The relative importance of climate, stand variables and liana abundance for carbon storage in tropical forests

Abstract

AbstractAimTo develop an integrative framework to evaluate variation in aboveground carbon storage (AGC). A model that can be applied to understand and predict how global‐change drivers influence tropical carbon sinks.LocationOld‐growth tropical forests world‐wide.MethodsUsing structural equation modelling (SEM), we propose an a priori model to evaluate the direct and indirect effects of climate, stand variables (basal area, tree diameter and wood density at plot level) and liana abundance onAGC. Our model indicated that stand variables increasedAGCwhile liana abundance decreasedAGCindirectly via negative effects on stand variables. We used a multigroupSEMto test the generality of our framework using a standardized dataset of 145 plots (0.1 ha) in dry, moist and wet tropical forests.ResultsOur model explained over 85% variation inAGCand showed a positive and consistent relationship between stand variables andAGCacross forests types. The effects of climate onAGCwere indirect rather than direct, with negative effects of temperature in all forests. Liana abundance reduced tree diameter and basal area in moist forests, but did not affectAGCin wet or dry forests.Main conclusionsOur results suggest that climate affectsAGCindirectly, via its direct influence on stand variables and liana abundance. The effects of lianas onAGCresult from reductions in stand variables and are as important as climate for moist forests, which harbour the greatest tropical carbon pools. Our model was consistent across forest types. This highlights the usefulness of an integrative framework to improve predictions of the effects of drivers of global change on tropical carbon sinks.