poorly developed. Geology & Soils Commonly found on steep slopes with relatively shallow, red, clayey and often rocky soils that are derived from a variety of parent materials, usually arenites and shales. Geological Groups include Table Mountain, Witteberg, Dwyka and Ecca. The dominant land types are Ib and Fc, followed by Ag and Fb. Climate Subjected to summer droughts, but regular winter rain may decrease the impact of these droughts. MAP is relatively low, generally 250–450 mm; the rainfall is nonseasonal, with slight optima in March and November. The mean coefﬁcient of variation in MAP is 35% for this vegetation unit; frost incidence varies from about 5 days of frost per annum in the east to around 65 days in the western parts. Mean monthly maximum and minimum temperatures for Willowmore are 37.7°C and –3.1°C for January and July, respectively, although there are smaller extremes in the east than the west. See also climate diagram for AT 3 Groot Thicket (Figure 10.4). Important Taxa Succulent Trees: Aloe ferox, Euphorbia tetragona. Small Trees: Acacia karroo, Boscia albitrunca, Cussonia spicata, Encephalartos lehmannii, Ozoroa mucronata, Pappea capensis, Schotia afra var. afra, Sideroxylon inerme. Tall Shrubs: Euclea undulata (d), Grewia robusta (d), Carissa bispinosa subsp. bispinosa, Dodonaea viscosa var. angustifolia, Elytropappus rhinocerotis, Gymnosporia polyacantha, Putterlickia pyracantha, Rhigozum obovatum, Rhus longispina, R. lucida. Succulent Shrubs: Crassula cultrata (d), C. ovata (d), C. rupestris subsp. commutata (d), Euphorbia ledienii (d), Portulacaria afra (d), Adromischus cristatus var. schonlandii, Cotyledon tomentosa subsp. tomentosa, Crassula tetragona subsp. robusta, Euphorbia mauritanica, E. polygona, Glotiphyllum oligocarpum, G. salmii, Pachypodium succulentum, Senecio junceus, Zygophyllum foetidum. Low Shrubs: Chrysocoma ciliata (d), Felicia muricata (d), Indigofera denudata (d), Aptosimum elongatum, Asparagus burchellii, A. mucronatus, A. subulatus, Eriocephalus africanus, E. capitellatus, E. ericoides, Euryops spathaceus, Felicia ﬁlifolia, Hermannia gracilis, Leucas capensis, Limeum aethiopicum (d), Lycium oxycarpum, Monechma spartioides, Pteronia adenocarpa, P. incana, Rosenia humilis, Selago albida, S. fruticosa, Solanum tomentosum. Semiparasitic Epiphytic Shrub: Viscum rotundifolium. Woody Succulent Climbers: Crassula perforata (d), Crassula pellucida subsp. marginalis, Sarcostemma viminale. Woody Climbers: Asparagus racemosus, Capparis sepiaria var. citrifolia, Cissampelos capensis, Rhoicissus digitata. Graminoids: Aristida adscensionis (d), A. congesta (d), Cynodon incompletus (d), Eragrostis obtusa (d), Setaria lindenbergiana (d), Tragus berteronianus (d), Cenchrus ciliaris, Cymbopogon pospischilii, Ehrharta calycina, Enneapogon desvauxii, Eragrostis curvula, Merxmuellera stricta, Sporobolus ﬁmbriatus. Succulent Herbs: Crassula muscosa (d), C. orbicularis (d), Crassula expansa, Psilocaulon junceum. Geophytic Herbs: Asplenium cordatum, Boophone disticha, Moraea pallida, Sansevieria hyacinthoides. Herbs: Aizoon glinoides (d), Troglophyton capillaceum (d), Hermannia pulverata, Lepidium africanum, Pollichia campestris, Stachys aethiopica. Endemic Taxa Succulent Shrubs: Aloe pictifolia. Succulent Herbs: Huernia brevirostris subsp. baviaana, H. echidnopsioides, Gasteria ellaphieae, G. glomerata, G. rawlinsonii, Haworthia glauca var. herrei, H. pungens, H. zantneriana var. minor, Stapelia kougabergensis, Tromotriche baylissii, T. longii. Geophytic Herbs: Albuca cremnophila, Bulbine cremnophila. Conservation Least threatened. Target 19%. About 11% statutorily conserved mainly in the Greater Addo Elephant National Park, Guerna Wilderness Area and Baviaanskloof Conservation Area. 3.5% conserved in addition in other reserves, for example in the Timbili Game Reserve and Brakkefontein Game Farm. Only about 1.5% transformed mainly through urbanisation and cultivation. Many parts have been opened up by overgrazing and poor management practices and fence-line contrasts along mountain slopes are fairly common, with thicket present on one side and absent on the other. Erosion is generally very low to moderate. Remarks Although there are several species endemic to the Groot Thicket, many Albany Centre endemics are shared with the Kowie, Gamka, Gamtoos and Sundays Thicket vegetation units. The Thicket vegetation here thus consists of a combination of many of the thicket species that occur within the central portion of the Albany Thicket Biome. Despite having a common denominating content of thicket species, the Groot Thicket units have a unique combination of species and/or have local endemic species present in their mosaic units (Vlok & Euston-Brown 2002). Some of the species present in this unit (e.g. Euphorbia polygona, E. tetragona, Ozoroa mucronata and Plumbago auriculata) indicate a close afﬁnity to more eastern portions of the Albany Valley Thicket. References Acocks (1953, 1988), Lloyd et al. (2002), Vlok & Euston-Brown (2002), Vlok et al. (2003). AT 4 Gamtoos Thicket VT 70 False Macchia (42%), VT 23 Valley Bushveld (35%) (Acocks 1953). Valley Bushveld (35%), Mosaic of South Coast Renosterveld (12%), Mesic Grassy Fynbos (11%) (Moll & Bossi 1984). LR 54 Central Lower Nama Karoo (28%), LR 63 South and South-west Coast Renosterveld (22%) (Low & Rebelo 1996, 1998). BHU 92 Steytlerville Broken Veld (27%), BHU 21 Humansdorp Grassy Fynbos (20%), BHU 30 Kromme Fynbos/Renosterveld Mosaic (20%) (Cowling & Heijnis 2001). STEP Gamtoos Valley Thicket (38%), STEP Gamtoos Arid Spekboomveld (20%) (Vlok & Euston-Brown 2002). Distribution Eastern Cape Province: Coastal basin of the Gamtoos River Valley, south of the Baviaanskloof Mountains and along some smaller river valleys such as that of the Kromme River. Also found north of the Baviaanskloof Mountains in more xeric conditions on some low ridges south and southeast of Steytlerville. Altitude 0–700 m. Vegetation & Landscape Features On the low mountain slopes in steeply sloping areas and on low ridges. Tall, dense thicket, where both the trees and shrubs and the succulent component are well represented. Few distinct strata can be differentiated within much of the vegetation, as the lower and upper canopy species are intertwined, often together with a wide variety of liana species linking the understorey species with the canopy. Occurs mostly as a fragmented community with large, dense stands restricted to south- and southwestfacing slopes that are protected against ﬁres. The structure of Albany hicket Biome 553 L. Mucina S % Figure 10.9 AT 4 Gamtoos Thicket: Nonsucculent face of Gamtoos Thicket on steep sandstone slopes of the Baviaanskloof River Valley (near Patensie, Eastern Cape). the dense stands of Gamtoos Thicket is similar to that of the Sundays Thicket, but it differs in the dominant species. Geology & Soils Mostly restricted to rocky, sandy-loamy soils derived from shale and sandstone of the Bokkeveld Group (Ceres and Tarka Subgroups) and Table Mountain Group (Nardouw Subgroup) as well as the Jurassic Enon conglomerates. Also found are fairly shallow clayey soils derived from the Gamtoos Group limestone, phyllite and arenite of the Kaan and Klein River Formations (Namibian Erathem). Fc land type covers half of the area, followed by Ae and Ib. Climate Nonseasonal rainfall with slight optima in March and November. MAP ranges from about 180 mm in the northwest inland areas to 850 mm in the southeast coastal sites. The coefﬁcient of variation in MAP is 32% for the unit, but varies from 22% at the coast to 38% inland. The mean daily maximum temperatures for January are 24°C at the coast and 31°C inland and the mean daily minimum temperatures for July are 3°C inland and 9°C at the coast. The incidence of frost is 7 days, but ranging widely from 3 days at the coast to more than 25 days of frost per year inland. See also climate diagram for AT 4 Gamtoos Thicket (Figure 10.4). Important Taxa Succulent Trees: Euphorbia triangularis (d), Aloe africana, A. speciosa, Euphorbia grandidens. Small Trees: Apodytes dimidiata, Canthium spinosum, Cussonia spicata, C. thyrsiﬂora, Maytenus undata, Pappea capensis, Ptaeroxylon obliquum, Schotia afra var. afra, Sideroxylon inerme, Vepris lan554 Albany hicket Biome 19 (2006) ceolata. Tall Shrubs: Allophylus decipiens, Azima tetracantha, Carissa bispinosa subsp. bispinosa, Crotalaria capensis, Ehretia rigida, Elytropappus rhinocerotis, Euclea racemosa, E. undulata, Grewia occidentalis, Gymnosporia capitata, G. heterophylla, G. polyacantha, Hippobromus pauciflorus, Maerua cafra, Mystroxylon aethiopicum, Nylandtia spinosa, Olea europaea subsp. africana, Pterocelastrus tricuspidatus, Putterlickia pyracantha, Rhus glauca, R. incisa, R. longispina, R. lucida, R. pterota, R. refracta, Scolopia zeyheri, Scutia myrtina. Low Shrubs: Felicia muricata (d), Anthospermum aethiopicum, Asparagus striatus, Chaetacanthus setiger, Eriocephalus africanus, E. algoensis, E. spathaceus, Jamesbrittenia microphylla, Lauridia tetragona, Oedera genistifolia, Phyllanthus maderaspatensis, Pteronia incana, Senecio linifolius. Succulent Shrubs: Portulacaria afra (d), Exomis microphylla var. axyrioides, Cotyledon campanulata, C. orbiculata var. oblonga, C. tomentosa subsp. tomentosa, Crassula cultrata, Delosperma ecklonis, Euphorbia mauritanica, E. polygona, Glottiphyllum linguiforme, Senecio oxyodontus, Tylecodon striatus, Zygophyllum debile. Semiparasitic Shrub: Osyris compressa. Semiparasitic Epiphytic Shrub: Viscum rotundifolium. Woody Climbers: Capparis sepiaria var. citrifolia (d), Rhoicissus digitata (d), Asparagus aethiopicus, A. racemosus, Jasminum angulare, Plumbago auriculata, Rhoiacarpos capensis. Woody Succulent Climber: Sarcostemma viminale. Herbaceous Climbers: Cynanchum ellipticum, Senecio deltoideus. Graminoids: Ehrharta calycina (d), E. erecta (d), Panicum deustum (d), Setaria sphacelata (d), Aristida congesta, Cenchrus ciliaris, Cynodon dactylon, Digitaria natalensis, Enneapogon desvauxii, E. scoparius, Eragrostis obtusa, Eustachys paspaloides, Ficinia indica, F. nodosa, Heteropogon contortus, Karroochloa curva, Leptochloa fusca, Melica racemosa, Panicum maximum, P. stapﬁanum, Pycreus polystachyos var. laxiﬂorus, Sporobolus africanus, S. ﬁmbriatus, Stipa dregeana, Themeda triandra, Tribolium hispidum. Succulent Herbs: Crassula expansa, C. muscosa, C. orbicularis, Plectranthus grandidentatus, P. madagascariensis, Senecio radicans. Geophytic Herbs: Asplenium cordatum, Bonatea speciosa var. antennifera, Bulbine alooides, B. frutescens, Chasmanthe aethiopica, Ornithogalum longibracteatum, Oxalis obtusa, Pelargonium pulverulentum, Sansevieria hyacinthoides. Herbs: Hypoestes aristata (d), Abutilon sonneratianum, Acalypha ecklonii, Blepharis integrifolia var. clarkei, Hibiscus pusillus, Indigastrum costatum subsp. macrum, Indigofera hedyantha, Peristrophe cernua, Stachys aethiopica. Endemic Taxa Small Tree: Cussonia gamtoosensis. Succulent Herbs: Huernia bayeri, Gasteria pulchra. Geophytic Herb: Lachenalia latimerae. Conservation Least threatened. Target 19%. A total of 6% of this vegetation unit is protected in statutory conservation areas: Baviaanskloof Conservation Area, Guerna and Berg Plaatz Wilderness Areas as well as Stinkhoutsberg, Kabeljousrivier, Loerie Dam and Seekoeirivier Nature Reserves. Private conservation areas (Hankey Forest Reserve No. 1, Monteaux Game Ranch, Lombardini Game Farm, Kabeljous River Natural Heritage Site, and Kromme River Mouth, Eastcot and Loerie Dam Nature Reserves) also protect some patches of this vegetation type. Some 12% of Gamtoos Thicket has been altered by cultivation and 1% by urbanisation. The alien Atriplex lindleyi subsp. inﬂata has invaded many degraded arid thicket areas, especially on soils with a high clay content. Erosion is variable. Remarks The structural characteristics and species present within the Gamtoos Thicket are intermediate between those of the Sundays River Thicket and Gouritz River Thicket (sensu Vlok & Euston-Brown 2002). However, the composition of the dominant species differs and there are several endemic species present in the Gamtoos Thicket, especially in the matrix vegeta- S % 19 (2006) tion, that only occur as fragmented clumps. The ﬂora that occur along its boundaries is shared and has been enriched