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

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South African Journal of Botany 2004, 70(4): 540–558 Printed in South Africa — All rights reserved

SOUTH AFRICAN JOURNAL OF BOTANY ISSN 0254–6299

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 off isolated mesas were investigated across Nama Karoo communities in the Eastern Cape, South Africa. Species composition and cover were measured in plots along a transect extending from the SE plains and slopes, across the plateaux, onto the NW slopes and plains of three mesas (Tafelberg, Folminkskop and Buffelskop). Data were then classified using the floristic-sociological approach, assisted by the computer package TWINSPAN. Canonical Correlation Analysis was used to analyse the relationship between vegetation and environmental patterns. Mesa communities were found to be distinctly different from plains communities, with no shared communities between the two habitats. The distribution of communities across the landscape is attributed to a soil-moisture gradient. Differences in habitat probably existed before the impact of domestic livestock, but overgrazing has likely exacerbated the differences. The potential to use mesas

as sources of seeds and propagules for the surrounding degraded plains is low, since few species are shared between the two habitats. However, generalist, palatable species such as Felicia muricata, Eragrostis obtusa, Pentzia incana etc. could have some potential for future restoration. Dolerite-capped mesas such as Tafelberg and Folminkskop had a general slope community shared between the two mesas. Aspect and the expected cooler, more moist conditions on SE slopes as factors determining community composition for the dolerite mesas were overridden by soil type and associated nutrient status. In xeric sandstone mesas such as Buffelskop, soil type and associated nutrient status were overridden by aspect and slope as determinants of community composition. Mesa habitats are generally not grazed heavily by livestock due to their inaccessible nature, and are not threatened by current land use practices. Plains habitats are often degraded, a consequence of 200 years of selective grazing.

Introduction Vegetation patterns in arid landscapes remain relatively understudied despite the fact that these landscapes comprise 47% of all terrestrial land (UNEP 1992). One of the largest continuous tracts of arid land in the southern hemisphere is the Karoo semi-desert encompassing two biomes, the Succulent Karoo of the winter rainfall region and the Nama Karoo occurring primarily in the summer rainfall area of southern Africa (Desmet and Cowling 1999). Information on this second largest biome (607 235km2) of South Africa (Rutherford and Westfall 1986, Palmer and Hoffman 1997) remains sparse and concentrated on a few nature reserves found along the edges of the biome, as evidenced by difficulties experienced by a recent vegetation mapping exercise (MacDonald 1998, Mucina et al. 2000). The Nama Karoo is an arid continental meseta (high altitude plateau) experiencing hot summers and cold winters (frosts occur often) as the entire region is situated between 1 000m and 1 400m above sea level, as a consequence of continental uplift. The Nama Karoo appears uniform, but the wide variety of parent materials and diversity of topographi-

cal features such as plains, dongas (erosion trenches), koppies (buttes) and flat-topped mountains (mesas), contribute dramatically to landscape heterogeneity. Mesas, which are the focus of this paper, are particularly characteristic of the Nama Karoo (Palmer and Hoffman 1997). These geomorphologic features are shaped by resistant strata of the Karoo Sequence (dolerite/basalt intrusions) that was formed between 345 million years (My) (Carboniferous) and 141My (Jurassic) ago. Landscape processes differ dramatically on and off mesas due to their elevation and often steep slopes (Figure 1). While disturbance, particularly grazing pressure, is presumably concentrated largely on the plains and lower slopes of mesas, other processes such as deposition, erosion, run-off of water and soil development vary dramatically over the habitat complex. To some extent, mesas could be regarded as habitat islands in a sea of surrounding plains habitats. While the patterns are not as distinctive as previously expected, these topographical features do contribute to richness and diversity at a landscape level, particularly in the northern parts of

South African Journal of Botany 2004, 70: 540–558

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the Nama Karoo (Burke et al. 2003). This paper focuses on mesas in the Middelburg district of the Eastern Cape, South Africa (Figure 2). The aims of the paper are firstly to investigate the extent to which mesas in this area support distinctive vegetation types, and secondly to determine the primary ecological factors that structure the vegetation of this interesting habitat complex and landscape feature. We comment on the regional context of our findings, and discuss the potential implications of our findings in the light of conservation and management (particularly restoration) of this semi-arid desert.

highly variable and patchy. Middelburg is characterised by continental temperature conditions with regular frosts in winter (Jones 2000). Average temperature for the district for mid summer is 20.9°C while the average winter temperature is 7.9°C. Sampling at Middelburg occurred from April 1998 to April 2000, but was generally undertaken in the wetter months, and at all times the rainfall was above average. Selection of sites Sites were established on three mesas and the plains sur-

Methods Study area

a

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 composed 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 rains comprise a small percentage of the annual rainfall. Typical for arid and semi-arid regions, rain is unpredictable,

0

250

500

750 1 000km

Eastern Cape, Middelburg 31°38´S, 25°08´E 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) indicating the three main habitats (mesa plateau, slopes, plains) and the common relationships of various disturbances to the habitats. Bandwidth indicates degree of disturbance. Figure adapted from Cooke et al. (1993)

Figure 2: The locality of sites sampled on and off three mesas in the Middelburg district of the Eastern Cape, South Africa. a) Map of South Africa indicating the location of Middelburg, Eastern Cape Province; b) Study sites. Transects are indicated by a straight line across the mesas

542

Pienaar, Esler and Mucina

rounding them. In all cases, sites were located on the NW and SE slopes and plains, representing the greatest exposure to maximum and minimum temperature extremes, respectively. A total of 17 sites were established on Tafelberg, of which three were on the plateau, three on each of the NW and SE slopes, and four on each of the NW and SE plains (directions taken from the centre of the plateau). Sites on the plateau were selected in such a way that one was located on the NW part of the plateau, one on the SE part of the 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 equal distances from the slopes, so as to minimise the possibility that vegetation might occur in a pattern at set distances from the cliff (formed by the dolerite cap). Sites on the slopes were selected in such a way that one was located on the lower slopes, one on the middle slopes, and one on the top slopes. Sites on the plains were approximately 300m apart, starting as close as possible to the bottom of the slopes. Features on the plains, such as ridges or hillocks were avoided as they may support plant communities specific to these features, and are not necessarily representative of the vegetation typically found on slopes, plains or plateaux. Folminkskop (1 437m, 242m above surroundings) and Buffelskop (1 440m, 245m above surroundings) are approximately 200m lower than Tafelberg (1 652m, 447m above surroundings). Folminkskop had a total of 15 sites, while Buffelskop had a total of 12 sites. Three sites were established on the plateau of Folminkskop, but on Buffelskop only two sites were established due to its shape (not a flat plateau). On both Folminkskop and Buffelskop only two sites were established on each of the NW and SE slopes due to shorter slopes than Tafelberg. These sites were located 1/3 from below and 2/3 from below on each of the slopes. Sites on the plains of Folminkskop and Buffelskop were selected the same way as those of Tafelberg. Within the constraints of the sampling design, the exact site to be sampled was selected randomly.

Cover was given as the maximum projected canopy cover (in %) of each perennial species. Some plants do not have a large circumference, but were very tall (1–2.5m). In such a case a higher value for cover was given than would normally have been the case in order to take the spatial size of the plant into consideration. Bare soil/debris was defined as the total area of visible bare soil/debris as seen from above when standing next to the subplot. Total percentage cover for a subplot often exceeded 100% and in extreme cases it was as high as 170%.

Field vegetation sampling

Grazing impact was estimated according to observed damage to plants, trampling and erosion in the area and the presence of plants normally associated with overgrazing, coupled with the knowledge that sheep are excluded in some cases from grazing on the mesas by fences surrounding them and the lack of watering points on them.

Three 5m x 5m plots at each site (see above) were sampled. Ten subplots of 1m2 were selected randomly from each 5m x 5m plot. Sites codes on the plains refer to the position of the sites in relation to the relative distance from the mesas. 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 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 base. Site codes for the slopes refer to the relative height of the site above the surroundings, e.g. Tafelberg SE slope lower (Field code: SESL L T) would refer to the lower slope on the SE aspect of Tafelberg mesa. All sites were permanently marked to enable future visitation. Plots were sampled for cover of perennial plant species (those species surviving longer than a year). Annuals, bulbous plants and seedlings were included whenever they were present in a plot. Where possible, no plant specimens were taken from inside the plots so as not to disturb the plots in any way.

Soil sampling and analysis Soil samples from several bulked samples (open- and closed-canopy soil samples were bulked to give one openand closed-canopy sample per site) taken from the top layers of soil (±125mm) were air-dried and analysed by the soil analysis laboratories at Elsenburg near Stellenbosch (Agricultural Research Council, Department of Agriculture). Soil was analysed for pH (KCl), resistance, acidity, contents of C, Na, P, K, Ca, Mg, Cu, Zn, Mn and Bo, soil texture, stone, sand, silt and clay (detailed soil analyses presented in Jones 2000). After soil analysis, open- and closed canopy values for the individual parameters were combined to yield one average value per parameter per site. Soil depth was measured in cm using a metal stake that was hammered into the soil. Rock cover was estimated as a percentage in each plot. Slope was not quantified, but since all areas were either on a slope or level we treated slope as a nominal variable. Relative soil moisture differences between plains and mesas was assumed on the basis of rock cover (cover estimated as percentages in plots), observed runoff, plant cover (cover estimated as percentages in plots), elevation (mesas clearly elevated above plains and often covered by clouds while plains are not, Pienaar, pers. obs.) and soil depth (measured in cm for every plot). Grazing impact

Classification of vegetation data All available relevés were captured into the National Vegetation Database (Mucina et al. 2000) using the programme package TvWin1.9c (Hennekens 1996, Hennekens and Schaminée 2001). As a first approximation the total data matrix was classified using TWINSPAN (Hill 1979). Further classification refinements included a series of ‘local’ TWINSPAN analyses (those limited only to portions of the analyses table) as well as re-shuffling of species and relevés aimed at optimisation of coincidence of groups of species with groups of relevés. The table manipulations were performed using the program Megatab 2.0 (Hennekens 1996). The final groups of relevés were interpreted as coenotaxa

Aspect

Field Code

Bare soil (%)

Rocks (%)

Soil Depth (cm)

pH (KCl)

Resistance (ohms)

