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Title: Forest fine-root production and nitrogen use under elevated CO2: Contrasting responses explained by a common principle

Abstract

Despite the importance of nitrogen (N) limitation of forest carbon (C) sequestration at rising atmospheric CO2 concentration, the mechanisms responsible are not well understood. To elucidate the interactive effects of elevated CO2 (eCO2) and soil N availability on forest productivity and C allocation, we hypothesized that 1) trees maximize fitness by allocating N and C to maximize their net growth, and 2) that N uptake is controlled by root exploration for N. We tested this model using data collected in FACE sites dominated by evergreen (Pinus taeda; Duke Forest) and deciduous (Liquidambar styraciflua; Oak Ridge National Laboratory ORNL) trees. The model explained 80-95% of variation in productivity and N-uptake data among eCO2, N fertilization and control treatments over six years. The model explains why fine-root production increased, and why N uptake increased despite reduced soil N availability under eCO2 at ORNL and Duke. In agreement with observations at other sites, soil N availability reduced below a critical level diminishes all eCO2 responses. At Duke, a negative feedback between reduced soil N availability and N uptake counteracted progressive reduction in soil N availability at eCO2. At ORNL, decreasing soil N availability was perpetuated as it generated no reduction in N uptake,more » due to strongly increased production of fast turnover fine-roots. This implies that species with fast root turnover could be more prone to progressive N limitation of carbon sequestration in woody biomass than species with slow root turnover, such as evergreens.« less

Authors:
 [1];  [2];  [2];  [3];  [4];  [2];  [2];  [2];  [2]
  1. International Institute for Applied Systems Analysis
  2. ORNL
  3. University of Michigan
  4. Boston University
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Oak Ridge National Environmental Research Park
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
946099
DOE Contract Number:  
DE-AC05-00OR22725
Resource Type:
Journal Article
Journal Name:
Global Change Biology
Additional Journal Information:
Journal Volume: 15; Journal Issue: 1; Journal ID: ISSN 1354-1013
Country of Publication:
United States
Language:
English
Subject:
09 BIOMASS FUELS; AVAILABILITY; BIOMASS; CARBON; CARBON SEQUESTRATION; EXPLORATION; FEEDBACK; FERTILIZATION; FORESTS; NITROGEN; ORNL; PRODUCTION; PRODUCTIVITY; SOILS; TREES

Citation Formats

Franklin, Oscar, McMurtrie, Ross E, Iversen, Colleen M, Crous, Kristine, Finzi, Adrien C, Tissue, David Thomas, Ellsworth, David, Oren, Ram, and Norby, Richard J. Forest fine-root production and nitrogen use under elevated CO2: Contrasting responses explained by a common principle. United States: N. p., 2009. Web. doi:10.1111/j.1365-2486.2008.01710.x.
Franklin, Oscar, McMurtrie, Ross E, Iversen, Colleen M, Crous, Kristine, Finzi, Adrien C, Tissue, David Thomas, Ellsworth, David, Oren, Ram, & Norby, Richard J. Forest fine-root production and nitrogen use under elevated CO2: Contrasting responses explained by a common principle. United States. doi:10.1111/j.1365-2486.2008.01710.x.
Franklin, Oscar, McMurtrie, Ross E, Iversen, Colleen M, Crous, Kristine, Finzi, Adrien C, Tissue, David Thomas, Ellsworth, David, Oren, Ram, and Norby, Richard J. Thu . "Forest fine-root production and nitrogen use under elevated CO2: Contrasting responses explained by a common principle". United States. doi:10.1111/j.1365-2486.2008.01710.x.
@article{osti_946099,
title = {Forest fine-root production and nitrogen use under elevated CO2: Contrasting responses explained by a common principle},
author = {Franklin, Oscar and McMurtrie, Ross E and Iversen, Colleen M and Crous, Kristine and Finzi, Adrien C and Tissue, David Thomas and Ellsworth, David and Oren, Ram and Norby, Richard J},
abstractNote = {Despite the importance of nitrogen (N) limitation of forest carbon (C) sequestration at rising atmospheric CO2 concentration, the mechanisms responsible are not well understood. To elucidate the interactive effects of elevated CO2 (eCO2) and soil N availability on forest productivity and C allocation, we hypothesized that 1) trees maximize fitness by allocating N and C to maximize their net growth, and 2) that N uptake is controlled by root exploration for N. We tested this model using data collected in FACE sites dominated by evergreen (Pinus taeda; Duke Forest) and deciduous (Liquidambar styraciflua; Oak Ridge National Laboratory ORNL) trees. The model explained 80-95% of variation in productivity and N-uptake data among eCO2, N fertilization and control treatments over six years. The model explains why fine-root production increased, and why N uptake increased despite reduced soil N availability under eCO2 at ORNL and Duke. In agreement with observations at other sites, soil N availability reduced below a critical level diminishes all eCO2 responses. At Duke, a negative feedback between reduced soil N availability and N uptake counteracted progressive reduction in soil N availability at eCO2. At ORNL, decreasing soil N availability was perpetuated as it generated no reduction in N uptake, due to strongly increased production of fast turnover fine-roots. This implies that species with fast root turnover could be more prone to progressive N limitation of carbon sequestration in woody biomass than species with slow root turnover, such as evergreens.},
doi = {10.1111/j.1365-2486.2008.01710.x},
journal = {Global Change Biology},
issn = {1354-1013},
number = 1,
volume = 15,
place = {United States},
year = {2009},
month = {1}
}