Vegetation of Mesas and Surrounding Plains in the Southeastern Nama Karoo, South Africa

View metadata, citation and similar papers at core.ac.uk brought to you by CORE

provided by Elsevier - Publisher Connector

Vegetation of mesas and surrounding plains in the southeastern Nama Karoo, South Africa

E Pienaar, KJ Esler* and L Mucina

Department of Botany, University of Stellenbosch, Private Bag X1, Matieland 7602, South Africa * Corresponding author, e-mail: [email protected]

Received 4 June 2003, accepted in revised form 16 April 2004

Plant community composition and distribution on and as sources of seeds and propagules for the surrounding off isolated mesas were investigated across Nama degraded plains is low, since few species are shared Karoo communities in the Eastern Cape, South Africa. between the two habitats. However, generalist, palatable Species composition and cover were measured in plots species such as Felicia muricata, Eragrostis obtusa, along a transect extending from the SE plains and Pentzia incana etc. could have some potential for future slopes, across the plateaux, onto the NW slopes and restoration. Dolerite-capped mesas such as Tafelberg plains of three mesas (Tafelberg, Folminkskop and and Folminkskop had a general slope community Buffelskop). Data were then classified using the floris- shared between the two mesas. Aspect and the expect- tic-sociological approach, assisted by the computer ed cooler, more moist conditions on SE slopes as fac- package TWINSPAN. Canonical Correlation Analysis tors determining community composition for the was used to analyse the relationship between vegeta- dolerite mesas were overridden by soil type and associ- tion and environmental patterns. Mesa communities ated nutrient status. In xeric sandstone mesas such as were found to be distinctly different from plains com- Buffelskop, soil type and associated nutrient status munities, with no shared communities between the two were overridden by aspect and slope as determinants of habitats. The distribution of communities across the community composition. Mesa habitats are generally landscape is attributed to a soil-moisture gradient. not grazed heavily by livestock due to their inaccessible Differences in habitat probably existed before the nature, and are not threatened by current land use prac- impact of domestic livestock, but overgrazing has likely tices. Plains habitats are often degraded, a conse- exacerbated the differences. The potential to use mesas quence of 200 years of selective grazing.

Introduction

Vegetation patterns in arid landscapes remain relatively cal features such as plains, dongas (erosion trenches), kop- understudied despite the fact that these landscapes com- pies (buttes) and flat-topped mountains (mesas), contribute prise 47% of all terrestrial land (UNEP 1992). One of the dramatically to landscape heterogeneity. Mesas, which are largest continuous tracts of arid land in the southern hemi- the focus of this paper, are particularly characteristic of the sphere is the Karoo semi-desert encompassing two biomes, Nama Karoo (Palmer and Hoffman 1997). These geomor- the Succulent Karoo of the winter rainfall region and the phologic features are shaped by resistant strata of the Karoo Nama Karoo occurring primarily in the summer rainfall area Sequence (dolerite/basalt intrusions) that was formed of southern Africa (Desmet and Cowling 1999). Information between 345 million years (My) (Carboniferous) and 141My on this second largest biome (607 235km2) of South Africa (Jurassic) ago. Landscape processes differ dramatically on (Rutherford and Westfall 1986, Palmer and Hoffman 1997) and off mesas due to their elevation and often steep slopes remains sparse and concentrated on a few nature reserves (Figure 1). While disturbance, particularly grazing pressure, found along the edges of the biome, as evidenced by diffi- is presumably concentrated largely on the plains and lower culties experienced by a recent vegetation mapping exercise slopes of mesas, other processes such as deposition, ero- (MacDonald 1998, Mucina et al. 2000). sion, run-off of water and soil development vary dramatical- The Nama Karoo is an arid continental meseta (high alti- ly over the habitat complex. tude plateau) experiencing hot summers and cold winters To some extent, mesas could be regarded as habitat (frosts occur often) as the entire region is situated between islands in a sea of surrounding plains habitats. While the pat- 1 000m and 1 400m above sea level, as a consequence of terns are not as distinctive as previously expected, these continental uplift. The Nama Karoo appears uniform, but the topographical features do contribute to richness and diversi- wide variety of parent materials and diversity of topographi- ty at a landscape level, particularly in the northern parts of South African Journal of Botany 2004, 70: 540–558 541 the Nama Karoo (Burke et al. 2003). This paper focuses on highly variable and patchy. Middelburg is characterised by mesas in the Middelburg district of the Eastern Cape, South continental temperature conditions with regular frosts in win- Africa (Figure 2). ter (Jones 2000). Average temperature for the district for mid The aims of the paper are firstly to investigate the extent summer is 20.9°C while the average winter temperature is to which mesas in this area support distinctive vegetation 7.9°C. types, and secondly to determine the primary ecological fac- Sampling at Middelburg occurred from April 1998 to April tors that structure the vegetation of this interesting habitat 2000, but was generally undertaken in the wetter months, complex and landscape feature. We comment on the region- and at all times the rainfall was above average. al context of our findings, and discuss the potential implica- tions of our findings in the light of conservation and man- Selection of sites agement (particularly restoration) of this semi-arid desert. Sites were established on three mesas and the plains sur- Methods

Study area a 0 250 500 750 1 000km

Vegetation of habitats on and surrounding mesas were investigated in the Middelburg district of the southern African Nama Karoo (centre approximately at 31°38’S and 25°08’E). The three studied mesas, Tafelberg, Buffelskop and Folminkskop (Figure 2b), rise from 232m to 447m above the surrounding plains. These distinctive landforms are com- posed of Karoo shale and sandstone, with two of the mesas (Tafelberg and Folminkskop) being capped with dolerite. Soils are defined as undifferentiated soils of the great escarpment (Ellis and Lamprechts 1986, Watkeys 1999). Mean annual rainfall and variation for Middelburg is 341 ± 115mm (Jones 2000). The majority of rains fall in late spring, summer and early autumn (October–March), while winter Eastern Cape, Middelburg rains comprise a small percentage of the annual rainfall. 31°38´S, 25°08´E Typical for arid and semi-arid regions, rain is unpredictable, b

Mesa plateau

Slopes Plains

Short-term soil erosion

Run-off

Sedimentation rate

Soil development

Grazing pressure

Figure 1: A characteristic mesa profile (with dolerite-capping) indi- Figure 2: The locality of sites sampled on and off three mesas in cating the three main habitats (mesa plateau, slopes, plains) and the Middelburg district of the Eastern Cape, South Africa. a) Map of the common relationships of various disturbances to the habitats. South Africa indicating the location of Middelburg, Eastern Cape Bandwidth indicates degree of disturbance. Figure adapted from Province; b) Study sites. Transects are indicated by a straight line Cooke et al. (1993) across the mesas 542 Pienaar, Esler and Mucina rounding them. In all cases, sites were located on the NW Cover was given as the maximum projected canopy cover and SE slopes and plains, representing the greatest expo- (in %) of each perennial species. Some plants do not have sure to maximum and minimum temperature extremes, a large circumference, but were very tall (1–2.5m). In such a respectively. case a higher value for cover was given than would normal- A total of 17 sites were established on Tafelberg, of which ly have been the case in order to take the spatial size of the three were on the plateau, three on each of the NW and SE plant into consideration. Bare soil/debris was defined as the slopes, and four on each of the NW and SE plains (direc- total area of visible bare soil/debris as seen from above tions taken from the centre of the plateau). Sites on the when standing next to the subplot. Total percentage cover plateau were selected in such a way that one was located on for a subplot often exceeded 100% and in extreme cases it the NW part of the plateau, one on the SE part of the was as high as 170%. plateau, and the third one in the central part of the plateau. The sites on the NW and SE parts of the plateau were not Soil sampling and analysis equal distances from the slopes, so as to minimise the pos- sibility that vegetation might occur in a pattern at set dis- Soil samples from several bulked samples (open- and tances from the cliff (formed by the dolerite cap). Sites on closed-canopy soil samples were bulked to give one open- the slopes were selected in such a way that one was locat- and closed-canopy sample per site) taken from the top lay- ed on the lower slopes, one on the middle slopes, and one ers of soil (±125mm) were air-dried and analysed by the soil on the top slopes. Sites on the plains were approximately analysis laboratories at Elsenburg near Stellenbosch 300m apart, starting as close as possible to the bottom of (Agricultural Research Council, Department of Agriculture). the slopes. Features on the plains, such as ridges or hillocks Soil was analysed for pH (KCl), resistance, acidity, contents were avoided as they may support plant communities spe- of C, Na, P, K, Ca, Mg, Cu, Zn, Mn and Bo, soil texture, cific to these features, and are not necessarily representa- stone, sand, silt and clay (detailed soil analyses presented tive of the vegetation typically found on slopes, plains or in Jones 2000). After soil analysis, open- and closed canopy plateaux. Folminkskop (1 437m, 242m above surroundings) values for the individual parameters were combined to yield and Buffelskop (1 440m, 245m above surroundings) are one average value per parameter per site. Soil depth was approximately 200m lower than Tafelberg (1 652m, 447m measured in cm using a metal stake that was hammered above surroundings). Folminkskop had a total of 15 sites, into the soil. Rock cover was estimated as a percentage in while Buffelskop had a total of 12 sites. Three sites were each plot. Slope was not quantified, but since all areas were established on the plateau of Folminkskop, but on either on a slope or level we treated slope as a nominal vari- Buffelskop only two sites were established due to its shape able. Relative soil moisture differences between plains and (not a flat plateau). On both Folminkskop and Buffelskop mesas was assumed on the basis of rock cover (cover esti- only two sites were established on each of the NW and SE mated as percentages in plots), observed runoff, plant cover slopes due to shorter slopes than Tafelberg. These sites (cover estimated as percentages in plots), elevation (mesas were located 1/3 from below and 2/3 from below on each of clearly elevated above plains and often covered by clouds the slopes. Sites on the plains of Folminkskop and while plains are not, Pienaar, pers. obs.) and soil depth Buffelskop were selected the same way as those of (measured in cm for every plot). Tafelberg. Within the constraints of the sampling design, the exact site to be sampled was selected randomly. Grazing impact

Field vegetation sampling Grazing impact was estimated according to observed dam- age to plants, trampling and erosion in the area and the Three 5m x 5m plots at each site (see above) were sampled. presence of plants normally associated with overgrazing, Ten subplots of 1m2 were selected randomly from each 5m coupled with the knowledge that sheep are excluded in x 5m plot. Sites codes on the plains refer to the position of some cases from grazing on the mesas by fences surround- the sites in relation to the relative distance from the mesas. ing them and the lack of watering points on them. Buffelskop NW plain 1, 2, 3, 4 (e.g. Field code: NWPL1, 2, 3, 4 B) would for instance refer to the four sites on the plain Classification of vegetation data on the NW side of the mesa Buffelskop, with 1 being closest to the base of the mesa and 4 being furthest away from the All available relevés were captured into the National base. Site codes for the slopes refer to the relative height of Vegetation Database (Mucina et al. 2000) using the pro- the site above the surroundings, e.g. Tafelberg SE slope gramme package TvWin1.9c (Hennekens 1996, Hennekens lower (Field code: SESL L T) would refer to the lower slope and Schaminée 2001). As a first approximation the total data on the SE aspect of Tafelberg mesa. All sites were perma- matrix was classified using TWINSPAN (Hill 1979). Further nently marked to enable future visitation. classification refinements included a series of ‘local’ Plots were sampled for cover of perennial plant species TWINSPAN analyses (those limited only to portions of the (those species surviving longer than a year). Annuals, bul- analyses table) as well as re-shuffling of species and relevés bous plants and seedlings were included whenever they aimed at optimisation of coincidence of groups of species were present in a plot. Where possible, no plant specimens with groups of relevés. The table manipulations were per- were taken from inside the plots so as not to disturb the plots formed using the program Megatab 2.0 (Hennekens 1996). in any way. The final groups of relevés were interpreted as coenotaxa Table 1: Structured relevé table of the Community Complex A (Slopes and Plateaux). The column ‘Diag.’ provides information on the diagnostic value of the taxa in the form of a composite South African JournalofBotany 2004,70:540–558 code. For instance the code A10 indicates that this particular species is considered diagnostic for the Community Group A1, while the code A11 indicates that this species is diagnostic (differential) for the Community A11. The code ‘X’ marks species of broad distribution across community spectra of the slopes and plateaux (some might still have a diagnostic value for respective plant communities within a Community Group). See Appendix 1 for species with low frequency. A, B or C in he field codes refer to the three plots sampled at each site