C (%)

Na (mg/kg)

Phosphate (mg/kg)

K (mg/kg)

Ca (me%)

Mg (me%)

Cu (mg/kg)

Zn (mg/kg)

Mn (mg/kg)

Bo (mg/kg)

Clay (%)

Silt (%) Coarse Sand (%)

Original relevé number

Diag.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Running number Community code 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2

1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 3 3 3 3 3 3 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 3 3 3 3 3 3

A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A

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

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

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 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

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

South African Journal of Botany 2004, 70: 540–558

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A10 A10

A11 A11 A11 A11 A11 A11 A11 A11 A11 A11 A11 A11 A11 A11 A11 A11 A11

A12 A12 A12

A13 A13 A13 A13

A20 A20 A20 A20 A20 A20 A20 A20 A20, A23

A21 A21 A21 A21 A21 A21 A21 A21 A21 A21 A21 A21 A21

A22 A22 A22 A22

Helichrysum zeyheri Pelargonium abrotanifolium

Dimorphotheca cuneata Bulbine frutescens Selago saxatilis Sutera halimifolia Dianthus basuticus Berkheya pinnatifida Crassula obovata var. obovata Diospyros austro-africana Rhadamanthus sp. Ruschia britteniae Moraea pallida Commelina africana Eriospermum sp. Panicum maximum Crassula orbicularis Kedrostis africana Crassula sp. B

Euclea crispa Heliophila suavissima Pachypodium succulentum

Eriocephalus africanus Felicia ovata Pentzia lanata Crassula cotyledonis

Rhus burchellii Rhigozum obovatum Haworthia sp. Kleinia longiflora Anacampseros albidiflora Cissampelos capensis Lycium cinereum Aloe striata Cenchrus ciliaris

Crassula lanuginosa Hermannia minutiflora Indigastrum parviflorum Fingerhuthia africana Euphorbia brachiata Lessertia carnosa Indigofera sessilifolia Polygala ephedroides Gymnosporia buxifolia Zygophyllum lichtensteinianum Blepharis mitrata Pellaea calomelanos Enneapogon desvauxii

Blepharis capensis Pseudocrossidium crinitum Pseudocrossidium replicatum Polygala sp.

Table 1 cont. r .

r r

. . . .

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. . . . . . . . .

. . . .

. . .

. . m r r r r . + r r r r + r r . . . r . . . . . . . . . . . . . . . . . r r . . r . . . . . . . . .

r .

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a r r . . r . . . . . . . . r . .

. r

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. . . .

. . .

a . r r . . . r . . . . . . . . .

. . . .

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. . . . . . . . .

. . . .

. . .

a r . r . . r a r . . . . . . r .

+ . r . . . r + r a r r . . . . .

. r m . r . . . . . r r . . . r r

. . . .

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. . . . . . . . .

. . . .

. a . . . . . . .

r . r . . r r r r a r r . r r . r

r + r . r . . a m .

. . . .

. r r

. . . . . . . . . . . . . . . . .

r .

. . . .

r r .

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. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . .

. . . . . . . . .

. . . .

r . r

. . . r . . . . . . . . . . . . .

. . . .

. . r

. . . . . . . . . . . . . . . . .

. . . .

r r r

. . . . . . . . . . . . . . . . .

. . . .

. . r . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . .

. . . r a . . . . . . . . . . . . . . . . . . . . . .

. . . .

r r r

. . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

. . . .

. . . . . . . . . . . . .

. . .

. . . . . . . . . . . . . . . . .

r r

. . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . r . . . . . . .

. . . . . . . . .

. + a . . . . . r . . .

r . .

. . . . . . . . . . . . . . . . .

r .

. 3 . . . . . . . . . . . . . . . . . . . . . . . . .

. . . .

. . r

. . . . . . . . . . . . . . . . .

r + r r . r r . . r a . + .

. 1 . . . . . . . . . . . . . . . . . . . . . . . . .

. . . .

. . r

. . . . . . . . . . . . . . . . .

r r

r . .

. . . . . . . . . . . . . . . . .

. .

. . . .

. . .

. . . . . . . . . . . . . . . . .

. .

. . . . . . . . .

. . . . . r . . .

. . . .

. . . .

. . . .

. . . . . . . . . . . . .

. . r . . . . . .

r b a r r r . . + . . r

. . .

. . . . . . . . . . . . . . . . .

r .

. r . . . . . . . . . . . . . . . . . . . . . . . 1 . . . . . . . . . . . . .

. . . . . . . . .

b r . r

. . .

. . . . . . . . . . . . . . . . .

. .

. . . .

r . . . . . . . . . . . .

. r r . r . . . .

. . . .

. . .

. . . r . . . . . . . . . . . . .

. . . .

. . .

. . . . . . . . . . . . . . . . .

. . . .

. . .

. . . . . . . . . . . . . . . . .

. .

. . . .

. . .

. . . . . . . . . . . . . . . . .

. .

. . . .

. . .

. . . . . . . . . . . . . . . . .

. .

. . . .

. . .

. . . . . . . . . . . . . . . . .

. .

. . . .

r r r . . . . . . . . . . . . . .

. . . r r r . . . . . . .

. . . .

. . . .

. . . .

r r r . . . . . . r + r . r . r . . . . . . . . . . . . . . . . . . . . . . .

. . . .

r . . . . . . . . . . . .

. a a . b b . a a a 1 a r r r r . r . . r + m r r . r r . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . .

. . r

. . . . . . . . . . . . . . . . .

. . . r + .

. . . .

r . . r . . . . . . . . .

. 1 . r r . . . .

. . . .

. . .

. . . . . . . . . . . . . . . . .

. .

. . . .

r r . . . . . . . . . . .

3 a r . . . . . .

. . . .

. . .

. . . . . . . . . . . . . . . . .

. .

. . . .

. r . . . . r . . . . . .

3 + . 1 . . . . a

. . . .

. . .

. . . . . . . . . . . . . . . . .

. .

. . . .

r r . . . . r . . . . . .

. + . r . . . . r

. . . .

. . .

. . . . . . . . . . . . . . . . .

. .

. . . .

. . .

. . . . . . . . . . . . . . . . .

. .

. . . .

. . . .

. . .

. . . . . . . . . . . . . . . . .

. .

. . . .

. . . .

. . . .

. . . + . . . . . 1 r . .

. . . . a m . . r . . . . r . . r r . . . . . . . . .

. . . .

. . .

. . . . . . . . . . . . . . . . .

. .

. . . r . . . r . . r m . . . . . . r . . . . r . . a . a . . r . . . . . . .

. 1 . + . . . . +

. . . .

. . .

. . . . . . . . . . . . . . . . .

. .

. . . .

. . . r r . . r a . . . .

. a r . . . . . .

. . . .

. . .

. . . . . . . . . . . . . . . . .

. .

. . . .

. . . r . r . r + . . . .

m a . . . r . . .

. . . .

. . .

. . . . . . . . . . . . . . . . .

. .

. . . .

. . .

. . . . . . . . . . . . . . . . .

. .

. . . .

r . . .

. . .

. . . . . . . . . . . . . . . . .

. .

. . . .

. . .

. . . . . . . . . . . r . . . . .

. .

. . . .

. . . .

. . . .

. . . . . . . . . . . r .

. . . .

. . . . . . . . . . . r .

r b b a r a + + . . r . . . . . . . . . . r . . . . . . . . . . . . . .

. . . .

. . .

. . . . . . . . . . . . . . . . .

. .

. . . . . . . . r . . . . . . . . . . . . . . . . m a . . . . . r . . . . . .

a b . . . . . . .

. . . .

. . .

. . . . . . . . . . . . . . . . .

. .

. . . .

. . . . . . . . . . . r .

+ b . . . . . . .

. . . .

. . .

. . . . . . . . . . . . . . . . .

. .

. a . . . . . . .

. . . .

. . .

. . . . . . . . . . . . . . . . .

. .

. . . .

. . . .

. . . .

. . .

. . . . . . . . . . . . . . . . .

. .

. . . .

. . .

. . . . r . . . . . . . . . . . .

r .

. . . .

. . . .

. . . . . . . . . . . . r

. . . .

. r . r . . . . . . . . r

. b a r . . . . . . . r . . . . . . . . r . . r . . +

. . . .

. . .

. . . . . . . . . . . . . . . . .

. .

. . . . . r r r r . . . . . . . . r . . . . . . r a . . . . r r . . . . . . .

. a . . . . . . .

. . . .

. . .

. . . . . . . . . . . . . . . . .

. .

. . . .

. r . r . . . . . . . . r

. . . r r . r . r

. . . .

. . .

. . . . . . . . . . . . . . . . .

r .

r . . .

. . .

. . . . . . . . . . . . . . . . .

. .

. . .

. . . . . . . . . . . . . . . . .

. .

. . . .

. r . . . . . . . . . . r

. . . .

. . . . . . . . . . . . .

. . .

. . . . . . . . . . . . . . . . .

. .

. . . . . . . . . . . . .

. . . . . . . . . . . . . . m m . + r . r r . r .

. . . . . . . . . . . . .

+ + r r r . r . r

. + . . . . . . . . . .

. . .

. . . . . . . . . . . . . . . . .

. .

. a . + . a 1 r . . . r . . . . . . . r . . r . . r . . r r . . r r . .

. . . .

. . .

. . . . . . . . . . . . . . . . .

. .

a + r r

. . . . . . . . . . . . .

a m r m . r r r .

. . . .

. . .

. . . . . . . . . . . . . . . . .

. .

. . . .

. . . . . . . . . . . . .

r 1 . . . r . + .

. . . .

. . .

r . . . . . . . . . . . . . . . .

. .

. . . .

. . . . . . . . . . . . .

. r . + . . . . b

. . . .

. . .

. . . . . . . . . . . . . . . . .

. .

. . . .

. . . . . . . . . . . . .

. 1 r + . . . . a

. . . .

. . .

. . . . . . . . . . . . . . . . .

. .

r . . .

. . . . . . . . . . . . .

r a . a . . r . a

. . . .

. . .

. . . . . . . . . . . . . . . . .

. .

. . . .

. . . . . . . . . . . . .

r r . . . r r r b

. . . .

. . .

. . . . . . . . . . . . . . . . .

. .

. . . .

