Objective The tropical monsoon rainforest area has high vegetation productivity and strong carbon sink capacity, playing a crucial role in the regional carbon balance. However, at present, the impact of different management patterns of tropical forests on soil respiration and its components remains unclear, which greatly limits the accurate simulation and assessment of carbon cycle process in this region under global change and high-intensity human influence.
Method The three management pattern forests in Xishuangbanna, Yunnan Province of southwestern China, namely the pure rubber forest, the rubber-coffee mixed forest and the artificial rainforest with high tree species diversity were taken as the research objects. By measuring indicators such as vegetation biomass, tree species functional traits, soil physical and chemical properties and microbial community structure, the effects and mechanisms of different management patterns of rubber forests on soil respiration and its components were explored.
Result (1) Soil respiration, litter layer respiration and autotrophic respiration all significantly increased with the increase of tree species diversity in the forest land, while the soil heterotrophic respiration showed no significant change. (2) With the increase of tree species diversity, the yield of litter and biomass of fine roots had significantly increased, and the litter turnover rate had significantly improved. Both soil carbon-nitrogen ratio and true bacterial biomass ratio decreased significantly with the increase in number of tree species. (3) There were significant differences in the influence mechanisms of different management patterns on various respiratory components of soil: the changes in soil autotrophic respiration were mainly affected by litter turnover rate and fine root biomass; the changes in respiration in the litter layer were mainly affected by specific leaf area and arbush mycorrhizal fungal biomass; while the soil heterotrophic respiration was mainly regulated by biomass ratio of true bacteria and arbush mycorrhizal fungal biomass.
Conclusion In the management of tropical plantations, tree species diversity is a key factor affecting soil respiration and composition. An increase in tree species diversity affects total soil respiration and autotrophic respiration by enhancing litter yield and quality and increasing root biomass, and influences litter layer respiration by increasing litter decomposition rate, changing plant leaf traits and microbial structure, and indirectly affects soil heterotrophic respiration by altering the structure of microbial community.
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