SPATIAL HETEROGENEITY OF A TROPICAL RAIN- FOREST IN SUMATRA - EFFECT OF TOPOGRAPHY ON FLORISTIC STRUCTURE

Tropical rain forests are characterized by a complex and spatially het erogeneous structure. It is essential to analyze the factors of this h eterogeneity in order to set up sustainable management policies in the se environments. We have studied the influence of topography on floris tic structure, considering 3 ha of forest with contrasted relief. Corr espondance analysis has shown that topography acts through drainage, l eading to different specific compositions on ridge, slope and valley. It operates also in relation to forest dynamics, favouring pioneer spe cies on steep slopes. In addition, this influence decreases as topogra phic heterogeneity is reduced; other factors related to forest interna l characteristics then govern floristic structure. Moreover, this stud y brings new data concerning floristic composition and ecology of fore sts in this area, as well as topographical preferences of many species . Topography appears to be a key factor regarding the structure and th e dynamics of tropical rain forests on contrasted relief, and should b e considered in modelling.