skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Effects of nitrogen additions on above- and belowground carbon dynamics in two tropical forests

Abstract

Anthropogenic nitrogen (N) deposition is increasing rapidly in tropical regions, adding N to ecosystems that often have high background N availability. Tropical forests play an important role in the global carbon (C) cycle, yet the effects of N deposition on C cycling in these ecosystems are poorly understood. We used a field N-fertilization experiment in lower and upper elevation tropical rain forests in Puerto Rico to explore the responses of above- and belowground C pools to N addition. As expected, tree stem growth and litterfall productivity did not respond to N fertilization in either of these Nrich forests, indicating a lack of N limitation to net primary productivity (NPP). In contrast, soil C concentrations increased significantly with N fertilization in both forests, leading to larger C stocks in fertilized plots. However, different soil C pools responded to N fertilization differently. Labile (low density) soil C fractions and live fine roots declined with fertilization, while mineral-associated soil C increased in both forests. Decreased soil CO2 fluxes in fertilized plots were correlated with smaller labile soil C pools in the lower elevation forest (R2 = 0.65, p\0.05), and with lower live fine root biomass in the upper elevation forest (R2 = 0.90,more » p\0.05). Our results indicate that soil C storage is sensitive to N deposition in tropical forests, even where plant productivity is not N-limited. The mineral-associated soil C pool has the potential to respond relatively quickly to N additions, and can drive increases in bulk soil C stocks in tropical forests.« less

Authors:
; ; ;
Publication Date:
Research Org.:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org.:
Earth Sciences Division
OSTI Identifier:
1051650
Report Number(s):
LBNL-5143E
Journal ID: ISSN 0168--2563
DOE Contract Number:  
DE-AC02-05CH11231
Resource Type:
Journal Article
Journal Name:
Biogeochemistry
Additional Journal Information:
Journal Volume: 104; Journal Issue: 1-3; Related Information: Journal Publication Date: 2011; Journal ID: ISSN 0168--2563
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; 58 GEOSCIENCES; Aboveground biomass; Dissolved organic carbon; Nutrient limitation; Roots; Soil density fractions; Soil respiration

Citation Formats

Cusack, D, Silver, W L, Torn, M S, and McDowell, W H. Effects of nitrogen additions on above- and belowground carbon dynamics in two tropical forests. United States: N. p., 2011. Web. doi:10.1007/s10533-010-9496-4.
Cusack, D, Silver, W L, Torn, M S, & McDowell, W H. Effects of nitrogen additions on above- and belowground carbon dynamics in two tropical forests. United States. doi:10.1007/s10533-010-9496-4.
Cusack, D, Silver, W L, Torn, M S, and McDowell, W H. Fri . "Effects of nitrogen additions on above- and belowground carbon dynamics in two tropical forests". United States. doi:10.1007/s10533-010-9496-4. https://www.osti.gov/servlets/purl/1051650.
@article{osti_1051650,
title = {Effects of nitrogen additions on above- and belowground carbon dynamics in two tropical forests},
author = {Cusack, D and Silver, W L and Torn, M S and McDowell, W H},
abstractNote = {Anthropogenic nitrogen (N) deposition is increasing rapidly in tropical regions, adding N to ecosystems that often have high background N availability. Tropical forests play an important role in the global carbon (C) cycle, yet the effects of N deposition on C cycling in these ecosystems are poorly understood. We used a field N-fertilization experiment in lower and upper elevation tropical rain forests in Puerto Rico to explore the responses of above- and belowground C pools to N addition. As expected, tree stem growth and litterfall productivity did not respond to N fertilization in either of these Nrich forests, indicating a lack of N limitation to net primary productivity (NPP). In contrast, soil C concentrations increased significantly with N fertilization in both forests, leading to larger C stocks in fertilized plots. However, different soil C pools responded to N fertilization differently. Labile (low density) soil C fractions and live fine roots declined with fertilization, while mineral-associated soil C increased in both forests. Decreased soil CO2 fluxes in fertilized plots were correlated with smaller labile soil C pools in the lower elevation forest (R2 = 0.65, p\0.05), and with lower live fine root biomass in the upper elevation forest (R2 = 0.90, p\0.05). Our results indicate that soil C storage is sensitive to N deposition in tropical forests, even where plant productivity is not N-limited. The mineral-associated soil C pool has the potential to respond relatively quickly to N additions, and can drive increases in bulk soil C stocks in tropical forests.},
doi = {10.1007/s10533-010-9496-4},
journal = {Biogeochemistry},
issn = {0168--2563},
number = 1-3,
volume = 104,
place = {United States},
year = {2011},
month = {4}
}