Forest structure predicts aboveground biomass better than community-weighted mean of traits, functional diversity, topography, and soil in a tropical forest across spatial scales
Tim Simmavong, Yuebo Su, Yun Deng, Bin Wang, Zhiliang Yao, Junjie Wu, Liqing Sha, Min Cao, Luxiang Lin
Abstract
Aboveground biomass of vegetation plays an important role in the global carbon cycle and climate change mitigation. Both abiotic and biotic factors can influence aboveground biomass directly, as well as indirectly, and these effects can depend on the spatial scale in which data are measured. We explored the direct and indirect effects of site topography, soil properties, forest structure, and functional traits on aboveground biomass at two spatial scales (i.e., 20 m × 20 m and 50 m × 50 m) in a tropical seasonal rainforest. We found that the relative importance of biotic factors was greater than that of abiotic factors across scales. Forest structure consistently had the greatest positive influence on aboveground biomass at both spatial scales. The mass ratio effect could act in driving aboveground biomass at the small spatial scale, while we found no evidence to support the niche complementarity effect at either scale. The relative importance of soil properties on aboveground biomass decreased with increasing spatial scale, while that of topography increased. The total effects of topography and soil properties on aboveground biomass were consistently positive across scales. We conclude that considering spatial scale is important to fully understand how biotic and abiotic factors drive aboveground biomass. Our results highlight the importance of focusing on forest structure and the scale dependence of the drivers of aboveground biomass in the context of forest management and restoration to improve forest carbon sequestration and mitigate climate change .