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Long-term nitrogen addition modifies microbial composition and functions for slow carbon cycling and increased sequestration in tropical forest soil.
- Source :
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Global change biology [Glob Chang Biol] 2019 Oct; Vol. 25 (10), pp. 3267-3281. Date of Electronic Publication: 2019 Aug 01. - Publication Year :
- 2019
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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 <superscript>-1</superscript>  year <superscript>-1</superscript> . Soil organic carbon (SOC) content increased under High-N, corresponding to a 33% decrease in CO <subscript>2</subscript> efflux, and reductions in relative abundances of bacteria as well as genes responsible for cellulose and chitin degradation. A 113% increase in N <subscript>2</subscript> 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 <subscript>2</subscript> 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.<br /> (© 2019 John Wiley & Sons Ltd.)
- Subjects :
- Carbon
Carbon Cycle
Forests
Nitrogen
Soil
Subjects
Details
- Language :
- English
- ISSN :
- 1365-2486
- Volume :
- 25
- Issue :
- 10
- Database :
- MEDLINE
- Journal :
- Global change biology
- Publication Type :
- Academic Journal
- Accession number :
- 31273887
- Full Text :
- https://doi.org/10.1111/gcb.14750