Ricerc@Sapienza

Aims: The majority of research on the diversity-productivity relationship has utilized aboveground plant biomass as a measure of overall ecosystem productivity and investigated successions with species-poor early stages. During this study we modelled patterns of plant diversity and carbon pools along a succession from pasture abandonment to submediterranean Quercus cerris woodland and investigated ecosystem productivity using biomass and soil carbon. Study area: The hilly-mountainous area of Tolfa in Central Italy. Methods: We used chronosequences to analyse changes in vascular plant species richness and composition across successional stages and along a gradient of productivity (i.e. of increasing carbon stocks). To test possible differences across successional stages species richness and carbon pool data were analysed through analysis of variance. Mixed model regression analyses were used to test the effect of the amount of the carbon stocks on the variation in plant species richness and composition. Results: We found a high variation in plant species richness along the succession, with grasslands and newly formed woods showing the highest values. The amount of carbon in biomass and soil increased along the succession, even if soil carbon did not differ significantly among successional stages. Plant species richness was not dependent on the variation in the carbon pools (i.e. biomass and soil carbon) along the succession, while plant species composition significantly responded to this variation. Conclusions: Our results strongly support the need to manage semi-natural ecosystems through a multi-functional perspective that values both carbon sequestration and biodiversity.