干旱区生态环境知识资源中心

Whilst vegetation composition and patterning are strongly influenced by hydrogeomorphic process and form, plant species may significantly influence hydrogeomorphic processes and landforms. A study in the semi-arid Baviaanskloof River catchment in South Africa involving 13 study sites revealed the interdependence of river valley morphology, surface-groundwater interactions and vegetation in narrow and wide valley sections. PRIMER analyses showed a strong link between plant distribution patterns and water availability. Two groups of sites were closely related to flow permanence. Wetted channel sites grouped closely while dry bed channel sites grouped closely. The analyses also indicated that the environmental variables which best explained the variation in vegetation at the differing geomorphic landforms were related to landform position (elevation and distance), sediment size (fine and coarse sand) and available phosphorus (i.e. human impacts). The different plants in turn also affected landforms through their influence on sediment erosion, transport and deposition. Specially, they build, maintained or modified geomorphic landforms at confined, semi- confined and unconfined valley settings across the valley floor.