A phyt osociological classification of the vegetation of the Jack Scott Nature

The vegetation of the Jack Scott Nature Reserve in the Central Bankenveld Veld Type is classi­ fied chiefly by the Braun-Blanquet Table Method. Habitat features, physiognomy, total floristic composition, differentiating species, woody plants and prominent grasses and forbs are presented for each community. Characterizing habitat features, in order of importance for the communities, are: exposure, soil texture, geology, slope, aspect, degree of rockiness and previous ploughing. The classification correlates well with the major physiographic and climatic variation in the Reserve and generally does not cut across main physiognomic types. The communities are potentially homo­ geneous management units.

The Jack Scott Private N ature Reserve is located 50 km w est-northw est of Pretoria in the Central V ariation o f A cocks ' (1953) Bankenveld Veld Type and covers approxim ately 3 100 ha (Fig. 1). The Bankenveld covers approxim ately 2 356 800 ha or 2 % of the area o f South Africa, and the C entral V ariation contains no state or provincial nature reserves. C onservation o f vegetation in this veld type variation is therefore at present dependent on m anage ment policies o f private landow ners (Edw ards. 1972a).
The purpose of this study was to provide a classi fication of the vegetation o f the Jack Scott N ature Reserve into ecological units correlated with stable and perm anent habitat conditions, distinguishing, therefore, areas o f uniform potential for m anage ment purposes. To this end. the classification is based mainly on the presence and absence o f groups o f associated species which show sim ilar response to the environm ent (G oodall. 1953). A ssociation-analysis (W illiams & Lam bert, 1959(W illiams & Lam bert, & 1960 was used to obtain a first approxim ation o f such a classification and was then supplem ented by the Braun-Blanquet Table M ethod (W erger. 1973. *1974).

History and management
The study area has been m anaged as a nature reserve for alm ost two decades, prior to which it belonged to m ining com panies for more than half a century. Occasional small diggings, old. deserted stone enclo sures and a few abandoned farm lands with charac teristic vegetation, bear witness to earlier hum an activities. Historical records indicate that fires occurred annually until the fifties, but are now restricted by roads and firebreaks. Except for fire breaks. no fixed burning program m e has been followed although some land was recently burnt to remove excess plant litter.
The Reserve is fenced with a game fence and is not sub-divided into camps. Nevertheless, dom estic anim als and game do not exert a hom ogeneous in fluence on the vegetation. A bout 100 ha of land surrounding the living quarters of farm labourers are overgrazed and tram pled by their restricted num ber o f dom estic stock.
G am e species occurring mainly in the grasslands are blesbuck, black wildebeest, zebra, springbuck and gemsbuck. A reas around salt licks are extremely tram pled and heavily grazed by game. Firebreaks, burned triennially on the same strip o f land, attract a considerable num ber o f game and are heavily grazed in some areas. A high dolom ite grassland area where these anim als concentrate, is also overgrazed and tram pled, but other grasslands are generally lightly grazed and in good condition. Giraffe, kudu, bushbuck and nyala concentrate mainly in the savanna and forest areas where they have little apparent influence on the vegetation. Also occurring in the reserve are eland, im pala, blue wildebeest, m ountain reedbuck, ostriches, jackal, leopard and brown hyaena. The ungulates are com pletely protected from hunting and efforts are being m ade to eradicate predators in order to increase the ungulate popula tion. Blesbuck are the m ost num erous o f the game species and num bered over 400 in January, 1972 (M ason, personal com m unication).
Exotic plants in the Reserve include a num ber of weeds, mostly annuals, in disturbed areas; a small num ber o f woody plants, such as Salix babylonica, Acacia dealbata and Melia azedarach along stream s, an Opuntia species on some steep slopes and a single Prunus persica tree in a stand o f natural vegetation; a local sward o f Pennisetum clandestinum and lawns o f Pennisetum clandestinum and Phylla nodiflora at two recreation areas.
A part from a relatively limited area around residen tial quarters, overgrazed and tram pled areas in d olo mite grassland, and a few small, isolated, heavilytram pled areas, the vegetation over most o f the Reserve is thus uncultivated and little disturbed by hum an and animal agency.

