Abstract
Kalahari Thomveld occupies an area of some 390,000 km2 in Namibia, Botswana and South Africa. It constitutes the southern portion of the arid or fine-leaved savanna on Kalahari sand codominated by grasses such as species of Eragrostis and Stipagrostis, and trees and shrubs, especially of the genus Acacia. Microclimatic and edaphic conditions in the subcanopy habitat under trees and shrubs often differ widely from those in the grassland. The subcanopy is unstable and subject to much disturbance, mainly due to its rich and varied fauna. A total of 132 plant species was recorded as typical for, or exclusive to the subcanopy habitat. These species tend to be widely to very widely distributed, and endemism was very low. Almost 50% were hemicryptophytes, 28% annuals and 9% succulents. The most common species were almost exclusively dispersed by animals, especially birds. Leguminosae, the family of most of the pioneer canopy formers, was almost absent from the subcanopy.
Résumé
Le “Veld” épineux du Kalahari occupe une superficie de quelque 390.000 km2 en Namibie, au Botswana et en Afrique du Sud. Il constitue la partie méridionale des savanes arides ou à feuilles étroites des sables du Kalahari, à dominance de Gramineae comme Eragrostis et Stipagrostis, ainsi que d’arbres et arbustes appartenant principalement au genre Acacia. Les conditions microclimatiques et édaphiques dans le milieu sous couvert d’arbres et d’arbustes diffèrent souvent de façon importante de celles en formation herbeuse. Le milieu sous couvert est instable et sujet à une grande perturbation, principalement en raison de sa faune riche et variée. On a relevé un total de 132 espèces typiques ou exclusives dans ce milieu. Ces espèces ont tendance à être largement à très largement réparties et l’endémisme y est très faible. A peu près 50% d’entre elles sont des hémicryptophytes, 28% des annuelles et 9% des succulentes. Les espèces les plus communes sont à peu près exclusivement disséminées par les animaux, principalement par les oiseaux. Les Leguminosae, famille représentative de la plupart des groupements pionniers de la voûte forestière, sont quasiment absentes de la strate sous couvert.
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Leistner, O.A. (1996). The subcanopy flora in the dynamics of the Kalahari Thornveld. In: van der Maesen, L.J.G., van der Burgt, X.M., van Medenbach de Rooy, J.M. (eds) The Biodiversity of African Plants. Springer, Dordrecht. https://doi.org/10.1007/978-94-009-0285-5_23
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