. . . . . . . . . . . . .

a r . . . r r r a

. . . .

. . .

. . . . . . . . . . . . . . . . .

. .

. . . .

. . . . . . . . . . . . .

a m . . . . . m b

. . . .

. . .

. . . . . . . . . . . . . . . . .

. .

544 Pienaar, Esler and Mucina

X X X X X X X X X-A21 X X X-A21 X-A22 X-A23 X-A24 X-A25 X-A12 X X X-A12 X-A13 X-A14 X X-A21 X X X X X-A13 X-A21 X-A22 X X X X X X X X X X X X X X X X X X X X X X X-A22

. . . . r . . a b + + m a a . . . . r . . . . . . . . . . . . . . . . . . . . . . . . . . r . . . . . . . .

. . . . . . . m 3 + r m r a r . . . + . . . . . . . . . . . . . . . . . . . . . . . . . . r . . . r . . . .

+ . . . . r . + b . 1 a 1 r . . . . r . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

b . . r . . 1 + a . . a 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . r . . . . .

a . . . . r + r b r r a + . . . . . . . . . . . . . . . . . . . . . . . . r . . . . . . . . . . a . . . r .

a . . + . r . r a . . a r r . 1 . . r . . . . . . . . . . . . . . . . . . r . . . . . . . . . . . . r . . .

m . . r . . . r a 1 r r a . . r r + . . . . . . . . . . r . . r . . . . . . . . . . . . . . . . . . . . . .

a . . . . . . r a + r 1 1 r . 1 r r . . . . . . . . . . . . . r . . . . . . . . . . . . . . . . . . . . . .

+ + . . . . . + b . r m + 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . r . . . . . . . . . . .

r . r . . r r . a b . r a r r . . . r + r r . . . . r . . . . . . . . . . . . . . . . . . . . r 1 . . r . r

1 . 1 . . . . . m . . r a r r . m r . a r . . . . r . . . . . . r . . . . . . . . . . . . . r . . . . r . r

1 . a . r r . . m a . . m r . . a . . + r r r . . . . . . . . . . . . . . . r . . . . . . . . . + . . . . r

. . 1 . . r . . b a r r m . . . a . . r . . r . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . r

r . r . r r . . a a r r 1 r . . a . . 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +

a . b . . r . . r a . r r r . r . . r + r . . . . 1 . . . . . . . . . . . . . . . . . . r . . . . . . . . .

a . 1 . r r . r a b r . r r . . . . . . . . . r . . . . . . . . + + . . . . . r . . . . . . . . . . . . r .

1 . a r m r + 1 r a . r r r . . + . . r r . . r . r . . . . . . . . r . . . . r . . . . r . . . . . . . . .

1 . a . . . . . r a . . . . . . . a . . . r . + . . . . . . . . . . . . . . . r . . . r . . . . . . . . . .

a . a . 1 + r 1 . a . 1 . r . . . . . r . . . . . . . . . . r . . . . . r . . . . . . . . . . . . . . . . .

a 1 a . 1 + . r . + . m . . r . . . . . r . . . . . r r r . r . . . . r . . . . . . . . . r . . . . . r . .

m . . . r 1 . r . a . a . . . r . . r . . . . . r . r r 1 . . . . . . . . . . . . . . . . . . . . . . r . r

. r a . + r a . . 1 . + . r + r . . . . . . . . r . . . r r . . 1 . . . r . . . . . . . . . . r . . . r . .

. m m r r r 1 . . . . + . . r . r . . . . . . . . + . . a r . . . . . . . . . . . . . . . . . . . r . r . .

r r + r r r a r . 1 . r r . . . . . . . . . . . r . . r r . . . . . . . . . . . r . . . . . . r . . . . . .

r r a . m r . . . r . r . r . r + . r . r . . r r . r r . . . . . . . . . . . . r . . . . . . . . . . r r .

+ + a . + . . . . r . r . . . r . a . . r . . 1 r . r r . . . . . . . . . . . . . . . . . . . a . . . r r .

. r a . a r r r . . . . r . . . a . r . r . . . . . . . . . . . . . . . . . . . . . . . . . r . . . . . . .

. . a . + . r . . . . . r . . . b . . . r . . . . . . . . . . . . . . . . . . . r . . . . . r . . . . . . .

. . a . m r r . . . . . m . r . a . . . r r . . r . r . . . . . . . . . . r . . . . . . . . . . . . . . . .

. . m . 1 r . . . . . r r + . . a . . . . r . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . + . 1 . . . r . . r . + . . a . . . . r . . r . r . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . a . r . . . . . . r 1 r . . m . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . r . .

. m b . . r . . . a . . . . . r . r . . + . . r r . . r . . . r . . . . . . . . . . . . . . . . . . . . r .

. + b . r . . . . . . r . r . . . . r . . . . . . . . . . . . . . . r r . . . . . . . . . . . . . . . r . .

. r b . + . . . . . . r . r . r r . . . . . . r . . . . . . . . . . . r . . . r . . . . . . . . . . . r . r

r r a . + . . r . . . r . r r r m . r . . . . . . . r . . . . . . . . . . . . . . . . . . . . . . . . r . r

. r a . a . a r . . . + . . . . . r . . . . . . . r . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. r r . b r 1 r . . . r . . r . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . r . . . . . .

. . + . a r a r . . . + . . . . . r . . . . . . . . . . . . r . . . . . . . . . . . . . . . . . . . . r . .

. r a . . . a + . . . r . . . . a . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . r . . r + r . r . r r . r . b . . . r . . . . . . . . . . . . . . . . . . . . . . . . . . . r . . r . .

1 + . . . + m r . . . r + r . . a . . . r . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 . . r . .

r + + r . 1 m . . r . r . . . . a a r . + . . . . . . . 1 . . . . . . . . . . . . . . . . . . . a . . r . .

. . r . r . + r . . . r m . . . 1 r . r a . . r . . . . . . . . . . . . r . . . . . . . . . . r . . . . . .

. . . . b r . . a r r r r r . r 1 . . . r . . . . . . r . r . . . . . . . . . . . . . . . . . r . . . . . r

. . . . b . . . a 1 r r . . . r 1 . . . r . . . . . . . . r . . a . . . . . . . . . . . . . . . . . . . . r

. . . . b r . . a 1 . r . r . r + r . . r . r . . . . r r r . . . . . . . . . . . . . . . . . r r . . . . r

. . . . a . . r . r r r r . . r a . . r r . . r . . . r + + . . . . . . r . . . . . . . . . . r m r . . . .

. . . . a . . . r + . r r . . . a . . r r . . r . . . . r r . . . . . . . . . . . . . . . . . r . . . . . .

+ m + . r 1 r . . . . r . . . r + . r . + . . . . . r . m . . r . . . . . . . . . . . . . . . . b . . r . .

r a r r + 1 . . . . . r . . . . r . . . r . . . . . . . 1 . . . . . . . . . . . . . . . . . . . b . . r . .

. 1 + . b r r r . . r 1 . . . r . . . . . . r . . . . . . . . . . . r . . . . . . . . . . r . . . . r r r r

r m r r r . r + . . + + . . r r . . . . . . . . . . . . r . . . . r . . . . . r . . . . r . . . . . r r . r

. b + . m r . r . . . r . . . r . . . . . . . . . . . . . . . . . 1 . a . . . . . 1 r . . . . r . . . . . 1

r + . . . r . . . . . . . . . . . . . 1 . . . . . . . . m . 1 . . . . . . . . . . . . . . r . . . . . r . r

r . . . r r . . . . . . . . . . . . . + . . . . . r . . r . + . . . . . . . . . . a . . . . . 1 . . . . . r

. 1 r . . r . . . . . . . . . . . . . . . . . . r + r r r . r . . r . . . . . . . . . . . . . r . . r r . .

r . . . . r m . . . . . . . . . . + . r r r . . . . . . . . a . . . . . . . . . r . . . . . . r . . . r . r

. r . . . r + r . . . . . . . . . . . r r r . . . m . r . . a . . . . . . . . . . + . r . . . r r . . r . r

. . . . . r . . . 1 . . . . . . . . . r . . . . r . r . + . r . . . . . . . . . r . . . . r . r a . . r . .

. r . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . r . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . r . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . r . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . r . . . . . . . . . . . . . . . . . . . . . . .

A1: Felicia filifolia–Themeda triandra Community Group; A11: Felicia filifolia–Dimorphotheca cuneata Community; A12: Felicia filifolia–Enneapogon scoparius Community; A13: Felicia filifolia–Eriocephalus africanus Community; A2: Rhigozum obovatum–Rhus burchellii Community Group; A21: Rhigozum obovatum–Gymnosporia buxifolia Community; A22: Rhigozum obovatum–Pegolettia baccaridifolia Community; A23: Rhigozum obovatum–Cenchrus ciliaris Community

Digitaria eriantha Sporobolus fimbriatus Enneapogon scoparius Eragrostis obtusa Aristida diffusa Felicia muricata Pentzia incana Tragus koelerioides Themeda triandra Felicia filifolia Wahlenbergia nodosa Eragrostis curvula Cymbopogon pospischilii Eustachys paspaloides Pegolettia retrofracta Asplenium cordatum Heteropogon contortus Asparagus laricinus Jamesbrittenia tysonii Pentzia punctata Asparagus striatus Lantana rugosa Hibiscus pusillus Stachys linearis Cheilanthes hirta Mestoklema elatum Crassula muscosa Trichodiadema rogersiae Helichrysum rosum Pentzia quinquefida Pegolettia baccaridifolia Pelargonium aridum Tarchonanthus camphoratus Euryops annae Hermannia pulchella Diospyros lycioides Fabronia abyssinica Sutherlandia frutescens Pteronia glauca Boophone disticha Crassula montana Cadaba aphylla Melianthus comosus Solanum tomentosum Aristida adscensionis Chrysocoma ciliata Senecio cotelydonis Asparagus burchellii Eriocephalus ericoides Gazania linearis Lepidium africanum Limeum aethiopicum Oxalis commutata Selago albida

Table 1 cont.