Physiography
Geological form ations in the Reserve are of the Transvaal System where it form s the southern rim of the Bushveld Basin with rocks dipping north at 15 to 30° (H aughton. 1969). F orm ations occurring in the Reserve (Fig. 2) are. from below and from south to north; shale slopes of the Timeball Hill Stage. This ridge is the southernm ost of three parallel ranges which m ark the transition from W itw atersrand high grassland to N orthern Transvaal wooded vegetation. The northern boundary of the Reserve runs along the sum m it o f this ridge with the highest points between I 520 m and 1 580 m in the west and between 1 360 m and I 420 m in the east. The rocky sum m it and northern slopes o f this range are formed by layered quartzite, which is more resistant to w eathering than the shale buried underneath south-facing talus slopes.
Diabase intrusions are largely limited to the northern part o f the Reserve where the dykes are associated with long north-south depressions and drainage lines in shale and quartzite.
Soils in the Reserve are generally residual and shallow. W eathering of dolom ite by solution of calcium and magnesium carbonates produces a silica rich sandy loam soil with m anganese and iron concretions. C hert weathers m echanically to a silicarich sandy loam soil. Shale, consisting mainly of iron-rich alum inium silicates produces a typical yellowish to reddish clay loam soil with m any term ite m ounds. Q uartzite, being a m etam orphic sandstone, form s a sandy soil mixed to a greater or lesser degree with finer clay material from the surrounding shale. Soil from the iron and magnesium-rich diabase is mixed with shale and quartzite colluvium. Soils associated with diabase dykes have a clay loam texture.

Climate
The Reserve is situated in a sum m er rainfall area with tem perate summers and frosty winters, classified as Cwb-clim ate in K oppen's system (Trew artha, 1954).
Average total radiation measured in Pretoria on a horizontal surface varies from between 560 and 580 ca l/c m 2/d a y in Decem ber, January and February to between 340 and 360 c a l/cm 2/d a y in May, June and July. Direct radiation on north-facing slopes at 26° S latitude is higher than on south-facing slopes, parti cularly during winter m onths. This difference in winter radiation becomes even more pronounced since diffuse radiation, which is not aspect dependent, accounts for only 2 0°/ of the total radiation in June as against 36% in January (Shulze. 1965). D ata from Pretoria (W est End), Pretoria (Forestry) and Irene (Fig. 1), suggest that tem peratures are lowest in June and July, with average m onthly m inim a about -5 C and an extreme minimum o f about -8 ,7 C (W eather Bureau, 1954). The average m onthly maxima in the hottest m onths from Novem ber to February can be as high as 33,7° C and the extreme maximum recorded at Pretoria (Forestry) is 37, 8 C during N ovem ber. The average period with at least occasional frost stretches from about April to Sep tem ber with frost usually occurring daily from May until August (Schulze, 1965).
Considerable variation in micro-and meso-climate may be expected in the Reserve due to variation in topography, soils and vegetation structure. The highlying southern part o f the Reserve and tributary valleys of the Skeerpoort River that have been cut through the chert divide, are exposed to cold catabatic winds flowing from the south during many clear, calm winter nights. Frost in valley bottom s suggests the occurrence o f therm al belts in sheltered valleys with sum m its cooling more than slopes and cold air collecting in valley bottom s. T em peratures on northfacing slopes will generally be higher than on southfacing slopes as a result of differences in am ount of radiation received.
Some idea o f the wind regime in the Reserve can be obtained by extrapolating from Pretoria and Jan Sm uts w eather stations (Schulze, 1965). N ortherly to easterly winds sim ilar to those experienced in P retoria are expected to predom inate slightly during sum m er, a strong predom inating south-w esterly com ponent, during winter. The strongest winds in the region are usually south-w esterly to southerly gusts o f short d u ratio n , accom panying thunder storm s, with the strongest winds occurring mainly in spring (Septem ber to N ovem ber). W hirlw inds due to strong instability and convection may occur on hot sum m er days.
Rain occurs m ainly as showers and thunderstorm s o f short duration. Average annual rainfall, based on d ata from M aryvale, H artebeeshoek and K rom draai ( Fig. 1), is between 670 and 745 mm with 85-90% falling from O ctober to M arch (W eather Bureau, 1965). Hail storm s occur, on the average, on four to five days per year, mainly during the rainy season (Schulze, 1965). A more detailed classification and 1: 30 000 vegeta tion m ap by Wells (1964) divided the vegetation on a structural and ecological basis into forest patches, tree com m unities, grasslands and m arshy areas. Tree com m unities, separated floristically from one another on the basis o f dom inant trees, were Protea caffra veld, Protea rouppelliae veld. Acacia cafjra veld, Acacia karroo veld and Burkea africana veld. G rasslands were divided physiographically into Valley G rasslands, Rocky G rassland, and Highland G rassland.

