Moderate size diversity of tree roots has largest effect on the carbon loss in tropical soils

Abstract

Abstract Most studies focused on the above‐ground diversity on leaf litter decomposition and soil respiration in tropical ecosystems, however, the mechanism understanding of root diversity on decomposition is still unclear. We selected the fine‐roots of 21 dominant tree species from a tropical rainforest in Xishuangbannan, China, then conducted a 360‐day and well‐replicated (21 replications) incubation decomposition experiment with a 0, 1, 3, 6, 9, 12, 15, 18 and 21 species gradient of root diversity. The fine‐root mass loss, CO2 release, and their potential drivers were analysed. The results showed that as fine‐root diversity increased, soil properties, microbial diversity and fungal biomass changed nonlinearly, leading to higher litter mass loss and soil CO2 release in the moderate diversity with 9, 12 and 15 species mixtures. Non‐additive effect analysis also indicated that synergistic effects were greater in these three mixtures than others on soil CO2 release and litter mass loss. The indirect effects of soil properties and microbial communities were larger than the direct effect of fine‐root diversity. Our findings suggest that fine‐root diversity has nonlinear relationships with litter decomposition and soil CO2 release in tropical forests, thus highlighting the importance of plant diversity due to its role in the carbon cycle under global change scenario. Read the free Plain Language Summary for this article on the Journal blog.