by the species typical of the adjacent units (Cowling 1983), e.g. Sundays Thicket. To a degree this is also true for the Baviaanskloof mountain zone, especially where the Gamtoos Thicket unit abuts the boundaries of the Groot Thicket units. Many species typical of both these major regions may co-occur along these overlapping areas, presenting rather diffuse patterns in species gradients (Vlok & Euston-Brown 2002). References Acocks (1953, 1988), Cowling & Campbell (1983), Cowling (1984), Pierce & Cowling (1984), Everard (1987), Midgley & Cowling (1993), Vlok & Euston-Brown (2002), Vlok et al. (2003), Kamineth (2004). AT 5 Sundays Noorsveld VT 24 Noorsveld (72%) (Acocks 1953). LR 6 Xeric Succulent Thicket (84%) (Low & Rebelo 1996, 1998). STEP Sundays Noorsveld (100%) (Vlok & EustonBrown 2002). Distribution Eastern Cape Province: Mostly north of the Klein Winterhoek Mountains, centred around Waterford and the Darlington Dam and a smaller area from Jansenville westwards. Also some patches south of this mountain range west of Kirkwood in the Sundays River Valley. Altitude 100–600 m. Vegetation & Landscape Features Flat lowlands where the vegetation is a dense, usually 1–2 m tall succulent thicket consisting of a mosaic of noors (Euphorbia caerulescens) and low karoo shrub vegetation (dominated by Pentzia incana and Rhigozum obovatum). Punctuated by solitary trees and shrub groups with Pappea capensis, Euclea undulata, Rhus longispina and Gymnosporia polyacantha. Geology & Soils Shale, mudstones and sandstones of the Beaufort and Ecca Groups of the Karoo Supergroup in the north as well as of the Mesozoic Uitenhage Group in the south. Often heavy, clayey soils, but may be sandy and of Quaternary origin. The Fc land type overwhelmingly dominates. Important Taxa Succulent Tree: Aloe ferox (d). Small Trees: Pappea capensis (d), Acacia karroo, Boscia albitrunca, B. oleoides, Schotia afra var. afra. Tall Shrubs: Grewia robusta (d), Gymnosporia polyacantha (d), Azima tetracantha, Cadaba aphylla, Carissa bispinosa subsp. bispinosa, Diospyros austro-africana, Euclea undulata, Gymnosporia capitata, Nymania capensis, Putterlickia pyracantha, Rhus longispina. Low Shrubs: Blepharis capensis (d), Jamesbrittenia microphylla (d), Lycium cinereum (d), L. oxycarpum (d), Pentzia incana (d), L. Mucina Climate Nonseasonal rainfall with slight optima in March and November, but primarily in late summer. MAP ranges from about 210 mm in the west to 320 mm in the east. The incidence of frost is only 5 days, ranging from 3 to 13 days of frost per year. Mean daily maximum and minimum temperatures are 29–32°C and 4–6°C for January and July, respectively, and this is consistent across the distribution of the vegetation type. Mean monthly maximum and minimum temperatures for the Mentz Dam weather station are 41.4°C and –2.2°C for January and July, respectively. See also climate diagram for AT 5 Sundays Noorsveld (Figure 10.4). Rhigozum obovatum (d), Aptosimum elongatum, Asparagus burchellii, A. crassicladus, A. striatus, A. suaveolens, A. subulatus, Barleria pungens, B. rigida, Chrysocoma ciliata, Eriocephalus ericoides, Felicia ﬁlifolia, F. muricata, Garuleum latifolium, Helichrysum rosum, H. zeyheri, Hermannia althaeoides, H. gracilis, Indigofera sessilifolia, Lantana rugosa, Leucas capensis, Lepidium africanum, Limeum aethiopicum, Monechma pseudopatulum, M. spartioides, Pelargonium aridum, Phyllanthus verrucosus, Phymaspermum parvifolium, Polygala seminuda, Rosenia humilis, Selago albida, S. fruticosa, S. triquetra, Solanum capense, S. tomentosum. Succulent Shrubs: Euphorbia caerulescens (d), Adromischus cristatus var. schonlandii, Aloe lineata, A. striata, Cotyledon orbiculata var. oblonga, C. velutina, C. woodii, Crassula corallina subsp. corallina, C. ovata, Delosperma frutescens, Drosanthemum lique, Euphorbia esculenta, E. mauritanica, E. pentagona, Mestoklema tuberosum, Pachypodium succulentum, Portulacaria afra, Trichodiadema barbatum. Semiparasitic Shrub: Thesium junceum. Semiparasitic Epiphytic Shrubs: Viscum continuum, V. obscurum, V. rotundifolium. Woody Succulent Climber: Sarcostemma viminale. Woody Climbers: Asparagus racemosus, Cissampelos capensis, Rhoicissus digitata. Graminoids: Aristida adscensionis (d), A. congesta (d), Cenchrus ciliaris (d), Cynodon incompletus (d), Ehrharta erecta (d), Eragrostis obtusa (d), Tragus berteronianus (d), Aristida barbicollis, A. diffusa, Chloris virgata, Cynodon dactylon, Digitaria argyrograpta, Ehrharta calycina, Enneapogon desvauxii, E. scoparius, Eragrostis chloromelas, E. curvula, E. lehmanniana, Fingerhuthia africana, Heteropogon contortus, Oropetium capense, Panicum coloratum, P. deustum, P. maximum, Setaria verticillata, Sporobolus ﬁmbriatus, Tragus racemosus. Herbaceous Climbers: Cynanchum ellipticum, C. gerrardii, Cyphia sylvatica, Kedrostis capensis, K. nana. Succulent Herbs: Mesembryanthemum aitonis (d), C. muscosa, Gasteria maculata, Mesembryanthemum crystallinum, Senecio radicans. Geophytic Herbs: Drimia intricata (d), D. anomala, Ledebouria undulata, Moraea polystachya, Oxalis stellata, Sansevieria aethiopica, Tritonia laxifolia. Herbs: Aizoon glinoides (d), Gazania krebsiana (d), Lasiopogon glomerulatus (d), Lotononis leptoloba (d), Abutilon sonneratianum, Amaranthus thunbergii, Boerhavia diffusa, Chamaesyce inaequilatera, Cucumis myriocarpus, Hermannia cernua, H. comosa, H. pulverata, Hibiscus pusillus, Indigastrum costatum subsp. macrum, Indigofera disticha, Figure 10.10 AT 5 Sundays Noorsveld: Low succulent thicket with Euphorbia caerulescens (Euphorbiaceae) north of Wolwefontein on the road to Jansenville in the Sundays River basin (Eastern Cape). Albany hicket Biome 555 S % Isoglossa ciliata, Lactuca dregeana, L. desertorum, Lessertia pauciﬂora, Leysera tenella, Lotononis calycina, Peucedanum typicum, Tetragonia echinata, T. microptera, Tribulus terrestris. Parasitic Herb: Hydnora africana. Vegetation & Landscape Features Undulating plains and low mountains and foothills covered with tall, dense thicket, where trees, shrubs and succulents are common, with many spinescent species. The transition between lower and upper canopies is obscured by the presence of a wide variety of lianas. The local dominance of Portulacaria afra increases and the relative abundance of woody species present decreases with increasing aridity. There is considerable structural heterogeneity within this vegetation unit. Conservation Least threatened. Target 19%. Almost 15% statutorily conserved in Greater Addo Elephant National Park and some 3% in private game ranches (Kuzuko, Voetpadskloof, Koedoeskop, Schuilpatdop Game Farm, Goodhope). About 4% transformed with cultivation the primary factor. Erosion is moderate to very low. Geology & Soils Mostly on deep (>1 m) red, loamy to clayey soils derived from the Sundays River and Kirkwood Formations (Mesozoic Uitenhage Group) in the south. In the Zuurberg Mountains, soils are more sandy and nutrient-poor and derived from the Bokkeveld and Witteberg Groups (Cape Supergroup). In the inland region of the Sundays River the soils are derived from Ecca Group shales and mudstones, and are heavy due to high clay content. Fc land type dominates the area, followed by Ae. References Acocks (1953, 1988), Van der Walt (1965), Hoffman (1989a, b), Hoffman & Cowling (1990), Du Toit & Blom (1995), Vlok & Euston-Brown (2002), Vlok et al. (2003). AT 6 Sundays Thicket VT 23 Valley Bushveld (42%), VT 24 Noorsveld (28%) (Acocks 1953). LR 6 Xeric Succulent Thicket (57%) (Low & Rebelo 1996, 1998). STEP Sundays Spekboomveld (55%) (Vlok & Euston-Brown 2002). Climate Nonseasonal rainfall with slight optima in March and October/November. MAP ranges from about 190 mm in the northwest to 480 mm in the southeast on the coast near Port Elizabeth. The coefﬁcient of variation in MAP is 29–38%, increasing with distance inland in a northwesterly direction. The incidence of frost is 8 days, but ranging widely from 3 days near the coast in the southeast to more than 24 days of frost per year in the more inland sites in the northwest. Mean monthly maximum and minimum temperatures for Jansenville are 41.3°C and –0.8°C for January and July, respectively, and corresponding values for Addo are 39.0°C and –0.3°C and for Uitenhage are 36.9°C and 1.3°C, both for February and July, respectively. See also climate diagram for AT 6 Sundays Thicket (Figure 10.4). L. Mucina Distribution Eastern Cape Province: From the surrounds of Uitenhage and the northern edge of Port Elizabeth into the lower Sundays River Valley to east of Colchester and northwards to the base of the Zuurberg Mountains and stretching westwards north of the Groot Winterhoek Mountains to roughly the Kleinpoort longitude. Also an extensive area north of the Klein Winterhoek Mountains including much of the Jansenville District and parts of the far-southern Pearston District and farwestern Somerset East District. Altitude 0–800 m. Figure 10.11 AT 6 Sundays Thicket: Dense thicket with Euphorbia triangularis (Euphorbiaceae) and Cussonia spicata (Araliaceae) along road from Addo to Zuurberg Inn (Eastern Cape). 556 Albany hicket Biome 19 (2006) Important Taxa Succulent Trees: Aloe africana (d), A. ferox, Euphorbia grandidens. Small Trees: Pappea capensis (d), Schotia afra var. afra (d), Acacia natalitia, Boscia albitrunca, Brachylaena ilicifolia, Cussonia spicata, Encephalartos lehmannii, Ptaeroxylon obliquum, Sideroxylon inerme. Tall Shrubs: Euclea undulata (d), Olea europaea subsp. africana (d), Azima tetracantha, Cadaba aphylla, Carissa bispinosa subsp. bispinosa, Diospyros pallens, Ehretia rigida, Grewia occidentalis, G. robusta, Gymnosporia buxifolia, G. capitata, G. polyacantha, Maerua cafra, Mystroxylon aethiopicum, Nymania capensis, Putterlickia pyracantha, Rhus incisa, R. longispina, Scutia myrtina. Low Shrubs: Pentzia globosa (d), Aptosimum elongatum, Asparagus burchellii, A. crassicladus, A. striatus, A. subulatus, Barleria obtusa, B. rigida, Blepharis capensis, Chascanum cuneifolium, Chrysocoma ciliata, Eriocephalus ericoides, Euryops algoensis, E. spathaceus, Felicia muricata, Garuleum latifolium, Hermannia althaeoides, Hibiscus aridus, Indigofera sessilifolia, Justicia orchioides, Lantana rugosa, Leucas capensis, Limeum aethiopicum, Lycium oxycarpum, Osteospermum imbricatum, Pteronia paniculata, Rhigozum obovatum, Rosenia humilis, Selago fruticosa, S. geniculata, Senecio linifolius, Solanum capense, S. tomentosum. Succulent Shrubs: Crassula ovata (d), Euphorbia caerulescens (d), E. ledienii (d), Portulacaria afra (d), Adromischus cristatus var. cristatus, A. sphenophyllus, Cotyledon campanulata, C. orbiculata var. oblonga, Crassula capitella subsp. capitella, C. capitella subsp. thyrsiﬂora, C. cotyledonis, C. cultrata, C. mesembryanthoides subsp. hispida, C. rogersii, Delosperma echinatum, D. uniﬂorum, Euphorbia mauritanica, Exomis microphylla, Kalanchoe rotundifolia, Lampranthus productus, Mestoklema tuberosum, Orbea pulchella, Pachypodium succulentum, Pelargonium carnosum, Psilocaulon articulatum, Zygophyllum foetidum. Semiparasitic Shrub: Osyris compressa. Semiparasitic Epiphytic Shrubs: Viscum crassulae, V. obscurum, V. rotundifolium. S % 19 (2006) Woody Succulent Climbers: Pelargonium peltatum (d), Crassula perforata, Cyphostemma quinatum, Sarcostemma viminale. Woody Climbers: Asparagus asparagoides, A. multiflorus, A. racemosus, A. volubilis, Behnia reticulata, Capparis sepiaria var. citrifolia, Cissampelos capensis, Plumbago auriculata, Rhoiacarpos capensis, Rhoicissus digitata. Herbaceous Climbers: Cynanchum ellipticum, Kedrostis capensis. Graminoids: Aristida adscensionis (d), A. congesta (d), Cynodon dactylon (d), C. incompletus (d), Eragrostis obtusa (d), Panicum maximum (d), Tragus berteronianus (d), Cenchrus ciliaris, Cyperus capensis, Digitaria argyrograpta, Ehrharta calycina, Enneapogon scoparius, Eragrostis curvula, Eustachys paspaloides, Heteropogon contortus, Panicum deustum, Sporobolus ﬁmbriatus, Stipa dregeana, Themeda triandra. Succulent Herbs: Senecio radicans (d), Crassula expansa, C. spathulata, Gasteria bicolor, Sansevieria aethiopica. Geophytic Herbs: Bulbine frutescens (d), Drimia intricata (d), Sansevieria hyacinthoides (d), Cyanella lutea, Cyrtanthus loddigesianus, C. spiralis, Drimia anomala, Freesia corymbosa, Hypoxis argentea, Justicia