M ETH O DS OF SA M PLIN G A N D SY NTH ESIS
Samples were divided pro rata on an area basis am ong a num ber o f geom orphological vegetationphysiognom ic units delineated on aerial photos and were placed at random within these units. A minimum o f ten sam ples per unit was regarded as sufficient. A fter placing 188 samples, only old farm lands were undersam pled (i.e. contained less than 10 samples) and they were therefore supplem ented with four additional samples. Subsequent to sam pling the 192 sites, an additional 37 sam pling sites were placed in the following classes, shown by a field check o f geological-physiognom ical variation to be undersam pled: two sites in wooded vegetation on dolom ite; five on w ooded vegetation on shale w ithout quartzite talus, and ten sites each on diabase, quartzite and m agnetite-quartzite.
The total num ber o f sam ples taken in the reserve was 229, giving an average sam pling intensity o f one per 13,5 ha.
Scheepers (personal com m unication) found a rectangular q u ad rat o f 4 m X 4 m the most efficient for highveld vegetation that is sim ilar to large parts o f the Reserve. The same size and shape were used in this study.
Physiographic data recorded include geology* rockiness, geom orphology, aspect and slope. Surface stones and soil colour, texture and stoniness were also noted for the top 5 cm o f soil. Percentage projected canopy cover and height for each stratum , as well as total percentage canopy cover, were recorded.
All vascular plants in quadrats were recorded and additional species occurring within 2 m of quadrats were noted separately. For 184 quadrats a Braun-Blanquet cover-abundance value (K ershaw , 1964) was estim ated for each species. A list o f trees and shrubs occurring within the same stand o f vegetation near sam pling sites, was included as part o f each relevé.
A first approxim ation of the final grouping of quadrats was obtained by norm al associationanalysis (W illiams & Lam bert, 1959(W illiams & Lam bert, , 1960. o f all relevés, and species occurring in eight or more relevés. To obtain a polythetic classification as well as an inverse analysis, relevés, and also species occurring in two or more relevés were further arranged following the B raun-Blanquet approach (Coetzee, 1972(Coetzee, . 1974M uller et al, 1972;W erger. 1973. 1974).

PLANT C O M M U N ITIES
The hierarchy o f plant com m unities recognized in the Jack Scott N ature Reserve is based on Braun-Blanquet tables which are sum m arized in a Sum m ary or Rom an The num ber of relevés sum m arized in a colum n is indicated in the table.
No attem pt is made at fixing the ranks o f syntaxa and the general diagnostic value o f species, which are im portant considerations when nam ing syntaxa in accordance with the nom enclatural principles o f the Braun-Blanquet School (W erger, 1973). Since priority is generally recognized in the B raun-Blanquet School, inform ation from a wider area is desirable in order to avoid prem ature ranking and nam ing o f syntaxa.
The nam ing of vegetation types is here based on a com bination of prom inent species, vegetation struc ture and habitat, and the names are diagnostic within the reserve when applied in their hierarchical context. Structural term s are those defined by Fosberg (1967). Com m unities are classified structurally and functionally into Fosberg's system with the code for each form ation given in brackets after each form ation name.
Lists o f woody plants occurring in com m unities include plants noted around quadrats in the same stands o f vegetation.
G rass, forb and sufTrutescent species with a cover abundance o f two or more (i.e. very abundant or covering 2 5 % or more o f the area) in at least 25% o f the relevés representing a com m unity, arc listed in Table 2 as prom inent species in the grass stratum o f that com m unity.    IV  1  1   III  I   I III  I   1 I III III II   III III  I  I III III  I  V  I 1  III II  I  III  I II  I II  I  I I I  V IV  I  I  III II   I III  I  1 V  I  III  III  I  III   IV V IV 11 IV  IV IV  V III  IV III  I I III   III IV III 1 11   I II III III III   11 1 III  I  III  I  I   II  I  I  I II   I II III  I I I I   V V II III 11  IV II III III IV   III II V IV IV   III IV  III II   11 III   11 II III   II  I III   1 III II  IV  1  III III  11 II  I  11 I I   III   I I   I I fS <N fN n iv I II V  II   II  I II   I  II   -I N  0 -1   IV III IV  II II III  III III II   III  1 II  I V  I  II   II I   III   II   IV   III   11 IV   III III III  III II II   IV  III  III  II

