Biodiversity and ecosystem trajectories: first results from a new LTER in southern France

Abstract

At a new long-term ecological research site in the Mediterranean climate zone of southern France, we have initiated a study of the ecological roles of biodiversity, especially plants and detritivores, at both ecosystem and landscape levels of complexity. In this paper, we describe the study site, experimental set-up, and the long-term objectives, methods and ecosystem attributes used to document the extant spatial organization 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 groups 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 diversity in six discriminant classes of landscape units sampled in a total 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) provided highly discriminatory axes for segregation of species assemblages among the 54 stations. Relevance of the preliminary data presented is briefly discussed in terms of long-term testing of various hypotheses related to biodiversity-ecosystem functioning interactions and ecosystem ‘development’ in a Mediterranean environment with very strong anthropic influences.