The impact of aspect on forest structure and floristics in some Eastern Australian sites

Aspect exerts a major influence on the structure and floristics of forests at upslope positions on steep ridges near the escarpment of north-eastern New South Wales. The vegetation of northwest facing sites differed from that of the southeast aspect in species richness and diversity, canopy cover, and canopy height, whilst differences between northeast and southwest aspects were significant for fewer attributes. The gross effect of aspect was in segregating eucalypt and rainforest communities. Aspect-induced differences in light, heat, moisture and edaphic conditions produced a sort of potential canopy species during recruitment. In the absence of substantial disturbance, the divergence of the structural character of developing forest canopies between aspects tends to enhance the floristic divergence in the subcanopy space. Although the study area is representative of a large region of forested steeplands in the hinterland of north-eastern New South Wales, the upper slope segments and four aspects studied can be expected to represent the extreme manipulation. In any event, it is unlikely that the extent of site divergence represented in these old-growth forests would be maintained under managed re-growth strategies.