Running number Diag. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 Community code AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA 111111111111111111111111222222222222222222222222222222222222222222 111111111222222222333333111111111111111111111111111111222222333333

Original relevé number 64 65 68 69 70 71 66 67 63 19 20 22 23 24 21 26 27 25 72 73 74 75 76 77 29 30 13 14 15 16 17 18 28 111 112 113 54 55 56 57 58 59 60 80 31 32 33 78 79 61 62 114 115 116 118 119 120 121 122 117 105 106 107 108 109 110

Aspect ------SE SE SE SE SE SE SE SE NW NW NW NW NW NW SE - - - NW NW NW NW NW NW NW SE SE SE SE SE SE NW NW - - - SE SE SE SE SE SE NW NW NW NW NW NW

Field Code PLNWB-T PLNWC-T PLCENC-T PLSEA-T PLSEB-T PLSEC-T PLCENA-T PLCENB-T PLNWA-T PLNWA-F PLNWB-F PLCENA-F PLCENB-F PLCENC-F PLNWC-F PLSEB-F PLSEC-F PLSEA-F SESUA-T SESUB-T SESUC-T SESMA-T SESMB-T SESMC-T SESUB-F SESUC-F NWSlA-F NWSlB-F NWSlC-F NWSUA-F NWSUB-F NWSUC-F SESUA-F PLNWA-B PLNWB-B PLNWC-B NWSlA-T NWSlB-T NWSlC-T NWSMA-T NWSMB-T NWSMC-T NWSUA-T SESlC-T SESlA-F SESlB-F SESlC-F SESlA-T SESlB-T NWSUB-T NWSUC-T PLSEA-B PLSEB-B PLSEC-B SESUB-B SESUC-B SESlA-B SESlB-B SESlC-B SESUA-B NWSlA-B NWSlB-B NWSlC-B NWSUA-B NWSUB-B NWSUC-B

Bare soil (%) 9.5 8.5 20.1 20.4 20.3 14.7 14.4 9.8 11.2 9.3 19.6 3.2 4.4 1.7 8.2 3.1 7.1 10.5 29 36.5 37 26.4 29 25.2 5.2 13.8 2 3.5 2.1 2.1 7.6 1 19.3 7.9 4.1 3.4 27.8 23.4 31.1 16.8 11.1 7 6 25.3 3.1 4.6 2.8 8.6 10 8.7 6.9 24.9 4.6 4.4 5.7 11.2 10.7 25.8 21 5.1 4.4 3 3.2 2 39.8 12.8

Rocks (%) 35.1 39.2 20.5 17.5 12 32.8 42.7 53.9 47.6 60.9 47.6 68.3 63.6 67.3 59.6 66.4 70.3 56.6 34.4 26.5 30.3 38.2 33.8 44.6 81.3 61.5 73.2 66.1 70.9 80.6 75 84.4 54.5 62.6 68.4 74.3 41.6 51 43.6 61.5 67.3 70.7 70.6 35.8 70.3 65.3 62.2 59.8 55.9 63.9 64.5 36.3 77.1 53.5 84.6 82.3 74 63 60.2 80.2 86.4 88.4 82.5 85.4 51.6 65.7

Soil Depth (cm) 42.5 31.5 48.5 22.5 44.5 51 26.5 8 39.5 32 39 41.5 54.5 56 37.5 34 53.5 29 80 30 60 80 80 80 42 27.5 19.5 80 80 50 32.5 61 25 22.5 19.5 28 30.5 13 23.5 51.5 44 8 62 39 43 41 19 9.5 46.5 80 7.5 12 17 9 56 31.5 41.5 27.5 50 80 80 80 65.5 56 80 55

pH (KCl) 5.35 5.35 5.4 5.3 5.3 5.3 5.4 5.4 5.35 5.6 5.6 5.4 5.4 5.4 5.6 5.55 5.55 5.55 5.7 5.7 5.7 6.55 6.55 6.55 6.95 6.95 7.55 7.55 7.55 7.55 7.55 7.55 6.95 5.95 5.95 5.95 6.7 6.7 6.7 7.25 7.25 7.25 5.75 6.05 3.45 3.45 3.45 6.05 6.05 5.75 5.75 5.95 5.95 5.95 5.9 5.9 7.5 7.5 7.5 5.9 8.05 8.05 8.05 6.95 6.95 6.95

Resistance (ohms) 1935 1935 2065 1690 1690 1690 2065 2065 1935 1500 1500 1480 1480 1480 1500 1580 1580 1580 1770 1770 1770 1240 1240 1240 710 710 1240 1240 1240 1015 1015 1015 710 1670 1670 1670 915 915 915 735 735 735 1580 800 590 590 590 800 800 1580 1580 1230 1230 1230 815 815 545 545 545 815 1100 1100 1100 970 970 970

C (%) 3.18 3.18 2.555 2.805 2.805 2.805 2.555 2.555 3.18 3.12 3.12 2.94 2.94 2.94 3.12 2.81 2.81 2.81 0.76 0.76 0.76 1.51 1.51 1.51 2.905 2.905 2.165 2.165 2.165 1.87 1.87 1.87 2.905 2.01 2.01 2.01 1.885 1.885 1.885 1.905 1.905 1.905 1.235 1.78 1.79 1.79 1.79 1.78 1.78 1.235 1.235 2.38 2.38 2.38 1.125 1.125 1.24 1.24 1.24 1.125 0.88 0.88 0.88 1.3 1.3 1.3

Na (mg/kg) 29.5 29.5 32.5 34.5 34.5 34.5 32.5 32.5 29.5 16 16 15 15 15 16 16.5 16.5 16.5 16 16 16 18.5 18.5 18.5 15 15 11 11 11 10 10 10 15 14.5 14.5 14.5 10.5 10.5 10.5 14.5 14.5 14.5 12 16 16.5 16.5 16.5 16 16 12 12 14.5 14.5 14.5 18 18 22 22 22 18 16.5 16.5 16.5 17 17 17

Phosphate (mg/kg) 20.5 20.5 18 28.5 28.5 28.5 18 18 20.5 31 31 16.5 16.5 16.5 31 22 22 22 123.5 123.5 123.5 120.5 120.5 120.5 53 53 36 36 36 33.5 33.5 33.5 53 112 112 112 67.5 67.5 67.5 38 38 38 66 24 41 41 41 24 24 66 66 158 158 158 163.5 163.5 75.5 75.5 75.5 163.5 200.5 200.5 200.5 526 526 526

K (mg/kg) 444 444 226.5 276.5 276.5 276.5 226.5 226.5 444 285.5 285.5 320.5 320.5 320.5 285.5 244.5 244.5 244.5 175 175 175 222.5 222.5 222.5 294.5 294.5 261.5 261.5 261.5 216.5 216.5 216.5 294.5 206.5 206.5 206.5 202 202 202 247 247 247 222 286 269.5 269.5 269.5 286 286 222 222 301 301 301 207 207 427 427 427 207 445.5 445.5 445.5 455.5 455.5 455.5

Ca (me%) 8.085 8.085 7.06 6.53 6.53 6.53 7.06 7.06 8.085 7.49 7.49 7.405 7.405 7.405 7.49 7.86 7.86 7.86 5.43 5.43 5.43 10.325 10.325 10.325 21.575 21.575 50.68 50.68 50.68 38.705 38.705 38.705 21.575 7.965 7.965 7.965 15.15 15.15 15.15 41.995 41.995 41.995 6.57 9.23 6.035 6.035 6.035 9.23 9.23 6.57 6.57 7.915 7.915 7.915 5.085 5.085 27.61 27.61 27.61 5.085 27.985 27.985 27.985 11.795 11.795 11.795

Mg (me%) 4.175 4.175 4.05 4.685 4.685 4.685 4.05 4.05 4.175 3.66 3.66 3.75 3.75 3.75 3.66 3.59 3.59 3.59 1.985 1.985 1.985 1.98 1.98 1.98 3.26 3.26 2.635 2.635 2.635 2840 2.84 2.84 3.26 5.815 5.815 5.815 2.795 2.795 2.795 6.33 6.33 6.33 2.84 5.17 3.595 3.595 3.595 5.17 5.17 2.84 2.84 2.62 2.62 2.62 2265 2.265 2.175 2.175 2.175 2.265 3.015 3.015 3.015 3.41 3.41 3.41

Cu (mg/kg) 4.955 4.955 4.1 4.025 4.025 4.025 4.1 4.1 4.955 6.23 6.23 7.735 7.735 7.735 6.23 5.26 5.26 5.26 1.28 1.28 1.28 2.455 2.455 2.455 4.81 4.81 2.45 2.45 2.45 3.29 3.29 3.29 4.81 2.18 2.18 2.18 3.88 3.88 3.88 3.665 3.665 3.665 3 5.025 4.035 4.035 4.035 5.025 5.025 3 3 2.27 2.27 2.27 0.905 0.905 1.41 1.41 1.41 0.905 1.21 1.21 1.21 1.765 1.765 1.765

Zn (mg/kg) 2.94 2.94 1.95 2.005 2.005 2.005 1.95 1.95 2.94 1.845 1.845 2.525 2.525 2.525 1.845 1.575 1.575 1.575 1.005 1.005 1.005 1.055 1.055 1.055 1.53 1.53 1.715 1.715 1.715 0.81 0.81 0.81 1.53 1.695 1.695 1.695 1.83 1.83 1.83 1.205 1.205 1.205 1.72 1.365 1.065 1.065 1.065 1.365 1.365 1.72 1.72 2.215 2.215 2.215 1.23 1.23 1.04 1.04 1.04 1.23 1.935 1.935 1.935 2.765 2.765 2.765

Mn (mg/kg) 382.1 382.1 261.55 278.75 278.75 278.75 261.55 261.55 382.1 230.45 230.45 325.75 325.75 325.75 230.45 210.9 210.9 210.9 75.585 75.585 75.585 95.44 95.44 95.44 107.9 107.9 113.2 113.2 113.2 106.455 106.455 106.455 107.9 78.595 78.595 78.595 127.45 127.45 127.45 85.385 85.385 85.385 201.3 199.9 132.7 132.7 132.7 199.9 199.9 201.3 201.3 105.425 105.425 105.425 56.22 56.22 76.7 76.7 76.7 56.22 67.415 67.415 67.415 78.6 78.6 78.6

Bo (mg/kg) 0.93 0.93 0.805 0.69 0.69 0.69 0.805 0.805 0.93 0.83 0.83 0.815 0.815 0.815 0.83 0.865 0.865 0.865 0.325 0.325 0.325 0.59 0.59 0.59 0.835 0.835 0.52 0.52 0.52 0.475 0.475 0.475 0.835 0.585 0.585 0.585 0.72 0.72 0.72 0.82 0.82 0.82 0.545 1030 0.525 0.525 0.525 1030 1030 0.545 0.545 0.675 0.675 0.675 0.56 0.56 0.93 0.93 0.93 0.56 0.83 0.83 0.83 0.85 0.85 0.85

Clay (%) 21 21 20.5 26 26 26 20.5 20.5 21 20 20 25 25 25 20 24 24 24 8 8 8 14 14 14 12 12 16 16 16 13 13 13 12 12 12 12 9 9 9 21 21 21 16 25 19 19 19 25 25 16 16 12 12 12 15 15 15 15 15 15 13 13 13 17 17 17

Silt (%) 17 17 15.5 14 14 14 15.5 15.5 17 11 11 14 14 14 11 12 12 12 6 6 6 9 9 9 8 8 11 11 11 9 9 9 8 7 7 7 7 7 7 8 8 8 10.5 10 8 8 8 10 10 10.5 10.5 7 7 7 11 11 11 11 11 11 12 12 12 9 9 9