Diabase and dolomite vegetation
This vegetation includes savanna and grass form a tions on diabase and dolom ite and is characterized by the presence of the Eustachys mutica species group (Table 1). Eustachys mutica, which occurs in all these com m unities and has a high fidelity for this vegetation, is associated with soils derived from diabase and dolom ite that are both rich in bases. Eustachys mutica is negatively associated with the Loudetia simplex group (Table 1), which is charac teristic o f the poorer soils on chert, shale and q u a rt zite.

.Acacia caffra Savanna on diabase
This com m unity occurs on the clay-loam soils of long depressions on diabase dykes, where the soil is moister and presumably, relatively rich in bases (Fig. 4).
The structure is generally deciduous thorn savanna (112/3) with Acacia caffra as the m ost prom inent tree. The Artemisia affra species group (Table 1)
The following shrub and tree species were recorded in relevés o f the com m unity with percentage presence indicated in brackets:

.2 .2 Acacia caffra-R uellia co rd ata Savanna
This mesic com m unity o f sheltered Acacia caffra valley vegetation, occurs on the lower parts o f northfacing slopes o f less than 30% and on south-facing slopes th at have over 12% slope. Structurally, the com m unity includes deciduous tho rn savanna (112/3) and m icrophyllous deciduous thorn savanna (1K2/5), with Acacia caffra as the most prom inent woody species (Fig. 5).
Several species, notably the dom inant grasses Setaria perennis, Eragrostis curvula and Themeda triandra occur in com m on with m any exposed cool, higher-altitude com m unities. These grasses, as well as the following species, differentiate the cooler mesic from the warm xeric variation o f the sheltered valleys:

.3 Grasslands and C ussonia paniculata Savanna on dolomite
Vegetation characterized by the Trichoneura grandiglumis species group occurs on the gently undulating dolom ite highlands in the south o f the Reserve and on the steep valley slopes form ed by tributaries o f the Skeerpoort River th at have cut through the chert.

.1 Grasslands on gently undulating dolomite high land
Two grassland com m unities on virtually pure dolom ite high terrain with slopes o f less than 12% (Fig. 6) are differentiated from grassland on steep, mixed dolom ite-chert slopes by the following species:
Structurally this com m unity falls into Fosberg's (1967) seasonal grass steppe (2G 2/1). Ozoroa panicu-losa occasionally occurs as an isolated shrub. The com m unity is characterized by Fingerhuthia sesleriaeformis, Euphorbia rhombifolia and Sutera burkeana and is further differentiated from the less rocky grassland on gently undulating dolom ite highland by the constancy o f the following species: Elephantorrhiza elephantina is a prom inent forb.
(b) G rassland on non-rocky dolom ite areas Rocks are few and inconspicuous in this com m unity which in heavily-grazed parts has the appearance of seasonal orthophyll m eadows (short grass) (1M 2/1), and in lightly-grazed areas may be classified as seasonal orthophyll tall grass (1L2/1). Euphorbia inaequilatera, an apophyte, is charac teristic, probably as a result o f heavy grazing. Some o f the following species, which differentiate this com m unity from the previous, are m ore constant in this com m unity, probably also as a result o f grazing pressure: Large areas in this com m unity are heavily grazed, especially firebreaks and the sum m it areas th at are constantly overgrazed and severely tram pled. Elyonurus argenteus increases in heavily-grazed parts o f the grassland. This is clearly evident when grazed areas within the Reserve are com pared with ungrazed areas outside. On firebreaks in lower parts o f the area where there is hardly any grazing, it can be seen th at within three years litter accum ulates to such an extent th at fire becomes necessary to m aintain the present vegetation.

