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Questions: Carbon dynamics in tropical forests is influenced by a variety of biotic and abiotic factors that act over temporal and spatial scales. At the local scale, carbon stock and dynamics can be determined by the environment and ecosystem diversity. Also, during forest regeneration, which is a temporal process, it is expected that those factors that influence carbon also change over time. Here we examine how carbon stock and dynamics are influenced by forest age, environment and functional diversity during forest regeneration. Using the relative effects of the different drivers of carbon dynamics, we attempt to discern the mechanisms (mass effect or niche complementarity) that explain those processes. Location: We carried out this study in Atlantic Forest of different ages during natural regeneration in southern Brazil. Methods: We measured environmental characteristics (soil physical and chemical attributes and canopy openness), estimated functional diversity and above‐ground carbon and its dynamics over time. We examined univariate and multivariate predictors of carbon stock and dynamics using structural equation models. Results: We found that age had the strongest influence on carbon stock, while environmental characteristics, functional and taxonomic diversities were much less important or unimportant. Our results suggest that the influence of time on tropical forest carbon dynamics overlaps and outweighs the effects due to environmental limits and mechanisms mediated by diversity (mass effects, niche complementarity). Conclusions: Natural regeneration can be an effective strategy for restoring carbon sequestration and methods that use manipulation of regenerating forests with the hope of improving the process are unlikely to bring additional advantage in terms of carbon sequestration. [ABSTRACT FROM AUTHOR]

Highlights • There is an indirect effect of plant diversity on litter decomposition. • Taxonomic, functional components and environmental factors affect litter decomposition. • The effects of diversity on the decomposition process vary with time. Abstract One of the challenges in predicting the effects of biodiversity on ecosystem functioning is understanding the balance between the importance of various diversity components and variations in the environment. In mega-diverse tropical forests, these relationships between plant diversity and ecosystem processes, such as litter decomposition, are poorly explored. While the direct effects of plant diversity on litter decomposition are relatively well known, the indirect effects of diversity, and the local community and microenvironment have rarely been investigated. We evaluated the indirect effects of plant diversity on litter decomposition in a tropical forest. We assessed diversity using different components (plant species richness, functional composition, and functional diversity), evaluated the environmental gradient (soil attributes, topography and canopy cover) and related it to the dynamics of litter decomposition. A 230-day in situ experiment was performed in the southern areas of the Brazilian Atlantic forest using litterbags filled with standard substrate (to test the indirect effects) to evaluate the decomposition rates. In parallel, we also conducted a taxonomic and functional survey of the vegetation in the area of influence of the decomposition experiment. We demonstrated that there is an indirect effect of plant diversity, via taxonomic and functional diversities, on litter decomposition. The indirect effect is more pronounced at the beginning of the decomposition process, and the influences of different components of diversity and ecological mechanisms (niche complementarity, mass effect and selection effect) vary over time. Our study revealed the importance of not only small-scale variations in the biotic component but also those of soil in ecosystem functioning in a megadiverse forest. In this way, we have contributed to a better understanding of the determinants of the decomposition process, in addition to those suggested by classical theoretical models (i.e., climate, litter composition and decomposers). [ABSTRACT FROM AUTHOR]

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Soil features are an important factor influencing plant growth and distribution in different parts of the tropics. We hypothesized that in forests recovering from a disturbance, the spatial and temporal variation of soil proprieties could determine differences in forest structure and composition. We addressed this question by comparatively assessing the soil traits and forest structure and diversity that occur in two contrasting soils in second growth tropical forests of southern Brazil: Cambisols (well-drained and nutrient-poor soil) and Gleisols (periodically flooded and with greater soil Al toxicity). Three replicates of four combinations of four forest ages (9–11, 15–20, 40–55, and >100 years since abandonment) and two soil types (Cambisol and Gleisol) were compared, thus encompassing 21 plots that covered 2.1 ha. A total of 3355 individuals of 151 tree species were sampled in all plots. Soil characteristics changed along the succession, with Al toxicity increasing as the forests aged. Cambisols and Gleisols differed in their nutritional and structural characteristics. Forests growing in both soil types exhibited higher species density, individual density and basal area along the successional gradient, but diversity (and evenness) was higher in forests growing in Gleisol soils. Moreover, soil characteristics (sand:clay, C:N, and Al and P concentrations) and forest age determined the differences in community assemblies among soils. Considering that soil characteristics are spatially and temporally variable in the tropics and that these variations are poorly measured in successional studies, we argue that small-scale variations in soil characteristics can potentially be a powerful factor influencing the successional trajectories of second growth tropical forests in tropical regions. [ABSTRACT FROM AUTHOR]

• Aboveground carbon stock and diversity increases with restoration time. • Old forests still accumulating carbon but supporting the maximum diversity. • Natural regeneration is important for carbon sequestration and conservation. • Atlantic Forest presents co-benefits during the recovery of biodiversity and carbon. To counter increasing CO 2 emissions and plant biodiversity loss, ecological restoration has been proposed as a means to sequester carbon as well as to increase species diversity in tropical landscapes. Here we examine how natural regeneration is associated with changing plant diversity and carbon stocks in the Atlantic Forest of southern Brazil. Aboveground carbon stocks and plant species diversity (using taxonomic, functional, phylogenetic and conservation metrics) were estimated in areas undergoing natural regeneration, ranging in age from seven to >80 years. Aboveground carbon, diversity and conservation metrics increase rapidly and concomitantly over time during forest natural regeneration, but even with carbon increase over time, we found the maximum taxonomic and phylogenetic diversity possible for the region. These results show the importance of considering regeneration as an alternative to increase carbon stocks, diversity, and species conservation in carbon-focused restoration plans. Our results showed co-benefits between carbon stocks, diversity, and conservation. Diversity (taxonomic, functional, and phylogenetic) increases along with carbon stocks, but functional evenness does not. Age of the areas also influences co-benefits, as they increase over time. Thus, we demonstrate that ecological restoration not only sequesters carbon and has benefits with respect to climate change but is also responsible for increasing biodiversity and conservation. This mutualism between different benefits of natural regeneration attends to a variety of international concerns. [ABSTRACT FROM AUTHOR]