BIODIVERSITY AND ECOSYSTEM TRAJECTORIES - FIRST RESULTS FROM A NEW LTER IN SOUTHERN FRANCE

At a new long-term ecological research site in the Mediterranean clima te zone of southern France, we have initiated a study of the ecologica l roles of biodiversity, especially plants and detritivores, at both e cosystem and landscape levels of complexity In this paper, we describe the study site, experimental set-up, and the long-term objectives, me thods and ecosystem attributes used to document the extant spatial org anization of above- and below-ground biodiversity related to landscape heterogeneity and past and present land use patterns, and to monitor ecosystem response to the experimental manipulation of functional grou ps among plants. Baseline data are provided for plant species richness and spectrum of growth forms in six different types of land units, as well as the results of a factorial correspondance analysis of plant d iversity in six discriminant classes of landscape units sampled in a t otal of 54 stations of 100 m(2) each situated along ten toposequences. Both habitat openness (related to vegetation structure) and degree of soil degradation (directly linked to former human activities) provide d highly discriminatory axes for segregation of species assemblages am ong the 54 stations. Relevance of the preliminary data presented is br iefly discussed in terms of long-term testing of various hypotheses re lated to biodiversity-ecosystem functioning interactions and ecosystem 'development' in a Mediterranean environment with very strong anthrop ic influences. (C) Elsevier, Paris.