South African Journal of Botany 2004, 70: 540–558 545

Field Code

Bare soil (%)

Rocks (%)

Soil Depth (cm)

pH (KCl)

Resistance (ohms)

C (%)

Na (mg/kg)

Phosphate (mg/kg)

K (mg/kg)

Ca (me%)

Mg (me%)

Cu (mg/kg)

Zn (mg/kg)

Mn (mg/kg)

Bo (mg/kg)

Clay (%)

Silt (%)

Coarse Sand (%)

Diag.

Original relevé number Aspect

Running number Community code

a a a a a a a a a a a a a b b b b b b b b b b b

1 1 1 1 1 1 1 1 1 1 1 1 2 2 2 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 4 4 4 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 3 3 3

1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2

B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B

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

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

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 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

-

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

546

Pienaar, Esler and Mucina

B10 B10 B10

B10 B10 B10 B10

B10 B10 B10 B10 B10 B10 B10 B10 B10

B10 B10 B10 B10 B10 B10

B11 B11 B11 B11 B11 B11 B11 B11 B11 B11 B11 B11 B11

B12 B12 B12

B13 B13 B13 B13

B14 B14 B14

B20 B20

Ruschia intricata Chrysocoma ciliata Bulbostylis humilis

Albuca setosa Mestoklema elatum Hertia pallens Salvia verbenaca

Talinum caffrum Berkheya heterophylla Phyllobolus sp. Aridaria noctiflora subsp. straminea Osteospermum leptolobum Digitaria eriantha Oligocarpus calendulaceus Sporobolus fimbriatus Gazania linearis

Eragrostis obtusa Drosanthemum duplessiae Pentzia globosa Crassula muscosa Tribulus terrestris Medicago laciniat*

Oropetium capense Indigofera sessilifolia Monsonia brevirostrata Anacampseros albidiflora Cyperus usitatus Tragus berteronianus Oxalis commutata Senecio radicans Heliophila suavissima Phymaspermum parvifolium Urochloa sp. Crassula sp. A Hypertelis sp.

Crassula sp. Adromischus sp. Jamesbrittenia atropurpurea

Zygophyllum incrustatum Senecio cotelydonis Cynodon dactylon Galenia africana

Convolvulus sagittatus Felicia ovata Thesium spartioides

Gnidia polycephala Rosenia humilis

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r . . .

. . .

South African Journal of Botany 2004, 70: 540–558 547

B22

B23

X X X X X X X X-B13 X-B21b X-B22 X X X-B21 X X-B21 X-B21b X X-B11,B21b X-B21 X X-B21b X X X X X X-B21b X

Eragrostis bicolor

Nenax microphylla

Eragrostis lehmanniana Pentzia incana Aristida adscensionis Tragus koelerioides Lycium cinereum Salsola sp. Enneapogon desvauxii Thesium hystrix Felicia muricata Chloris virgata Geigeria ornativa Aristida diffusa Asparagus burchellii Blepharis mitrata Fingerhuthia africana Lepidium africanum Selago albida Eriocephalus ericoides Trichodiadema rogersiae Plinthus karooicus Helichrysum lucilioides Aptosimum procumbens Limeum aethiopicum Hermannia pulverata Moraea pallida Eragrostis curvula Enneapogon scoparius Pteronia glauca . r r + . . r . r . . b r r . . . a . . . . . . . . . .

.

.

. . . . . . . . .

r + a a r . r . r . . a . r r . . r . . . . . . . r . .

.

.

. . . . . . . . .

r + + m . . r . r . . a . r r . r a . . . . . . . r r .

.

.

. . . . . . . r .

r a b . . . + . r r . . . . . . . . r . . . . . . . . .

.

.

. . . . . . . . r

r a a . + . + . . r . . . . . . . . . . . . . . . . . .

.

.

. . . . . . . . .

r 1 b . r . 1 . . r . . . . . r . . . . . . . . r . . .

.

.

. . . . . . . . .

. a b . a . r . . . . . . . . r . 1 . . . . . . . . . .

.

.

. . . . . . . . .

r b a . r . r r . . r . . . . r . m . . . . . . . . . .

.

.

. . . . . . . . .

r m a . . + r . . . . r . . . r . + r . . . . . . . . .

.

.

. . . . . . . . .

r a 3 r . . . . . . . . . . r . r a r . . . . . . . . .

.

.

. . . . . . . . .

. 1 3 . r . . . . . r . . . r . . r r . . . . . . . . .

.

.

. . . . . . . . .

r a 3 r a r . . . . r . . . . r r . r . . . . . . . . .

.

.

. . . . . . . . .

1 b + r . + r . . . . . r r . . . . r . . . r . . . r .

.

.

. . . . . r . . .

m b m r . + r . . . . . r r r . . . . . . . r r . . . .

.

.

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r a r r . . + . . . . . 1 r . . r . r a r . . . . . a .

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.

.

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.

.

. . . . . . . . .

+ . + . b r . r . . . . r . . . . . + r . . r . . . . r

.

.

. . . . . . . . .

a . a r a a . a r . r . . . . . r . r . . r r r . . . .

.

.

r . . . . . . . .

m . a . + + . r r . . . . . r . + . . . . r . . . . . .

.

.

. . . . . . . . .

r 1 + . r r . r r . . . . . . . . . . r . . . . . . . .

.

r

. . . . . . . . .

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. . . . . . . . .

. r + . a + . r . . . . . . . r r . r r . . . . . . . .

. m + r r a + . . r r . r . . . . . . r . r r . r r . . .

. . r + r 1 + . r . . . . . . . r . . r . 1 . . . . . . .

.

. + .

. . . . . . . . .

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.

.

. . . . . . . . .

. + + r b 1 . a r r . . . . . . . . . . . . . . . . . .

.

.

. . . . . . . . .

r + + r . a . r r r . . . . . . r . . . a . . r . . . .

.

.

. . . . . . . . .

. m 3 . b + r r . r . . . . . . . . . . r r . . . . . .

.

.

. . . . . . . . .

. 1 a . r r . . . . . . . . . . . . . . . r . . . . . .

.

.

. . . . . . . . .

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.

.

. . . . . . . . .

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.

.

r a . 1 r r . r . . . 1 . . . . . . . . . . . . . . . .

.

.

r m . r . . . . . . . . . . . . . . . . . r r . . . . .

.

.

. 1 a . m r . . . . . . . . . . . . . . . . . . . . .

r a . 1 . . . . . . . . . . . . . . . . . . . . . . . .

.

.

m . . . . . . . .

. a r b . . . r . . . a r . . . . . . r . . r . . . . .

.

.

a + r . . . . . .

. b . a . . . . . . . a . . . . . . . . . r . . . . . .

.

.

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. a r r r . . . . . . a r . r . . . . 1 . r . . . . . .

.

.

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+ 1 . r r . a . . . . . . . . . . . . . . . . . . . . .

.

.

b . b . r . . . .

1 m . r 1 . a . . . . . . . . . . . . . . . . . . . . .

.

.

m . b . r . . . .

+ b . a . . a . . . . . r . . . . . . 1 . r . . . . . .

.

.

a a m r . . . . .

b a . . . . . . . . . . . . . . . . . . . . r . . . . .

.

.

r . 1 . . . . . .

a b . m . . . r . . . . . . . . . . . . . . . . . . . .

.

.

a r + . . . . . .

r a . r . . b . . . . . . . . . r . . . . . . . . . . .

.

.

a . a . r r . . .

a b r r . . . . . . . . . . a . . . r . . . . . . . . .

.

.

a . r r . r . . .

a r . a . . 1 r + . . 1 . . . r r m . r + r . . . . . .

.

.

. a + r . . r . r

a r . a . . m m r . . + r . . r r . . . r + . . . . . .

.

.

r a m r r . r r +

m + . a . . m r r . . + r . . r . r . . r + . . . . . .

.

.

r a m r r . . r +

r a . a . . a r . . . . r . . . . . r r . + . r . . . .

.

.

a a m r . r r r r

r a . a . . m r . . . . r . . . . . . r r r . r . . . .

.

.

b a 1 r . r r . r

. m . r r . + . . . . r . . r . . . . . . . . . . . a .

.

.

. a . . . . . . .

. r . m . . r + . . . r . . r . . r r . r . r . . r a .

.

.

r + . r . . . . .

. + . a . . r r . . . r . . r . . . . . 1 . . . . . + .

.

.

a m . . . . . . .

r r . r . . r . . . . . . 1 . . . . . . . . + . . . . .

.

.

r 1 . r . . . . .

+ 1 . r r r . . . . . . . . . . r r . . r r r . . . . +

.

.

r r . a . . . . .

. . . . . . . . .

. . . . r . . . .

. . . . . . . . .

. m + . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . .

r a . . . . r . . . . . . r . . . . . . r . r . . . . .

.

a + . . a . . . . r . . . . . . . . . . . . . . . . . .

.

+ . . . r . . . . r . . . . . . . . . . . . r . . . . .

.

a r . . + . . . . + . . . . . . . . . . . . . . . . . .

.

b . . . . . . . . . . . . . . . . . . . . . . . . . . .

.

a . . . . . . . . . . . . . . . . . . . . . . . . . . .

.

a . . . . . . . . . . . . . . . . . . . . . . . . . . .

.

r + a r . r . r . . . . . . . . . . . . . . . . . . . .

.

. m . + a r 1 .

1 r . 1 . . . . .

r + a r . r . r . . r . . r . . . . . . . r . . . . . .

r

.

. . . . . . . . .

r r 1 + . r . r . . . + . . . . . . . . r . . . . . . .

r

.

. . . r . r . . .

B1: Aristida adscensionis–Eragrostis obtusa Community Group; B11: Aristida adscensionis–Ruschia intricata Community; B12: Aristida adscensionis–Jamesbrittenia atropurpurea Community; B13: Aristida adscensionis–Zygophyllum incrustatum Community; B14: Helichrysum lucilioides–Thesium spartioides Community; B2: Eragrostis lehmanniana–Eragrostis bergiana Community Group; B21: Pentzia incana–Eragrostis bergiana Community; B22: Eragrostis lehmanniana–Eragrostis bicolor Community; B23: Eragrostis lehmanniana–Rosenia humilis Community

B21 B21 B21 B21 B21 B21 B21 B21 B21

Eragrostis bergiana Blepharis capensis Zygophyllum lichtensteinianum Pteronia sordida Chenopodium mucronatum Melolobium microphyllum Indigofera zeyheri Polygala asbestina Jamesbrittenia tysonii

Table 2 cont.