.3 .2 Grassland and C ussonia paniculata Savanna on steep dolomite slopes
This vegetation type occurs on steep er-th an -12 % rocky slopes o f dolom ite mixed with chert, th at are exposed to cold southerly w eather (Fig. 8). It includes seasonal orthophyll tall grass (1L 2/1) and m esophyllous, evergreen sclerophyll savanna [111/2 (a)] with scattered C. paniculata trees on south-facing slopes in these exposed valleys.
The following species differentiate grassland and Cussonia paniculata Savanna o f steep dolom ite slopes from the two grassland com m unities on gently undul ating dolom ite highland: (i) Pellaea calomelanos and Vellozia retinervis, which occur on rocky slopes; (ii) Microchloa caffra, which occurs on rocky dolom ite slopes in exposed areas as well as in mesic areas o f sheltered valleys: (iii) Tristachya rehmannii, which is a d om inant grass in this exposed valley vegetation, and Bulbostylis burchellii. Both species are found on sandy loam soils o f exposed areas, including highlands: (iv) Schizachyrium sanguineum and Urelytrum squarrosum, prom inent in this vegetation (Table 2) and Loudetia simplex, are three species found on acid soils derived from chert, quartzite and shale; and (v) Rhynchelytrum setifolium, another prom inent grass in this com m unity, and one which occurs in all com m unities o f the Reserve, is m arkedly m ore constant on steep slopes o f exposed valleys than on the gently undulating dolom ite highland.

. Chert vegetation with or without scattered small rock outcrops
Rolling chert grassland covers m ost o f the thick chert cap o f the high central-w estern part o f the Reserve whereas Protea caffra Savanna occurs on chert hills and sum m its in the m ore strongly-dissected central and central-eastern parts where the chert is thinner (Fig. 9).
The chert grasslands have a num ber o f charac terizing species that occur neither in the chert savan nas nor in dolom ite and shale vegetation. But the only species th at differentiate chert savannas from chert grassland occur also on diabase, shale and dolom ite, indicating a relationship o f the chert savanna to these latter com m unities. The difference between grasslands and Protea caffra Savanna on chert slopes o f less than 30% cannot be related to any observed differences in geology, soil texture, rockiness, stoniness, altitude, slope, aspect or disturb ance, other than the previously m entioned thickness o f the underlying chert cap. On chert slopes o f more than 30% , Protea caffra Evergreen Savanna occurs on south-facing slopes, and deciduous savanna on north-facing slopes. The chert vegetation is charac terized by the Monocymbium ceresiiforme species group (Table 1).

Grasslands on chert and chert-rich dolomite
Seasonal orthophyll tall grass (1L 2/1) on chert and mixed chert-dolom ite soils are characterized by Digitaria brazzae and Oxygonum dregeanum and further differentiated from savannas on chert by: (i) Digitaria monodactyla and Lotononis tenella, which also occur on steep dolom ite slopes in exposed valleys with chert-capped sum m its, where a chert influence also exists, and in non-rocky dolom ite grasslands, where the effect o f the dolom ite parent m aterial has dim inished as a result o f leaching; and (ii) Kohautia amatymbica and Pentanisia angustifo lia , which occur also on shale.

