Floristic and life form diversity in post-pasture successions on a Mediterranean island (Corsica)

The landscapes of the French island of Corsica are the result of the grazing tradition which has always occupied a pivotal position in the island's economy. Furthermore, in the last fifty years, a reduction in the pressure from human activity has lead to changes in plant cover. This article intends to study the evolution of dynamic mechanisms during the secondary successions and the effect of changes in vegetation on plant diversity. Our study was based on a simultaneous study of 375 plots carried out between May and September from 1996 to 1998. We studied the floristic composition of each stage both qualitatively (life form, adaptive strategy and seed dispersal mode) and quantitatively (species richness, equitability, Shannon index). The results show a change in species and environmental conditions, with a progressive move from heliophilic grassland and low shrub species with an S or SR strategy, anemochoric and with a high tolerance for soil quality to a final stage of dense forest composed of competitive (C or CS) zoochoric or barochoric phanerophytes. Moreover, the turning point in Corsica in terms of floristic diversity lies between 20 and 55 years after land abandonment. Successions are due to a series of rapid interactions. Thus, when a site is given reserve or protected area status, we need to take into account the fact that it will evolve according to the biological traits of the species. From a research point of view, we need to look at process diversity and the role of each of the species present during the successions.