548 Pienaar, Esler and Mucina

549

South African Journal of Botany 2004, 70: 540–558

(or in more general terms — plant communities), characterised by a combination of diagnostic species and additional ecological and topographical information. At this stage we refrain from describing these vegetation types as formal syntaxa (in terms of the Code of Phytosociological Nomenclature (Weber et al. 2000, 3rd edn.), and prefer to use a neutral term ‘Community’ and ‘Community Group’. We present, for technical reasons, the results of the vegetation classification in the form of two relevés x species tables. One of the tables (Table 1) features the coenotaxa of the Community Group 1 (Slopes and Plateaux), while the other (Table 2) features the coenotaxa of the Community Group B (Plains). The original % cover values were replaced (for presentation purposes) by the cover-abundance categories 5 (75–100% of cover), 4 (51–74%), 3 (25–50%), 2b (12.5–24%), 2a (4–12.4%) and 2m (<4%), 1 (<3%), + (<2%) and r (<1%) (see Barkman et al. 1964). Details for each relevé, including site codes, location and altitude are presented in Table 3. Species occurring at low frequencies are detailed in Appendix 1.

munities. Plains (B) are subdivided into Community Groups B1 and B2, constituting four and three communities, respectively.

Definitions of diagnostic species and dominance

Community Group (CG) A1 (Folminkskop and Tafelberg dolerite plateaux, Tafelberg SE upper and middle slopes) occurs in areas that are relatively high in Na, Zn, Bo and silt. The soils have higher resistance, status of Mn, Mg, Clay, C, Cu and bare soil in comparison with CG A2 (all other NW and SE slopes, and the Buffelskop plateau). The environmental variables most strongly correlated with the axis are Na, P, Mn, silt and slope. Exceptions to this are Tafelberg SE upper and middle slopes that are more similar to CG A2 regarding environmental variables, but are floristically grouped with CG A1 (see Community A13). CG A1 occurs in areas that are higher in Ca, K, coarse sand, pH, P, have more rocks and deeper soils in comparison with CG A1 (Figure 4).

We prefer to use the neutral term ‘differential species’ for floristic characterisation of the coenotaxa. The differential species has validity only on the same level of syntaxonomic hierarchy; hence it may differentiate only coenotaxa of the same rank (Mucina 1993). Ideally such a species should be unique to one coenotaxon, but this case is rather rare. We choose the constancy of 80% for a species within the considered coenotaxon as the borderline value for that species to be still considered differential. Analysis of species–environmental relationships A series of ordinations were performed to analyse environmental gradients across the landscape as well as linkages between the distribution of species and environmental variables. Ordination was conducted firstly on the entire data set, thereafter, partial data sets were analysed for each of the community groups. Ordination was done using Canonical Correlation Analysis (CCA; Jongman et al. 2000), using default options of the program package CANOCO4 (Ter Braak and Šmilauer 1998). Nomenclature of plants Nomenclature of plant taxa follows the checklist of the National Vegetation Database (Mucina et al. 2000) imbedded within the local TvWin 1.98c database, and which features the national flora checklist of PRECIS system of the National Botanical Institute dated January 2000, as well as Germishuizen and Meyers (2003). Results The species x relevé matrix is divided into two main groups of communities: Slopes and Plateaux (Table 1, A) and Plains (Table 2, B). Slopes and Plateaux (A) are subdivided into Community Groups A1 and A2, each constituting three com-

Complexes: Slopes and Plateaux (A) and Plains (B) Vegetation of Slopes and Plateaux (A) is classified as Open Grassy Shrubland, while that of Plains (B) is classified as Open Dwarf Shrubland. Both are different facies of shrubby semi-desert. The environmental variables most strongly correlated with the axis are rocks, bare soil, slope, C and Mn. Communities of the Slopes and Plateaux are more rocky and have higher values of silt, clay, Bo, Mg, Zn, Mn, Cu and C in comparison with communities on the Plains, while the Plains communities are generally higher in percentage bare soil, coarse sand, P, Ca, Na and K. The Plains communities also have deeper soils, higher resistance and higher pH than Slopes and Plateaux communities (Figure 3). Complex A: Slopes and Plateaux

Community Group A1 Felicia filifolia–Themeda triandra Grassy Shrubland Community Group A1 occurs on Tafelberg plateau, Folminkskop plateau, and Tafelberg SE upper and middle slopes. This CG is the least impacted by domestic herbivory of all the 4 CGs, and the vegetation is in a relatively non-degraded condition. Palatable species are common to dominant with unpalatable species occurring at low densities, and soil erosion is minimal. A11 Felicia filifolia–Dimorphotheca cuneata Shrubby Grassland This community occurs on Tafelberg plateau, where soils have relatively high status of Na, K, Zn, Mg, Mn, C, Bo and Cu, they are silty and clayey, and show high levels of resistance (Figure 5). The environmental variables most strongly correlated with the axis are P, slope, coarse sand, Mn and silt. Aspect and slope values are absent, as Tafelberg is flat on top. Tafelberg is the highest mesa in the vicinity of the study area, and dolerite caps of Beaufort Group origin, topped both Tafelberg and Folminkskop. Tafelberg plateau

550

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Table 3: Site details for each relevé sampled in the Middelburg District of the Eastern Cape, SA Rel. no. 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, 67, 68 69, 70, 71 72, 73, 74 75, 76, 77 78, 79, 80 81, 82, 83 84, 85, 86 87, 88, 89 90, 91, 92 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, 33 129, 130, 131 132, 34, 35 36, 37, 38 39, 40, 41 93, 94, 95 96, 97, 98 99, 100, 101 102, 103, 104 105, 106, 107 108, 109, 110 111, 112, 113 114, 115, 116 117, 118, 119 120, 121, 122 123, 124, 125 126, 127, 128

Mesa Tafelberg Tafelberg Tafelberg Tafelberg Tafelberg Tafelberg Tafelberg Tafelberg Tafelberg Tafelberg Tafelberg Tafelberg Tafelberg Tafelberg Tafelberg Tafelberg Tafelberg Folminkskop Folminkskop Folminkskop Folminkskop Folminkskop Folminkskop Folminkskop Folminkskop Folminkskop Folminkskop Folminkskop Folminkskop Folminkskop Folminkskop Folminkskop Buffelskop Buffelskop Buffelskop Buffelskop Buffelskop Buffelskop Buffelskop Buffelskop Buffelskop Buffelskop Buffelskop Buffelskop

Site location NW Plain 4 NW Plain 3 NW Plain 2 NW Plain 1 NW Slope lower NW Slope middle NW Slope upper Plateau NW Plateau Center Plateau SE SE Slope upper SE Slope middle SE Slope lower SE Plain 1 SE Plain 2 SE Plain 3 SE Plain 4 NW Plain 4 NW Plain 3 NW Plain 2 NW Plain 1 NW Slope lower NW Slope upper Plateau NW Plateau Center Plateau SE SE Slope upper SE Slope lower SE Plain 1 SE Plain 2 SE Plain 3 SE Plain 4 NW Plain 4 NW Plain 3 NW Plain 2 NW Plain 1 NW Slope lower NW Slope upper Plateau NW Plateau SE SE Slope upper SE Slope lower SE Plain 1 SE Plain 2

Site code NW PL 4 – T NW PL 3 – T NW PL 2 – T NW PL 1 – T NW SL – T NW SM – T NW SU – T PL NW – T PL CEN – T PLAT SE – T SE SL U – T SE SL M – T SE SL L – T SE PL 1 – T SE PL 2 – T SE PL 3 – T SE PL 4 – T NW PL 4 – F NW PL 3 – F NW PL 2 – F NW PL 1 – F NW SL – F NW SU – F PL NW – F PL CEN – F PLAT SE – F SE SL U – F SE SL L – F SE PL 1 – F SE PL 2 – F SE PL 3 – F SE PL 4 – F NW PL 4 – B NW PL 3 – B NW PL 2 – B NW PL 1 – B NW SL – B NW SU – B PL NW – B PLAT SE – B SE SL U – B SE SL L – B SE PL 1 – B SE PL 2 – B

and Folminkskop plateau are correlated with the same environmental factors, but the values for Tafelberg are higher than those for Folminkskop. This could be explained by the similarities in geology and soils, but a difference in height (Tafelberg is approximately 200m higher than Folminkskop). Both Enneapogon scoparius and Asparagus striatus occurred throughout the rest of CG A, but are remarkably absent in this community. This community has not been impacted by domestic herbivores for 40 years and is grazed by indigenous antelope such as Kudu (Tragelaphus strepsiceros) and Grey Rhebok (Pelea capreolus) and Smith’s Red Rock Rabbit (Pronolagus rupestris). The vegetation is in a relatively non-degraded condition and is dominated by highly palatable grasses.

