Patterns of endemism within the Karoo National Park , South Africa

A checklist of 864 plant taxa representing 355 genera and 93 families is given for the Karoo National Park. A total of 121 species are endemic to the Nama-Karoo, with Asteraceae the most common with 33 taxa. followed by Mesembryanthemaceae with 26 taxa. Phytochorological affinities indicate that 19.8% of the species are from the NamaKaroo Biome only, another 19.8% are distributed over two biomes, and 41% of the species have a widespread distribution. The Karoo National Park conserves 30% of the recognized endemics of the Nama-Karoo Biome.

The vegetation of the upper plateau, on top of the Nuweveld Mountain Range, consists of montane grass land on undulating rocky dolerite.These higher areas contain many taxa known to occur in the winter rainfall area of the southwestern Cape, whereas areas with soils derived from doleritic origin on the middle plateau sup port numerous summer rainfall species (Figure 2).This combination has allowed for succulents of considerable interest (P.Bruyns pers.comm.).The upper plateau of the Nuweveld Mountain Range falls away in a northerly direction (Figure 2), with a rapid change in vegetation from the mesic vegetation to a xeric dwarf shrub land scape.typical of the lower elevations south of Beaufort West.In these areas, dolerite-derived substrate and deep soils are replaced by more fertile sandstone, siltstone and mudstone-derived soils.
On the dolerite of a slightly lower middle plateau (Figure 2), montane grassland is replaced by a grassy shrubland.On the low-lying plains a strong aridity gra dient can also be detected from east to west, with spars er.grassy, succulent taxa in the west and dwarf shrubs dominating to the east.Rubin & Palmer (1996) created a baseline inventory of the homogeneous plant communities of the Park.This study explores the floristic composition of the Karoo National Park, relative to the floristic richness of the rest of the Karoo Biome.and the floristic relationship with other biomes.

METHODS
Plant species data of the Karoo National Park have been collected by many people since the proclamation of the Park in 1979.Valuable contributions were made by B. Randall, a botanist who was resident in the Park from 1987 to 1988.D. Shearing, who worked on a field guide for Karoo plants.P. Bruyns.who concentrated on succu lents and geophytes, and C. van Ginkel who started the phytosociological survey.A checklist is provided with information included after each taxon, i.e.: author name, collector's name and number, specimen location, biome distribution, and growth form.
Grass species were divided into C3 and C4 categories with the help of Watson & Dallwitz (1992), and for the rest of the plant species list, the growth form and possi ble synonyms for each species were obtained from the PRECIS database, National Botanical Institute.

RESULTS
A total of 864 species and infraspecific taxa (see checklist), representing 355 genera and 93 families (Table 2) was recorded in the study area.Two veld types are rep resented by the original section of the Karoo National Park (Figure 3), namely the Karroid Broken Veld (VT 26) which covers approximately 66% and Karroid Merxmuellera Mountain Veld replaced by Karoo (VT 42) which covers approximately 33% of the original 33 000 ha of the park (Acocks 1988).A total of 121 species (14%) are endemic to the Nama-Karoo (Table 1).Species of Asteraceae are the most common with 33 taxa, fol-

DISCUSSION
The Nama-Karoo Biome includes 21 Veld Types (Acocks 1988), and ± 2 147 taxa, 18% of which are endemic (Gibbs Russell 1987).Although the Karoo National Park only effectively conserves representative samples of one of these 21 Veld Types, namely the Karroid Broken Veld (VT 26), it nevertheless protects 30% of the recognized flora of the Nama-Karoo Biome.The Park is therefore an important conservation area.Nine families (in bold.Table 2) encompass over 50% of the species in the Park.A similar pattern was noted in the Karoo Nature Reserve near Graaff-Reinet (Palmer 1989), and as with Gibbs Russell (1987) no differential occurrence could be found for important families of the Nama-Karoo Biome.Therefore, unlike the other five major biomes, the Nama-Karoo Biome does not appear to be floristically distinct (Gibbs Russell 1987).
The major biomes fall into two groups, namely those with winter rainfall and those with summer rainfall (Gibbs Russell 1987).The Nama-Karoo Biome.which is distinguished by extreme temperature, (i.e.very hot sum mers and very cold winters,) and autumn and spring rain fall peaks (Rutherford & Westfall 1994), shares half of its species with that of the Savanna Biome.A further 30% of the Karoo Biome species are shared with the Grassland Biome and a third with the Fynbos Biome (Gibbs Russell 1987).
The Nama-Karoo Biome remains one of the least stud ied of southern Africa's biomes (Palmer & Hoffman 1996).The recent (1997)(1998)(1999)(2000) extensions of the Park incorporate further sections of the Karroid Broken Veld (Veld Type 26), and to a lesser extent, Merxmuellera Mountain Veld replaced by Karoo vegetation (Veld Type 42), as well as small areas of previously excluded Veld Types, namely Central Upper Karoo (Acocks 1988: Veld Type 27) and Mountain Renosterbosveld (Veld Type 43) (Figure 3).Central Upper Karoo or Upper Nama-Karoo (50) in Low & Rebelo (1996), occupies the central part of the upper plateau of the Upper Karoo, w hile the Mountain Renosterbosveld or Escarpment Mountain Renosterveld (60) in Low & Rebelo (1996), is located on the slopes and foothills of the Nuweveld Mountains.Very little is known about this form of Renosterveld and the conservation sta tus is very poor (Low & Rebelo 1996).
The only other Veld Type adjacent to the Park is the Central Lower Karoo (Acocks 1988: Veld Type 30), or Central Lower Nama-Karoo (54) in Low & Rebelo (1996).The area supporting this Veld Type is separated from the Park by the national road (N 1). is flat and stony and plant species given in Acocks (1988) appear to be similar to those in the Park.Nevertheless, this Veld Type was given a high conservation priority rating by Hilton-Taylor & Le Roux (1989).presumably because it was not included in a conservation area, and should be consid ered for inclusion in the Park.

CHECKLIST OF THE VASCULAR PLANTS OF THE KAROO NATIONAL PARK
The nomenclature and arrangement of the checklist follow Arnold & De Wet (1993), with synonyms/name changes provided by the National Botanical Institute.The species name (in roman type) is followed by the author name (in italics) according to Brummitt & Powell (1992), collector name and number(s) (in italics), specimen location, biome distribution and growth form.The categories are separated by commas.Lichens and fungi do not have biome distri bution and growth form details. In grasses, C3 and C4 depict the photosynthetic pathways.
FIGURE 2.-The topography of the Karoo xNationai Park against the Nuweveld Mountain Range.

FIGURE 3 .
FIGURE 3.-The expansion of the Karoo National Park and the location of the Acocks (1988) Veld Types in and surround ing the park.

TABLE 2 .
-Number of genera and species in the plant families collected in the Karoo National Park.Families in bold type encompass >50% of spp.