Coarse Sand (%) 62 62 64 60 60 60 64 64 62 69 69 61 61 61 69 64 64 64 86 86 86 77 77 77 80 80 73 73 73 78 78 78 80 81 81 81 84 84 84 72 72 72 74 65 73 73 73 65 65 74 74 81 81 81 74 74 74 74 74 74 75 75 75 74 74 74 543 544 Pienaar, Esler and Mucina ...... a1r+m1r1arrm rrrr ...... r.rrr...... rr....r...... rrr..r.... rrrr rrrrrr.r aaa1a1a++1 . amaabra++baar ...... rrrrrr.r.r ...... rr...... rrrr ...... r...... rrrrr ...... ar+...... +rrr..r..baabab A21 ...... r...... r...... r...... r...rrr...... A21 ...... rr+r.r....rm+rr...... rr...... A21 ...... r.r...... r...... A21 ...... r...... rr...... r...... r...... A21 ...... r...... A20 ...... rr.rr..r.....r...... r...rr...... A20 ...... r.rr...r+...rrm A20, A23 A21 ...... r..rr. A20 ...... ra...... r. A20 ...... A20 ...... r+mrr.1r+...... rr....rm.++a... A13 ...... r...+...... A13 ...... r..r...... A10 ..rr..am.r...ra.+..r....r+...... A10 rrr.r+r.rrrr+rr.rrrr.r A11 ..maaar+...... r...... A11 rrrr.r..rA11 r.+rr.rrm...... A11 rrr.rr...... r...... r...... A11 r+r.....r...... r...... A11 r..r..r...... A11 .r...rrr...... A11 ....rar+...... A11 .....rrr...... A11 ...r..r...... A20 ...... r...... rr.r..r...... r..rr...rr. A20 ...... rr.r..rr...rrr. A21 ...... rrr...... A21 ...... r.rr...... A21 ...... 1...... a.a+.ma...ra...... A21 ...... a.1...... A21 ...... A22 ...... mma...r... A11 .....r..r...... A11 ...... r.r...... A12 ...... a...rrr.r.r....r...... A12 ...... rr.r.r...... A21 ...... r.r....r...rr...... A21 ...... rrr...... A20 ...... 1...... 3...... aa.bb.33...... marbba+...ba..a.++ar..rraa A11 ...... aa...... A11 ...... rrr...... A11 ...... rrr...... r...... A11 .rr...... A11 ..r...r...... A22 ...... +r+...... A12 ...... rr. A13 ...... +abrba...... r...... r.+...... A13 ...... A22 ...... rrr...... A22 ...... r.r...... obovata i s i a a crinitum replicatum s

var. s s a cuneata albidiflora sp.

succulentum arviflorum

africanus capensi desvauxi sp. abrotanifolium africana zeyher

africana

minutiflora innatifid

brachiata sessilifoli obovatum suavissima

p sp.

africana mitrata capensi

carnosa lanuginosa cotyledonis obovata orbiculari basuticu

maximum ephedroides

sp. B

britteniae

sp. calomelanos frutescens lanata m s s s cinereum crispa

s halimifoli

ovata

burchellii a

striata

nacampseros loe Hermannia Blephari Fingerhuthia Euphorbia Lessertia Indigofera Helichrysum A A Indigastrum Cissampelo Cenchrus ciliaris Crassula Haworthia Kleinia longiflora Crassula Rhus Pelargonium Dimorphotheca Bulbine Selago saxatilis Sutera Dianthu Berkheya Crassula Diospyros austro-africana Rhadamanthus Ruschia Kedrosti Lycium Polygala Gymnosporia buxifolia Zygophyllum lichtensteinianum Blephari Pseudocrossidium Pentzi Crassula Euclea Heliophila Pachypodium Pellaea Enneapogon Rhigozu Moraea pallida Commelina Eriospermum Panicum Crassula Pseudocrossidium Eriocephalus Felicia Polygala Table 1 cont. Table Table 1 cont. South African JournalofBotany 2004,70:540–558

Digitaria eriantha X . .+baama+r11 . raa11aam. . r r+...... r.....1r...... +r.r.rr.r...... Sporobolus fimbriatus X ...... +...... 1.rmrr+r.....m+rrrr.r.++...... ma1mb+.1.r.r..... Enneapogon scoparius X ...... r1a1rb1aaaa . am+aaaaam+abbbaar+ar .+r .....+r+r+..r...... Eragrostis obtusa X ...r.+r...... r.....rr...... r...... r.r...... Aristida diffusa X r...... r.r.rm.11r+rrm+a+m11r.r++aba....rbbbaar+brm.r...... Felicia muricata X ..r.rr...r.rrrrrr.++1rrrr.r.rr..r....rr.r+1.r.r..11r.rrrrrrr...... Pentzia incana X ...1+....r...... +.r..a1a..rrr...... a1aa+mm+.....r.rr....m+...... Tragus koelerioides X am++rrrr+...... r1.1rr..r..r...... rrrr+rr.r...r...r+r....r...... Themeda triandra X-A21 b3babaaabammbarar r ...... r...... aaa.r...... Felicia filifolia X ++ . . r . 1+ . b . aaaabaaa+a1 . 1r r ...... a...... r.r.r11r+...... 1...... Wahlenbergia nodosa X +r1.r.rrr...rr.r...... rr.r...r+...... Eragrostis curvula X-A21 m m aaaar1mr r . r r r . r . 1ma++r r r . . . r r r . r r r+r+rrrrrrrrrrrr1+r...... Cymbopogon pospischilii X-A22 a r 1 1 + r a 1 + a a m m 1 r r r ...... r..rrmr.1...... r+.mr..rr...... Eustachys paspaloides X-A23 aar..r.r1rrr.rrrr.r..r..r....++r.rrr.....r..r.r...... Pegolettia retrofracta X-A24 . r ...... rr...... r.+r.....r...... r.r..r...... r...... Asplenium cordatum X-A25 .....1r1...... r.....rr..rr...... r.rr...... rrrr.r.rrr...... Heteropogon contortus X-A12 ...... rr..maaa..+.....r.+.abaaam. . rm. . . abaa111+aa+r ...... Asparagus laricinus X ...... +r..r...... a...... a...... r...r.r...ar..r...... +...... Jamesbrittenia tysonii X r+r..r...r....r.....r...r.r...... r.r...... r...... r...... Pentzia punctata X-A12 ...... +a+r1+.r.r...... r...rr.....1+.rrr...... Asparagus striatus X-A13 ...... rrr..r.r..r....rrrrr...+...... rr+arrrrr+r...... rr...... Lantana rugosa X-A14 ...... r.r.....r...... rrr...... rr...... Hibiscus pusillus X ...... rr...... r....r...... Stachys linearis X-A21 ...... rr+...... r1...... r.r...... r...rr...... Cheilanthes hirta X ...... rr.rrr..r.r.r...... r..r...... Mestoklema elatum X ...... r...1.r.....+...... r...... r+.m...... Crassula muscosa X ...... r...... rr...rr..r.r....r...... r...... r..r...... Trichodiadema rogersiae X ...... rr..rrr...... r...... r.rr...... r.r...... Helichrysum rosum X-A13 ...... r...... r1rar...... 1...r+rm1.r.mrr..+...... Pentzia quinquefida X-A21 ...... rr...... rrr+r...... Pegolettia baccaridifolia X-A22 ...... rr...... r...... 1+raar....rr Pelargonium aridum X ...... rr...... r...... r...... Tarchonanthus camphoratus X ...... r....+.....1...... a...... Euryops annae X ...... +...... r1..r...... Hermannia pulchella X ...... r...... r...... r...... Diospyros lycioides X ...... r...... rr...... a...... Fabronia abyssinica X ...... r..r...... r...r...... Sutherlandia frutescens X ....rr...... r...... Pteronia glauca X ...... r...... Boophone disticha X ...... rrr...... r...... r...... Crassula montana X ...... rr..r...... r.r...... Cadaba aphylla X ...... 1.a..+...... Melianthus comosus X ...... r...... r...... Solanum tomentosum X ...... r...... r....r.. Aristida adscensionis X ...... r.r...... r...... Chrysocoma ciliata X rr...... r...... r..r....r...... Senecio cotelydonis X ...... r...... rr...... Asparagus burchellii X ...... r...... r.r.a...... r.....rr.rrr....r.1rrrr...... Eriocephalus ericoides X ...ra....1.+...... r1a...rm.bb...... ra..r... Gazania linearis X .r...... r...... r...... Lepidium africanum X .....r...... rr...r...... Limeum aethiopicum X ...... rr...... rrrr.rr.....r.rrr..r.rrr...... rrrr.r.rrrr...... Oxalis commutata X ....r...... r...... rr...... r...... r...... Selago albida X-A22 ...... rrrr+...... r...... rr...... rrr....rr1rr.rr......

A1: Felicia filifolia–Themeda triandra Community Group; A11: Felicia filifolia–Dimorphotheca cuneata Community; A12: Felicia filifolia–Enneapogon scoparius Community; A13: Felicia filifo-

lia–Eriocephalus africanus Community; A2: Rhigozum obovatum–Rhus burchellii Community Group; A21: Rhigozum obovatum–Gymnosporia buxifolia Community; A22: Rhigozum obova- 545 tum–Pegolettia baccaridifolia Community; A23: Rhigozum obovatum–Cenchrus ciliaris Community Table 2: Structured relevé table of the Community Complex B (Plains). The column ‘Diag.’ collects information on the diagnostic value of the taxa in form of a composite code. For instance 546 the code B10 indicates that this particular species is considered diagnostic for the Community Group B1, while the code B11 indicates that this species is diagnostic (differential) for the Community B11. The code ‘X’ marks species of broad distribution across community spectra of the plains (some might still have a diagnostic value for respective plant communities within a Community Group). Alien species are marked by an asterisk. See Appendix 1 for species with low frequency

Diag.

Running number 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 Community code BBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB 111111111111111111111111111111111222222222222222222222222222222222 111111111111222333333333333333444111111111111111111111111222222333 aaaaaaaaaaaaabbbbbbbbbbb

Original relevé number 84 85 86 81 82 83 90 91 92 87 88 89 39 40 41 35 36 37 38 34 132 43 44 45 46 51 52 53 42 47 48 49 50 126 127 128 129 130 131 7 8 6 10 12 9 11 1 2 3 4 5 123 124 125 102 103 104 96 98 97 93 94 95 99 100 101

Aspect ------

Field Code SEPL2A-T SEPL2B-T SEPL2C-T SEPL1A-T SEPL1B-T SEPL1C-T SEPL4A-T SEPL4B-T SEPL4C-T SEPL3A-T SEPL3B-T SEPL3C-T SEPL4A-F SEPL4B-F SEPL4C-F SEPL2C-F SEPL3A-F SEPL3B-F SEPL3C-F SEPL2B-F SEPL2A-F NWPl4B-T NWPl4C-T NWPL3A-T NWPL3B-T NWPL1A-T NWPL1B-T NWPL1C-T NWPl4A-T NWPL3C-T NWPL2A-T NWPL2B-T NWPL2C-T SEPL2A-B SEPL2B-B SEPL2C-B SEPL1A-F SEPL1B-F SEPL1C-F NWPL2A-F NWPL2B-F NWPL3C-F NWPL1A-F NWPL1C-F NWPL2C-F NWPL1B-F NWPl4A-F NWPl4B-F NWPl4C-F NWPL3A-F NWPL3B-F SEPL1A-B SEPL1B-B SEPL1C-B NWPL1A-B NWPL1B-B NWPL1C-B NWPL3A-B NWPL3C-B NWPL3B-B NWPl4A-B NWPl4B-B NWPl4C-B NWPL2A-B NWPL2B-B NWPL2C-B

Bare soil (%) 41.6 52.9 41.1 47.3 57.7 58.8 43.5 53.5 63.3 28.3 30.5 36.5 56.8 64.3 55.9 38.7 97.7 78.3 63.3 49.2 52 90.1 88.6 76.6 75.7 91.8 76.3 70.9 37.6 73 71.6 73.6 91.6 78.4 65.6 73.3 49.6 56.4 48.6 49.1 63.6 45.6 69.6 62.7 47.7 59.4 44.3 43.6 32.9 46.8 48.7 9.9 7.6 9.3 17.9 24.1 29.5 76.8 88.6 81 76.7 86.9 77.7 83.7 83.5 85

Rocks (%) 30.2 10.9 28.3 0 0 0 0 0 0 13.3 2.7 0.3 4.5 3.3 6.3 0.4 0.1 0.4 0 0.4 0.6 0.2 0.2 0 0 0 0 0 0.1 0 0 0 0.1 0.4 23.3 12.7 9.5 15.3 19.4 2 1.4 2.5 0.5 0.4 0.9 0.5 11.7 9.6 23.6 4.4 2.4 72 74.5 70.4 0.3 62.2 50.6 0 9.6 9.8 0 0 0.1 0.8 0.2 0.8

