Carbon and biodiversity cobenefits of second-growth tropical forest: The role of leaf phenology

Abstract

Second-growth tropical forests offer important carbon and biodiversity cobenefits, as well as different leaf functional types of tree species. Leaf deciduousness is an important functional trait that can contribute to seasonal and spatial changes in carbon balance. We investigated the distribution pattern of carbon stock, species richness, and functional dominance among trees with differing leaf phenology (evergreen, semideciduous and deciduous) as well as the carbon and biodiversity cobenefits of tree communities in contrasting topographical conditions in a second-growth tropical Atlantic forest. We tested the hypotheses that topographic conditions shape differences in species richness and aboveground carbon stock between leaf phenology groups, as well as the carbon-biodiversity cobenefits within the tree communities. We studied fourteen 20 m × 40 m plots established in the forest with contrasting topographical conditions. We selected the mean functional traits related to carbon stock capacity in tropical forest: wood density and maximum tree height and calculated community-weighted mean metrics based on these traits. Aboveground biomass of trees for each stem sampled was calculated from a combination of variables using the general allometric equation. We constructed linear mixed-effect models (LMMs, with random and fixed effects) to test the cobenefits between aboveground carbon stock and leaf phenology group (evergreen, semideciduous and deciduous species) on species richness at community level. Our results showed that evergreen species had a higher richness, while the deciduous species had a greater contribution to aboveground carbon stock. Thus, the leaf phenology groups can affect the relationships between species richness and aboveground carbon stock. The deciduous species are key to maintaining higher carbon stock with smaller numbers of species; meanwhile evergreen species are important to maintain a higher species richness. Leaf phenology groups could be responsible for important cobenefits (i.e. positive aboveground carbon stock and species richness relationship) in Atlantic forests. Therefore, this study showed a relevant result on the relative contribution of leaf phenology groups in the carbon and biodiversity cobenefits along topographic gradients. In addition, our results allow for the selection of key tree species to improve management, conservation and restoration practices in the Atlantic forest in order to protect threatened biodiversity as a cobenefit of maintaining forests and the carbon they store.