Linking plant functional traits to soil properties in tropical forest restoration

Native tree plantation is one of the most common ecological restoration techniques used in tropical forests since it catalyzes ecological succession and contributes to the recovery of ecosystem processes. This study assessed the effect of functional trait composition (leaf area, specific leaf area, leaf dry matter content, leaf P, leaf C, leaf N, and wood density), functional diversity (functional richness, functional evenness, functional divergence, and Rao entropy), and aboveground biomass on soil properties in communities undergoing ecological restoration in the Brazilian Atlantic Forest. The experiment was conducted in a native tree plantation with four treatments based on ecological species groups that were implemented 19 years ago. Structural equation models were used to assess the role of vegetation attributes (trait composition, functional diversity, and aboveground biomass) on soil properties (chemical properties, respiration, and microbial enzymatic activity). Our results showed that trait composition was a more important driver of changes in soil properties than functional diversity or aboveground biomass. The community-weight mean (CWM) of specific leaf area was negatively associated with soil carbon (-0.63) and soil microbial enzymatic activity (-0.77) and positively related to soil phosphorous content (0.72). Functional diversity (Rao entropy index) was negatively correlated with carbon microbial biomass (-0.89). Aboveground biomass alone did not explain changes in soil ecosystem processes. These results underscore the significance of using plant functional traits as an integrated tool to evaluate the links between below and aboveground components in restoration sites of tropical forests.