.1 .1 Grasslands on chert-rich dolomite
A bout 50% o f the dolom ite region is paricularly rich in chert and has grasslands characterized by Hemizygia pretoriae and Hermannia lancifolia. These grasslands are further differentiated from grasslands on pure chert by Digitaria tricholaenoides, Geigeria burkei subsp. burkei and Babiana hypogea.
(a) G rassland on rocky chert-rich dolom ite areas The rocky variation o f chert-rich grassland, found on m oderate to steep slopes, is differentiated from the non-rocky variation by:  Leucas neuflizeana, which is restricted to chert and chert-rich dolom ite soils; Polygala hottentotta, which occurs also on dolom ite o f the highlands and cooler, exposed valleys; Crabbea angustifolia, which is restricted to dolom ite and chert; and Diplachne biflora and Setaria perennis, with wider distributions.
(ii) The com m unity o f south-facing slopes is characterized by Helichrysum galpinii and Sporobolus eylesii and differentiated from the north-facing slope com m unity by: Helichrysum adscendens, characteristic o f the vege tation on south-facing shale, chert and chert-rich dolom ite slopes; Pentanisia angustifolia and Thesium transvaalense, which occur mainly on highland chert and shale soils; and Dicoma gerrardii, which occurs widely on dolom ite o f exposed highlands and on chert The distributions o f the differentiating species o f this com m unity and com parison with those o f the form er com m unity, suggest that the two com m unities occur on soils with differing nutritional status. The com m unity o f south-facing slopes is differentiated by species th at are associated with poor soils and cool, mesic conditions, whereas differentiating species o f the com m unity on north-facing slopes have wider distributions on dolom ite. (b) G rassland on non-rocky, chert-rich dolom ite areas.
The non-rocky, chert-rich grassland is differen tiated from the two com m unities on rocky, chertrich dolom ite by Anthericum cooperi, which charac terizes grassland on non-rocky dolom ite and nonrocky, chert-rich dolom ite, and Digitaria brazzae, which is otherwise restricted to chert-derived soils.

.1 .Grasslands on chert
G rasslands on chert are differentiated from grass lands on chert-rich dolom ite by Nolletia rarifolia, which is characteristic o f the vegetation on soils derived from chert and shale. (a) G rassland on rocky chert areas.
This grassland is distinguished from grasslands on non-rocky chert areas by Loudetia simplex, Vellozia retinervis and Schizachyrium sanguineum. (b) G rassland on non-rocky chert areas.

.Savannas on chert.
Savannas on chert are differentiated from grass lands on chert and chert-rich dolom ite by: (i) Ruellia cor data, which also occurs in wooded vegetation o f chert areas containing m any boulders, on diabase dykes and in all dolom ite com m unities; (ii) Heteropogon con tortus, which also occurs on diabase dolom ite and shale; (iii) Pellaea calomelanos, which is very constant on rocky dolom ite slopes and in chert areas with m any boulders; and (iv) Oxalis obliquifolia and Senecio serra, occurring also on diabase and in some dolom ite and shale com m unities.

..1 Deciduous savanna on chert
Deciduous, broad, sclerophyll shrub savanna (1K 2/2) occurs on north-facing chert slopes th at have a slope angle o f more than 30%. The com m unity is distinguished from evergreen savannas on chert by Ochna pulchra and Sphenostylis angustifolius. The following woody species were noted in and near quadrats with the percentage presence given in parentheses:

Fagara capensis
O f the four sam ples representing this com m unity, three are very fragm entary stands, which explains the low percentage presence o f w oody species.

..Protea caffra Evergreen Savanna on very steep south-facing chert slopes
Evergreen broad sclerophyll shrub savanna (1 K l/2 ) occurs in exposed areas on south-facing chert slopes with m ore than 30% slope angle. The com m unity, represented by only three relevés, is characterized by Helichrysum setosum, Mohria cajfrorum and Senecio serra and also differentiated from other chert savan nas by: (i) Crassula transvaalensis, Monocymbium ceresii-J orme and Hemizygia pretoriae, otherwise restricted to grasslands; and (ii) Helichrysum adscendens and Alloteropsis semialata, which are most constant in com m unities o f steep to very steep, south-facing slopes underlain by shale and chert-rich dolom ite.