cuneata subsp. cuneata, Moraea stricta, Oxalis smithiana, Spiloxene trifurcillata, Trachyandra afﬁnis, Tritonia securigera, Tritonia strictifolia, Urginea altissima. Herbs: Abutilon sonneratianum, Aizoon glinoides, Arctotheca calendula, Chamaesyce inaequilatera, Commelina benghalensis, Cotula heterocarpa, Cyanotis speciosa, Cypselodontia eckloniana, Emex australis, Gazania krebsiana, Hibiscus pusillus, Hypoestes aristata, Indigastrum costatum subsp. macrum, Lepidium africanum, Lotononis glabra, Stachys aethiopica. Biogeographically Important Taxa (S Southern limit) Succulent Climber: Ceropegia ampliata var. ampliata S. Herbaceous Climber: Fockea sinuataS. Epiphytic Parasitic Herb: Cuscuta bifurcata. Geophytic Herb: Pelargonium campestre. Endemic Taxa Small Tree: Encephalartos horridus. Succulent Shrubs: Aloe bowiea, A. gracilis, Bergeranthus addoensis, Glottiphyllum grandiﬂorum, Orthopterum coegana, Ruschia aristata, Trichodiadema rupicola. Succulent Climbers: Aptenia haeckeliana, Ceropegia dubia. Succulent Herbs: Haworthia arachnoidea var. xiphiophylla, H. aristata, Huernia longii subsp. longii. Geophytic Herbs: Brachystelma cummingii, B. schoenlandianum, B. tabularium, Pelargonium ochroleucum, Strelitzia juncea, Tritonia dubia. Herbs: Arctotis hispidula, Argyrolobium crassifolium, Lessertia carnosa, Lotononis monophylla, Senecio scaposus var. addoensis, Wahlenbergia oocarpa. Conservation Least threatened. Target 19%. Protected statutorily in Greater Addo Elephant National Park, Groendal Wilderness Area as well as in Swartkops Valley and Springs Nature Reserves. Private conservation areas, especially game farms (Kuzuko, Koedoeskop, Schuilpatdop, Tregathlyn, Citruslandgoed, Voetpadskloof) and a couple of nature reserves contribute to conservation of this vegetation type as well. More than 6% already transformed (cultivated, urban development). Sundays Thicket has also been highly degraded through grazing by livestock (Hoffman & Cowling 1990, 1991, Lloyd et al. 2002, Lechmere-Oertel 2003). The degraded state resembles a secondary thornveld or grassland, dominated by invasive weedy species. In this state, most of the original thicket species are lost. Erosion is moderate to very low. Remarks The considerable research interest in the Sundays Thicket unit is linked to the popular Addo National Park (now encompassing also the former Zuurberg National Park and a series of inland and coastal nature reserves forming the Greater Addo Elephant National Park)—the only locality in the Cape housing an extant population of elephant (Loxodonta africana) and an indigenous population of Cape buffalo (Synceros caffer). References Archibald (1955), Pentzhorn & Olivier (1974), Pentzhorn et al. (1974), Aucamp (1976, 1979), Cowling (1983, 1984), Aucamp & Tainton (1984), Everard (1987), Hoffman (1989a, b), Hoffman & Cowling (1990, 1991), La Cock (1992), Stuart-Hill (1992), Midgley & Cowling (1993), StuartHill & Aucamp (1993), Johnson (1998), Johnson et al. (1999), Kerley et al. (1999a, b), Sigwela (1999), Lombard et al. (2001), Todkill (2001), Cowling & Kerley (2002), Lloyd et al. (2002), Vlok & Euston-Brown (2002), LechmereOertel (2003), Vlok et al. (2003), Sigwela et al. (2004). AT 7 Coega Bontveld VT 23 Valley Bushveld (87%) (Acocks 1953). Valley Bushveld (98%) (Moll & Bossi 1984). LR 7 Mesic Succulent Thicket (72%) (Low & Rebelo 1996, 1998). BHU 95 Sundays Mesic Succulent Thicket (70%) (Cowling & Heijnis 2001). STEP Grass Ridge Bontveld (100%) (Vlok & Euston-Brown 2002). Distribution Eastern Cape Province: Northeast of Port Elizabeth just inland of Algoa Bay; mainly around Coega, but also in small patches in Addo (Zuurkop; Pentzhorn & Olivier 1974). Altitude 0–400 m. Vegetation & Landscape Features On moderately undulating plains, where a mosaic of low thicket (2–3 m) built mainly of bush clumps occurs. Secondary open grassland occurs over wide stretches. This unit is often restricted to ‘islands’ in a matrix of typical valley thicket. The species present are a mixture of Fynbos, Grassland and Succulent Karoo elements. Geology & Soils Outcrops of limestone (Nanaga Formation), and calcareous paleo-dune ﬁelds of the Cenozoic Algoa Group. The soils are shallow clay soils that are often lime-rich. Most of the area of this unit is primarily classiﬁed as the Fc land type, with Ae land type of minor importance. Climate Nonseasonal rainfall with optima in March and October. MAP ranges from about 400 mm inland in the west to 550 mm in the east and closer to the coast. The coefﬁcient of variation in MAP ranges between 30% and 32%. The incidence of frost is only 3 days, not varying across the range of the vegetation unit. Mean monthly maximum and minimum temperatures for the nearby Port Elizabeth are 32.1°C and 3.4°C for February and July, respectively. See also climate diagram for AT 7 Coega Bontveld (Figure 10.4). Important Taxa Succulent Trees: Aloe africana, A. ferox. Small Trees: Schotia afra var. afra, Sideroxylon inerme. Tall Shrubs: Euclea undulata (d), Carissa bispinosa subsp. bispinosa, Dovyalis caffra, Ehretia rigida, Euclea crispa, Gymnosporia capitata, Hippobromus pauciﬂorus, Maerua cafra, Mystroxylon aethiopicum, Pterocelastrus tricuspidatus, Putterlickia pyracantha, Rhus longispina, R. lucida, R. pyroides var. gracilis, Scutia myrtina. Low Shrubs: Helichrysum anomalum (d), Jamesbrittenia microphylla (d), Tephrosia capensis var. acutifolia (d), Acmadenia obtusata, Agathosma capensis, Asparagus falcatus, A. multiﬂorus, A. striatus, Blepharis capensis, Chaetacanthus setiger, Chascanum cuneifolium, Clutia daphnoides, Disparago ericoides, Felicia muricata, Hermannia althaeoides, H. ﬂammea, H. holosericea, Lantana rugosa, Limeum aethiopicum, Lobostemon trigonus, Muraltia squarrosa, Osteospermum imbricatum, O. polygaloides, Passerina rubra, Wahlenbergia tenella. Succulent Shrubs: Crassula expansa (d), Ruschia hamata (d), Aloe arborescens, Carpobrotus edulis, Crassula capitella subsp. capitella, C. ericoides, C. perfoliata, C. perforata, C. tetragona subsp. robusta. Semiparasitic Shrub: Osyris compressa. Woody Succulent Climbers: Pelargonium peltatum, Sarcostemma viminale. Woody Climbers: Asparagus racemosus, Jasminum angulare, Rhoiacarpos capensis, Rhoicissus digitata. Herbaceous Climber: Kedrostis capensis. Graminoids: Aristida diffusa (d), Cynodon dactylon (d), C. incompletus (d), Eustachys paspaloides (d), Heteropogon contortus (d), Merxmuellera disticha (d), Panicum maximum (d), Setaria sphacelata (d), Stipa Albany hicket Biome 557 S % dregeana (d), Themeda triandra (d), Cymbopogon marginatus, C. pospischilii, Digitaria argyrograpta, D. natalensis, Ehrharta calycina, E. erecta, Eragrostis capensis, E. curvula, E. obtusa, Helictotrichon capense, Melica racemosa, Panicum deustum, Pentaschistis pallida, Sporobolus ioclados. Succulent Herbs: Mesembryanthemum aitonis (d), C. muscosa, Geophytic Herbs: Sansevieria hyacinthoides (d), Bulbine favosa, B. inamarxiae. Moraea pallida, Oxalis smithiana. Herbs: Aizoon rigidum (d), Gazania krebsiana (d), Hypoestes aristata (d), Indigastrum costatum subsp. macrum (d), Senecio burchellii (d), Sutera campanulata (d), Arctotheca calendula, Berkheya heterophylla, Gazania jurineifolia, Hibiscus pusillus, Lotononis glabra, Monsonia emarginata, Scabiosa albanensis. Biogeographically Important Taxa (E Eastern limit, W Western limit) Graminoids: Ficinia truncataE, Tribolium uniolaeW (d). Herb: Gibbaria scabraE. Endemic Taxa Succulent Shrubs: Euphorbia globosa, Rhombophyllum rhomboideum. Low Shrub: Anginon rugosum. Geophytic Herb: Ledebouria sp. nov. (‘coriacea’ S. Venter ined.). Conservation Target 19%. A total of 10% of this vegetation unit is protected in the Greater Addo Elephant National Park and almost 4% in the private Grassridge Nature Reserve. Some 4% of Coega Bontveld has been altered by cultivation and 2% by urbanisation. The recent building of the trafﬁc infrastructure around the new harbour near Port Elizabeth has encroached heavily into the area of the Coega Bontveld and the construction of an Industrial Development Zone in the area constitutes a serious threat to this vegetation type. Erosion is moderate to low. Remarks There are areas in the Eastern Cape north and east of Grahamstown where calcrete resists weathering to form relatively ﬂat landscapes surrounded by eroded valleys. The calcrete in these areas breaks down to form white clay that has been commercially harvested in the past for the production of crockery and pottery. The vegetation in all these areas is structurally and ﬂoristically similar to Coega Bontveld and they contain a number of taxa with Cape links, e.g. Agathosma ovata. There are also ﬂoristic links of Coega Bontveld to the local dune thicket vegetation. 19 (2006) Vegetation & Landscape Features On mainly steep and north-facing (dry) slopes. Tall thickets dominated by succulent euphorbias and aloes with a thick understorey composed of thorny shrubs, woody lianas (Capparis, Secamone, Rhoicissus, Aloe), and shrubby succulents (Crassulaceae, Asphodelaceae). Moister south-facing slopes support thorny thickets dominated by low evergreen trees (Cussonia, Euclea, Hippobromus, Pappea, Ptaeroxylon, Schotia) and shrubs (Azima, Carissa, Gymnosporia, Putterlickia) with fewer succulent shrubs and trees. The herbaceous layer is poorly developed. Geology & Soils Clayey soils over Weltevrede and Lake Mentz (Darlington Dam) Formation sandstone and shale (Witteberg Group) and on Dwyka tillite (early Karoo) as well as Algoa Group calcareous sandstone in the south. Occurs on a wide variety of land types including Fc, Fa, Ae and Fb. Climate Nonseasonal rainfall with optima in March and October/November. MAP ranges from around 340 mm in the west (north of the Zuurberg) to 650 mm in the east (at the coast near Port Alfred). The coefﬁcient of variation in MAP is 30%, but varies from 27% at the coast to 34% inland. The incidence of frost is only 3 days, but ranges from 0 days at the coast to more than 17 days of frost per year inland. Mean monthly maximum and minimum temperatures for Bathurst are 35.0°C and 5.6°C for February and July, respectively. See also climate diagram for AT 8 Kowie Thicket (Figure 10.4). Important Taxa Succulent Trees: Euphorbia grandidens (d), E. tetragona (d), E. triangularis (d), Aloe africana, A. speciosa. Small Trees: Schotia afra var. afra (d), Acacia natalitia, Brachylaena ilicifolia, Commiphora harveyi, Cussonia spicata, Elaeodendron croceum, Encephalartos altensteinii, E. latifrons, E. trispinosus, Maytenus undata, Pappea capensis, Ptaeroxylon obliquum, Schotia latifolia, Sideroxylon inerme. Tall Shrubs: Azima tetracantha (d), Croton rivularis (d), Gymnosporia polyacantha (d), Scutia myrtina (d), Acokanthera oppositifolia, Allophylus decipiens, Calpurnia aurea, Carissa bispinosa subsp. bispinosa, Clausena anisata, Coddia rudis, Ehretia rigida, References Acocks (1953, 1988), Pentzhorn & Olivier (1974), Vlok & Euston-Brown (2002), Vlok et al. (2003). AT 8 Kowie Thicket Distribution Eastern Cape Province: In the river valleys of the Bushmans, Kariega, Kowie, Kleinemonde and Kap Rivers from near the Great Fish River Mouth to Kenton-on-Sea, extending inland up these valleys past Grahamstown to just past Riebeeck East and Alicedale to north of the Zuurberg. Altitude 0–700 m. 558 Albany hicket Biome L. Mucina VT 23 Valley Bushveld (44%), VT 7 Eastern Province Thornveld (29%) (Acocks 1953). Valley Bushveld (93%) (Moll & Bossi 1984). LR 6 Xeric Succulent Thicket (25%), LR 16 Eastern Thorn Bushveld (24%), LR 5 Valley Thicket (21%) (Low & Rebelo 1996, 1998). STEP Albany Valley Thicket (38%), STEP Albany Thicket (31%) (Vlok & Euston-Brown 2002). Figure 10.12 AT 8 Kowie Thicket: Dense Euphorbia triangularis-dominated thicket on slopes facing the Settlers Dam in the Thomas Baines Nature Reserve (near Grahamstown, Eastern Cape). S % 19 (2006) Euclea undulata, Flueggea verrucosa, Grewia occidentalis, Gymnosporia capitata, G. heterophylla, Hippobromus pauciﬂorus, Maerua cafra, Mystroxylon aethiopicum, Olea europaea subsp. africana, Putterlickia pyracantha, Rhus longispina, R. lucida, R. pyroides var. gracilis, R. refracta, Scolopia zeyheri. Low Shrubs: Asparagus striatus, A. subulatus, Chrysocoma ciliata, Galenia secunda, Hermannia althaeoides, Leonotis ocymifolia, Limeum aethiopicum, Pavonia praemorsa, Pelargonium