Habitat Plain Plain Plain Plain Slope Slope Slope Plateau Plateau Plateau Slope Slope Slope Plain Plain Plain Plain Plain Plain Plain Plain Slope Slope Plateau Plateau Plateau Slope Slope Plain Plain Plain Plain Plain Plain Plain Plain Slope Slope Plateau Plateau Slope Slope Plain Plain

Latitude 31°38.44’S 31°38.35’S 31°38.13’S 31°38.06’S 31°38.41’S 31°38.49’S 31°38.56’S 31°38.63’S 31°38.84’S 31°38.83’S 31°38.92’S 31°38.99’S 31°39.03’S 31°39.52’S 31°39.61’S 31°39.72’S 31°39.83’S 31°33.20’S 31°33.29’S 31°33.41’S 31°33.50’S 31°33.66’S 31°33.71’S 31°33.80’S 31°33.83’S 31°33.94’S 31°33.99’S 31°34.02’S 31°34.14’S 31°34.25’S 31°34.38’S 31°34.47’S 31°31.37’S 31°31.42’S 31°31.49’S 31°31.57’S 31°31.67’S 31°31.70’S 31°30.00’S 31°31.84’S 31°30’S 31°30’S 31°31.95’S 31°32.02’S

Longitude 25°08.77’E 25°08.90’E 25°08.86’E 25°08.65’E 25°09.38’E 25°09.61’E 25°09.79’E 25°09.90’E 25°10.00’E 25°10.12’E 25°15.10’E 25°10.46’E 25°10.59’E 25°10.98’E 25°11.12’E 25°11.24’E 25°11.36’E 25°7.71’E 25°7.81’E 25°8.82’E 25°8.03’E 25°8.17’E 25°8.25’E 25°8.29’E 25°8.37’E 25°8.41’E 25°8.46’E 25°8.59’E 25°8.72’E 25°8.80’E 25°8.89’E 25°9.02’E 25°6.45’E 25°6.56’E 25°6.69’E 25°6.81’E 25°6.95’E 25°6.97’E 25°’E 25°7.07’E 25°’E 25°’E 25°7.40’E 25°7.52’E

Altitude (m) 1 250 1 250 1 250 1 200 1 300 1 400 1 600 1 650 1 650 1 650 1 400 – 1 300 1 200 1 250 1 200 1 200 1 250 1 250 1 250 1 300 1 350 1 400 1 450 1 450 1 400 1 350 1 300 1 250 1 250 1 250 1 250 1 200 1 200 1 250 1 250 1 300 1 350 1 350 1 400 1 250 1 250 1 200 1 200

A12 Felicia filifolia–Enneapogon scoparius Shrubby Grassland This community occurs on Folminkskop plateau, on substrates generally more rocky than in Communities A11 and A13. Soils supporting this community are characterised by relatively lower status of Na, K, Zn, Mg, Mn, C, Bo, Cu, lower resistance, and silt and clay content as compared to Tafelberg plateau (Community A11). These soil characteristics show relatively higher values in this particular community as compared to Tafelberg SE slope (Community A13) (Figure 5). The environmental variables most strongly correlated with the axis are P, slope, coarse sand, Mn and silt. 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

pH (KCI) PHOSPHAT Ca COURSAND

Slopes ROCKS

Community A11 Community A13

K Bo

SOIL DEPTH Na

Mg Na

Zn Cu SILTPER CLAYPER

C

Ca

BARE SOIL

RESISTAN

RESISTAN

SILTPER Mn

Plateaux Mn

-1.0

+1.0

Figure 3: An ordination diagram showing the distribution of sites in relation to available environmental factors for the main division in the data: (A) Slopes and Plateau habitats and (B) Plains habitats. Eigenvalues: Axis 1: 0.735, Axis 2: 0.544 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 (KCl) – pH (KCL), PHOSPHAT – Phosphates (P), Plateau – Plateau (nominal variable), RESISTAN – Resistance, ROCKS – Rocks, SILTPER – Silt %, slopes – slopes (nominal variable), SOIL DEPTH – Soil depth, Zn – Zinc

CLAYPER

Cu

Community A12

Plateaux

-1.0

-1.0

+1.0

Figure 5: An ordination diagram showing the distribution of sites in relation to available environmental factors for Communities A11, A12 and A13. Eigenvalues: Axis 1: 0.578, Axis 2: 0.446. Refer to Figure 3 for key to environmental variables

negligible, as grazing frequency is very low. The community is however grazed regularly by indigenous herbivores such as Kudu, Grey Rhebok and Hare. Vegetation is in a relatively non-degraded condition, with palatable plants being common to dominant. A13 Felicia filifolia–Eriocephalus africanus Grassy Shrubland

+1.0 K PHOSPHAT

Zn

Na SILTPER RESISTAN Plateaux

Bo

Mn CLAYPER C Cu

SOIL DEPTH Mg BARE SOIL

Ca

pH (KCI) ROCKS COURSAND Slopes

Community Group A1 -1.0

ROCKS

C Bo

Slopes and Plateaux habitats (A) Plain habitats (B) -1.0

K

Zn

-1.0

Community Group A2

+1.0

Figure 4: An ordination diagram showing the distribution of sites in 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

This community occurs on Tafelberg SE slope upper and middle. The environmental variables most strongly correlated with the axis are P, slope, content of coarse sand, silt, and Mn. The soils show a relatively high status of P, coarse sand, Ca, have more bare soil, and are deeper than those of the dolerite plateau Communities A11 and A12 (Figure 5). In terms of habitat attributes, this community has more in common with that of a typical slope Community A21, than with the plateau communities of Tafelberg and Folminkskop, but floristically it is similar to the Plateau communities on dolerite. The overriding effect of moisture might explain this, due to the high elevation and the SE-facing aspect of this community. The community is also characterised by a complete absence of Themeda triandra and Heteropogon contortus. The community is grazed by indigenous herbivores and occasionally by domestic herbivores (i.e. sheep, cattle), but more regularly so than Tafelberg plateau (Community A11) or Folminkskop plateau (Community A12). Vegetation is in good condition, with palatable plants being common to dominant.

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Community Group A2 Rhigozum obovatum–Rhus burchellii Grassy Tall Shrubland Community Group A2 occurs on Folminkskop SE slope upper and lower, Folminkskop NW slope upper and lower, Buffelskop plateau NW and SE, Tafelberg NW slope upper, middle and lower, Tafelberg SE slope lower, Buffels SE plain 1B, Buffelskop SE slope upper and lower, Buffelskop NW slope upper and lower. Impact by domestic livestock ranged from negligible to high. Vegetation condition ranged from pristine (upper slopes) to moderately degraded (lower slopes of Buffelskop). Highly palatable species are common to dominant in the pristine areas with unpalatable species occurring at low densities. Moderately degraded areas are dominated by less palatable to moderately palatable plants and erosion is minimal. A21 Rhigozum obovatum–Gymnosporia Grassy Tall Shrubland

buxifolia

This community occurs on Folminkskop SE slope upper and lower, Folminkskop NW slope upper and lower, Buffelskop plateau NW and SE, Tafelberg NW slope upper, middle and lower, Tafelberg SE slope lower. It is a general slope community occurring throughout the entire study area. The soils supporting this shrubland community showed relatively high status of Mn, Mg, C, Cu, Ca and clay content in comparison to the communities found on Buffelskop SE and Buffelskop NW slopes (Figure 6). The environmental variables most strongly correlated with the axis are P, Cu, Zn, Na and Mg. This slope community is regularly grazed by indigenous

+1.0

Na BARE SOIL

COURSAND

SILTPER

Plateaux SOIL DEPTH

K RESISTAN pH (KCI) PHOSPHAT Bo

Cu

-1.0

-1.0

A22 Rhigozum obovatum–Pegolettia baccaridifolia Tall Shrubland This community occurs on Buffelskop SE slope, where the soils show relatively high contents of coarse sand, silt, Na, K, P and Bo, and have high values of pH and resistance (Figure 6). It also has a higher incidence of bare soil and deeper soils in comparison to the Communities A21 and A23. The environmental variables most strongly correlated with the axis are P, Cu, Zn, Na and Mg. The community is grazed regularly by indigenous herbivores (less regularly than Tafelberg and Folminkskop), and frequently by domestic herbivores. Buffelskop is more readily accessible to livestock. Impact of domestic herbivores on this community is moderate to high. Buffelskop consists of sandstone (as opposed to Folminkskop and Tafelberg that are both capped by dolerite), and the slopes are very steep and unstable. Both of these factors probably play an important role in shaping this community. Palatable plants are less frequent and have lower dominance, and vegetation is dominated 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 dominate overgrazed patches. A23 Rhigozum obovatum–Cenchrus ciliaris Grassy Tall Shrubland

Community A22

Mn

herbivores and occasionally by domestic herbivores. Grazing by domestic herbivores occurs much more frequently than on CG A1, and is concentrated on the lower half of these slopes. Lack of watering points and inaccessibility of the terrain force animals to stay on the lower half of the slopes. It is observed that domestic animals walk down to water points on the surrounding plains towards mid-morning. Impact by these domestic herbivores is not considered to be significant as vegetation is in very good condition, with palatable species common to dominant.

C CLAYPER Ca Slopes Mg

Zn ROCKS

Community A21 Community A23

+1.0

Figure 6: An ordination diagram showing the distribution of sites in relation to available environmental factors for Communities A21, A22 and A23. Eigenvalues: Axis 1: 0.557, Axis 2: 0.433. Refer to Figure 3 for key to environmental variables

This community occurs on Buffelskop NW slope, upper and lower. The soils are skeletal and show higher contents of Zn in comparison to the community occupying the SE slopes (Community A22). Soils show higher content of coarse sand and silt, higher values of pH and resistance, and higher status of Na, K, P, Bo. The bare patches are more common in this community than in the Community A21 (Figure 6). The environmental variables most strongly correlated with the axis are P, Cu, Zn, Na and Mg. The community is grazed regularly by indigenous herbivores (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 comprised of sandstone (as opposed to Folminkskop and Tafelberg that are both capped by dolerite), and the slopes are very steep and unstable. Both these factors probably play important roles in shaping this community. Palatable plants are less frequent and have lower dominance, and vegetation is dominated by a different set of plants in comparison with the dominants on Tafelberg and Folminkskop.

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B11 Aristida adscensionis–Ruschia intricata Grassy Dwarf Degraded Shrubland

Complex B: Plains Community Group B1 (Tafelberg SE plains, Tafelberg NW plains, Folminkskop SE plain, sampling stations 2, 3 and 4; Figure 7) occurs in two distinct habitat types — one showing relatively higher resistance and coarser sands and the other showing relatively higher status of Mn, clay, silt, K, Na, P, Zn and C, with on average, higher percentage bare soil and deeper soils. Community Group B2 (Buffelskop NW plain 1, 2, 3, 4; Buffelskop SE Plain 1 and 2; Folminkskop NW Plain 1, 2, 3, 4; Folminkskop SE Plain 1) is supported by soils showing higher status of Bo, Mg, Ca, C, and higher pH, as compared to CG B1. The soils of the CG B2 are more skeletal and show higher coarse sand content (Figure 7). The environmental variables most strongly correlated with the axis are Mn, resistance, P, pH and Ca.

Relevés of this community are on Tafelberg SE plains (1, 2, 3, 4). The soils supporting this community show higher resistance, and have more rocks and coarse sand in comparison to Communities B12, B13 and B14 (Figure 8). The environmental variables most strongly correlated with the axis are Bo, soil depth, clay, Mn, silt and bare soil. This community is regularly impacted by indigenous herbivores such Springbok, Kudu and Steenbok and in the past was heavily impacted by domestic herbivores. Vegetation is degraded, with unpalatable plants dominating. Erosion has taken place to the extent that many plants are growing on pedestals. In the five years prior to this study, Nguni (a breed) cattle farming replaced sheep farming in this community.

