土壤碳
自行车
相对物种丰度
环境化学
化学
土壤有机质
温带森林
农学
氮气
植物凋落物
微生物种群生物学
氮气循环
垃圾箱
丰度(生态学)
土壤水分
生态系统
生物
生态学
细菌
有机化学
考古
历史
遗传学
作者
Jing Tian,Jennifer A. J. Dungait,X. L. Lu,Yunfeng Yang,Iain P. Hartley,Wei Zhang,Jiangming Mo,Guirui Yu,Jizhong Zhou,Yakov Kuzyakov
摘要
Abstract Nitrogen (N) deposition is a component of global change that has considerable impact on belowground carbon (C) dynamics. Plant growth stimulation and alterations of fungal community composition and functions are the main mechanisms driving soil C gains following N deposition in N‐limited temperate forests. In N‐rich tropical forests, however, N deposition generally has minor effects on plant growth; consequently, C storage in soil may strongly depend on the microbial processes that drive litter and soil organic matter decomposition. Here, we investigated how microbial functions in old‐growth tropical forest soil responded to 13 years of N addition at four rates: 0 (Control), 50 (Low‐N), 100 (Medium‐N), and 150 (High‐N) kg N ha −1 year −1 . Soil organic carbon (SOC) content increased under High‐N, corresponding to a 33% decrease in CO 2 efflux, and reductions in relative abundances of bacteria as well as genes responsible for cellulose and chitin degradation. A 113% increase in N 2 O emission was positively correlated with soil acidification and an increase in the relative abundances of denitrification genes ( narG and norB ). Soil acidification induced by N addition decreased available P concentrations, and was associated with reductions in the relative abundance of phytase. The decreased relative abundance of bacteria and key functional gene groups for C degradation were related to slower SOC decomposition, indicating the key mechanisms driving SOC accumulation in the tropical forest soil subjected to High‐N addition. However, changes in microbial functional groups associated with N and P cycling led to coincidentally large increases in N 2 O emissions, and exacerbated soil P deficiency. These two factors partially offset the perceived beneficial effects of N addition on SOC storage in tropical forest soils. These findings suggest a potential to incorporate microbial community and functions into Earth system models considering their effects on greenhouse gas emission, biogeochemical processes, and biodiversity of tropical ecosystems.
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