odoratissimum, Polygala myrtifolia, Pteronia incana, Selago fruticosa, Senecio linifolius, Solanum rigescens. Succulent Shrubs: Aloe arborescens (d), Crassula cultrata (d), Portulacaria afra (d), Aptenia cordifolia, Bergeranthus scapiger, Cotyledon orbiculata var. oblonga, C. velutina, Crassula muscosa, C. tetragona subsp. acutifolia, Delosperma ecklonis, Euphorbia kraussiana, Exomis microphylla var. axyrioides, Kalanchoe rotundifolia, Mestoklema tuberosum, Senecio oxyodontus. Semiparasitic Epiphytic Shrubs: Viscum obscurum, V. rotundifolium. Woody Succulent Climbers: Pelargonium peltatum (d), Sarcostemma viminale (d), Aloe ciliaris, Crassula perforata, Senecio macroglossus. Woody Climbers: Capparis sepiaria var. citrifolia (d), Plumbago auriculata (d), Asparagus aethiopicus, A. multiﬂorus, A. racemosus, Dalechampia capensis, Ficus burttdavyi, Jasminum angulare, Rhoiacarpos capensis, Rhoicissus digitata, Secamone ﬁliformis. Herbaceous Climbers: Acharia tragodes, Cynanchum ellipticum, Cyphia sylvatica, Didymodoxa caffra, Senecio deltoideus. Graminoids: Cynodon dactylon (d), C. incompletus (d), Cyperus albostriatus (d), Ehrharta erecta (d), Eragrostis curvula (d), Karroochloa curva (d), Panicum deustum (d), Setaria sphacelata (d), Sporobolus ﬁmbriatus (d), Themeda triandra (d), Cyperus textilis, Eragrostis obtusa, Melica racemosa, Panicum maximum. Megaherb: Dracaena aletriformis. Succulent Herbs: Plectranthus grandidentatus (d), Crassula expansa, Gasteria bicolor, Plectranthus madagascariensis, P. verticillatus, Senecio radicans. Geophytic Herbs: Sansevieria aethiopica (d), S. hyacinthoides (d), Asplenium cordatum, Bulbine frutescens, Cheilanthes hirta, Strelitzia reginae, Veltheimia bracteata. Herbs: Achyranthes aspera (d), Commelina benghalensis (d), Hypoestes aristata (d), Leidesia procumbens (d), Abutilon sonneratianum, Centella asiatica, Commelina africana, Conyza scabrida, Ecbolium ﬂanaganii, Emex australis, Lepidium africanum, Phyllopodium cuneifolium, Senecio burchellii, Sida ternata, Tetragonia microptera, Troglophyton capillaceum. Endemic Taxa Succulent Herb: Faucaria nemorosa. Geophytic Herb: Albuca crudenii. Herb: Wahlenbergia kowiensis. Conservation Least threatened. Target 19%. A total of 5% of this vegetation unit is protected in various statutory reserves, including the Water’s Meeting, Kowie, Cycad, Blaauwkrantz, Kap River Nature Reserves. A further 14% is conserved in private conservation areas such as game ranches (Shamwari, Emlanjeni, Amakhala, Fourie Safaris, Hunters Lodge, Elephant Park and Schotia Safaris) and in the Aylesbury Nature Reserve. Transformation 7%, mainly by cultivation. Erosion is moderate to very low. Remarks This is bioclimatically the core of the Albany Thicket Biome and the major ﬂoristic node of the Albany Centre of Endemism. It is located adjacent to a wide variety of other vegetation types, including Zuurberg Quartzite Fynbos, Zuurberg Shale Fynbos, Southern Coastal Forest, Albany Coastal Belt, Albany Broken Veld, Great Fish Noorsveld and Eastern Cape Thornveld. This indicates the varying ﬂoristic inﬂuences on this vegetation and many species from different vegetation types may co-occur along these overlapping areas. References Dyer (1937), Acocks (1953, 1988), Vlok & Euston-Brown (2002), Vlok et al. (2003), Kamineth (2004). AT 9 Albany Coastal Belt VT 1 Coastal Forest and Thornveld (29%), VT 2 Alexandria Forest (29%) (Acocks 1953). Valley Bushveld (73%) (Moll & Bossi 1984). LR 16 Eastern Thorn Bushveld (33%), LR 48 Coastal Grassland (21%) (Low & Rebelo 1996, 1998). STEP Berlin Savanna Thicket (22%), STEP Grahamstown Grassland Thicket (14%), STEP Hamburg Dune Thicket (11%), STEP Paterson Savanna Thicket (7%) (Vlok & Euston-Brown 2002). Distribution Eastern Cape Province: Within 15 km (sometimes up to 30 km) of the Indian Ocean coastline, from Kei Mouth to the Sundays River, interrupted by many valleys. Altitude 10–400 m. Vegetation & Landscape Features On the gently to moderately undulating landscapes and dissected hilltop slopes close to the coast, dominated by short grasslands punctuated by scattered bush clumps or solitary Acacia natalitia trees. Geology & Soils The area covered by this unit is geologically complex and includes Beaufort Group mudstone and sandstone in the northeast, Nanaga Formation arenite and sand in the west and Bokkeveld, Witteberg and Ecca sandstone and shale in between, and a thin strip of Quaternary sand along the coast. The pure grasslands are limited to the Nanaga and Quaternary sands, whereas thornveld is prominent on the more ﬁnely textured soils derived from the Beaufort and Bokkeveld mudstone, arenite and shale. The most important land types include Db, Fa and Ae. Climate In general the climate is ameliorated by the proximity to the coast. MAP ranges from 450 mm inland in the southwest to 900 mm in the northeast, and decreases slightly from the coast inland. The rainfall is nonseasonal with optima in March and October/November, but summer rainfall increases with distance northeastwards. The coefﬁcient of variation in rainfall is 31% in the southwest inland areas, decreasing to 21% in the extreme northeasterly parts. There is a strong rainfall gradient across this unit, with higher rainfall further northeast, which inﬂuences species composition, with more subtropical elements up the coast and more drought-tolerant elements farther west. There is little variation in temperature from season to season and frost occurs on average for only 3 days a year in the inland sites and never at the coast. Mean monthly maximum and minimum temperatures for East London are 32.3°C and 5.3°C for March and July, respectively. See also climate diagram for AT 9 Albany Coastal Belt (Figure 10.4). Important Taxa Tall Tree: Erythrina caffra. Succulent Tree: Euphorbia triangularis. Small Trees: Acacia natalitia (d), Brachylaena elliptica, Canthium spinosum, Cussonia spicata, Ficus sur, Ochna arborea, Sideroxylon inerme, Zanthoxylum capense. Tall Shrubs: Clausena anisata, Clerodendrum glabrum, Coddia rudis, Croton rivularis, Diospyros villosa var. parvifolia, Grewia occidentalis, Gymnosporia heterophylla, Hippobromus pauciflorus, Mystroxylon aethiopicum, Pavetta lanceolata, Psydrax obovata, Pterocelastrus tricuspidatus, Rhus lucida, Scutia myrtina, Tarchonanthus camphoratus, Turraea obtusifolia. Low Shrubs: Rhynchosia ciliata (d), Carissa bispinosa subsp. bispinosa, Chaetacanthus setiger, Helichrysum asperum var. albidulum, Pelargonium alchemilloides, Phyllanthus maderaspatensis, Selago corymbosa, Senecio pterophorus, Tephrosia capensis var. acutifolia. Semiparasitic Epiphytic Shrub: Viscum obscurum. Woody Succulent Climbers: Crassula pellucida subsp. marginalis, Sarcostemma viminale. Woody Climbers: Asparagus aethiopicus, A. racemosus, Capparis sepiaria var. citrifolia, Clematis brachiata, Rhoiacarpos capensis, Rhoicissus digitata, R. tridentata, Secamone alpini, Tecoma capensis. Herbaceous Climbers: Rhynchosia caribaea, R. totta, Thunbergia capensis, Zehneria Albany hicket Biome 559 S % scabra. Graminoids: Brachiaria serrata (d), Cynodon dactylon (d), Dactyloctenium australe (d), Digitaria natalensis (d), Ehrharta calycina (d), Eragrostis capensis (d), E. curvula (d), E. plana (d), Heteropogon contortus (d), Panicum deustum (d), P. maximum (d), Setaria sphacelata (d), Sporobolus africanus (d), Themeda triandra (d), Tristachya leucothrix (d), Cymbopogon marginatus, Ehrharta erecta, Elionurus muticus, Melica racemosa, Setaria megaphylla, Trachypogon spicatus. Succulent Herb: Plectranthus verticillatus (d). Geophytic Herbs: Cheilanthes hirta, Moraea pallida, Oxalis smithiana, Sansevieria hyacinthoides, Strelitzia reginae. Herbs: Chamaecrista mimosoides (d), Abutilon sonneratianum, Acalypha ecklonii, Centella asiatica, Commelina africana, C. benghalensis, Cynoglossum hispidum, Eriosema squarrosum, Lactuca inermis, Lobelia erinus, Monsonia emarginata, Phyllopodium cuneifolium, Senecio burchellii, Sonchus dregeanus. Endemic Taxa Succulent Shrub: Bergeranthus concavus. Succulent Herbs: Brachystelma franksiae var. grandiﬂorum, Bulbine frutescens var. nov. (‘chalumnensis’ Baijnath ined.), Faucaria subintegra, Haworthia coarctata var. tenuis, H. cooperi var. venusta, H. reinwardtii var. reinwardtii f. chalumnensis, Stapelia praetermissa var. luteola, S. praetermissa var. praetermissa. Geophytic Herbs: Bobartia gracilis, Apodolirion amyanum, Aspidoglossum ﬂanaganii, Drimia chalumnensis. Low Shrub: Acmadenia kiwanensis. Herb: Monsonia galpinii. Conservation Least threatened. Target 19%. Only 1% of this vegetation unit is protected in 20 local-authority and provincial nature reserves as well as in the Greater Addo Elephant National Park (including Alexandria Coast Reserve West) as well as in number of private conservation areas. About 12% of the Albany Coastal Belt has recently been altered by cultivation, 1% by plantation forestry and 4% by urbanisation. According to land-cover data, at least 7% consists of degraded vegetation. It is difﬁcult, however, to determine the proportion of the vegetation that is in a secondary state, since land-cover data do not distinguish between primary and secondary vegetation. Erosion is very low to moderate. 19 (2006) Committees Drift in the east, as well as unmapped patches in the Ecca Pass and its surroundings. Altitude 100–500 m. Vegetation & Landscape Features Prevalent on plateaus and mildly sloping ﬂanks of ridges supporting succulent thicket of low to medium height dominated by the local endemic Euphorbia bothae (a hybrid crowd) as well as other Euphorbia species intermixed with sclerophyllous bush clumps (Euclea, Grewia, Gymnosporia, Putterlickia, Schotia), groups of succulent shrubs (Crassula, Cotyledon, Pelargonium), patches of rhizomatous herbs (Sansevieria hyacinthoides, Strelitzia reginae) and accompanied by species-rich grass ﬂora. Portulacaria afra is dominant on rocky outcrops. Geology & Soil Mostly ﬁnely laminated clastic sediments of the Ecca Group (particularly the Fort Brown Formation) supporting skeletal shallow soils (Glenrosa and Mispah). Fc is the overwhelmingly dominant land type, Fb only of minor importance. Climate Nonseasonal rainfall with optima in March and October/November. MAP ranges from about 360 mm to 500 mm, with the higher rainfall generally in the central parts. The incidence of frost is 3 days per annum, varying little across the range of the unit, except in the extreme eastern part where no frost occurs. Mean monthly maximum and minimum temperatures for Tyefu weather station are 39.6°C and 2.1°C for January and July, respectively. See also climate diagram for AT 10 Great Fish Noorsveld (Figure 10.4). Important Taxa Succulent Trees: Aloe africana, A. ferox. Small Trees: Schotia afra var. afra (d), Acacia natalitia, Boscia albitrunca, Remarks The seaboard region that contains this unit is a mosaic of a wide variety of structural vegetation types, ranging from grassland to forest. This variation reﬂects post-disturbance succession gradients as well as natural variation in geology, soil patterns and distribution of water in the landscape. The forests of the region have been mapped as different vegetation units (see Chapter on Forests in this book). Admittedly, this vegetation unit exempliﬁes a deviation from our mapping philosophy by featuring current-state rather than potential vegetation. We assume that the current vegetation mosaic so typical of the Albany Coastal Belt is a creation of man and the original (presettlement) vegetation was dominated by nonseasonal, dense thicket. The area of this unit was prime agricultural land which attracted early settlers who, presumably, cleared the dense thicket cloak for pastures. References Acocks (1953, 1988), Judd (2001), Vlok & Euston-Brown (2002), Vlok et al. (2003). VT 23 Valley Bushveld (100%) (Acocks 1953). Valley Bushveld (94%) (Moll & Bossi 1984). LR 6 Xeric Succulent Thicket (84%) (Low & Rebelo 1996, 1998). STEP Fish Noorsveld (100%) (Vlok & Euston-Brown 2002). Distribution Eastern Cape Province: One large patch surrounded mainly by Great Fish Thicket in the valley of the Great Fish River (north of Grahamstown) and spans a broad band from around Pigott’s (Carlisle) Bridge in the west to around 560 Albany hicket Biome L. Mucina AT 10 Great Fish Noorsveld Figure 10.13 AT 10 Great Fish