Community Group B1 Aristida adscensionis–Eragrostis obtusa Grassy Dwarf Shrubland

B12 Aristida adscensionis–Jamesbrittenia atropurpurea Grassy Dwarf Shrubland

This community group occurs on Tafelberg SE plains, Tafelberg NW plains and Folminkskop SE plain 2, 3, 4. This community group is moderately to severely impacted by domestic livestock, and lightly grazed by indigenous animals such as Kudu, Springbok (Antidorcas marsupialis) and Steenbok (Raphicerus campestris). Vegetation condition ranges from good to severely degraded. Unpalatable plants dominate the vegetation, with palatable species still being common. We found very variable evidence of soil erosion.

This community occurs on Folminkskop SE plain 4. The soils have higher levels of Zn, K, Bo, Mg, Na, Cu, C, P, clay and silt, higher values of pH and are deeper then the soils of the Community B11, but less so than those of the Communities B13 and B14 (Figure 8). The environmental variables most strongly correlated with the axis are Bo, Mn, soil depth, clay, silt and bare soil. Domestic livestock, as well as indigenous herbivores such as Kudu, Springbok and Steenbok extensively graze this 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

SILTPER Mn

SOIL DEPTH

CLAYPERCu

Community B14

K Bo

ROCKS

Mg

BARE SOIL

PHOSPHAT

C

Na

pH (KCI)

RESISTAN COURSAND

Ca

Zn

Community B13 SOIL DEPTH SILTPER K Bo Na CLAYPER Mg Mn PHOSPHAT BARE SOIL

ROCKS

Community Group B1

RESISTAN

-1.0

-1.0

Community B11

Community Group B2

Cu

Zn

Ca C

pH (KCI)

COURSAND

Community B12 +1.0

Figure 7: An ordination diagram showing the distribution of sites in relation to available environmental factors for Community Groups B1 and B2. Eigenvalues: Axis 1: 0.605, Axis 2: 0.518. Refer to Figure 3 for key to environmental variables

-1.0

-1.0

+1.0

Figure 8: An ordination diagram showing the distribution of sites in relation to available environmental factors for Communities B12, B12, B13 and B14. Eigenvalues: Axis 1: 0.605, Axis 2: 0.448. Refer to Figure 3 for key to environmental variables

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Slopes/Plateaux habitats. This could possibly be ascribed to increased soil moisture due to close levels of underground water. Jamesbrittenia atropurpurea also occurs only in this community. The surface erosion is minimal.

Pienaar, Esler and Mucina

+1.0

SILTPER

Mn Bo Mg K

CLAYPER

Cu

PHOSPHAT pH (KCI)

B13 Aristida adscensionis–Zygophyllum incrustatum Grassy Dwarf Shrubland Community B13 occurs on Folminkskop SE plain 2 and 3, and Tafelberg NW plain (1, 3, 4). The soils have higher levels 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 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 indigenous herbivores (Kudu, Springbok and Steenbok) as well as by excessive grazing by domestic herbivores. Vegetation is degraded and characterised by many denuded areas dominated by unpalatable plants. Erosion has taken place to the extent that plants often form pedestals. B14 Helichrysum lucilioides–Thesium spartioides Open Dwarf Shrubland 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 Communities B11, B12 and B13, and are distinguished from the Community B13 by lower levels of Zn (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 indigenous herbivores (Kudu, Springbok, Steenbok), as well as excessive grazing by domestic herbivores. Vegetation is degraded with many denuded areas. Erosion has taken place to the extent that plants are on pedestals. This community is slightly impoverished and is characterised by the complete absence of Aristida adscensionis, Eragrostis obtusa and E. lehmanniana, species common throughout the rest of the community group. Community Group B2 Eragrostis lehmanniana– Eragrostis bergiana Grassy Dwarf Shrubland Relevés of this CG are made on Folminkskop SE plain 1; Folminkskop NW plain 1, 2, 3, 4; Buffelskop NW plain 1, 2, 3, 4 and Buffelskop SE plain 1, 2. Occasional grazing by indigenous herbivores as well as excessive grazing by domestic herbivores impacts the community. This community group represents the most degraded of the four community groups. The high frequency of Blepharis capensis (spiny, unpalatable species commonly thriving on disturbed and overgrazed land) is an indication of over-utilisation and degradation of this community.

BARE SOIL

C

Community B22

Na

Community B21

Ca

SOIL DEPTH

ROCKS

Community B23

RESISTAN COURSAND

-1.0 -1.0

+1.0

Figure 9: An ordination diagram showing the distribution of sites in relation to available environmental factors for communities B21, B22 and B23. Eigenvalues: Axis 1: 0.807, Axis 2: 0.545. Refer to Figure 3 for key to environmental variables

B21 Pentzia incana–Eragrostis bergiana Grassy Dwarf Shrubland This community occurs on Folminkskop NW plain 1, 2, 3, 4; Folminkskop SE plain 1; Buffelskop NW plain 1, 3, 4. The soils show lower status of Mn, Bo, Cu, Mg, K, Na, Zn, Ca, P, bare soil and higher pH than the soils of the Community B22, but show higher values of these soil characteristics than those of the Community B23 (Figure 9). The resistance of the soils supporting the Community B23 is higher than that for the Community B21. The environmental variables most strongly correlated with the axis are coarse sand, Mn, silt, clay and Cu. Occasional grazing by indigenous herbivores as well as excessive grazing by domestic herbivores impacts the community. Vegetation is overgrazed and in poor condition with sparse plant cover, while unpalatable plants are common to dominant. Shallow soil occurs in pockets and Blepharis capensis is present in high densities. B22 Eragrostis lehmanniana–Eragrostis bicolor Grassy Shrubland This community occurs on Buffelskop NW plain 3 and 4. The environmental variables most strongly correlated with the axis are coarse sand, Mn, silt, clay and Cu. Soils contain more Mn, Bo, Cu, Mg, K, Na, Zn, P, Ca, Bare soil and higher 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.

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Vegetation is degraded with sparse cover and much bare soil. This community is impoverished, possibly as a result of a narrow distribution in the landscape and consequent under-sampling of the community. B23 Eragrostis lehmanniana–Rosenia humilis Shrubby Grassland This community occurs in Buffelskop NW plain 2. The soils had lower contents of Mn, Bo, Cu, Mg, K, Na, Zn, Ca, P, less bare soil, and lower values of pH than the soils of the Communities B21 and B22, and are relatively higher in percentage coarse sand and resistance (Figure 9). The environmental variables most strongly correlated with the axis are coarse sand, Mn, silt, clay and Cu. This community is regularly impacted by indigenous herbivores as well as by domestic herbivores. Vegetation is in an overgrazed, degraded condition and plant cover is sparse. This community is impoverished, possibly as a result of a narrow distribution in the landscape that resulted in under-sampling. Species diversity of this community is very low. Discussion Vegetation patterns Mesas (their plateaux and slopes) are distinctly different in composition compared to the surrounding plains, with no shared communities between mesas and their surroundings. These distinct communities can be clearly ordered along a soil-moisture gradient. Shallow and rocky soils, coupled with very little runoff and naturally higher precipitation due to increased elevation, support formation of more mesic habitats on the mesas in comparison with the surrounding plains habitats. Plains have little rock cover, high percentage of bare soils, slightly shallower soils and higher runoff rates than mesas. These factors result in a more xeric habitat. Habitat differences such as these probably existed before the impact of domestic stock introduced by European settlers (Hoffman et al. 1997), but overgrazing has probably exacerbated the differences. Overgrazing results in more denuded vegetation with larger areas of bare soil than naturally existed in the plains habitats. This then results in an increase in xeric conditions through the loss of plant cover and water through runoff and more rapid evaporation than would normally occur (Fuls 1992). Toxic, spinescent and unpalatable plant species are generally not grazed as severely as palatable species and are therefore selected for under high grazing pressure (Milton and Dean 1990, Milton and Hoffman 1994, Milton 1995). This thus resulted in a change of the dominance structure of plant communities in favour of these unpalatable plants. Tafelberg plateau, Folminkskop plateau and the SE slopes of Tafelberg each have distinct communities, linked to specific environmental factors that play a role in these communities. All other slopes with the exception of Buffelskop are however grouped into one big general slope community, with no distinction between SE and NW slopes. This suggests that aspect and the expected cooler, moister conditions on

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SE slopes as factors determining community composition are overridden by soil type and associated nutrient status. Soils of the SE and NW slopes are both derived from dolerites and are characterised by relatively higher levels of C, Cu, Zn, Mn, Mg, Bo, silt and clay in comparison with plains habitats. Buffelskop is the only mesa that is topped by a sandstone layer and not by a dolerite cap. Plant communities for the slopes of Buffelskop are distinct, separate communities that are not linked to any other communities in the study and have distinct soil composition. The slopes of Buffelskop are more arid and less compacted in comparison with those of Tafelberg and Folminkskop. Under certain circumstances, sandstone absorbs more water than dolerite and the exceptionally low plant cover and steep sides lead to higher runoff, resulting in a more xeric habitat. In xeric sandstone mesas such as Buffelskop, aspect and slope override soil type and associated nutrient status as determinants of community composition. Mesas are distinct in composition and can be regarded as islands of one vegetation type in a sea of another vegetation type (plains). Mesa habitats in the Middelburg District are under-utilised by livestock because of their general inaccessibility (steep slopes, extremely rocky terrain, cliffs and fences) coupled with the absence of natural springs or artificial water points on them. Mesa habitats are not currently threatened by development, but do have a higher conservation status than the surrounding plains due to their undisturbed nature. Plains habitats are used extensively for stock production, and the vegetation is in a state of degradation ranging from light to severe. Toxic, spinescent and unpalatable plants are common. In severely degraded areas, soil erosion has taken place to the extent that plants occur on pedestals. Less disturbed areas of plains habitat are now restricted to specific locations such as road verges or railway lines where grazing is absent, but for the most part plains habitats have been altered in one way or another through grazing by livestock (E Pienaar, pers. obs.). Regional linkages Plant communities for the Middelburg study area are very similar in structure and some textural characteristics such as composition of dominating life-forms and participation of high-rank taxa (families and genera). However, none of the plant communities identified in our study could be identified with communities described in other parts of Nama Karoo, such as in the upper Gariep (Orange) River valley (Werger 1973), Camdebo and Aberdeen plains and surrounding mountains (Palmer 1991), or in the Karoo National Park located near Beaufort West in the Western Cape Province (Rubin and Palmer 1996). We refrain from formal syntaxonomic comparison of our area with other regions of the Nama Karoo because of insufficient data coverage in the biome as a whole. Ecological factors and processes at work in the Middelburg District are very similar to those in the rest of the Nama Karoo, with the most important driving force being a topographic-moisture gradient (Palmer and Cowling 1994,