Soil Depth (cm) 5 6 5 26.2 20.5 15.4 10.8 9.8 8.3 7.9 11.9 9.8 41 53 42.5 80 80 80 80 80 80 80 80 80 80 80 80 80 80 80 80 80 80 80 55 36.5 80 80 80 47.5 39 54 45 46 50 18 45 42 55.5 48.5 39 57.5 62 80 75 80 80 80 80 80 80 80 80 80 80 80

pH (KCl) 5.2 5.2 5.2 5.6 5.6 5.6 5.45 5.45 5.45 5.5 5.5 5.5 6.9 6.9 6.9 7.3 7 7 7 7.3 7.3 6.6 6.6 6.1 6.1 5.6 5.6 5.6 6.6 6.1 6.2 6.2 6.2 7.8 7.8 7.8 7.8 7.8 7.8 7.7 7.7 7.65 7.7 7.7 7.7 7.7 7.7 7.7 7.7 7.65 7.65 7.75 7.75 7.75 7.6 7.6 7.6 7.65 7.65 7.65 7.8 7.8 7.8 6.85 6.85 6.85

Resistance (ohms) 3275 3275 3275 2935 2935 2935 1290 1290 1290 3885 3885 3885 1230 1230 1230 835 475 475 475 835 835 730 730 900 900 1380 1380 1380 730 900 1020 1020 1020 1890 1890 1890 1750 1750 1750 775 775 1150 1120 1120 775 1120 1120 1120 1120 1150 1150 1025 1025 1025 1305 1305 1305 420 420 420 560 560 560 2530 2530 2530

C (%) 0.395 0.395 0.395 0.755 0.755 0.755 0.79 0.79 0.79 0.52 0.52 0.52 1.155 1.155 1.155 1.37 0.625 0.625 0.625 1.37 1.37 1.4 1.4 0.82 0.82 0.505 0.505 0.505 1.4 0.82 1.11 1.11 1.11 0.455 0.455 0.455 0.69 0.69 0.69 1.025 1.025 1.135 0.415 0.415 1.025 0.415 0.415 0.415 0.415 1.135 1.135 1.71 1.71 1.71 0.6 0.6 0.6 2.655 2.655 2.655 0.61 0.61 0.61 0.295 0.295 0.295

Na (mg/kg) 12.5 12.5 12.5 36.5 36.5 36.5 28.5 28.5 28.5 39.5 39.5 39.5 20.5 20.5 20.5 70 392 392 392 70 70 30 30 75.5 75.5 16 16 16 30 75.5 50 50 50 15 15 15 13.5 13.5 13.5 34 34 13 14.5 14.5 34 14.5 14.5 14.5 14.5 13 13 25.5 25.5 25.5 43 43 43 293.5 293.5 293.5 0 0 0 14 14 14

Phosphate (mg/kg) 90.5 90.5 90.5 131.5 131.5 131.5 100.5 100.5 100.5 71 71 71 80.5 80.5 80.5 309 93.5 93.5 93.5 309 309 209.5 209.5 88 88 92 92 92 209.5 88 90.5 90.5 90.5 153.5 153.5 153.5 47.5 47.5 47.5 266.5 266.5 59 40.5 40.5 266.5 40.5 40.5 40.5 40.5 59 59 134.5 134.5 134.5 109 109 109 258 258 258 337 337 337 59 59 59

K (mg/kg) 131.5 131.5 131.5 179.5 179.5 179.5 138 138 138 169 169 169 268 268 268 466 331.5 331.5 331.5 466 466 526 526 385 385 290.5 290.5 290.5 526 385 440.5 440.5 440.5 266.5 266.5 266.5 133 133 133 445 445 308.5 180 180 445 180 180 180 180 308.5 308.5 290 290 290 166 166 166 533 533 533 603 603 603 149.5 149.5 149.5

Ca (me%) 3.12 3.12 3.12 3.66 3.66 3.66 3.17 3.17 3.17 2.83 2.83 2.83 9.63 9.63 9.63 16.745 7.375 7.375 7.375 16.745 16.745 11.275 11.275 4.125 4.125 3.195 3.195 3.195 11.275 4.125 4.83 4.83 4.83 17.22 17.22 17.22 54.7 54.7 54.7 39.08 39.08 29.585 18.785 18.785 39.08 18.785 18.785 18.785 18.785 29.585 29.585 41.105 41.105 41.105 7.74 7.74 7.74 33.175 33.175 33.175 36.535 36.535 36.535 2.81 2.81 2.81

Mg (me%) 0.955 0.955 0.955 1.26 1.26 1.26 1.005 1.005 1.005 0.995 0.995 0.995 3.095 3.095 3.095 4.74 5.375 5.375 5.375 4.74 4.74 4.765 4.765 3.585 3.585 2.125 2.125 2.125 4.765 3.585 4.29 4.29 4.29 2.935 2.935 2.935 2.15 2.15 2.15 4.04 4.04 3.76 2.535 2.535 4.04 2.535 2.535 2.535 2.535 3.76 3.76 3.915 3.915 3.915 1.57 1.57 1.57 8.62 8.62 8.62 20.72 20.72 20.72 1.805 1.805 1.805

Cu (mg/kg) 0.725 0.725 0.725 0.855 0.855 0.855 0.775 0.775 0.775 0.86 0.86 0.86 2.84 2.84 2.84 5.18 4.04 4.04 4.04 5.18 5.18 2.735 2.735 2.015 2.015 1.395 1.395 1.395 2.735 2.015 2.81 2.81 2.81 1.545 1.545 1.545 1.385 1.385 1.385 1.995 1.995 1.875 1.36 1.36 1.995 1.36 1.36 1.36 1.36 1.875 1.875 1.12 1.12 1.12 0.99 0.99 0.99 4.23 4.23 4.23 2.315 2.315 2.315 0.695 0.695 0.695

Zn (mg/kg) 0.95 0.95 0.95 0.905 0.905 0.905 2.85 2.85 2.85 0.945 0.945 0.945 1.725 1.725 1.725 2.16 1.05 1.05 1.05 2.16 2.16 1.665 1.665 1.12 1.12 1.355 1.355 1.355 1.665 1.12 1.395 1.395 1.395 1.83 1.83 1.83 0.82 0.82 0.82 1.27 1.27 1.38 0.605 0.605 1.27 0.605 0.605 0.605 0.605 1.38 1.38 1.325 1.325 1.325 0.79 0.79 0.79 2.01 2.01 2.01 2.135 2.135 2.135 0.835 0.835 0.835

Mn (mg/kg) 45.19 45.19 45.19 79.915 79.915 79.915 56.525 56.525 56.525 62.3 62.3 62.3 169.55 169.55 169.55 266 212.6 212.6 212.6 266 266 202.05 202.05 173.9 173.9 146.35 146.35 146.35 202.05 173.9 293.6 293.6 293.6 79.905 79.905 79.905 51.46 51.46 51.46 138.65 138.65 98.31 63.03 63.03 138.65 63.03 63.03 63.03 63.03 98.31 98.31 66.95 66.95 66.95 70.425 70.425 70.425 290.45 290.45 290.45 196.45 196.45 196.45 41.53 41.53 41.53

Bo (mg/kg) 0.155 0.155 0.155 0.265 0.265 0.265 0.26 0.26 0.26 0.26 0.26 0.26 0.495 0.495 0.495 0.82 0.885 0.885 0.885 0.82 0.82 0.695 0.695 0.625 0.625 0.345 0.345 0.345 0.695 0.625 0.885 0.885 0.885 0.29 0.29 0.29 0.28 0.28 0.28 0.965 0.965 0.56 0.32 0.32 0.965 0.32 0.32 0.32 0.32 0.56 0.56 0.62 0.62 0.62 0.335 0.335 0.335 1785 1785 1785 1935 1935 1935 0.19 0.19 0.19 Pienaar, EslerandMucina

Clay (%) 10 10 10 10 10 10 11 11 11 11 11 11 16 16 16 22 25 25 25 22 22 22 22 20.5 20.5 13.5 13.5 13.5 22 20.5 20 20 20 12 12 12 12 12 12 14 14 13 11 11 14 11 11 11 11 13 13 13 13 13 10 10 10 32 32 32 33 33 33 8 8 8

Silt (%) 3 3 3 4 4 4 0 0 0 1 1 1 8 8 8 19 14 14 14 19 19 17.5 17.5 6.5 6.5 5.5 5.5 5.5 17.5 6.5 13 13 13 7 7 7 8 8 8 7 7 5 4 4 7 4 4 4 4 5 5 6 6 6 5 5 5 30 30 30 23 23 23 3 3 3

Coarse Sand (%) 87 87 87 86 86 86 89 89 89 88 88 88 76 76 76 59 61 61 61 59 59 60.5 60.5 73 73 81 81 81 60.5 73 67 67 67 81 81 81 80 80 80 79 79 82 85 85 79 85 85 85 85 82 82 81 81 81 85 85 85 38 38 38 44 44 44 89 89 89 Table 2 cont. South African JournalofBotany 2004,70:540–558

Ruschia intricata B10 rrraabmaa+aaa.r...... Chrysocoma ciliata B10 r+r.rra1m.rr.r...... r...... Bulbostylis humilis B10 .rrrr..rr..rrr...... r...... r......

Albuca setosa B10 ...... arr...... rrrrrrrr+.r...... r...... 4...... r. Mestoklema elatum B10 ...... +..a.rr1ar.rr+aa.r..r...... Hertia pallens B10 ...... +....r....r...... Salvia verbenaca B10 ...... r...... r..rr...... r......

Talinum caffrum B10 ...... r...r..r..rrrrrr..r...... Berkheya heterophylla B10 ...... r..rr+..rr.r.rr.r...... r Phyllobolus sp. B10 ...... a..r.rrrrr.r+.r..r...... Aridaria noctiflora subsp. straminea B10 ...... r.r.r..r...... r...... Osteospermum leptolobum B10 ...... r.a.....a+r...... Digitaria eriantha B10 ...... r...... rr...... Oligocarpus calendulaceus B10 ...... +...... rr...... Sporobolus fimbriatus B10 ...... r...... rrr...... Gazania linearis B10 ...... r...... rr......

Eragrostis obtusa B10 rr.1+r+r+rrr+.rr..r+m..rrrrrr...... Drosanthemum duplessiae B10 ..rr..m+..rmr.1armaar..rr.+..r...... Pentzia globosa B10 ...... raa...1.r1a1...... Crassula muscosa B10 r..r.r..r.rr...... r.....r....r...... Tribulus terrestris B10 ...rrr...... r...... r...... r...... Medicago laciniat* B10 ...... r...... r....r......

Oropetium capense B11 +++rrr...... Indigofera sessilifolia B11 r+r.r.1r.a1r...... +.r...... Monsonia brevirostrata B11 .rrrrrrrrrrr...... Anacampseros albidiflora B11 rr...... rrr...... r...... Cyperus usitatus B11 ...rr.arr...... Tragus berteronianus B11 ...+marrr...... Oxalis commutata B11 ...rrrrrr...... r...... Senecio radicans B11 .....rrrr.rr...... Heliophila suavissima B11 ...... rrr...... Phymaspermum parvifolium B11 ....rr....+...... Urochloa sp. B11 ...r.r...... Crassula sp. A B11 ....r...r...... Hypertelis sp. B11 ...... r.r......

Crassula sp. B12 ...... arr...... Adromischus sp. B12 ...... b++...... Jamesbrittenia atropurpurea B12 ...... rr......

Zygophyllum incrustatum B13 ...... a.1aab . . rma. aab . . r . . . . r r ...... Senecio cotelydonis B13 ...... rr1ar...... Cynodon dactylon B13 ...... r...... rrrrrr.1r...... Galenia africana B13 ...... rrr.r.rr......

Convolvulus sagittatus B14 ...... rr...... Felicia ovata B14 ...... rr...... r...... Thesium spartioides B14 ...... r.r......