Noorsveld: Stand of Strelitzia reginae (Strelitziaceae) in Noorsveld near Ecca Pass (north of Grahamstown, Eastern Cape). The low succulent is Euphorbia x bothae, an endemic taxon to this vegetation unit. S % 19 (2006) Cussonia spicata, Pappea capensis, Ptaeroxylon obliquum. Tall Shrubs: Azima tetracantha (d), Grewia robusta (d), Brachylaena ilicifolia, Cadaba aphylla, Ehretia rigida, Euclea undulata, Gymnosporia capitata, Lantana rugosa, Rhigozum obovatum. Low Shrubs: Asparagus striatus, A. subulatus, Ballota africana, Becium burchellianum, Chrysocoma ciliata, Garuleum latifolium, Hermannia althaeoides, Indigofera sessilifolia, Jatropha capensis, Leucas capensis, Limeum aethiopicum, Phyllanthus maderaspatensis, Pteronia incana, Selago fruticosa, Senecio linifolius, S. pterophorus, Solanum tomentosum. Succulent Shrubs: Cotyledon orbiculata var. oblonga (d), Mestoklema tuberosum (d), Portulacaria afra (d), Crassula nudicaulis, C. tetragona subsp. acutifolia, Euphorbia mauritanica, E. pentagona, E. rectirama, Kalanchoe rotundifolia, Orthopterum waltoniae, Pachypodium succulentum. Semiparasitic Shrub: Thesium lineatum. Semiparasitic Epiphytic Shrub: Viscum rotundifolium. Woody Succulent Climbers: Crassula perforata, Cyphostemma quinatum. Woody Climbers: Asparagus racemosus (d), A. multiﬂorus, Rhoicissus digitata. Graminoids: Aristida congesta (d), Cynodon dactylon (d), Cyperus bellus (d), Digitaria argyrograpta (d), Panicum deustum (d), Paspalum distichum (d), Sporobolus ﬁmbriatus (d), S. nitens (d), Tragus koelerioides (d), Chloris virgata, Cymbopogon pospischilii, Cynodon incompletus, Ehrharta erecta, Eragrostis chloromelas, E. curvula, E. lehmanniana, E. obtusa, Karroochloa curva, Leptochloa fusca, Microchloa caffra, Oropetium capense, Panicum coloratum, P. gilvum, P. maximum, P. stapﬁanum, Themeda triandra. Succulent Herb: Crassula expansa (d), C. muscosa, Mesembryanthemum aitonis, Senecio radicans. Geophytic Herbs: Sansevieria hyacinthoides (d), Strelitzia reginae (d), Bulbine asphodeloides, B. narcissifolia, Cyrtanthus smithiae. Herbs: Aizoon glinoides, Amellus strigosus subsp. pseudoscabridus, Atriplex suberecta, Commelina africana, Dolichos hastaeformis, Lepidium africanum, Pharnaceum dichotomum, Salvia stenophylla. Biogeographically Important Taxon Geophytic Herb: Drimia acarophylla (shared with Great Fish Thicket). Endemic Taxon Succulent Shrub: Euphorbia x bothae (d). Conservation Least threatened. Target 19%. Good examples of the Great Fish Noorsveld are conserved in a series of statutory nature reserves around and north of the Ecca Pass. A total of about 3% of the vegetation is in the Great Fish River Complex Nature Reserve, which includes the Andries Vosloo Nature Reserve. An additional 31% is conserved in several large-scale private reserves and game farms, mainly the Kwande Private Game Reserve. Great Fish Noorsveld has been relatively little transformed: only about 3% by cultivation. Erosion is moderate to high. This vegetation type contains the largest wild populations of the famous Strelitzia reginae—a ﬂagship plant of South Africa. References Palmer (1981), Palmer et al. (1988), Vlok & Euston-Brown (2002), Brink & Dold (2003), Vlok et al. (2003). AT 11 Great Fish Thicket VT 23 Valley Bushveld (38%), VT 37 False Karroid Broken Veld (30%) (Acocks 1953). LR 52 Eastern Mixed Nama Karoo (26%), LR 6 Xeric Succulent Thicket (19%), LR 16 Eastern Thorn Bushveld (17%) (Low & Rebelo 1996, 1998). STEP Fish Spekboom Thicket (42%), STEP Hartebeest Karroid Thicket (24%) (Vlok & Euston-Brown 2002). Distribution Eastern Cape Province: Mainly in the lower Great Fish River and Keiskamma River Valleys (including the smaller intervening river valleys nearer the coast) extending up the Great Fish River Valley northwards to Cookhouse and into the southernmost part of the Cradock District. Extending up the Keiskamma River Valley as far as its conﬂuence with the Tyume River. Also includes the lower reaches of the Koonap River and part of its upper reaches immediately north of Adelaide, as well as parts of the Kat River and Little Fish River Valleys. Altitude 0–1 000 m. Vegetation & Landscape Features Steep slopes of deeply dissected rivers supporting short, medium and tall thicket types (Palmer 1981, Palmer et al. 1988, Evans et al. 1997), where both the woody trees and shrubs and the succulent component are well developed, with many spinescent shrubs. Portulacaria afra is locally dominant, decreasing in relative abundance and is replaced by Euphorbia bothae with increasing aridity. With increasing moisture status on southern aspects and in the riparian zone, P. afra is replaced by woody elements and tall emergent Euphorbia tetragona and E. triangularis. There is distinct clumping of the vegetation, which is linked to zoogenic mounds, formed principally by termites (Microhodotermes viator), earthworms (Microchaetus), mole rats (Cryptomus hottentotus) and aardvarks (Orycteropus afer)—these islands of concentrated nutrients and moisture have richer, deep soils and are often occupied by long-lived woody shrubs and trees such as Pappea capensis and Boscia oleoides and provide deep soils for endemic geophytes. The closed canopy of the Portulacaria afra-dominated thicket is another distinctive feature of parts of the Great Fish Thicket. There is high heterogeneity within this vegetation unit, which has been divided into nine distinct subtypes (Vlok & Euston-Brown 2002). Geology & Soils Mostly on shallow (<1 m) clay soils (Glenrosa and Mispah) derived from the Adelaide and Estcourt Formations (Beaufort Group, Karoo Supergroup) mudstone and arenite. Half of the area falls within the Fc land type, with Fb the only other one of some importance. Climate Nonseasonal rainfall with slight optima in March and October/November. MAP ranges from about 300 mm in the western inland areas to 600 mm in the eastern coastal areas. The coefﬁcient of variation in MAP is 32%, but varies from 29% at the coast to 36% inland. The mean daily maximum temperatures for January are 26°C at the coast and 30°C inland and the mean daily minimum temperatures for July are 0°C inland and 9°C at the coast. The incidence of frost is 3 days, but ranging widely from 0 days at the coast to more than 60 days in the upper reaches of the river valley. See also climate diagram for AT 11 Great Fish Thicket (Figure 10.4). Important Taxa Succulent Trees: Euphorbia triangularis (d), Aloe ferox, Euphorbia tetragona. Small Trees: Pappea capensis (d), Acacia natalitia, Boscia albitrunca, Brachylaena ilicifolia, Cussonia spicata, Ozoroa mucronata, Ptaeroxylon obliquum, Schotia afra var. afra, Zanthoxylum capense. Tall Shrubs: Euclea undulata (d), Allophylus decipiens, Azima tetracantha, Carissa bispinosa subsp. bispinosa, Coddia rudis, Diospyros scabrida var. cordata, Ehretia rigida, Flueggea verrucosa, Grewia occidentalis, G. robusta, Gymnosporia capitata, G. heterophylla, Hippobromus pauciﬂorus, Mystroxylon aethiopicum, Olea europaea subsp. africana, Putterlickia pyracantha, Rhus incisa, R. refracta, Scolopia zeyheri, Scutia myrtina. Low Shrubs: Asparagus striatus (d), Chaetacanthus setiger (d), Chrysocoma ciliata (d), Asparagus subulatus, Felicia muricata, Hermannia althaeoides, Indigofera sessilifolia, Leucas capensis, Limeum aethiopicum, Lycium cinereum, Phyllanthus maderaspatensis, Selago fruticosa. Succulent Shrubs: Crassula cordata (d), C. ovata (d), Portulacaria afra (d), Aloe tenuior, Delosperma ecklonis, Kalanchoe rotundifolia, Mestoklema tuberosum, Tetradenia barberae. Semiparasitic Epiphytic Shrub: Viscum rotundifolium. Woody Succulent Climbers: Crassula perforata, Albany hicket Biome 561 S % 19 (2006) & Aucamp (1993), Evans et al. (1997), Lloyd et al. (2002), Vlok & Euston-Brown (2002), Vlok et al. (2003), Kamineth (2004). AT 12 Buffels Thicket A.I. Kamineth VT 1 Coastal Forest and Thornveld (40%), VT 23 Valley Bushveld (39%) (Acocks 1953). LR 48 Coastal Grassland (31%), LR 5 Valley Thicket (30%) (Low & Rebelo 1996). STEP Mountcoke Grassland Thicket (45%), STEP Buffels Thicket (32%) (Vlok & Euston-Brown 2002). Figure 10.14 AT 11 Great Fish Thicket: Valley slopes clad in dense succulent thicket in the Sam Knott Nature Reserve (near Grahamstown, Eastern Cape). Cyphostemma quinatum, Pelargonium peltatum, Sarcostemma viminale. Woody Climbers: Asparagus multiﬂorus, A. racemosus, Capparis sepiaria var. citrifolia, Jasminum angulare, Plumbago auriculata, Rhoicissus digitata. Graminoids: Aristida congesta (d), Cynodon incompletus (d), Digitaria eriantha (d), Ehrharta erecta (d), Eragrostis obtusa (d), Panicum deustum (d), P. maximum (d), P. stapﬁanum (d), Setaria sphacelata (d), Sporobolus ﬁmbriatus (d), S. nitens (d), Themeda triandra (d), Tragus berteronianus (d), T. koelerioides (d), Cymbopogon pospischilii, Eragrostis chloromelas, E. curvula, Eustachys paspaloides. Herbs: Cyanotis speciosa (d), Hypoestes aristata (d), Salvia scabra (d), Abutilon sonneratianum, Aizoon glinoides, Hibiscus pusillus, Lepidium africanum, Sida ternata. Succulent Herbs: Crassula expansa (d), Senecio radicans. Geophytic Herb: Sansevieria hyacinthoides (d). Endemic Taxa Succulent Shrub: Euphorbia cumulata. Low Shrub: Euryops gracilipes. Succulent Herbs: Haworthia angustifolia var. paucifolia, H. cummingii, H. cymbiformis var. incurvula, H. cymbiformis var. ramosa. Herb: Zaluzianskya vallispiscis. Conservation Least threatened. Target 19%. A total of 6% of this vegetation unit is protected in seven statutory reserves, especially in the Great Fish River Complex Nature Reserve and 4.5% in addition in at least nine private conservation areas. Great Fish Thicket has not been radically altered, only 3% by cultivation and 1% by urbanisation. Erosion is very variable, from high to low. Remarks This is the easternmost vegetation unit assigned to the Albany Thicket Biome, except for Buffels Thicket that only occurs near the coast. The climate in these deep, wide river valleys is hotter and dryer than the surrounding countryside and the area covered by this vegetation unit may constitute an effective physical barrier to species migration in an east-west direction through this region. The vegetation unit also marks the transition between more concentrated summer rainfall and nonseasonal rainfall. The northeastern side of this vegetation unit is marked by the east-west-running Amathole-Winterberg mountain ranges (with its band of Eastern Cape Escarpment Thicket), further enhancing the barrier nature of this area. References Acocks (1953, 1988), Palmer (1981), Cowling (1984), Everard (1987), Palmer et al. (1988), La Cock (1992), Stuart-Hill (1992), Stuart-Hill 562 Albany hicket Biome Distribution Eastern Cape Province: In river valleys centred around East London, including the Tyolomnqa River, Buffalo River, Nahoon River, Gqunube River, Kwelera River and stretching between 40 and 50 km inland (including some areas around King William’s Town and Komga), and a small area in the Great Kei River Valley between about 10 and 20 km from the coast. It also occurs in the valley bottom in Keiskammahoek north of Dimbaza. Altitude 0–700 m. Vegetation & Landscape Features Steep slopes of river valleys in highly dissected hills and moderately undulating plains, where short, dense and tangled thicket stands reach up to 10 m. The dense thicket grades into more open, shorter thornveld at the edges of the valley slopes. Geology & Soils Mudstones and sandstones derived from the Beaufort Group of the Karoo Supergroup as well as Jurassic Dolerite Suite intrusions. The shallow soils (Glenrosa and Mispah) derived from these rocks are ﬁne-grained, nutrientpoor silts, but the presence of forests leads to the development of humus-rich, deep soils. Half of the area is classiﬁed as Fa land type, while Fb and Bd are of subordinate importance. Climate Mild climate with few extremes, ameliorated by the close proximity of the Indian Ocean. Rainfall is 500–840 mm per year, and has a coefﬁcient of variation of 22–29%, the higher coefﬁcients occurring in the more inland, less steep sites. The rainfall occurs in spring and early to midsummer, but typically of the Eastern Cape it may occur at any time of the year. Mean monthly maximum and minimum temperatures for East London are 32.3°C and 5.3°C for March and July, respectively, with very little chance of frost. See also climate