..3 Protea caffra Evergreen Savanna on chert slopes o f less than 30%
Species th at differentiate this com m unity from Protea caffra Evergreen Savanna th at occurs on very steep, south-facing slopes, are: Chaetacanthus burchel lii, Setaria perennis, Themeda triandra, Parinari capensis.
Two variations o f the com m unity occur, the m ajor variation and an ecotonal variation occurring on the transition to Acacia caffra Savanna o f sheltered valleys. Both variations are evergreen broad sclero phyll shrub savanna (1K 1/2) with Protea caffra form ing the upper stratum and Ochna pulchra, which is an abundant shrub in the grass layer.

(a) Protea caffra-Bulbostylis burchellii Savanna
This main variation o f the com m unity is differen tiated from the ecotonal variation by:

Shale vegetation
Vegetation on shale includes evergreen savannas on steep south-facing slopes and on sum m its, deciduous savanna on steep, rocky slopes, at low altitudes, and grassland on gentle slopes and steep, non-rocky north-facing slopes (Fig. 10). These com m unities are characterized by the Bulbostylis oritrephes species group (Table 1)

Protea caffra Evergreen savannas on shale
The Protea evergreen broad sclerophyll shrub savannas ( I K 1 /2 ) on shale include three com m unities on sum m its and south-facing slopes with m ore than 12% slope o f the Timeball Hill Stage. The upper stratum consists only o f low Protea caffra trees. The characteristic species o f these savannas is Vernonia natalensis, and they are differentiated from other com m unities on shale by Protea caffra, Pearsonia sessilifolia and Rhynchosia totta.

.1 .1 Protea caffra-A lloteropsis sem ialata Savanna o f non-rocky, upper pediment slopes and nonrocky summits
This com m unity occurs on very steep, upper pedim ent slopes and sum m its on soil mainly derived from shale but usually mixed with quartzite colluvium. The com m unity is characterized by Senecio erubescens and a Polygala sp. (BJC795) and is differentiated from other evergreen savannas on shale by: (i) Alloteropsis semialata and Helichrysum adscendens, both occuring also on very steep, south-facing chert slopes and south-facing, chert-rich dolom ite slopes; and (ii) Thesium transvaalense, which has a wide distri bution on chert and chert-rich dolom ite.
Protea caffra Savanna o f non-rocky, upper slopes and sum m its is also differentiated from Protea caffra Savanna on lower pedim ent slopes by Polygala amatymbica and Loudetia simplex. (ii) Pellaea calomelanos and Vellozia retinervis which occur widely on rocky areas; and (iii) Anthospermum rigidum and Rhynchelytrum seti folium , two widely-occurring species.

.2 Grasslands and deciduous savanna on shale
Deciduous shrub savanna (1K2) on shale is repre sented by only three relevés from steep rocky slopes in low areas o f the north-eastern part o f the Reserve and includes m icrophyllous deciduous thorn shrub savanna (1K 2/5) with Acacia caffra as the m ost prom inent woody plant, and deciduous, broad sclerophyll shrub savanna (1K 2/2) with Mundulea sericea. Seasonal orthophyll tall grass (1L2/1), represented by 19 relevés, occurs on non-rocky, north-facing slopes steeper than 12% and on all slopes with a less-than-12% -slope angle, with or w ithout shale outcrops.
G rasslands and deciduous savanna on shale are characterized by Phyllanthus incurvis and further differentiated from evergreen savannas on shale by:

Vegetation with abundant large boulders, on quartzite outcrop and on massive chert outcrops
This vegetation is characterized by the Aristida transvaalensis species group (Table 1). Q uartzite com m unities, which occur on the sum m its and northfacing slopes o f the Timeball Hill Stage, are less exposed to cold winds from the south than the chert com m unities.