Gnidia polycephala B20 ...... rrr.r...... r.r Rosenia humilis B20 ...... +rr+...... rr+ 547 548 Pienaar, Esler and Mucina .... abaar r r ...... rr+ ...... Eragrostis lehmanniana–Eragrostis rrrr.. aaaaarmar r aaaaaa+m1r r . . . . . rrrrrr.r.ra1...... r Community; B23: Eragrostis lehmanniana–Rosenia Community; B2: ...... r...... rrr Community; B12: Aristida adscensionis–Jamesbrittenia atropurpurea ...... r...r..r...... r.r...... r...... aa1 ...... rr+...... rrr...+1+baraaamrr...r+ra+ ...... r...... a.....rrr...... rrrr Community; B22: Eragrostis lehmanniana–Eragrostis bicolor Community; B14: Helichrysum lucilioides–Thesium spartioides ...... r.r...... rrr...... m.r...r..r...... r...... r1..ar.aaa...... +rr.r.r1.rr...... r ....r.a...... aa+...... r.rrarrr.r.arr....r..r...... r..rmrrr.+r...... rrr ...... r...rrr.r..rr..r.r...... +rr...... r...... r. ....rr1r..r...... rr....r.r..r..... rrrrr.rr.r+r..rrr.....r rrrr..r Community Group; B11: Aristida adscensionis–Ruschia intricata Community Group; B11: ...... a...r..rr...... r.1..1....r..rr...... rr..r....rr....r..rr..r....r+++r....r...... r...... rr.r..rr...... r...r.r.....r...... r.+rr.r...... r.....r...r...r..rr...... rr...... r...... r...... r...... rr...... r...... r...... r...... +...... r...... r.r..r....r+.r....r...... r.rr...... r...... r..+rar..ra...braba+raa1rb.brrarr....rr1...... r...r.ar+...... + . . r++ . a+a r a+ r++++1a+ r+ r r r ...... r..rr...... r...... r. .rrrrr.rrr.r1mrmrr+amr.m.r.r rrrr.... rrr++1rrr...rr+...... r...... aaa..b.1mmam+rrr.r...... rrr...... rrr...... r.r...... 1.r...... r. r ra+babbaa333+mrb . r+aa++r+r++3a r++aa1abma1abba...... 1r+r .++m1+r r+aamr+r1a+. ramaaba1mbababr r . . .++r baa.....r...... r...... 1..aaa...... 1++..rrr...... + +am...... r.rrrr..r.r...rrrrr..rrr1r1barrra.mrr X X X X X-B21b . .X ...... X X-B21bX . . r . . . . . X-B21 . . . r . . . . X-B11,B21b a r a . . . 1 m + a r X X-B21b . . . . . X X X-B13X-B21b X-B22 ...... r . r r r . . X X-B21 . r r ...... r r . . r ...... r ...... X X X X-B21 X X X B21B21 ...... r...... 1amamabmaraaa.rrab.rarr1....m+... B21 ...... mr.+rr..a.r.. B21 ...... r..bbm1+ar+mmm1...... r...... r...r... B21 ...r...... r++rr...... B22 ...... r.+...... m.+ar1... B23 ...... rr X B21B21 ...... r...... rr...r..rr...... r...... B21 ...... r...... rr...rr...... r B21 ...... rr.rr...... r...... rrr...... rogersiae tysonii

mucronatum

ericoides scoparius desvauxii Community Group; B21: Pentzia incana–Eragrostis bergiana africana

lucilioides

procumbens pulverata burchellii

curvula bergiana bicolor lehmanniana Community

mitrata capensis africanum

asbestina hystrix

ornativa glauca sordida karooicus

aethiopicum

diffusa adscensionis incana

cinereum albida koelerioides virgata

sp. muricata

microphylla

Aristida adscensionis–Eragrostis obtusa Helichrysum Aptosimum Limeum Hermannia Moraea pallida Eragrostis Enneapogon Pteronia Plinthus Trichodiadema Selago Eriocephalus Salsola Enneapogon Thesium Felicia Chloris Blepharis Fingerhuthia Lepidium Lycium Geigeria Aristida Asparagus Tragus Aristida Eragrostis Zygophyllum lichtensteinianum Pentzia Blepharis Pteronia Eragrostis Nenax Eragrostis Melolobium microphyllum Indigofera zeyheri Polygala Jamesbrittenia Chenopodium humilis Table 2 cont. Table bergiana B1: Community; B13: Aristida adscensionis–Zygophyllum incrustatum South African Journal of Botany 2004, 70: 540–558 549

(or in more general terms — plant communities), charac- munities. Plains (B) are subdivided into Community Groups terised by a combination of diagnostic species and addition- B1 and B2, constituting four and three communities, respec- al ecological and topographical information. At this stage we tively. refrain from describing these vegetation types as formal syn- taxa (in terms of the Code of Phytosociological Complexes: Slopes and Plateaux (A) and Plains (B) Nomenclature (Weber et al. 2000, 3rd edn.), and prefer to use a neutral term ‘Community’ and ‘Community Group’. Vegetation of Slopes and Plateaux (A) is classified as Open We present, for technical reasons, the results of the veg- Grassy Shrubland, while that of Plains (B) is classified as etation classification in the form of two relevés x species Open Dwarf Shrubland. Both are different facies of shrubby tables. One of the tables (Table 1) features the coenotaxa of semi-desert. The environmental variables most strongly cor- the Community Group 1 (Slopes and Plateaux), while the related with the axis are rocks, bare soil, slope, C and Mn. other (Table 2) features the coenotaxa of the Community Communities of the Slopes and Plateaux are more rocky Group B (Plains). The original % cover values were replaced and have higher values of silt, clay, Bo, Mg, Zn, Mn, Cu and (for presentation purposes) by the cover-abundance cate- C in comparison with communities on the Plains, while the gories 5 (75–100% of cover), 4 (51–74%), 3 (25–50%), 2b Plains communities are generally higher in percentage bare (12.5–24%), 2a (4–12.4%) and 2m (<4%), 1 (<3%), + (<2%) soil, coarse sand, P, Ca, Na and K. The Plains communities and r (<1%) (see Barkman et al. 1964). Details for each also have deeper soils, higher resistance and higher pH relevé, including site codes, location and altitude are pre- than Slopes and Plateaux communities (Figure 3). sented in Table 3. Species occurring at low frequencies are detailed in Appendix 1. Complex A: Slopes and Plateaux

Definitions of diagnostic species and dominance Community Group (CG) A1 (Folminkskop and Tafelberg dolerite plateaux, Tafelberg SE upper and middle slopes) We prefer to use the neutral term ‘differential species’ for occurs in areas that are relatively high in Na, Zn, Bo and silt. floristic characterisation of the coenotaxa. The differential The soils have higher resistance, status of Mn, Mg, Clay, C, species has validity only on the same level of syntaxonomic Cu and bare soil in comparison with CG A2 (all other NW hierarchy; hence it may differentiate only coenotaxa of the and SE slopes, and the Buffelskop plateau). The environ- same rank (Mucina 1993). Ideally such a species should be mental variables most strongly correlated with the axis are unique to one coenotaxon, but this case is rather rare. We Na, P, Mn, silt and slope. Exceptions to this are Tafelberg SE choose the constancy of 80% for a species within the con- upper and middle slopes that are more similar to CG A2 sidered coenotaxon as the borderline value for that species regarding environmental variables, but are floristically to be still considered differential. grouped with CG A1 (see Community A13). CG A1 occurs in areas that are higher in Ca, K, coarse sand, pH, P, have Analysis of species–environmental relationships more rocks and deeper soils in comparison with CG A1 (Figure 4). A series of ordinations were performed to analyse environmental gradients across the landscape as well as linkages Community Group A1 Felicia filifolia–Themeda triandra between the distribution of species and environmental vari- Grassy Shrubland ables. Ordination was conducted firstly on the entire data set, thereafter, partial data sets were analysed for each of Community Group A1 occurs on Tafelberg plateau, the community groups. Ordination was done using Folminkskop plateau, and Tafelberg SE upper and middle Canonical Correlation Analysis (CCA; Jongman et al. 2000), slopes. using default options of the program package CANOCO4 This CG is the least impacted by domestic herbivory of all (Ter Braak and Šmilauer 1998). the 4 CGs, and the vegetation is in a relatively non-degraded condition. Palatable species are common to dominant Nomenclature of plants with unpalatable species occurring at low densities, and soil erosion is minimal. Nomenclature of plant taxa follows the checklist of the National Vegetation Database (Mucina et al. 2000) imbed- A11 Felicia filifolia–Dimorphotheca cuneata Shrubby ded within the local TvWin 1.98c database, and which fea- Grassland tures the national flora checklist of PRECIS system of the National Botanical Institute dated January 2000, as well as This community occurs on Tafelberg plateau, where soils Germishuizen and Meyers (2003). have relatively high status of Na, K, Zn, Mg, Mn, C, Bo and Cu, they are silty and clayey, and show high levels of resist- Results ance (Figure 5). The environmental variables most strongly correlated with the axis are P, slope, coarse sand, Mn and The species x relevé matrix is divided into two main groups silt. Aspect and slope values are absent, as Tafelberg is flat of communities: Slopes and Plateaux (Table 1, A) and Plains on top. Tafelberg is the highest mesa in the vicinity of the (Table 2, B). Slopes and Plateaux (A) are subdivided into study area, and dolerite caps of Beaufort Group origin, Community Groups A1 and A2, each constituting three com- topped both Tafelberg and Folminkskop. Tafelberg plateau 550 Pienaar, Esler and Mucina

Table 3: Site details for each relevé sampled in the Middelburg District of the Eastern Cape, SA

Rel. no. Mesa Site location Site code Habitat Latitude Longitude Altitude (m) 42, 43, 44 Tafelberg NW Plain 4 NW PL 4 – T Plain 31°38.44’S 25°08.77’E 1 250 45, 46, 47 Tafelberg NW Plain 3 NW PL 3 – T Plain 31°38.35’S 25°08.90’E 1 250 48, 49, 50 Tafelberg NW Plain 2 NW PL 2 – T Plain 31°38.13’S 25°08.86’E 1 250 51, 52, 53 Tafelberg NW Plain 1 NW PL 1 – T Plain 31°38.06’S 25°08.65’E 1 200 54, 55, 56 Tafelberg NW Slope lower NW SL – T Slope 31°38.41’S 25°09.38’E 1 300 57, 58, 59 Tafelberg NW Slope middle NW SM – T Slope 31°38.49’S 25°09.61’E 1 400 60, 61, 62 Tafelberg NW Slope upper NW SU – T Slope 31°38.56’S 25°09.79’E 1 600 63, 64, 65 Tafelberg Plateau NW PL NW – T Plateau 31°38.63’S 25°09.90’E 1 650 66, 67, 68 Tafelberg Plateau Center PL CEN – T Plateau 31°38.84’S 25°10.00’E 1 650 69, 70, 71 Tafelberg Plateau SE PLAT SE – T Plateau 31°38.83’S 25°10.12’E 1 650 72, 73, 74 Tafelberg SE Slope upper SE SL U – T Slope 31°38.92’S 25°15.10’E 1 400 75, 76, 77 Tafelberg SE Slope middle SE SL M – T Slope 31°38.99’S 25°10.46’E – 78, 79, 80 Tafelberg SE Slope lower SE SL L – T Slope 31°39.03’S 25°10.59’E 1 300 81, 82, 83 Tafelberg SE Plain 1 SE PL 1 – T Plain 31°39.52’S 25°10.98’E 1 200 84, 85, 86 Tafelberg SE Plain 2 SE PL 2 – T Plain 31°39.61’S 25°11.12’E 1 250 87, 88, 89 Tafelberg SE Plain 3 SE PL 3 – T Plain 31°39.72’S 25°11.24’E 1 200 90, 91, 92 Tafelberg SE Plain 4 SE PL 4 – T Plain 31°39.83’S 25°11.36’E 1 200 1, 2, 3 Folminkskop NW Plain 4 NW PL 4 – F Plain 31°33.20’S 25°7.71’E 1 250 4, 5, 6 Folminkskop NW Plain 3 NW PL 3 – F Plain 31°33.29’S 25°7.81’E 1 250 7, 8, 9 Folminkskop NW Plain 2 NW PL 2 – F Plain 31°33.41’S 25°8.82’E 1 250 10, 11, 12 Folminkskop NW Plain 1 NW PL 1 – F Plain 31°33.50’S 25°8.03’E 1 300 13, 14, 15 Folminkskop NW Slope lower NW SL – F Slope 31°33.66’S 25°8.17’E 1 350 16, 17, 18 Folminkskop NW Slope upper NW SU – F Slope 31°33.71’S 25°8.25’E 1 400 19, 20, 21 Folminkskop Plateau NW PL NW – F Plateau 31°33.80’S 25°8.29’E 1 450 22, 23, 24 Folminkskop Plateau Center PL CEN – F Plateau 31°33.83’S 25°8.37’E 1 450 25, 26, 27 Folminkskop Plateau SE PLAT SE – F Plateau 31°33.94’S 25°8.41’E 1 400 28, 29, 30 Folminkskop SE Slope upper SE SL U – F Slope 31°33.99’S 25°8.46’E 1 350 31, 32, 33 Folminkskop SE Slope lower SE SL L – F Slope 31°34.02’S 25°8.59’E 1 300 129, 130, 131 Folminkskop SE Plain 1 SE PL 1 – F Plain 31°34.14’S 25°8.72’E 1 250 132, 34, 35 Folminkskop SE Plain 2 SE PL 2 – F Plain 31°34.25’S 25°8.80’E 1 250 36, 37, 38 Folminkskop SE Plain 3 SE PL 3 – F Plain 31°34.38’S 25°8.89’E 1 250 39, 40, 41 Folminkskop SE Plain 4 SE PL 4 – F Plain 31°34.47’S 25°9.02’E 1 250 93, 94, 95 Buffelskop NW Plain 4 NW PL 4 – B Plain 31°31.37’S 25°6.45’E 1 200 96, 97, 98 Buffelskop NW Plain 3 NW PL 3 – B Plain 31°31.42’S 25°6.56’E 1 200 99, 100, 101 Buffelskop NW Plain 2 NW PL 2 – B Plain 31°31.49’S 25°6.69’E 1 250 102, 103, 104 Buffelskop NW Plain 1 NW PL 1 – B Plain 31°31.57’S 25°6.81’E 1 250 105, 106, 107 Buffelskop NW Slope lower NW SL – B Slope 31°31.67’S 25°6.95’E 1 300 108, 109, 110 Buffelskop NW Slope upper NW SU – B Slope 31°31.70’S 25°6.97’E 1 350 111, 112, 113 Buffelskop Plateau NW PL NW – B Plateau 31°30.00’S 25°’E 1 350 114, 115, 116 Buffelskop Plateau SE PLAT SE – B Plateau 31°31.84’S 25°7.07’E 1 400 117, 118, 119 Buffelskop SE Slope upper SE SL U – B Slope 31°30’S 25°’E 1 250 120, 121, 122 Buffelskop SE Slope lower SE SL L – B Slope 31°30’S 25°’E 1 250 123, 124, 125 Buffelskop SE Plain 1 SE PL 1 – B Plain 31°31.95’S 25°7.40’E 1 200 126, 127, 128 Buffelskop SE Plain 2 SE PL 2 – B Plain 31°32.02’S 25°7.52’E 1 200