diagram for AT 12 Buffels Thicket (Figure 10.4). Important Taxa Succulent Trees: Euphorbia triangularis (d), Aloe ferox, Euphorbia grandidens. Small Trees: Acacia natalitia, Apodytes dimidiata, Brachylaena ilicifolia, Calodendrum capense, Canthium ciliatum, C. mundianum, Cussonia spicata, C. thyrsiﬂora, Dombeya tiliacea, Elaeodendron croceum, Eugenia zeyheri, Harpephyllum caffrum, Heteromorpha arborescens, Ochna arborea, Pappea capensis, Ptaeroxylon obliquum, Schotia afra var. afra, S. latifolia, Sideroxylon inerme, Trimeria trinervis, Vepris lanceolata, Zanthoxylum capense, Ziziphus mucronata. Tall Shrubs: Allophylus decipiens (d), Azima tetracantha (d), Scutia myrtina (d), Suregada africana (d), Acalypha glabrata, Acokanthera oppositifolia, Allophylus melanocarpus, Buddleja dysophylla, Carissa bispinosa subsp. bispinosa, Chaetacme aristata, Chrysanthemoides monilifera, Clerodendrum glabrum, Coddia rudis, Croton rivularis, Diospyros scabrida var. cordata, D. simii, D. villosa var. parvifolia, Ehretia rigida, Euclea natalensis, E. undulata, Grewia occidentalis, Gymnosporia buxifolia, G. heterophylla, G. nemorosa, Hippobromus pauciﬂorus, Maytenus acuminata, Mystroxylon aethiopicum, Olea S % 19 (2006) europaea subsp. africana, Pavetta lanceolata, Putterlickia pyracantha, P. verrucosa, Rhus gueinzii, R. lucida, Scolopia zeyheri. Low Shrubs: Pavonia praemorsa (d), Senecio pterophorus (d), Euphorbia kraussiana, Lauridia tetragona, Lippia javanica, Lycium cinereum, Rubus rigidus, Solanum rigescens. Succulent Shrubs: Aptenia cordifolia (d), Exomis microphylla var. axyrioides, Senecio oxyodontus. Woody Succulent Climbers: Cyphostemma quinatum, Sarcostemma viminale. Woody Climbers: Rhoicissus digitata (d), Asparagus aethiopicus, A. racemosus, Capparis sepiaria var. citrifolia, Dalbergia obovata, Jasminum angulare, Plumbago auriculata, Rhoicissus tomentosa, R. tridentata, Secamone alpini, Tecoma capensis, Uvaria caffra. Graminoids: Cynodon dactylon (d), Cyperus albostriatus (d), C. textilis (d), Digitaria argyrograpta (d), D. natalensis (d), Ehrharta erecta (d), Microchloa caffra (d), Panicum deustum (d), P. maximum (d), Schoenoxiphium sparteum (d), Setaria megaphylla (d), S. sphacelata (d), Paspalum dilatatum. Herbaceous Climbers: Senecio deltoideus (d), Coccinia quinqueloba, Cynanchum ellipticum, Helinus integrifolius. Succulent Herbs: Sansevieria hyacinthoides (d), Plectranthus grandidentatus. Geophytic Herbs: Moraea pallida, Ornithogalum longibracteatum, Cheilanthes hirta. Herbs: Commelina benghalensis (d), Conyza scabrida (d), Galopina circaeoides (d), Hypoestes aristata (d), Abutilon sonneratianum, Sida ternata. Endemic Taxon Woody Succulent Climber: Ceropegia radicans subsp. smithii. Conservation Vulnerable. Target 19%. About 1% is protected in statutory reserves (Umtiza, Bridle Drift, Fort Pato, Nahoon, Bluebend, King William’s Town Nature Reserves) and in addition 0.7% in private nature conservation areas. Transformation 21%, mainly by cultivation, urban and built up areas, and plantations. At least 15% consists of vegetation in a degraded state. Erosion very low to moderate. References Acocks (1953, 1988), Low & Rebelo (1996), Vlok & EustonBrown (2002), Vlok et al. (2003), Kamineth (2004). AT 13 Eastern Cape Escarpment Thicket VT 21 False Thornveld of Eastern Province (34%), VT 23 Valley Bushveld (20%) (Acocks 1953). LR 52 Eastern Mixed Nama Karoo (26%), LR 15 Subarid Thorn Bushveld (23%), LR 5 Valley Thicket (20%) (Low & Rebelo 1996, 1998). STEP Escarpment Thicket (74%) (Vlok & Euston-Brown 2002). Distribution Eastern Cape Province: At the southern foot of the steep escarpment slopes of the Amathole, Winterberg and Swaershoek Mountains from the western ﬂank of the Keiskammahoek District to just west of Somerset East as well as on the foothills of mountains and on hills in the mountainous regions centred within a radius of 25–35 km south and west of Cradock. Altitude 450–1 250 m. Vegetation & Landscape Features Steeply sloping escarpment and mountain slopes, hills and lowlands of the region where it forms a medium high, semi-open to closed thicket dominated by Olea europaea subsp. africana and Acacia natalitia 3–7 m tall, grading into thornveld lower down and often into escarpment forest higher up the slopes. Geology & Soils Mudstones and arenite of the Adelaide Subgroup of the Karoo Supergroup as well as Jurassic dolerite intrusions. The soils derived from these rocks are ﬁne-grained, nutrient-poor silts or more nutrient-rich red clays. Soils are often shallow, on moderate to steep slopes and the surface rock cover is high. The major land types are Fc as well as Ib and Fb. Climate Nonseasonal rainfall with optima in March and November, with February and March being the maximum months. MAP ranges from about 400–700 mm per annum on the southern side of the escarpment and from 310–400 mm per annum on the northern side around Cradock, increasing with elevation. The coefﬁcient of variation in MAP is 25–35%, increasing with decreasing amounts of rainfall. The incidence of frost is 16 days, but ranging widely from fewer than 5 days to more than 35 days of frost per year, the areas with more frost occurring higher up the escarpment slopes where snow may occur in winter. Mean monthly maximum and minimum temperatures for Somerset East are 38.6°C and –1.0°C for January and July, respectively. See also climate diagram for AT 13 Eastern Cape Escarpment Thicket (Figure 10.4). Important Taxa Succulent Trees: Aloe ferox, Euphorbia tetragona. Small Trees: Acacia karroo (d), Cussonia spicata. Tall Shrubs: Olea europaea subsp. africana (d), Scutia myrtina (d), Buddleja auriculata, Euclea crispa, E. undulata, Grewia occidentalis, Gymnosporia heterophylla, Hippobromus pauciﬂorus, Leucosidea sericea, Myrsine africana, Rhus dentata, R. lucida, R. tomentosa, Scolopia zeyheri. Low Shrubs: Anthospermum rigidum subsp. pumilum, Argyrolobium collinum, Asparagus striatus, Chaetacanthus setiger, Felicia filifolia, F. muricata, Hermannia althaeoides, Lantana rugosa, Pelargonium alchemilloides, Phyllanthus maderaspatensis, Polygala fruticosa, Selago corymbosa, Solanum rigescens. Succulent Shrubs: Bergeranthus artus, Crassula obovata. Semiparasitic Epiphytic Shrub: Viscum rotundifolium. Woody Climbers: Asparagus aethiopicus, Plumbago auriculata. Herbaceous Climber: Senecio deltoideus (d). Graminoids: Aristida congesta (d), Cynodon incompletus (d), Ehrharta calycina (d), E. erecta (d), Eragrostis chloromelas (d), E. curvula (d), Panicum maximum (d), Sporobolus ﬁmbriatus (d), Tragus berteronianus (d), Aristida diffusa, A. junciformis subsp. junciformis, Cymbopogon marginatus, C. pospischilii, Cynodon dactylon, Eragrostis obtusa, Heteropogon contortus, Melica decumbens, Panicum deustum, P. stapﬁanum, Sporobolus africanus. Succulent Herbs: Stapelia glabricaulis. Geophytic Herbs: Drimia uniﬂora (d), Bulbine asphodeloides, B. narcissifolia, Drimia intricata. Herbs: Cyanotis speciosa (d), Amaranthus praetermissus, Blepharis integrifolia var. clarkei, Commelina africana, Dianthus caespitosus, Gerbera piloselloides, Hibiscus aethiopicus, H. pusillus, Hypoestes aristata, Senecio retrorsus, Sida ternata. Conservation Target 19%. Eastern Cape Escarpment Thicket has been permanently altered, with 3% through cultivation and 1% through urbanisation. A total of 5% of this vegetation unit is statutorily conserved in local-authority nature reserves (Bosberg), provincial nature reserves (primarily the Mpofu Game Reserve and Bush Nek Outspan) and in the Mountain Zebra National Park. A further about 2% is protected in private conservation areas. Erosion is very variable, from very low to high. Remarks Close ﬂoristic relationship and similar structure to AT 14 Camdebo Escarpment Thicket to the west and Gs 17 Tarkastad Montane Shrubland to the north, and also grades into the more mesic Buffels Thicket to the east. References Acocks (1953, 1988), Vlok & Euston-Brown (2002), Vlok et al. (2003), Brown & Bezuidenhout (2005). AT 14 Camdebo Escarpment Thicket VT 37 False Karroid Broken Veld (41%), VT 25 Succulent Mountain Scrub (Spekboomveld) (33%) (Acocks 1953). LR 54 Central Lower Nama Karoo (41%), LR 5 Valley Thicket (40%) (Low & Rebelo 1996, 1998). STEP Escarpment Spekboomveld (41%), STEP Escarpment Valley Thicket (22%) (Vlok & Euston-Brown 2002). Albany hicket Biome 563 L. Mucina S % Figure 10.15 AT 14 Camdebo Escarpment Thicket: Crassula arborescens (Crassulaceae) in succulent thicket in the Rooiberg east of Aberdeen (Eastern Cape). Distribution Eastern Cape Province: South-sloping face of the Great Escarpment, forming an arc from Bruintjieshoogte in the east via the Coetzeeberg Mountains and Graaff-Reinet (including Spandaukop and the isolated Rooiberg) to Kamdebooberg and Aberdeen in the west. Altitude varies from 570–1 600 m, with most of the area between 700–1 200 m. Vegetation & Landscape Features Occurs on the rugged, broken and steeply sloping escarpment and mountain slopes of the region where it forms a 2–3 m tall, largely succulent thicket of Portulacaria afra-dominated clumps. Heavy browsing by goats reduces or eliminates P. afra and low trees (Pappea capensis and Boscia oleoides) remain. 19 (2006) Important Taxa Succulent Tree: Aloe ferox. Small Trees: Acacia karroo (d), Pappea capensis (d), Boscia albitrunca, B. oleoides, Cussonia paniculata, C. spicata, Maytenus undata, Schotia afra var. afra. Tall Shrubs: Euclea undulata (d), Gymnosporia polyacantha (d), Buddleja glomerata, Cadaba aphylla, Carissa bispinosa subsp. bispinosa, Diospyros lycioides, D. pallens, Ehretia rigida, Grewia robusta, Gymnosporia capitata, G. heterophylla, Olea europaea subsp. africana, Rhus longispina, R. lucida. Low Shrubs: Blepharis mitrata (d), Chrysocoma ciliata (d), Lycium schizocalyx (d), Pentzia incana (d), Rhigozum obovatum (d), Aptosimum elongatum, Asparagus burchellii, A. mucronatus, A. striatus, A. suaveolens, Blepharis capensis, B. villosa, Eriocephalus ericoides, Felicia ﬁlifolia, F. muricata, Garuleum latifolium, Helichrysum dregeanum, H. zeyheri, Hermannia ﬁlifolia, Indigofera sessilifolia, Lantana rugosa, Lycium oxycarpum, Macledium spinosum, Monechma spartioides, Pegolettia retrofracta, Peliostomum origanoides, Rosenia humilis, Solanum capense, Sutera halimifolia. Succulent Shrubs: Portulacaria afra (d), Crassula ovata, C. rogersii, Euphorbia mauritanica, E. obesa, Kleinia longiﬂora, Mestoklema tuberosum, Pachypodium succulentum, Trichodiadema barbatum. Semiparasitic Epiphytic Shrub: Viscum rotundifolium. Woody Succulent Climber: Sarcostemma viminale. Woody Climbers: Asparagus racemosus, Cissampelos capensis, Dioscorea elephantipes, Rhoicissus digitata, R. tridentata. Graminoids: Aristida adscensionis (d), A. congesta (d), Cenchrus ciliaris (d), Digitaria eriantha (d), Enneapogon desvauxii (d), Eragrostis lehmanniana (d), E. obtusa (d), Heteropogon contortus (d), Aristida diffusa, Cynodon incompletus, Enneapogon scoparius, Eragrostis chloromelas, E. curvula, Eustachys paspaloides, Fingerhuthia africana, Panicum maximum, Sporobolus ﬁmbriatus, Themeda triandra, Tragus berteronianus, T. koelerioides. Succulent Herb: Mesembryanthemum aitonis. Geophytic Herbs: Boophone disticha, Drimia anomala, D. intricata, Moraea polystachya. Herbs: Abutilon sonneratianum, Aizoon glinoides, A. rigidum, Asplenium cordatum, Cheilanthes deltoidea, Gazania krebsiana, Hermannia coccocarpa, H. comosa, H. pulverata, Hibiscus pusillus, Lepidium africanum, Pollichia campestris, Troglophyton capillaceum. Endemic Taxa Succulent Shrubs: Astroloba corrugata, Bergeranthus sp. nov. (‘nanus’ A.P. Dold ined.), Delosperma karrooicum, Trichodiadema olivaceum. Succulent Herb: Haworthia marumiana var. batesiana, Huernia kennedyana. Geophytic Herbs: Apodolirion bolusii, Dierama grandiﬂorum. Geology & Soil Sandstone and mudstone of the Permian Adelaide Subgroup (Beaufort Group), interrupted in places by dykes of Jurassic Karoo dolerites. Shallow skeletal soils (varying in depth from 20–30 cm) of Mispah form, with organically rich orthic A-horizon, moderately acidic. Land types are Ib and Fc on shallow substrates and Da duplex soils on dolerite dykes. Conservation Least threatened. Target 19%. About 5% of this vegetation unit is statutorily protected in the Karoo Nature Reserve and a further 15% in private conservation areas (Samara Private