Plant communities of the Soutpansberg Arid Northern Bushveld

Theo H.C Mostert,Rachel E Mostert,George J Bredenkamp

doi:10.4102/koedoe.v51i1.687

Theo H.C Mostert, Rachel E Mostert + Show 1 more

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https://doi.org/10.4102/koedoe.v51i1.687

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Abstract

The Soutpansberg Arid Northern Bushveld is one of eight major vegetation types (MVT) described for the Soutpansberg-Blouberg region. The plant communities of this MVT are described in detail. Main ecological drivers of the vegetation structure and species composition of these communities are discussed and some conservation recommendations are made. Phytosociological data from a subset of 72 Braun-Blanquet sample plots collected in the Soutpansberg Arid Northern Bushveld were classified using Two-way Indicator Species Analysis (TWINSPAN) and ordinated using a Detrended Correspondence Analysis (DECORANA). The resulting classification was further refined with table-sorting procedures based on the Braun-Blanquet floristic-sociological approach to vegetation classification using the computer software MEGATAB and JUICE. Eight plant communities were identified and described as Commiphora tenuipetiolata-Adansonia digitata short open woodland, Ledebouria ovatifolia-Commiphora mollis short bushland, Phyllanthus reticulatus-Acacia nigrescens short bushland, Tinnea rhodesiana-Combretum apiculatum short bushland, Dichrostachys cinerea subsp. africana-Spirostachys africana low thickets, Themeda triandra-Pterocarpus rotundifolius short closed grassland on steep basaltic slopes, Cyperus albostriatus-Syzygium cordatum sandveld wetlands, and Sesamothamnus lugardii-Catophractes alexandri tall sparse shrubland. These plant communities are event-driven ecosystems, predominantly infl uenced by frequent droughts, exposure to desiccation and unpredictable rainfall events. The complex topography of the Soutpansberg further contributes to the aridity of these ecosystems. The classifi cation and ordination analyses show similar groupings in the vegetation of the Soutpansberg Arid Mountain Bushveld. This confi rms the usefulness of complimentary analysis, using both classifi cation and ordination methods on a single data set in order to examine patterns and to search for group structure.Conservation implications: The results from this study will alter existing regional vegetation maps profoundly. The described plant communities of these arid event-driven ecosystems should be used as benchmark examples of the region’s primary vegetation. Conservation and management planning should be based on these vegetation units.

Highlights

The arid systems of the Limpopo Province and most of the southern African savannas (Du Plessis 2001; Siebert et al 2003a) have only been sampled in localised patches, such as in areas of high conservation value or high economic value
The analysis of the vegetation data of the Adansonia digitata-Acacia nigrescens Soutpansberg Arid Northern Bushveld major vegetation type (MVT) resulted in the identification of eight plant communities (Table 1 - online supplement)
The first two divisions created by the classification separated the azonal Sesamothamnus lugardii-Catophractes alexandri tall sparse shrubland and the Cyperus albostriatusSyzygium cordatum sandveld wetlands from the remaining zonal communities

Summary

Introduction

The arid systems of the Limpopo Province and most of the southern African savannas (Du Plessis 2001; Siebert et al 2003a) have only been sampled in localised patches, such as in areas of high conservation value or high economic value. The vegetation of many areas remains to be investigated and described in order to complete the puzzle of patchy vegetation studies throughout the province One such an undersampled region is the arid northern bushveld of the Soutpansberg mountain range (Berger et al 2003). Acocks (1953) mapped the vegetation of this area as Mixed Bushveld (18) on the plain directly north of the Soutpansberg Mountain, Sourish Mixed Bushveld (19) along the northern foot-slopes, and Sour Bushveld (20) south of the northernmost ridges. He described these veld types as ‘a Deadalian maze of variations and transitions’. This subunit may compare most closely to the Limpopo Sweet Bushveld (Mucina & Rutherford 2006)

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