and Folminkskop plateau are correlated with the same envi- A12 Felicia filifolia–Enneapogon scoparius Shrubby ronmental factors, but the values for Tafelberg are higher Grassland than those for Folminkskop. This could be explained by the similarities in geology and soils, but a difference in height This community occurs on Folminkskop plateau, on sub- (Tafelberg is approximately 200m higher than Folminkskop). strates generally more rocky than in Communities A11 and Both Enneapogon scoparius and Asparagus striatus A13. Soils supporting this community are characterised by occurred throughout the rest of CG A, but are remarkably relatively lower status of Na, K, Zn, Mg, Mn, C, Bo, Cu, lower absent in this community. This community has not been resistance, and silt and clay content as compared to impacted by domestic herbivores for 40 years and is grazed Tafelberg plateau (Community A11). These soil characteris- by indigenous antelope such as Kudu (Tragelaphus strep- tics show relatively higher values in this particular communi- siceros) and Grey Rhebok (Pelea capreolus) and Smith’s ty as compared to Tafelberg SE slope (Community A13) Red Rock Rabbit (Pronolagus rupestris). The vegetation is (Figure 5). The environmental variables most strongly corre- in a relatively non-degraded condition and is dominated by lated with the axis are P, slope, coarse sand, Mn and silt. highly palatable grasses. Due to the lower elevation, sheep occasionally graze the plateau but the impact of domestic grazing is considered South African Journal of Botany 2004, 70: 540–558 551

+1.0 +1.0 PHOSPHAT Slopes BARE SOIL SOIL DEPTH COURSAND Slopes pH (KCI) PHOSPHAT ROCKS Ca COURSAND Community A11

Community A13 Ca K SOIL DEPTH Bo Na Mg Na BARE SOIL Zn RESISTAN K C Cu SILTPER CLAYPER RESISTAN Zn ROCKS SILTPER Mn Plateaux CLAYPER Mn Cu Community A12 C Bo Slopes and Plateaux habitats (A) Plain habitats (B) Plateaux -1.0 -1.0 -1.0 +1.0 -1.0 +1.0

Figure 3: An ordination diagram showing the distribution of sites in Figure 5: An ordination diagram showing the distribution of sites in relation to available environmental factors for the main division in relation to available environmental factors for Communities A11, the data: (A) Slopes and Plateau habitats and (B) Plains habitats. A12 and A13. Eigenvalues: Axis 1: 0.578, Axis 2: 0.446. Refer to Eigenvalues: Axis 1: 0.735, Axis 2: 0.544 Figure 3 for key to environmental variables Key: BARE SOIL – Bare soil, Bo – Boron, C – Carbon, Ca – Calcium, CLAYPER – Clay %, COURSAND – Coarse sand, Cu – Copper, K – Potassium, Mg – Magnesium, Mn – Manganese, Na – Sodium, pH negligible, as grazing frequency is very low. The community (KCl) – pH (KCL), PHOSPHAT – Phosphates (P), Plateau – Plateau is however grazed regularly by indigenous herbivores such (nominal variable), RESISTAN – Resistance, ROCKS – Rocks, SILT- as Kudu, Grey Rhebok and Hare. Vegetation is in a relative- PER – Silt %, slopes – slopes (nominal variable), SOIL DEPTH – Soil ly non-degraded condition, with palatable plants being com- depth, Zn – Zinc mon to dominant.

A13 Felicia filifolia–Eriocephalus africanus Grassy +1.0 Shrubland

K This community occurs on Tafelberg SE slope upper and Zn PHOSPHAT middle. The environmental variables most strongly correlat- Na ed with the axis are P, slope, content of coarse sand, silt, SILTPER and Mn. The soils show a relatively high status of P, coarse RESISTAN Plateaux Bo sand, Ca, have more bare soil, and are deeper than those of the dolerite plateau Communities A11 and A12 (Figure 5). In Mn SOIL DEPTH terms of habitat attributes, this community has more in com- CLAYPER pH (KCI) C Mg ROCKS mon with that of a typical slope Community A21, than with Ca the plateau communities of Tafelberg and Folminkskop, but Cu BARE SOIL COURSAND floristically it is similar to the Plateau communities on Slopes dolerite. The overriding effect of moisture might explain this, due to the high elevation and the SE-facing aspect of this community. Community Group A1 Community Group A2 The community is also characterised by a complete absence of Themeda triandra and Heteropogon contortus. The community is grazed by indigenous herbivores and -1.0 occasionally by domestic herbivores (i.e. sheep, cattle), but -1.0 +1.0 more regularly so than Tafelberg plateau (Community A11) or Folminkskop plateau (Community A12). Vegetation is in good condition, with palatable plants being common to dom- Figure 4: An ordination diagram showing the distribution of sites in inant. relation to available environmental factors for Community Groups A1 and A2. Eigenvalues: Axis 1: 0.635, Axis 2: 0.491. Refer to Figure 3 for key to environmental variables 552 Pienaar, Esler and Mucina

Community Group A2 Rhigozum obovatum–Rhus herbivores and occasionally by domestic herbivores. burchellii Grassy Tall Shrubland Grazing by domestic herbivores occurs much more frequently than on CG A1, and is concentrated on the lower Community Group A2 occurs on Folminkskop SE slope half of these slopes. Lack of watering points and inaccessi- upper and lower, Folminkskop NW slope upper and lower, bility of the terrain force animals to stay on the lower half of Buffelskop plateau NW and SE, Tafelberg NW slope upper, the slopes. It is observed that domestic animals walk down middle and lower, Tafelberg SE slope lower, Buffels SE plain to water points on the surrounding plains towards mid-morn- 1B, Buffelskop SE slope upper and lower, Buffelskop NW ing. Impact by these domestic herbivores is not considered slope upper and lower. to be significant as vegetation is in very good condition, with Impact by domestic livestock ranged from negligible to palatable species common to dominant. high. Vegetation condition ranged from pristine (upper slopes) to moderately degraded (lower slopes of A22 Rhigozum obovatum–Pegolettia baccaridifolia Tall Buffelskop). Highly palatable species are common to domi- Shrubland nant in the pristine areas with unpalatable species occurring at low densities. Moderately degraded areas are dominated This community occurs on Buffelskop SE slope, where the by less palatable to moderately palatable plants and erosion soils show relatively high contents of coarse sand, silt, Na, is minimal. K, P and Bo, and have high values of pH and resistance (Figure 6). It also has a higher incidence of bare soil and A21 Rhigozum obovatum–Gymnosporia buxifolia deeper soils in comparison to the Communities A21 and Grassy Tall Shrubland A23. The environmental variables most strongly correlated with the axis are P, Cu, Zn, Na and Mg. This community occurs on Folminkskop SE slope upper and The community is grazed regularly by indigenous herbi- lower, Folminkskop NW slope upper and lower, Buffelskop vores (less regularly than Tafelberg and Folminkskop), and plateau NW and SE, Tafelberg NW slope upper, middle and frequently by domestic herbivores. Buffelskop is more read- lower, Tafelberg SE slope lower. It is a general slope com- ily accessible to livestock. Impact of domestic herbivores on munity occurring throughout the entire study area. The soils this community is moderate to high. Buffelskop consists of supporting this shrubland community showed relatively high sandstone (as opposed to Folminkskop and Tafelberg that status of Mn, Mg, C, Cu, Ca and clay content in comparison are both capped by dolerite), and the slopes are very steep to the communities found on Buffelskop SE and Buffelskop and unstable. Both of these factors probably play an impor- NW slopes (Figure 6). The environmental variables most tant role in shaping this community. Palatable plants are less strongly correlated with the axis are P, Cu, Zn, Na and Mg. frequent and have lower dominance, and vegetation is dom- This slope community is regularly grazed by indigenous inated by a different set of plants in comparison with the dominants on Tafelberg and Folminkskop. Spiny Blepharis capensis colonises disturbed ground and has a tendency to +1.0 dominate overgrazed patches.

A23 Rhigozum obovatum–Cenchrus ciliaris Grassy Tall Community A22 Shrubland Na This community occurs on Buffelskop NW slope, upper and COURSAND lower. The soils are skeletal and show higher contents of Zn BARE SOIL SILTPER in comparison to the community occupying the SE slopes Plateaux SOIL DEPTH K RESISTAN pH (KCI) (Community A22). Soils show higher content of coarse sand PHOSPHAT Bo and silt, higher values of pH and resistance, and higher status of Na, K, P, Bo. The bare patches are more common in Zn this community than in the Community A21 (Figure 6). The Mn ROCKS C environmental variables most strongly correlated with the CLAYPERCa axis are P, Cu, Zn, Na and Mg. Slopes Community A21 Cu The community is grazed regularly by indigenous herbi- Mg Community A23 vores (less regularly than Tafelberg and Folminkskop), and is grazed frequently by domestic herbivores (fenced and actively used as a grazing camp). Impact of domestic herbivores on this community is moderate to high. Buffelskop is -1.0 comprised of sandstone (as opposed to Folminkskop and -1.0 +1.0 Tafelberg that are both capped by dolerite), and the slopes are very steep and unstable. Both these factors probably Figure 6: An ordination diagram showing the distribution of sites in play important roles in shaping this community. Palatable relation to available environmental factors for Communities A21, plants are less frequent and have lower dominance, and A22 and A23. Eigenvalues: Axis 1: 0.557, Axis 2: 0.433. Refer to vegetation is dominated by a different set of plants in com- Figure 3 for key to environmental variables parison with the dominants on Tafelberg and Folminkskop. South African Journal of Botany 2004, 70: 540–558 553

Complex B: Plains B11 Aristida adscensionis–Ruschia intricata Grassy Dwarf Degraded Shrubland Community Group B1 (Tafelberg SE plains, Tafelberg NW plains, Folminkskop SE plain, sampling stations 2, 3 and 4; Relevés of this community are on Tafelberg SE plains (1, 2, Figure 7) occurs in two distinct habitat types — one showing 3, 4). The soils supporting this community show higher relatively higher resistance and coarser sands and the other resistance, and have more rocks and coarse sand in com- showing relatively higher status of Mn, clay, silt, K, Na, P, Zn parison to Communities B12, B13 and B14 (Figure 8). The and C, with on average, higher percentage bare soil and environmental variables most strongly correlated with the deeper soils. Community Group B2 (Buffelskop NW plain 1, axis are Bo, soil depth, clay, Mn, silt and bare soil. 2, 3, 4; Buffelskop SE Plain 1 and 2; Folminkskop NW Plain This community is regularly impacted by indigenous herbi- 1, 2, 3, 4; Folminkskop SE Plain 1) is supported by soils vores such Springbok, Kudu and Steenbok and in the past showing higher status of Bo, Mg, Ca, C, and higher pH, as was heavily impacted by domestic herbivores. Vegetation is compared to CG B1. The soils of the CG B2 are more skele- degraded, with unpalatable plants dominating. Erosion has tal and show higher coarse sand content (Figure 7). The taken place to the extent that many plants are growing on environmental variables most strongly correlated with the pedestals. In the five years prior to this study, Nguni (a breed) axis are Mn, resistance, P, pH and Ca. cattle farming replaced sheep farming in this community.