.5 Steppe scrub and scrub on massive chert outcrops
The com m unity is characterized by Sutera caerulea and includes deciduous sclerophyll steppe scrub (2B 2/2) and deciduous sclerophyll scrub (IB 2 /3 ), with plants growing in crevices and very shallow humic sandy loam soils am ongst massive solid chert rocks.
The following woody species were recorded:

. Grasslands on abandoned farm lands
These secondary grasslands include seasonal o rth o phyll tall grass (1L2/1) and seasonal orthophyll meadows (short grass) (1M 2/1) and are characterized by the Cynodon dactylon species group (Table 1). Twelve o f the thirteen quadrats in abandoned lands were on clay-loam soils. These quadrats do not show a very localized variation on sandy-loam soils o b served to be dom inated by Eragrostis gummiflua, which is a prom inent grass on such soils. The two variations that were sampled, are:

I Cynodon dactylon-Them eda triandra Grassland
This com m unity, representing a later stage in the secondary succession, is differentiated from Cynodon dactylon-Conyza podocephala grassland on abandoned lands, by:

Krantz, riparian and kloof communities
The vegetation in these habitats was not sampled by quadrats and is not included in Table 1. The following is a general description o f this vegetation. 6 . 1 Krantz vegetation K rantz com m unities include a range of form ations, namely evergreen, succulent steppe scrub (2B1/5) and evergreen, succulent shrub steppe savanna (2E1/4) in which Aloe mutabilis is a prom inent species: deciduous sclerophyll steppe scrub (2B 2/2); and deciduous sclerophyll shrub steppe savanna (2E2/2).
A chasm ophyte. f icus ingens, is conspicuous on krantzes, and Aloe mutabilis occurs generally in rock crevices and in shallow soil against shale krantzes along the Skeerpoort River and its tributaries (Fig.  12). A bundant shrubs and trees include: (a) Broed-ieafed seasonal submerged meadows (1P2/2) in which Berula thunbergii, a rooted plant with floating leaves, is abundant.
(e) Seasonal orthophyll tall grass (1L2/1), in which dense stands o f Hyparrhenia tamba occur on flat areas, as well as on slopes and along stream s. In some places isolated individuals o f riparian-forest tree and shrub species, o r o f Acacia karroo occur in this tall grass. In localized places Hyparrhenia tamba also form s a dense undergrow th in riparian forest and in Acacia karroo deciduous thorn scrub (thornhush) (1B2/4).

.3 Riparian scrub
This scrub occurs on flat areas and gentle slopes in and along stream s, generally in less sheltered areas than riparian forest. The vegetation includes: (a) evergreen orthophyll swamp scrub [1B1/3 (a)], with Salix woodii as a prom inent shrub or small tree.

.4 Riparian and kloof forests
These forests are found along stream s th at are sheltered by high, steep slopes, on deep soils at the foot o f krantzes, or on steep slopes in sheltered kloofs. The vegetation includes evergreen broad sclerophyll forest (1A 1 /6 ) with Olea africana as dom inant tree species, and dry-season deciduous

D ISCU SSIO N A N D C O NC LUSIO N S
The sam pling strategy used in this study adequately represented floristic types th a t cover large areas in the Reserve. Im p o rtan t types th at cover small areas and are related to obvious physiographic variation are also usually well sam pled. The floristic classification presented accom m odates all but two relevés o f the sam pled variation. The classification is related to con spicuous h abitat differences. A t a broad level, vegeta tion differences are associated with soil texture, geol ogy, exposed highlands or low, sheltered valleys, very rocky areas, and abandoned farm lands. Subdivisions into lesser com m unities are associated with slope, aspect, degree o f rockiness and geology.
The plant com m unities recognized are distinguished by their total floristic com position and are polythetically separable on the presence and absence o f groups o f associated species th at are related to specific environm ental factors. The main vegetation types th at include a num ber o f com m unities are distinguished on the basis o f their total floristic com position, which includes less conspicuous but good ecologically-differentiating species and are also fairly well differentiated by prom inent species as shown in Table 2 Table 1 and to descriptions o f com m u nities. Table 1 is incom plete in respect o f woody plants because o f the small size o f the quadrats, but the percentage presence o f woody plants in com m u nities is provided in the text. Structural, functional form ations o f krantzes, along stream s and in kloofs are largely specific for different habitats. Species lists for these physiognomic-ecological com m unities show them to be floristically well differentiated.
Finally, from this study o f a small area in the C entral Bankenveld, it is concluded th at this Veld Type V ariation includes a large num ber o f plant com m unities, which represent natural ecosystems o f which none are officially conserved (Edw ards, 1972a & b).