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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 species in plots

Total number of species 192

Restricted to mesas Restricted to plains Shared species

Number of species 84 51 57

% 43.8 26.6 29.7

Total species richness 54 55 47 100 45 13 52 34 60 29 50 8 18

Relevés 9 9 6 30 6 6 12 3 15 3 24 6 3

Community Community A11 Community A12 Community A13 Community A21 Community A22 Community A23 Community B11 Community B12 Community B13 Community B14 Community B21 Community B22 Community B23

Rubin and Palmer 1996). Vegetation in the Middelburg study area is strongly influenced by a soil-moisture gradient associated with an increase in elevation from the plains habitats to the higher lying mesa habitats. Degraded shrublands are said to be a consequence of grazing by sheep (Palmer 1989), and species indicative of disturbance (Geigeria ornativa, Tribulus terrestris and the exotic Salsola kali ) and other species (Chrysocoma ciliata, Eragrostis obtusa, Felicia muricata and Pentzia incana) are the same as those found in degraded shrublands of the Middelburg District. Restoration potential It has been proposed that mesas could provide sources of re-colonisation for species in decline in degraded surrounding plains habitats (Burke et al. 2003). This study indicated approximately 30% of species that are shared between mesas and their surroundings, although not all of these species can be regarded as good colonisers. More species in total occur only on mesas (44% of species sampled in all plots) in comparison to species that are restricted to plains habitats (27%) or that are shared between mesas and plains habitats. This reflects the larger species pool found on mesas, although alpha diversity on mesas is not significantly higher on mesas compared to their surroundings (Table 4). Larger mesas such as Tafelberg (447m above surroundings) share more species with the surrounding plains than smaller mesas, although the plateau is more distinct than that of smaller mesas (data not shown). Species shared between plains and mesa habitats included various valuable grazing species, including generalist species such as Eragrostis obtusa, Felicia muricata, F. ovata, Fingerhuthia africana, Jamesbrittenia tysonii, Limeum aethiopicum, Pentzia incana, Selago albida, Tragus koeleri-

Min. 14 13 14 12 12 4 14 19 5 15 4 2 8

Max. 27 23 22 28 28 7 24 22 34 20 22 5 14

Mode 17 23 22 18 N/A 7 18 22 22 N/A 11 5 N/A

oides and Trichodiadema rogersiae. Highly palatable species such as Felicia muricata and Limeum aethiopicum occur at higher frequencies on mesas than on plains habitats, a possible consequence of increased grazing pressure on the plains. Species such as these may also have potential for restoration of surrounding degraded plains. Conclusions Although mesas and plains are similar in alpha diversity, the communities occurring on these habitats are distinctly different from each other. No communities are shared between mesas and plains habitats. The distribution and composition of communities across the Middelburg landscape are mainly attributed to a soil moisture gradient. Aspect and the expected cooler, moister conditions on SE slopes as factors determining community composition for the dolerite mesas are overridden by soil type and associated nutrient status. In xeric sandstone mesas such as Buffelskop, aspect and slope as determinants of community composition override soil type and associated nutrient status. Mesas are distinct in composition and can be regarded as islands of one vegetation type in a sea of another vegetation type. Plant communities in the Middelburg study area are similar in composition to communities identified in other parts of the Nama Karoo, with many shared genera and species. Acknowledgements — This study was supported by a European Community grant (EC ERBIC18CT970141) and in South Africa by an NRF grant to KJ Esler (GUN: 203492). Many people and institutions provided valuable logistic support. We would like to acknowledge W Asher, C Ayliffe, R Gilfillan, P McEwan for allowing us to work on their farms. F Jones provided assistance with the location of the study sites. F Jones, NC and NO Hendricks assisted with the

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collection of soils for analysis. L Mucina thanks the University of the Free State, QwaQwa Campus for logistic support (Research Grant # 4676).

References Barkman JJ, Doing H, Segal S (1964) Kritische Bemerkungen und Vorschläge zur quantitativen Vegetationsanalyse. Acta Botanica Neerlandica 13: 394–419 Burke A, Esler K, Pienaar E, Barnard P (2003) Species richness and floristic relationships between mesas and their surroundings southern African Nama Karoo. Diversity and Distributions 9: 43–53 Cooke R, Warren A, Goudie A (1993) Desert Geomorphology. UCL Press, London. ISBN 1857280172 Desmet PG, Cowling RM (1999) The climate of the karoo a functional approach. In: Dean WRJ, Milton SJ (eds) The Karoo: Ecological Patterns and Processes. Cambridge University Press, Cambridge. pp 3–16. ISBN 0521554500 Ellis F, Lambrechts JJN (1986) Soils. In: Cowling RM, Roux PW, Pieterse AJH (eds) The Karoo Biome: a Preliminary Synthesis. Part 1. Physical Environment. South African National Scientific Programmes Report 124: 18–38 Fuls ER (1992) Ecosystem modification created by patch-overgrazing in semi-arid grassland. Journal of Arid Environments 23: 59–69 Germishuizen G, Meyer NL (2003) Plants of southern Africa: an annotated checklist. Strelitzia 14, National Botanical Institute, Pretoria. ISBN 1919795995 Hennekens SM (1996) MEGATAB: A Visual Editor for Phytosociological Tables. Version 1. IBN, Wageningen & Giesen and Geurts, Ulft Hennekens SM, Schaminée JHJ (2001) TURBOVEG, a comprehensive data base management system for vegetation data. Journal of Vegetation Science 12: 589–591 Hill MO (1979) TWINSPAN. A FORTRAN Program for Arranging Multivariate Data in an Ordered Two-way Table by Classification of the Individuals and Attributes. Ecology and Systematics, Cornell University, Ithaca, NY Hoffman MT, Cousins B, Meyer T, Petersen A, Hendricks H (1997) Historical and contemporary land use and the desertification of the karoo. In: Dean WRJ, Milton SJ (eds) The Karoo: Ecological Patterns and Processes. Cambridge University Press, Cambridge. pp 257–273. ISBN 0521554500 Jones FE (2000) An Assessment of the Potential for Utilization of Soil-stored Seed, from on- and off “Conservation Island” (Isolated mountains), as an Indicator of Restoration Potential of Degraded Sites in Semi-arid Karoo Areas. MSc Thesis, University of Stellenbosch, South Africa Jongman RHG, Ter Braak CJF, Van Tongeren OFR (2000) Data Analysis in Community and Landscape Ecology. Cambridge University Press, Cambridge. ISBN 9022009084 MacDonald DJ (1998) VEGMAP: a collaborative project for a new vegetation map of South Africa. South African Journal of Science 93: 424–426

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Milton SJ (1995) Effects of rain, sheep and tephritid flies on seed production of two arid Karoo shrubs in South Africa. Journal of Applied Ecology 32: 137–144 Milton SJ, Dean WRJ (1990) Seed production in rangelands of the southern Karoo. South African Journal of Science 86: 231–233 Milton SJ, Hoffman MT (1994) The application of state-and-transition models to rangeland research and management in arid succulent and semi-arid grassy Karoo, South Africa. African Journal of Range and Forage Science 11: 18–26 Mucina L (1993) Nomenklatorische und syntaxonomishe Definitionen, Konzepte und Methoden. In: Mucina L, Grabherr G, Ellmauer T (eds) Die Pflanzengesellschaften Österreichs. Teil I. Anthropogene Vegetation. Gustav Fischer Verlag, Jena. pp 19–28. ISBN 3334604527 Mucina L, Bredenkamp GJ, Hoare DB, McDonald DJ (2000) A national vegetation database for South Africa. South African Journal of Science 96: 497–498 Palmer AR (1989) The vegetation of the Karoo Nature Reserve, Cape Province. 1. A phytosociological reconnaissance. South African Journal of Botany 55: 215–230 Palmer AR (1991) A syntaxonomic and synecological account of the vegetation of the eastern Cape midlands. South African Journal of Botany 57: 76–94 Palmer AR, Cowling RM (1994) An investigation of topo-moisture gradients in the eastern Karoo, South Africa, and the identification of factors responsible for species turnover. Journal of Arid Environments 26: 135–147 Palmer AR, Hoffman MT (1997) Nama-karoo. In: Cowling RM, Richardson DM, Pierce SE (eds) Vegetation of Southern Africa. Cambridge University Press, Cambridge. pp 167–188. ISBN 0521571421 Rubin F, Palmer AR (1996) The physical environment and major plant communities of the Karoo National Park, South Africa. Koedoe 39: 25–52 Rutherford MC, Westfall RH (1986) The biomes of southern Africa an objective categorization. Memoirs of the Botanical Survey of South Africa 54: 1–98 Ter Braak CJF, Šmilauer P (1998) CANOCO Reference manual and user’s Guide to Canoco for Windows: Software for Canonical Community Ordination (version 4). Microcomputer Power, Ithaca, NY UNEP (1992) World atlas of desertification. Edward Arnold, London Watkeys MK (1999) Soils of the arid south-western zone of Africa. In: Dean WRJ, Milton SJ (eds) The Karoo: Ecological Patterns and Processes. Cambridge University Press, Cambridge. pp 17–26. ISBN 0521554500 Weber HE, Moravec J, Theurillat J-P (2000) International Code of Phytosociological Nomenclature. 3rd edn. Journal of Vegetation Science 11: 739–768 Werger MJA (1973) An account of the plant communities of Tussen die Riviere Game Farm, Orange Free State. Bothalia 11: 165–176 Werger MJA (1973) A phytosociological study of the Upper Orange River Valley. Memoirs of the Botanical Survey of South Africa 46: 1–98

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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 leptophylla 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)