Game Reserve, Asanta Sana Game Reserve, Rupert Game Farm, Buchanon Game Farm, Hoeksfontein Game Farm and Glen Harry Game Reserve). Camdebo Escarpment Thicket has been transformed by only about 1%, through cultivation, but this vegetation has been subjected to degradation through grazing by domestic goats in many places. It is likely that it extended further down the slopes in recent history. Clear fenceline contrasts can be recognised both by satellite imagery and in the ﬁeld (Lloyd et al. 2002). Erosion is moderate to high. Climate Nonseasonal rainfall with optima in March and November and with February and March being the maximum months. MAP ranges from about 270–550 mm, increasing with elevation. The incidence of frost is 25 days, but ranging widely from fewer than 8 days to more than 40 days of frost per year, the areas with more frost occurring higher up the escarpment slopes where snow may occur in winter. Mean monthly maximum and minimum temperatures for Graaff-Reinet are 38.6°C and –0.3°C for January and July, respectively. See also climate diagram for AT 14 Camdebo Escarpment Thicket (Figure 10.4). Remarks The dominance of Portulacaria afra is the main link of this unit with the Albany Thicket Biome, as earlier classiﬁed (Palmer 1988, 1991a, b). The overall ﬂoristic composition suggests rather that this is a marginal Nama-Karoo unit whose thicket structure can be ascribed to special regional habitat conditions, in particular geomorphology and associated microclimate. P. afra is a facultative C3 /CAM plant, and its distribution may be linked to CAM being activated following the extreme daily variation in temperature and moisture (Guralnick & Ting 1987) as often experienced on these south-facing slopes. The 564 Albany hicket Biome S % 19 (2006) distribution of P. afra, an important indicator of this thicket, has been modelled using a correlative modelling approach (Robertson & Palmer 2002). References Acocks (1953, 1988), Palmer (1988, 1989, 1991a, b), Lloyd et al. (2002), Robertson & Palmer (2002), Vlok & Euston-Brown (2002), Vlok et al. (2003). 9. Credits The Albany Thicket region was mapped using original sources, including contributions of D.B. Hoare (eastern and western parts) and A.R. Palmer (portion of western part); much of the latter was replaced by a detailed unpublished STEP map (Vlok & Euston-Brown 2002). The STEP source (counting more than 100 mapping units) was simpliﬁed by M.C. Rutherford and L. Mucina (for the main key see Table 10.1) and many of the more marginal (edge) STEP units were reconciled with other sources. The delimitation of the AT units was also inﬂuenced by the delimitation of AZa 6, Gs 18, Gs 16, SVs 6 and SVs 7 (all D.B. Hoare) as well as by placement of the forest patches (socalled Forest Biome forest map; see also Credits in the chapter on Forests). A.P. Dold contributed considerably to the species lists, Albany endemic species in particular. A.R. Palmer contributed to descriptions of units AT 2, 3, 11 and 14. D.B. Hoare contributed to the text of all mapping units except for AT 1. L. Mucina wrote AT 1 and contributed to the text of all other AT units. R.G. Lechmere-Oertel contributed to the text of AT 4 and 6; J.H.J. Vlok and D.I.W. Euston-Brown contributed to the text (list of species in particular) of AT 2 and 3. The introductory text is the result of a joint effort by (in order of the volume of the contribution) D.B. Hoare (all major sections), A.R. Palmer (Sections 1, 2 and 3), R.G. Lechmere-Oertel (Sections 5 and 6), L. Mucina (sections 4.3 and 7) and Ş.M. Procheş (Section 4.1). The section 3.2 of the introductory text was shaped by A.R. Palmer and R.A. Ward. M.C. Rutherford considerably improved section 3.3. L.W. Powrie and M.C. Rutherford provided physicogeographical information extracted from various GIS sources for the descriptions and constructed the climate diagrams. The references were compiled and collated by L. Mucina. M. Rouget, and others within the Directorate of Biodiversity Programmes, Policy & Planning of SANBI, provided quantitative information for each vegetation unit on conservation status and targets, areas currently conserved and areas transformed. The STEP map and accompanying reports were kindly provided by the Terrestrial Ecology Unit, now of the Nelson Mandela Metropolitan University, Port Elizabeth (available at the website www.zoo.upe.ac.za/step). R.A. Ward corrected the geological terminology in the descriptions. Photographs were contributed by L. Mucina, D.B. Hoare, A.R. Palmer, Ş.M. Procheş and A.I. Kamineth. 10. References Acocks, J.P.H. 1953. Veld types of South Africa. Mem. Bot. Surv. S. Afr. No. 28: 1–192. Acocks, J.P.H. 1979. The ﬂora that matched the fauna. Bothalia 12: 673– 709. Acocks, J.P.H. 1988. Veld types of South Africa, edn 3. Mem. Bot. Surv. S. Afr. No. 57: 1–146. Archibald, E.E.A. 1955. An ecological survey of the Addo Elephant National Park. J. S. Afr. Bot. 20: 137–154. Aucamp, A.J. 1976. The role of the browser in the bushveld of the eastern Cape. Proc. Grassl. Soc. S. Afr. 11: 135–138. Aucamp, A.J. 1979. Die produksiepotensiaal van die Valleibosveld as weiding vir Boer- en Angorabokke. D.Sc. thesis, Dept of Botany, Univ. of Pretoria. Aucamp, A.J. & Tainton, N.M. 1984. Veld management in the Valley Bushveld of the Eastern Cape. Dept of Agriculture Bulletin 41, Dohne Research Station, Stutterheim, South Africa. Axelrod, D.I. & Raven, P.H. 1978. Late Cretaceous and Tertiary vegetation history of Africa. In: Werger, M.J.A & Van Bruggen, A.C. (eds), Biogeography and ecology of southern Africa, pp. 77–130. Dr W. Junk, The Hague. Bamford, M.K. 2000. Cenozoic macro-plants. In: Partridge, T.C. & Maud, R.R. (eds), The Cenozoic of southern Africa, pp. 351–356. Oxford Univ. Press, Oxford. Birch, N.V., Avis, A.M. & Palmer, A.R. 1999. The effect of land-use on the vegetation communities along a topo-moisture gradient in the mid-Fish River Valley, South Africa. Afr. J. Range Forage Sci. 16: 1–8. Boureau, E., Salard-Cheboldaeff, M., Koeningeur, J.-C. & Louvet, P. 1983. Evolution des ﬂores et de la végétation Tertiaires en Afrique, au nord de l’Equateur. Bothalia 14: 355–367. Brink, E. & Dold, A.P. 2003. Drimia acarophylla (Hyacinthaceae), a new species from Eastern Cape, South Africa. S. Afr. J. Bot. 69: 396–400. Brown, L.R. & Bezuidenhout, H. 2005. The vegetation of the farm Ingleside and Welgedacht of the Mountain Zebra National Park, Eastern Cape. Koedoe 48: 23–42. Burgess, N.D., D’Amico Hales, J., Underwood, E., Dinerstein, E., Olson, D., Itoua, I., Schipper, J., Ricketts, T. & Newman, K. 2004. Terrestrial ecoregions of Africa and Madagascar: a conservation assessment. Island Press, Washington. Cábido, M., Acosta, A., Carranza, M.L. & Díaz, S. 1992. La vegetación del Chaco Arido en el W de la Provincia de Córdoba, Argentina. Doc. Phytosociol. N.S. 14: 447–456. Cábido, M., Manzur, A., Carranza, M.L. & Gonzalez Albarracin, C. 1994. La vegetación y el medio físico del Chaco Arido en la Provincia de Córdoba, Argentina Central. Phytocoenologia 24: 423–460. Cain, S.A. 1950. Life forms and phytoclimate. Bot. Rev. 16: 1–32. Cleaver, G., Brown, L.R. & Bredenkamp, G.J. 2005. The phytosociology of the Vermaaks, Marnewicks and Buffelsklip valleys of the Kammanassie Nature Reserve, Western Cape. Koedoe 48: 1–16. Cowling, R.M. 1983. Phytochorology and vegetation history in the southeastern Cape, South Africa. J. Biogeogr. 10: 393–419. Cowling, R.M. 1984. A syntaxonomic and synecological study in the Humansdorp region of the fynbos biome. Bothalia 15: 175–227. Cowling, R.M. & Campbell, B.M. 1983. A comparison of fynbos and nonfynbos coenoclines in the lower Gamtoos River Valley, southeastern Cape, South Africa. Vegetatio 53: 161–178. Cowling, R.M., Cartwright, C.R., Parkington, J.E. & Allsopp, J. 1999. Fossil wood charcoal assemblages from Elands Bay Cave, South Africa: implications for Late Quaternary vegetation and climates in the winter-rainfall fynbos biome. J. Biogeogr. 26: 367–378. Cowling, R.M. & Heijnis, C.E. 2001. The identiﬁcation of Broad Habitat Units as biodiversity entities for systematic conservation planning in the Cape Floristic Region. S. Afr. J. Bot. 67: 15–38. Cowling, R.M. & Hilton-Taylor, C. 1994. Patterns of plant diversity and endemism in southern Africa: an overview. In: Huntley, B.J. (ed.), Botanical diversity in southern Africa, pp. 31–52. Oxford Univ. Press, Cape Town. Cowling, R.M. & Kerley, G.I.H. 2002. Impacts of elephants on the ﬂora and vegetation of subtropical thicket in the Eastern Cape. In: Kerley, G.I.H., Wilson, S.L. & Massey, A. (eds), Elephant conservation and management in the Eastern Cape, pp. 55–72. Terrestrial Ecology Research Unit Report 35, Univ. of Port Elizabeth. Cowling, R.M., Lombard, A.T., Rouget, M., Kerley, G.I.H., Wolf, T., SimsCastley, R., Knight, A., Vlok, J.H.J., Pierce, S.M., Boshoff, A.F. & Wilson, S.L. 2003. A conservation assessment for the Subtropical Thicket Biome. Terrestrial Ecology Research Unit Report 43, Univ. of Port Elizabeth. www. zoo.upe.ac.za/step Cowling, R.M., Procheş, Ş. & Vlok, J.H.J. 2005. On the origin of southern African subtropical thicket vegetation. S. Afr. J. Bot. 71: 1–23. Danckwerts, J.E. 1984. The importance of a correct stocking rate. Dohne Agric. 6, 2: 4–7. Davies, T.J., Barraclough, T.G., Chase, M.W., Soltis, P.S. & Soltis, D.E. 2004. Darwin’s abominable mystery: insights from a supertree of the angiosperms. Proc. Natl. Acad. Sci. U.S.A. 101: 1904–1909. Dupéron-Laudoueneix, M. & Dupéron, J. 1995. Inventory of Mesozoic and Cenozoic woods from Equatorial and North Equatorial Africa. Rev. Palaeobot. Palynol. 84: 439-480. Du Toit, P.C.V. & Blom, C.D. 1995. Diet selection by sheep and goats in the Noorsveld. Afr. J. Range Forage Sci. 12: 27–37. Dyer, R.A. 1937. The vegetation of the divisions of Albany and Bathurst. Mem. Bot. Surv. S. Afr. No. 17: 1–138. Evans, N., Avis, T. & Palmer, A.R. 1997. Changes to the vegetation of the mid-Fish River valley, Eastern Cape, South Africa, in response to land-use, as revealed by a direct gradient analysis. Afr. J. Range Forage Sci. 14: 68–74. Everard, D.A. 1987. A classiﬁcation of the subtropical transitional thicket in the eastern Cape, based on syntaxonomic and structural attributes. S. Afr. J. Bot. 51: 329–340. Everard, D.A. 1991. Is Subtropical Thicket the missing biome of South Africa? Albany hicket Biome 565 S % In: Zacharias, P.J.K., Stuart-Hill, G.C. & Midgley, J.J. (eds), Proceedings of the ﬁrst Valley Bushveld/Subtropical Thicket Symposium, pp. 1–3. Grassland Society of Southern Africa, Howick. Gibbs Russell, G.E. & Robinson, E.R. 1981. Phytogeography and speciation in the vegetation of the eastern Cape. Bothalia 13: 467–472. Gottschling, M., Mai, D.H. & Hilger, H.H. 2002. The systematic position of Ehretia fossils (Ehretiaceae, Boraginales) from the European Tertiary and implications for character evolution. Rev. Paleobot. Palynol. 121: 149–156. Grobler, P.J. & Marais, J. 1967. Die plantegroei van die Nasionale Bontebokpark, Swellendam. Koedoe 10: 132–146. Grubb, P.J. 2003. Interpreting some outstanding features of the ﬂora and vegetation of Madagascar. Persp. Plant Ecol. Evol. Syst. 6: 125–146. Guralnick, L.J. & Ting, I.P. 1987. Physiological changes in Portulacaria afra (L.) Jacq. during a summer drought and rewatering. Plant Physiol. 85: 481–486. Haschick, S.H. 2002. Body size inﬂuences on foraging behaviour of thicket biome browsers. Ph.D. thesis, Dept of Zoology, Univ. of Port Elizabeth. Hoffman, M.T. 1989a. A preliminary investigation of the phenology of subtropical thicket and karroid shrubland in the lower Subday River Valley. S. Afr. J. Bot. 55: 586-597. Hoffman, M.T. 1989b. Vegetation studies and the impact of grazing in the semi-arid Eastern Cape. Ph.D. thesis, Dept of Botany, Univ. of Cape Town. Hoffman, M.T. & Cowling, R.M. 1990. Desertiﬁcation in the lower Sundays River Valley, South Africa. J. Arid Environ. 9: 105–117. Hoffman, M.T. & Cowling, R.M. 1991. Phytochorology and endemism along aridity and grazing gradients in the lower Sundays River Valley, South Africa: implications for vegetation history. J. Biogeogr. 