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Title: Responses of soil respiration to elevated CO 2, air warming, and changing soil water availability in an old-field grassland

Abstract

Responses of soil respiration to atmospheric and climatic change will have profound impacts on ecosystem and global C cycling in the future. This study was conducted to examine effects on soil respiration of the concurrent driving factors of elevated atmospheric CO2 concentration, rising temperature, and changing precipitation in a constructed old-field grassland in eastern Tennessee, USA. Model ecosystems of seven old-field species in 12 open-top chambers (4 m in diameter) were treated with two CO2 (ambient and ambient plus 300 ppm) and two temperature (ambient and ambient plus 3 C) levels. Two split plots with each chamber were assigned with high and low soil moisture levels. During the 19-month experimental period from June 2003 to December 2004, higher CO2 concentration and soil water availability significantly increased mean soil respiration by 35.8% and 15.7%, respectively. The effects of air warming on soil respiration varied seasonally from small reductions to significant increases to no response, and there was no significant main effect. In the wet side of elevated CO2 chambers, air warming consistently caused increases in soil respiration, whereas in other three combinations of CO2 and water treatments, warming tended to decrease soil respiration over the growing season but increase it overmore » the winter. There were no interactive effects on soil respiration among any two or three treatment factors irrespective of testing time period. Temperature sensitivity of soil respiration was reduced by air warming, lower in the wet than the dry side, and not affected by CO2 treatment. Variations of soil respiration responses with soil temperature and soil moisture ranges could be primarily attributable to the seasonal dynamics of plant growth and its responses to the three treatments. Using a conceptual model to interpret the significant relationships of treatment-induced changes in soil respiration with changes in soil temperature and moisture observed in this study, we conclude that elevated CO2, air warming, and changing soil water availability had both direct and indirect effects on soil respiration via changes in the three controlling factors: soil temperature, soil moisture, and C substrate. Our results demonstrate that the response of soil respiration to climatic warming should not be represented in models as a simple temperature response function. A more mechanistic understanding of the direct and indirect impacts of concurrent global change drivers on soil respiration is needed to facilitate the interpretation and projection of ecosystem and global C cycling in response to atmospheric and climate change.« less

Authors:
 [1];  [2];  [2];  [3]
  1. Chinese Academy of Sciences
  2. ORNL
  3. University of Tennessee, Knoxville (UTK)
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:
931979
DOE Contract Number:  
DE-AC05-00OR22725
Resource Type:
Journal Article
Resource Relation:
Journal Name: Global Change Biology; Journal Volume: 13; Journal Issue: 11
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; AIR; AVAILABILITY; CLIMATIC CHANGE; MOISTURE; PLANT GROWTH; RESPIRATION; RESPONSE FUNCTIONS; SOILS; WATER; WATER TREATMENT; Air warming; atmospheric CO2 concentration; old-field grassland; soil respiration; soil water availability; temperature sensitivity

Citation Formats

Wan, Shiqiang, Norby, Richard J, Childs, Joanne, and Weltzin, Jake. Responses of soil respiration to elevated CO2, air warming, and changing soil water availability in an old-field grassland. United States: N. p., 2007. Web. doi:10.1111/j.1365-2486.2007.01433.x.
Wan, Shiqiang, Norby, Richard J, Childs, Joanne, & Weltzin, Jake. Responses of soil respiration to elevated CO2, air warming, and changing soil water availability in an old-field grassland. United States. doi:10.1111/j.1365-2486.2007.01433.x.
Wan, Shiqiang, Norby, Richard J, Childs, Joanne, and Weltzin, Jake. Mon . "Responses of soil respiration to elevated CO2, air warming, and changing soil water availability in an old-field grassland". United States. doi:10.1111/j.1365-2486.2007.01433.x.
@article{osti_931979,
title = {Responses of soil respiration to elevated CO2, air warming, and changing soil water availability in an old-field grassland},
author = {Wan, Shiqiang and Norby, Richard J and Childs, Joanne and Weltzin, Jake},
abstractNote = {Responses of soil respiration to atmospheric and climatic change will have profound impacts on ecosystem and global C cycling in the future. This study was conducted to examine effects on soil respiration of the concurrent driving factors of elevated atmospheric CO2 concentration, rising temperature, and changing precipitation in a constructed old-field grassland in eastern Tennessee, USA. Model ecosystems of seven old-field species in 12 open-top chambers (4 m in diameter) were treated with two CO2 (ambient and ambient plus 300 ppm) and two temperature (ambient and ambient plus 3 C) levels. Two split plots with each chamber were assigned with high and low soil moisture levels. During the 19-month experimental period from June 2003 to December 2004, higher CO2 concentration and soil water availability significantly increased mean soil respiration by 35.8% and 15.7%, respectively. The effects of air warming on soil respiration varied seasonally from small reductions to significant increases to no response, and there was no significant main effect. In the wet side of elevated CO2 chambers, air warming consistently caused increases in soil respiration, whereas in other three combinations of CO2 and water treatments, warming tended to decrease soil respiration over the growing season but increase it over the winter. There were no interactive effects on soil respiration among any two or three treatment factors irrespective of testing time period. Temperature sensitivity of soil respiration was reduced by air warming, lower in the wet than the dry side, and not affected by CO2 treatment. Variations of soil respiration responses with soil temperature and soil moisture ranges could be primarily attributable to the seasonal dynamics of plant growth and its responses to the three treatments. Using a conceptual model to interpret the significant relationships of treatment-induced changes in soil respiration with changes in soil temperature and moisture observed in this study, we conclude that elevated CO2, air warming, and changing soil water availability had both direct and indirect effects on soil respiration via changes in the three controlling factors: soil temperature, soil moisture, and C substrate. Our results demonstrate that the response of soil respiration to climatic warming should not be represented in models as a simple temperature response function. A more mechanistic understanding of the direct and indirect impacts of concurrent global change drivers on soil respiration is needed to facilitate the interpretation and projection of ecosystem and global C cycling in response to atmospheric and climate change.},
doi = {10.1111/j.1365-2486.2007.01433.x},
journal = {Global Change Biology},
number = 11,
volume = 13,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}