Long-term nitrogen addition modifies microbial composition and functions for slow carbon cycling and increased sequestration in tropical forest soil

Journal Article · 18 July 2019 · Global Change Biology

DOI: https://doi.org/10.1111/gcb.14750 · OSTI ID:1580939

Tian, Jing ^[1]; Dungait, Jennifer A. J. ^[2]; Lu, Xiankai ^[3]; Yang, Yunfeng  ^[4]; Hartley, Iain P. ^[2]; Zhang, Wei ^[3]; Mo, Jiangming  ^[3]; Yu, Guirui  ^[5]; Zhou, Jizhong ^[6]; Kuzyakov, Yakov  ^[7]

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1. China Agricultural Univ., Beijing (China); Chinese Academy of Sciences (CAS), Beijing (China). Key Lab. of Ecosystem Network Observation and Modeling, Inst. of Geographic Sciences and Natural Resources Research
2. Univ. of Exeter, Exeter (United Kingdom)
3. Chinese Academy of Sciences (CAS), Guangzhou (China). Key Lab. of Vegetation Restoration and Management of Degraded Ecosystems and Guangdong Provincial Key Lab. of Applied Botany
4. Tsinghua Univ., Beijing (China)
5. Chinese Academy of Sciences (CAS), Beijing (China). Key Lab. of Ecosystem Network Observation and Modeling, Inst. of Geographic Sciences and Natural Resources Research
6. Tsinghua Univ., Beijing (China). State Key Joint Lab. of Environment Simulation and Pollution Control; Univ. of Oklahoma, Norman, OK (United States). Inst. for Environmental Genomics; Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
7. Univ. of Gottingen, Gottingen (Germany); Central South Univ. of Forestry and Technology, Changsha (China)

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 CO₂ efflux, and reductions in relative abundances of bacteria as well as genes responsible for cellulose and chitin degradation. A 113% increase in N₂O 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 N₂O 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. Finally, 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.

• Research Organization: Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
• Sponsoring Organization: National Key R&D Program of China; National Natural Science Foundation of China (NNSFC); USDOE Office of Science (SC)
• Grant/Contract Number: AC02-05CH11231
• OSTI ID: 1580939
• Journal Information: Global Change Biology, Journal Name: Global Change Biology Journal Issue: 10 Vol. 25; ISSN 1354-1013
• Publisher: WileyCopyright Statement
• Country of Publication: United States
• Language: English