18: 189–201. Ingrouille, M.J., Chase, M.W., Fay, M.F., Bowman, D., Van der Bank, M. & Bruijn, A.D.E. 2002. Systematics of Vitaceae from the viewpoint of plastid rbcL sequence data. Bot. J. Linn. Soc. 138: 421–432. Johnson, C.F. 1998. Vulnerability, irreplaceability and reserve selection for the elephant-impacted ﬂora of the Addo Elephant National Park, Eastern Cape, South Africa. M.Sc. thesis, Dept of Botany, Rhodes Univ., Grahamstown. Johnson, C.F., Cowling, R.M. & Phillipson, P.B. 1999. The ﬂora of the Addo Elephant National Park, South Africa: are threatened species vulnerable to elephant damage? Biodiv. Conserv. 8: 1447–1456. Judd, R.A. 2001. The coastal grasslands of the Eastern Cape west of the Kei River. Ph.D. thesis, Dept of Botany, Rhodes Univ., Grahamstown. Kamineth, A.I. 2004. The population dynamics and distribution of tree euphorbias in thicket. M.Sc. thesis, Dept of Botany, Univ. of Port Elizabeth. Kerley, G.I.H., Boshoff, A.F. & Knight, M.H. 1999a. Ecosystem integrity and sustainable landuse in the Thicket Biome, South Africa. Ecosystem Health 5: 104–109. Kerley, G.I.H., Knight, M.H. & De Kock, M. 1995. Desertiﬁcation of subtropical thicket in the Eastern Cape, South Africa: are there alternatives? Environ. Monit. Assess. 37: 211–230. Kerley, G.I.H., Tongway, D. & Ludwig, J.A. 1999b. Effects of goat and elephant browsing on soil resources in Succulent Thicket, Eastern Cape, South Africa. In: Proceedings of the VIth International Rangeland Congress 1, pp. 116, 117. Townsville, AU. Klak, C., Reeves, G. & Hedderson, T. 2004. Unmatched tempo of evolution in southern African semi-desert ice plants. Nature 427: 63–65. Koechlin, J., Guillamet, J.L. & Morat, P. 1974. Flore et Végétation de Madagascar. J. Cramer, Vaduz. La Cock, G. 1992. The conservation status of Subtropical Transitional Thicket, and regeneration through seeding of shrubs in the Xeric Succulent Thicket of the Eastern Cape. Report, Eastern Cape Scientiﬁc Services, Cape Nature Conservation, Port Elizabeth. Lechmere-Oertel, R.G. 2003. The effect of goat browsing on ecosystem patterns and processes in succulent thicket, South Africa. Ph.D. thesis, Dept of Botany, Univ. of Port Elizabeth. Lewis, J.P. 1991. Three levels of ﬂoristical variation in the forests of Chaco, Argentina. J. Veg. Sci. 2: 125–130. Lloyd, J.W., Van den Berg, E., Van Wyk, E. & Palmer, A.R. 2002. Patterns of degradation and degradation in the Thicket Biome. Terrestrial Ecology Research Unit Report 39, Univ. of Port Elizabeth, South Africa. www.zoo. upe.ac.za/step Lombard, A.T., Johnson, C.F., Cowling, R.M. & Pressey, R.L. 2001. Protecting plants from elephants: botanical reserve scenarios within Addo Elephant National Park, South Africa. Biol. Conserv. 102: 191–203. Low, A.B. & Rebelo, A.[T.]G. (eds) 1996. Vegetation of South Africa, Lesotho and Swaziland. A companion to the vegetation map of South Africa, Lesotho and Swaziland. Dept of Environmental Affairs and Tourism, Pretoria. Lubke, R.A., Everard, D.A. & Jackson, S. 1986. The biomes of the eastern Cape with emphasis on their conservation. Bothalia 16: 251–261. Martin, A.R.H. & Noel, A.R.A. 1960. The ﬂora of Albany and Bathurst. Rhodes Univ., Grahamstown. Matteuci, S. 1987. The vegetation of Falcón State, Venezuela. Vegetatio 566 Albany hicket Biome 19 (2006) 70: 67–91. Midgley, J.J. 1991. Valley bushveld dynamics and tree euphorbias. In: Zacharias, P.J.K., Stuart-Hill, G.C. & Midgley, J.J. (eds), Proceedings of the ﬁrst Valley Bushveld/Subtropical Thicket Symposium, pp. 8, 9. Grassland Society of Southern Africa, Howick. Midgley, J.J. & Cowling, R.M. 1993. Regeneration patterns in Cape subtropical transitional thicket; where are all the seedlings? S. Afr. J. Bot. 59: 496–499. Moll, E.J. & Bossi, L. 1984. A current assessment of the extent of the natural vegetation of the fynbos biome. S. Afr. J. Sci. 80: 355–358. Moolman, H.J. & Cowling, R.M. 1994. The impact of elephant and goat grazing on the endemic ﬂora of South African succulent thicket. Biodiv. Conserv. 67: 53–59. Muir, J. 1929. The vegetation of the Riversdale area, Cape Province. Mem. Bot. Surv. S. Afr. No. 13: 1–82. O’Connor, T.G. & Bredenkamp, G.J. 1997. Grassland. In: Cowling, R.M., Richardson, D.M. & Pierce, S.M. (eds), Vegetation of southern Africa, pp. 215–257. Cambridge Univ. Press, Cambridge. O’Connor, T.G. & Roux, P.W. 1995. Vegetation changes (1949–71) in a semiarid, grassy dwarf shrubland in the Karoo, South Africa: inﬂuence of rainfall variability and grazing by sheep. J. Appl. Ecol. 32: 612–626. Olson, D.M., Dinerstein, E., Wikramanayake, E.D., Burgess, N.D., Powell, G.V.N., Underwood, E.C., D’Amico, J.A., Itoua, I., Strand, H.E., Morrison, J.C., Loucks, C.J., Allnutt, T.F., Ricketts, T.H., Kura, Y., Lamoureux, J.F., Wettengel, W.W., Hedao, P. & Kassem, K.R. 2001. Terrestrial ecoregions of the world: a new map of life on earth. BioScience 51: 933–938. Owen-Smith, N. & Danckwerts, J.E. 1997. Herbivory. In: Cowling, R.M., Richardson, D.M. & Pierce, S.M. (eds), Vegetation of southern Africa, pp. 397–420. Cambridge Univ. Press, Cambridge. Palmer, A.R. 1981. A study of vegetation of the Andries Vosloo Kudu Reserve, Cape Province. M.Sc. thesis, Dept of Botany, Rhodes Univ., Grahamstown. Palmer, A.R. 1988. Vegetation ecology of the Camdebo and Sneeuberg regions of the Karoo Biome, South Africa. Ph.D. thesis, Dept of Botany, Rhodes Univ., Grahamstown. Palmer, A.R. 1989. The vegetation of the Karoo Nature Reserve, Cape Province. I. A phytosociological reconnaissance. S. Afr. J. Bot. 55: 215–230. Palmer, A.R. 1990. A qualitative model of vegetation history in the eastern Cape midlands, South Africa. J. Biogeogr. 17: 35–46. Palmer, A.R. 1991a. A syntaxanomic and synecological account of the vegetation of the eastern Cape midlands. S. Afr. J. Bot. 57: 76–94. Palmer, A.R. 1991b. Vegetation/environment relationships in the central area of the Cape Midlands, South Africa. Coenoses 6: 29-38. Palmer, A.R., Crook, B.J.S. & Lubke, R.A. 1988. Aspects of the vegetation and soil relationships in the Andries Vosloo Kudu Reserve, Cape Province. S. Afr. J. Bot. 54: 309–314. Palmer, A.R., Kakembo, V., Lloyd, W. & Ainslie, A. 2004. Degradation patterns and trends in the Succulent Thicket. In: Proceedings of the Thicket Forum held at Zuurberg Inn, Addo Elephant National Park, May 2004, pp. 1–10. Pell, S.K. 2004. Molecular systematics of the cashew family (Anacardiaceae). Ph.D. thesis, Louisiana State Univ., Baton Rouge, LA. Pentzhorn, B.L. & Olivier, M.C. 1974. A systematic checklist of ﬂowering plants of the Addo Elephant National Park. Koedoe 17: 121–136. Pentzhorn, B.L., Robbertse, P.J. & Olivier, M.C. 1974. The inﬂuence of the African elephant on the vegetation of the Addo Elephant National Park. Koedoe 17: 137–158. Pierce, S.M. & Cowling, R.M. 1984. Phenology of fynbos, renosterveld and subtropical thicket in the southeastern Cape. S. Afr. J. Bot. 3: 1–16. Pierce, S.[M.], Cowling, R., Lombard, M., Rouget, M., Wolf, T., Vlok, J., Knight, A., Boshoff, A. & Wilson, S. 2005. A STEP forward. Safeguarding the biodiversity of the south-eastern Cape region. Veld & Flora 91,2: 86–89. Procheş, Ş., Cowling, R.M., Goldblatt, P., Manning, J. & Snijman, D.A. 2006. An overview of the Cape geophytes. Biol. J. Linn. Soc. 87: 27–43. Raunkiaer, C. 1934. The life forms of plants and statistical plant geography. Oxford Univ. Press, Oxford. Rebelo, A.G., Cowling, R.M., Campbell, B.M. & Meadows, M. 1991. Plant communities of the Riversdale Plain. S. Afr. J. Bot. 57: 10–28. Robertson, M.P. & Palmer, A.R. 2002. Predicting the extent of succulent thicket under current and future climate scenarios. Afr. J. Range Forage Sci. 19: 21–28. Rutherford, M.C., Midgley, G.F., Bond, W.J., Powrie, L.W., Roberts, R. & Allsopp, J. 1999. South African country study on climate change. Plant biodiversity: vulnerability and adaptation assessment. Report, National Botanical Institute, Kirstenbosch. Rutherford, M.C. & Westfall, R.H. 1986. Biomes of southern Africa: an objective categorization. Mem. Bot. Surv. S. Afr. No. 63: 1–94. Salard-Cheboldaeff, M. & Dejax, J. 1991. Evidence of Cretaceous to recent West African intertropical vegetation from continental sediment spore-pollen analysis. J. Afr. Earth Sci. 12: 353–361. S % 19 (2006) Scholes, R.J. 1997. Savanna. In: Cowling, R.M., Richardson, D.M. & Pierce, S.M. (eds), Vegetation of southern Africa, pp. 258–277. Cambridge Univ. Press, Cambridge. Scholes, R.J. & Walker, B.H. 1993. An African savanna: synthesis of the Nylsvley study. Cambridge Univ. Press, Cambridge. Scholtz, A. 1985. Palynology of the Upper Cretaceous lacustrine sediments of the Arnot pipe, Banke, Namaqualand. Ann. S. Afr. Mus. 95: 1–109. Schrire, B.D., Lavin, M. & Lewis, G.P. 2005. Global distribution patterns of the Leguminosae: insights from recent phylogenies. Biol. Skrif. 55: 375–422. Schulze, R.E. 1997. Climate. In: Cowling, R.M., Richardson, D.M. & Pierce, S.M. (eds), Vegetation of southern Africa, pp. 21–42. Cambridge Univ. Press, Cambridge. Sigwela A.M. 1999. Goats and kudu in subtropical thicket dietary competition and seed dispersal efﬁciency. M.Sc. thesis, Dept of Zoology, Univ. of Port Elizabeth. Sigwela, A.M., Lechmere-Oertel, R.G., Kerley, G.I.H. & Cowling, R.M. 2004. Quantifying the costs of unsustainable domestic herbivory for biodiversity and ecosystem functioning in succulent thicket, Eastern Cape, South Africa. In: Allsopp, N., Palmer, A.R., Milton, S.J., Kirkman, K.P., Kerley, G.I.H., Hurt, C.R. & Brown, C.J. (eds), Proceedings of the VII International Rangelands Congress, pp. 1521–1526. Document Transformation Technologies. Skead, J. 1989. Historical mammal incidence in the Cape Province. Vol. II. Cape Department of Nature and Environmental Conservation, Cape Town. Smith, G.E. & Marx, G. 1990. Notes on the vegetation and succulent ﬂora of the Eastern Cape. Aloe 27: 56–66. Smith, N. & Wilson, S.L. 2002. Changing land use trends in the Thicket Biome: pastoralism to game farming. Terrestrial Ecology Research Unit Report 38, Univ. of Port Elizabeth. Story, R. 1952. A botanical survey of the Keiskammahoek District. Mem. Bot. Surv. S. Afr. No. 27: 1–184. Stuart-Hill, G.C. 1992. Effects of elephants and goats on the Kaffrarian succulent thicket of the eastern Cape, South Africa. J. Appl. Ecol. 29: 699–710. Stuart-Hill, G.C. & Aucamp, A.J. 1993. Carrying capacity of the succulent Valley Bushveld of the Eastern Cape. Afr. J. Range Forage Sci. 10: 1–10. Stuart-Hill, G.C. & Danckwerts, J.E. 1988. Inﬂuence of domestic and wild animals on the future of succulent Valley Bushveld. Pelea 7: 45–56. Taylor, H.C. 1970. IBP Checksheet for the Riversdale Nature Reserve. Report, Botanical Research Institute, Pretoria. Todkill, W.B. 2001. Towards the rehabilitation of degraded succulent thicket in the Addo Elephant National Park. M.Sc. thesis, Dept of Botany, Univ. of Port Elizabeth. Van der Walt, P.T. 1965. A plant ecological survey of the Noorsveld. M.Sc. thesis, Dept of Botany, Univ. of Natal, Pietermaritzburg. Van Wyk, A.E. & Smith, G.F. 2001. Regions of ﬂoristic endemism in southern Africa: a review with emphasis on succulents. Umdaus Press, Hatﬁeld. Victor, J.E. & Dold, A.P. 2003. Threatened plants of the Albany Centre of Floristic Endemism, South Africa. S. Afr. J. Sci. 99: 437–446. Vlok, J.H.J. & Euston-Brown, D.I.W. 2002. Subtropical Thicket Ecosystem Planning Project (STEP). Biological Survey Report (plants and birds). Terrestrial Ecology Research Unit Report, Univ. of Port Elizabeth. www.zoo. upe.ac.za/step Vlok, J.H.J., Euston-Brown, D.I.W. & Cowling, R.M. 2003. Acocks’s Valley Bushveld 50 years on: new perspectives on the delimitation, characterisation and origin of subtropical thicket vegetation. S. Afr. J. Bot. 69: 27–51. Webb, L.J. 1978. A general classiﬁcation of Australian rainforests. Australian Plants 9: 349–363. White, F. 1983. Vegetation of Africa: a descriptive memoir to accompany the UNESCO/AETFAT/UNSO vegetation map of Africa. UNESCO, Paris. White, F. & Moll, E.J. 1978. The Indian Ocean coastal belt. In: Werger, M.J.A. & Van Bruggen, A.C. (eds), Biogeography and ecology of southern Africa, pp. 561–598. Dr W. Junk, The Hague. World Wildlife Fund 2001. The heat is on…impacts of climate change on plant diversity in South Africa. National Botanical Institute, Kirstenbosch. Zachos, J., Pagani, M., Sloan, L., Thomas, E. & Billups, K. 2001. Trends, rhythms, and aberrations in global climate 65 Ma to present. Science 292: 686–693. Albany hicket Biome 567

Log In

Albany Thicket Biome

Albany Thicket Biome

Related Papers

RELATED PAPERS