Community Group B1 Aristida adscensionis–Eragrostis B12 Aristida adscensionis–Jamesbrittenia atropurpurea obtusa Grassy Dwarf Shrubland Grassy Dwarf Shrubland

This community group occurs on Tafelberg SE plains, This community occurs on Folminkskop SE plain 4. The Tafelberg NW plains and Folminkskop SE plain 2, 3, 4. soils have higher levels of Zn, K, Bo, Mg, Na, Cu, C, P, clay This community group is moderately to severely impact- and silt, higher values of pH and are deeper then the soils of ed by domestic livestock, and lightly grazed by indigenous the Community B11, but less so than those of the animals such as Kudu, Springbok (Antidorcas marsupialis) Communities B13 and B14 (Figure 8). The environmental and Steenbok (Raphicerus campestris). Vegetation condi- variables most strongly correlated with the axis are Bo, Mn, tion ranges from good to severely degraded. Unpalatable soil depth, clay, silt and bare soil. plants dominate the vegetation, with palatable species still Domestic livestock, as well as indigenous herbivores such being common. We found very variable evidence of soil as Kudu, Springbok and Steenbok extensively graze this erosion. community. The condition of the vegetation is good, but unpalatable plants are still common. This community is exceptional for a plains community because of the presence of Enneapogon scoparius, usually associated with

+1.0 +1.0 SOIL DEPTH SILTPER Mn Community B14 K CLAYPERCu Bo ROCKS Mg BARE SOIL PHOSPHAT C pH (KCI) RESISTAN Na Community B13 Ca COURSAND Zn SOIL DEPTH SILTPER K Bo Na CLAYPER ROCKS PHOSPHAT Mg Mn BARE SOIL Cu Community Group B1 Community Group B2 Community B11 Zn Ca C pH (KCI)

COURSAND RESISTAN Community B12 -1.0 -1.0 -1.0 +1.0 -1.0 +1.0

Figure 7: An ordination diagram showing the distribution of sites in Figure 8: An ordination diagram showing the distribution of sites in relation to available environmental factors for Community Groups relation to available environmental factors for Communities B12, B1 and B2. Eigenvalues: Axis 1: 0.605, Axis 2: 0.518. Refer to B12, B13 and B14. Eigenvalues: Axis 1: 0.605, Axis 2: 0.448. Refer Figure 3 for key to environmental variables to Figure 3 for key to environmental variables 554 Pienaar, Esler and Mucina

Slopes/Plateaux habitats. This could possibly be ascribed to +1.0 SILTPER Mn increased soil moisture due to close levels of underground CLAYPER Community B22 Cu Bo water. Jamesbrittenia atropurpurea also occurs only in this Mg K community. The surface erosion is minimal. PHOSPHAT Na pH (KCI) B13 Aristida adscensionis–Zygophyllum incrustatum Grassy Dwarf Shrubland BARE SOIL C Community B21

Community B13 occurs on Folminkskop SE plain 2 and 3, Ca and Tafelberg NW plain (1, 3, 4). The soils have higher lev- SOIL DEPTH els of K, Bo, Mg, Cu, C, Na, P, pH, clay and silt and are deeper soils than soils of Communities B11 and B12. Soils are slightly poorer in these elements in comparison with soils ROCKS of Community B14 (Figure 8). The environmental variables most strongly correlated with the axis are Bo, soil depth, clay, Mn, silt and bare soil. The community is impacted by occasional grazing by Community B23 RESISTAN indigenous herbivores (Kudu, Springbok and Steenbok) as well as by excessive grazing by domestic herbivores. -1.0 COURSAND Vegetation is degraded and characterised by many denuded -1.0 +1.0 areas dominated by unpalatable plants. Erosion has taken place to the extent that plants often form pedestals. Figure 9: An ordination diagram showing the distribution of sites in relation to available environmental factors for communities B21, B14 Helichrysum lucilioides–Thesium spartioides Open B22 and B23. Eigenvalues: Axis 1: 0.807, Axis 2: 0.545. Refer to Dwarf Shrubland Figure 3 for key to environmental variables

Relevés of this community were on Tafelberg NW plain 2. The soils showed higher values of K, Bo, Mg, Na, Cu, C, clay, silt, P, pH and are deeper than those of the B21 Pentzia incana–Eragrostis bergiana Grassy Dwarf Communities B11, B12 and B13, and are distinguished from Shrubland the Community B13 by lower levels of Zn (Figure 8). The environmental variables most strongly correlated with the This community occurs on Folminkskop NW plain 1, 2, 3, 4; axis are Bo, soil depth, clay, Mn, silt and bare soil. Folminkskop SE plain 1; Buffelskop NW plain 1, 3, 4. The The community is impacted by occasional grazing by soils show lower status of Mn, Bo, Cu, Mg, K, Na, Zn, Ca, P, indigenous herbivores (Kudu, Springbok, Steenbok), as well bare soil and higher pH than the soils of the Community B22, as excessive grazing by domestic herbivores. Vegetation is but show higher values of these soil characteristics than degraded with many denuded areas. Erosion has taken those of the Community B23 (Figure 9). The resistance of place to the extent that plants are on pedestals. This com- the soils supporting the Community B23 is higher than that munity is slightly impoverished and is characterised by the for the Community B21. The environmental variables most complete absence of Aristida adscensionis, Eragrostis strongly correlated with the axis are coarse sand, Mn, silt, obtusa and E. lehmanniana, species common throughout clay and Cu. the rest of the community group. Occasional grazing by indigenous herbivores as well as excessive grazing by domestic herbivores impacts the com- Community Group B2 Eragrostis lehmanniana– munity. Vegetation is overgrazed and in poor condition with Eragrostis bergiana Grassy Dwarf Shrubland sparse plant cover, while unpalatable plants are common to dominant. Shallow soil occurs in pockets and Blepharis Relevés of this CG are made on Folminkskop SE plain 1; capensis is present in high densities. Folminkskop NW plain 1, 2, 3, 4; Buffelskop NW plain 1, 2, 3, 4 and Buffelskop SE plain 1, 2. B22 Eragrostis lehmanniana–Eragrostis bicolor Grassy Occasional grazing by indigenous herbivores as well as Shrubland excessive grazing by domestic herbivores impacts the community. This community group represents the most degrad- This community occurs on Buffelskop NW plain 3 and 4. The ed of the four community groups. The high frequency of environmental variables most strongly correlated with the Blepharis capensis (spiny, unpalatable species commonly axis are coarse sand, Mn, silt, clay and Cu. Soils contain thriving on disturbed and overgrazed land) is an indication more Mn, Bo, Cu, Mg, K, Na, Zn, P, Ca, Bare soil and high- of over-utilisation and degradation of this community. er pH than the soils of the Communities B21 and B23, and have lower resistance and less coarse sand than the soils of the Communities B21 and B23 (Figure 9). This community is regularly impacted by indigenous herbivores and heavily impacted by domestic herbivores. South African Journal of Botany 2004, 70: 540–558 555

Vegetation is degraded with sparse cover and much bare SE slopes as factors determining community composition soil. This community is impoverished, possibly as a result of are overridden by soil type and associated nutrient status. a narrow distribution in the landscape and consequent Soils of the SE and NW slopes are both derived from under-sampling of the community. dolerites and are characterised by relatively higher levels of C, Cu, Zn, Mn, Mg, Bo, silt and clay in comparison with B23 Eragrostis lehmanniana–Rosenia humilis Shrubby plains habitats. Grassland Buffelskop is the only mesa that is topped by a sandstone layer and not by a dolerite cap. Plant communities for the This community occurs in Buffelskop NW plain 2. The soils slopes of Buffelskop are distinct, separate communities that had lower contents of Mn, Bo, Cu, Mg, K, Na, Zn, Ca, P, less are not linked to any other communities in the study and bare soil, and lower values of pH than the soils of the have distinct soil composition. The slopes of Buffelskop are Communities B21 and B22, and are relatively higher in per- more arid and less compacted in comparison with those of centage coarse sand and resistance (Figure 9). The envi- Tafelberg and Folminkskop. Under certain circumstances, ronmental variables most strongly correlated with the axis sandstone absorbs more water than dolerite and the excep- are coarse sand, Mn, silt, clay and Cu. tionally low plant cover and steep sides lead to higher runoff, This community is regularly impacted by indigenous her- resulting in a more xeric habitat. In xeric sandstone mesas bivores as well as by domestic herbivores. Vegetation is in such as Buffelskop, aspect and slope override soil type and an overgrazed, degraded condition and plant cover is associated nutrient status as determinants of community sparse. This community is impoverished, possibly as a result composition. of a narrow distribution in the landscape that resulted in Mesas are distinct in composition and can be regarded as under-sampling. Species diversity of this community is very islands of one vegetation type in a sea of another vegetation low. type (plains). Mesa habitats in the Middelburg District are under-utilised by livestock because of their general inacces- Discussion sibility (steep slopes, extremely rocky terrain, cliffs and fences) coupled with the absence of natural springs or artifi- Vegetation patterns cial water points on them. Mesa habitats are not currently threatened by development, but do have a higher conserva- Mesas (their plateaux and slopes) are distinctly different in tion status than the surrounding plains due to their undis- composition compared to the surrounding plains, with no turbed nature. shared communities between mesas and their surroundings. Plains habitats are used extensively for stock production, These distinct communities can be clearly ordered along a and the vegetation is in a state of degradation ranging from soil-moisture gradient. Shallow and rocky soils, coupled with light to severe. Toxic, spinescent and unpalatable plants are very little runoff and naturally higher precipitation due to common. In severely degraded areas, soil erosion has taken increased elevation, support formation of more mesic habi- place to the extent that plants occur on pedestals. Less dis- tats on the mesas in comparison with the surrounding plains turbed areas of plains habitat are now restricted to specific habitats. Plains have little rock cover, high percentage of locations such as road verges or railway lines where grazing bare soils, slightly shallower soils and higher runoff rates is absent, but for the most part plains habitats have been than mesas. These factors result in a more xeric habitat. altered in one way or another through grazing by livestock (E Habitat differences such as these probably existed before Pienaar, pers. obs.). the impact of domestic stock introduced by European set- tlers (Hoffman et al. 1997), but overgrazing has probably Regional linkages exacerbated the differences. Overgrazing results in more denuded vegetation with larger areas of bare soil than natu- Plant communities for the Middelburg study area are very rally existed in the plains habitats. This then results in an similar in structure and some textural characteristics such as increase in xeric conditions through the loss of plant cover composition of dominating life-forms and participation of and water through runoff and more rapid evaporation than high-rank taxa (families and genera). However, none of the would normally occur (Fuls 1992). plant communities identified in our study could be identified Toxic, spinescent and unpalatable plant species are gen- with communities described in other parts of Nama Karoo, erally not grazed as severely as palatable species and are such as in the upper Gariep (Orange) River valley (Werger therefore selected for under high grazing pressure (Milton 1973), Camdebo and Aberdeen plains and surrounding and Dean 1990, Milton and Hoffman 1994, Milton 1995). mountains (Palmer 1991), or in the Karoo National Park This thus resulted in a change of the dominance structure of located near Beaufort West in the Western Cape Province plant communities in favour of these unpalatable plants. (Rubin and Palmer 1996). We refrain from formal syntaxo- Tafelberg plateau, Folminkskop plateau and the SE slopes nomic comparison of our area with other regions of the of Tafelberg each have distinct communities, linked to spe- Nama Karoo because of insufficient data coverage in the cific environmental factors that play a role in these commu- biome as a whole. nities. All other slopes with the exception of Buffelskop are Ecological factors and processes at work in the however grouped into one big general slope community, with Middelburg District are very similar to those in the rest of the no distinction between SE and NW slopes. This suggests Nama Karoo, with the most important driving force being a that aspect and the expected cooler, moister conditions on topographic-moisture gradient (Palmer and Cowling 1994, 556 Pienaar, Esler and Mucina

