Plant communities, landforms, and soils of a geomorphically active drainage basin, Southern Alps, New Zealand

Abstract

Abstract The plant commumtles in a mountainous drainage basin in the Southern Alps, Westland, New Zealand, were classified from 92 vegetation descriptions. Nine forest and shrubland communities were defined from the presence/absence of 264 species and from differences in canopy cover. Their composition and distribution, inferred from ordination and descriptions of landforms and soils, were determined primarily by the influences of mass movement disturbance and elevation. Erosional and depositional landform units of varying age and surface stability contained soils of different stages of development. Seral communities occupied well-drained and often frequently disturbed recent soils. Mature forest/shrubland dominated stable landforms characterised by yellow-brown earths or gley podzol soils. Although specific relationships of individual species with factors such as soil nutrient status are consistent with other studies in Westland, landform age and surface stability, soil depth, soil drainage, and other physical disturbances, such as treefalls, appear to be equally critical determinants.