The role of Diversity on tropical forest bioMass dynamics: effects of disturbance and biogeography

ended

The importance of biodiversity in supporting ecosystem functioning, especially biomass productivity, has motivated numerous research questions. However, controversial results have been found so far while testing a direct link between diversity metrics and biomass, an approach that discards the fact that biomass is a composition of three other variables: number of stems, wood density and mean aboveground volume. It is only possible to access the role of diversity on biomass by separating the components of AGB, since diversity operates through different (and non-exclusive) ecological mechanisms that act separately on different AGB components: the selection effect (SE) and the complementarity effect (CE). The SE (or “sampling effect”) emerge as a result of a hyper-diverse community having a greater chance of containing particularly productive species, while the CE states that plant communities consisting of multiple species that coevolved to occupy different environmental niches can partition limited resources more efficiently, thus providing greater biomass compared to that expected from monocultures. This proposal aims at developing a new conceptual framework that will help test 1) how diversity drives variation in biomass and productivity through different ecological mechanisms acting on specific components of biomass; 2) whether historical disturbances influence the current effect of diversity on biomass and biomass productivity and; 3) whether the effect of diversity on biomass and biomass productivity differ among the Neotropics, Afrotropics and Asian tropical forests. These objectives will be achieved via i) disaggregating AGB in wood density, stem density and mean aboveground volume components and ii) separating the effect of SE and CE to assess the effects of diversity metrics on AGB components through specific indirect pathways, including effects related to variation in forest characteristics across continents and canopy packing.