Table 4: Comparative species richness in different habitats and communities in the study area. Total species richness is the cumulative number of species encountered in all relevés of a community. Min. and Max. refer to the lowest and highest species richness encountered in a relevé of a community type; mode is the most frequently encountered species richness in a set of relevés in a community

Total number of species Total species in plots 192

Number of species % Restricted to mesas 84 43.8 Restricted to plains 51 26.6 Shared species 57 29.7

Community Total species richness Relevés Min. Max. Mode Community A11 54 9 14 27 17 Community A12 55 9 13 23 23 Community A13 47 6 14 22 22 Community A21 100 30 12 28 18 Community A22 45 6 12 28 N/A Community A23 13 6 4 7 7 Community B11 52 12 14 24 18 Community B12 34 3 19 22 22 Community B13 60 15 5 34 22 Community B14 29 3 15 20 N/A Community B21 50 24 4 22 11 Community B22 8 6 2 5 5 Community B23 18 3 8 14 N/A

Rubin and Palmer 1996). Vegetation in the Middelburg study oides and Trichodiadema rogersiae. Highly palatable area is strongly influenced by a soil-moisture gradient asso- species such as Felicia muricata and Limeum aethiopicum ciated with an increase in elevation from the plains habitats occur at higher frequencies on mesas than on plains habi- to the higher lying mesa habitats. Degraded shrublands are tats, a possible consequence of increased grazing pressure said to be a consequence of grazing by sheep (Palmer on the plains. Species such as these may also have poten- 1989), and species indicative of disturbance (Geigeria orna- tial for restoration of surrounding degraded plains. tiva, Tribulus terrestris and the exotic Salsola kali) and other species (Chrysocoma ciliata, Eragrostis obtusa, Felicia Conclusions muricata and Pentzia incana) are the same as those found in degraded shrublands of the Middelburg District. Although mesas and plains are similar in alpha diversity, the communities occurring on these habitats are distinctly differ- Restoration potential ent from each other. No communities are shared between mesas and plains habitats. The distribution and composition It has been proposed that mesas could provide sources of of communities across the Middelburg landscape are main- re-colonisation for species in decline in degraded surround- ly attributed to a soil moisture gradient. Aspect and the ing plains habitats (Burke et al. 2003). This study indicated expected cooler, moister conditions on SE slopes as factors approximately 30% of species that are shared between determining community composition for the dolerite mesas mesas and their surroundings, although not all of these are overridden by soil type and associated nutrient status. In species can be regarded as good colonisers. More species xeric sandstone mesas such as Buffelskop, aspect and in total occur only on mesas (44% of species sampled in all slope as determinants of community composition override plots) in comparison to species that are restricted to plains soil type and associated nutrient status. Mesas are distinct habitats (27%) or that are shared between mesas and plains in composition and can be regarded as islands of one vege- habitats. This reflects the larger species pool found on tation type in a sea of another vegetation type. Plant com- mesas, although alpha diversity on mesas is not significant- munities in the Middelburg study area are similar in compo- ly higher on mesas compared to their surroundings (Table sition to communities identified in other parts of the Nama 4). Larger mesas such as Tafelberg (447m above surround- Karoo, with many shared genera and species. ings) share more species with the surrounding plains than smaller mesas, although the plateau is more distinct than Acknowledgements — This study was supported by a European that of smaller mesas (data not shown). Community grant (EC ERBIC18CT970141) and in South Africa by Species shared between plains and mesa habitats includ- an NRF grant to KJ Esler (GUN: 203492). Many people and institu- ed various valuable grazing species, including generalist tions provided valuable logistic support. We would like to acknowl- edge W Asher, C Ayliffe, R Gilfillan, P McEwan for allowing us to species such as Eragrostis obtusa, Felicia muricata, F. work on their farms. F Jones provided assistance with the location ovata, Fingerhuthia africana, Jamesbrittenia tysonii, Limeum of the study sites. F Jones, NC and NO Hendricks assisted with the aethiopicum, Pentzia incana, Selago albida, Tragus koeleri- South African Journal of Botany 2004, 70: 540–558 557

collection of soils for analysis. L Mucina thanks the University of the Milton SJ (1995) Effects of rain, sheep and tephritid flies on seed Free State, QwaQwa Campus for logistic support (Research Grant production of two arid Karoo shrubs in South Africa. Journal of # 4676). Applied Ecology 32: 137–144 Milton SJ, Dean WRJ (1990) Seed production in rangelands of the References southern Karoo. South African Journal of Science 86: 231–233 Milton SJ, Hoffman MT (1994) The application of state-and-transi- Barkman JJ, Doing H, Segal S (1964) Kritische Bemerkungen und tion models to rangeland research and management in arid suc- Vorschläge zur quantitativen Vegetationsanalyse. Acta Botanica culent and semi-arid grassy Karoo, South Africa. African Journal Neerlandica 13: 394–419 of Range and Forage Science 11: 18–26 Burke A, Esler K, Pienaar E, Barnard P (2003) Species richness and Mucina L (1993) Nomenklatorische und syntaxonomishe floristic relationships between mesas and their surroundings Definitionen, Konzepte und Methoden. In: Mucina L, Grabherr G, southern African Nama Karoo. Diversity and Distributions 9: Ellmauer T (eds) Die Pflanzengesellschaften Österreichs. Teil I. 43–53 Anthropogene Vegetation. Gustav Fischer Verlag, Jena. pp Cooke R, Warren A, Goudie A (1993) Desert Geomorphology. UCL 19–28. ISBN 3334604527 Press, London. ISBN 1857280172 Mucina L, Bredenkamp GJ, Hoare DB, McDonald DJ (2000) A Desmet PG, Cowling RM (1999) The climate of the karoo a func- national vegetation database for South Africa. South African tional approach. In: Dean WRJ, Milton SJ (eds) The Karoo: Journal of Science 96: 497–498 Ecological Patterns and Processes. Cambridge University Press, Palmer AR (1989) The vegetation of the Karoo Nature Reserve, Cambridge. pp 3–16. ISBN 0521554500 Cape Province. 1. A phytosociological reconnaissance. South Ellis F, Lambrechts JJN (1986) Soils. In: Cowling RM, Roux PW, African Journal of Botany 55: 215–230 Pieterse AJH (eds) The Karoo Biome: a Preliminary Synthesis. Palmer AR (1991) A syntaxonomic and synecological account of the Part 1. Physical Environment. South African National Scientific vegetation of the eastern Cape midlands. South African Journal Programmes Report 124: 18–38 of Botany 57: 76–94 Fuls ER (1992) Ecosystem modification created by patch-overgraz- Palmer AR, Cowling RM (1994) An investigation of topo-moisture ing in semi-arid grassland. Journal of Arid Environments 23: gradients in the eastern Karoo, South Africa, and the identification 59–69 of factors responsible for species turnover. Journal of Arid Germishuizen G, Meyer NL (2003) Plants of southern Africa: an Environments 26: 135–147 annotated checklist. Strelitzia 14, National Botanical Institute, Palmer AR, Hoffman MT (1997) Nama-karoo. In: Cowling RM, Pretoria. ISBN 1919795995 Richardson DM, Pierce SE (eds) Vegetation of Southern Africa. Hennekens SM (1996) MEGATAB: A Visual Editor for Cambridge University Press, Cambridge. pp 167–188. ISBN Phytosociological Tables. Version 1. IBN, Wageningen & Giesen 0521571421 and Geurts, Ulft Rubin F, Palmer AR (1996) The physical environment and major Hennekens SM, Schaminée JHJ (2001) TURBOVEG, a compre- plant communities of the Karoo National Park, South Africa. hensive data base management system for vegetation data. Koedoe 39: 25–52 Journal of Vegetation Science 12: 589–591 Rutherford MC, Westfall RH (1986) The biomes of southern Africa Hill MO (1979) TWINSPAN. A FORTRAN Program for Arranging an objective categorization. Memoirs of the Botanical Survey of Multivariate Data in an Ordered Two-way Table by Classification South Africa 54: 1–98 of the Individuals and Attributes. Ecology and Systematics, Ter Braak CJF, Šmilauer P (1998) CANOCO Reference manual and Cornell University, Ithaca, NY user’s Guide to Canoco for Windows: Software for Canonical Hoffman MT, Cousins B, Meyer T, Petersen A, Hendricks H (1997) Community Ordination (version 4). Microcomputer Power, Ithaca, Historical and contemporary land use and the desertification of NY the karoo. In: Dean WRJ, Milton SJ (eds) The Karoo: Ecological UNEP (1992) World atlas of desertification. Edward Arnold, London Patterns and Processes. Cambridge University Press, Watkeys MK (1999) Soils of the arid south-western zone of Africa. Cambridge. pp 257–273. ISBN 0521554500 In: Dean WRJ, Milton SJ (eds) The Karoo: Ecological Patterns Jones FE (2000) An Assessment of the Potential for Utilization of and Processes. Cambridge University Press, Cambridge. pp Soil-stored Seed, from on- and off “Conservation Island” (Isolated 17–26. ISBN 0521554500 mountains), as an Indicator of Restoration Potential of Degraded Weber HE, Moravec J, Theurillat J-P (2000) International Code of Sites in Semi-arid Karoo Areas. MSc Thesis, University of Phytosociological Nomenclature. 3rd edn. Journal of Vegetation Stellenbosch, South Africa Science 11: 739–768 Jongman RHG, Ter Braak CJF, Van Tongeren OFR (2000) Data Werger MJA (1973) An account of the plant communities of Tussen Analysis in Community and Landscape Ecology. Cambridge die Riviere Game Farm, Orange Free State. Bothalia 11: 165–176 University Press, Cambridge. ISBN 9022009084 Werger MJA (1973) A phytosociological study of the Upper Orange MacDonald DJ (1998) VEGMAP: a collaborative project for a new River Valley. Memoirs of the Botanical Survey of South Africa 46: vegetation map of South Africa. South African Journal of Science 1–98 93: 424–426

Edited by RM Cowling 558 Pienaar, Esler and Mucina

Appendix 1: Lists of species occurring only once or twice in respective table. The symbols ‘a’ and ‘m’ stay for 2a and 2m cover-abundance categories. The number in the brackets indicates the address (original relevé number) for each record

Table 1: Adromischus sp. r (115), Albuca sp. A r (80, 61), Albuca juncifolia r (78, 79), Aptosimum procumbens r (65), Buddleja glomerata + (116), Carissa haematocarpa a (80), Chascanum cuneifolium r (25, 115), Chenopodium mucronatum r (122), Chenopodium sp. r (71), Clematis brachiata r (28), Crassula perfoliata r (15), Crassula sp. r (20), Crassula tetragona r (20), Cyperus sp. r (21), Dimorphotheca zeyheri r (24), Dipcadi sp. r (78), Eragrostis lehmanniana r (30), Hermannia filifolia r (121), Hermannia linearifolia r (32), Indigofera exigua r (64, 65), Melica racemosa r (68), Melolobium microphyllum r (63, 113), Opuntia sp. r (22, 27), Oxalis heterophylla r (23), Phymaspermum parvifolium r (68), Plagiochasma rupestre r (29), Pleiospilos compactus r (14, 15), Plinthus karooicus r (114), Polhillia connata r (20), Polygala lep- tophylla r (78), Portulaca oleracea r (77), Rhus erosa r (63), Talinum caffrum r (33), Thesium hystrix r (56, 60), Turbina sp. r (78), Viscum rotundifolium r (33)

Table 2: Albuca sp. r (52, 42), Asparagus laricinus r (44), Commelina africana r (90, 91), Convolvulus boedeckerianus r (48), Crassula sp. C r (45), Euphorbia brachiata r (132, 11), Gnaphalium confine r (45), Helichrysum zeyheri r (39), Hermannia filifolia r (129), + (131), Heteropogon contortus r (84), Hibiscus pusillus r (84), Indigofera exigua r (83, 91), Ornithogalum sp. r (42, 125), Pegolettia retrofracta r (3), Pentzia lanata r (3), Pentzia sphaerocephala r (9), Polygala sp. r (49), Portulaca oleracea r (34), Pseudognaphalium oligandrum r (42), Psilocaulon junceum m (123), Selago geniculata r (91)