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Title: Temperature-independent diel variation in soil respiration observed from a temperate deciduous forest

Abstract

The response of soil respiration (Rs) to temperature depends largely on the temporal and spatial scales of interest and how other environmental factors interact with this response. They are often represented by empirical exponential equations in many ecosystem analyses because of the difficulties in separating covarying environmental responses and in observing below ground processes. The objective of this study was to quantify a soil temperature-independent component in Rs by examining the diel variation of an Rs time series measured in a temperate deciduous forest located at Oak Ridge, TN, USA between March and December 2003. By fitting 2 hourly, continuous automatic chamber measurements of CO2 efflux at the soil surface to a Q10 function to obtain the temperature-dependent respiration (Rt) and plotting the diel cycles of Rt, Rs, and their difference (Ri), we found that an obvious temperature-independent component exists in Rs during the growing season. The diel cycle of this component has a distinct day/night pattern and agrees well with diel variations in photosynthetically active radiation (PAR) and air temperature. Elevated canopy CO2 concentration resulted in similar patterns in the diel cycle of the temperature-independent component but with different daily average rates in different stages of growing season. Wemore » speculate that photosynthesis of the stand is one of the main contributors to this temperature-independent respiration component although more experiments are needed to draw a firm conclusion. We also found that despite its relatively small magnitude compared with the temperature-dependent component, the diel variation in the temperature-independent component can lead to significantly different estimates of the temperature sensitivity of soil respiration in the study forest. As a result, the common practice of using fitted temperature-dependent function from night-time measurements to extrapolate soil respiration during the daytime may underestimate daytime soil respiration.« less

Authors:
 [1];  [1];  [1];  [1];  [1];  [1]
  1. ORNL
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 International Affairs (IA)
OSTI Identifier:
1003689
DOE Contract Number:  
DE-AC05-00OR22725
Resource Type:
Journal Article
Resource Relation:
Journal Name: Global Change Biology; Journal Volume: 12
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; AIR; DAILY VARIATIONS; ECOSYSTEMS; FORESTS; PHOTOSYNTHESIS; RADIATIONS; RESPIRATION; SENSITIVITY; SOILS

Citation Formats

Post, Wilfred M, Liu, Qing, Edwards, Nelson T, Gu, Lianhong, Childs, Joanne, and Lenhart, Suzanne M. Temperature-independent diel variation in soil respiration observed from a temperate deciduous forest. United States: N. p., 2006. Web.
Post, Wilfred M, Liu, Qing, Edwards, Nelson T, Gu, Lianhong, Childs, Joanne, & Lenhart, Suzanne M. Temperature-independent diel variation in soil respiration observed from a temperate deciduous forest. United States.
Post, Wilfred M, Liu, Qing, Edwards, Nelson T, Gu, Lianhong, Childs, Joanne, and Lenhart, Suzanne M. Sun . "Temperature-independent diel variation in soil respiration observed from a temperate deciduous forest". United States.
@article{osti_1003689,
title = {Temperature-independent diel variation in soil respiration observed from a temperate deciduous forest},
author = {Post, Wilfred M and Liu, Qing and Edwards, Nelson T and Gu, Lianhong and Childs, Joanne and Lenhart, Suzanne M},
abstractNote = {The response of soil respiration (Rs) to temperature depends largely on the temporal and spatial scales of interest and how other environmental factors interact with this response. They are often represented by empirical exponential equations in many ecosystem analyses because of the difficulties in separating covarying environmental responses and in observing below ground processes. The objective of this study was to quantify a soil temperature-independent component in Rs by examining the diel variation of an Rs time series measured in a temperate deciduous forest located at Oak Ridge, TN, USA between March and December 2003. By fitting 2 hourly, continuous automatic chamber measurements of CO2 efflux at the soil surface to a Q10 function to obtain the temperature-dependent respiration (Rt) and plotting the diel cycles of Rt, Rs, and their difference (Ri), we found that an obvious temperature-independent component exists in Rs during the growing season. The diel cycle of this component has a distinct day/night pattern and agrees well with diel variations in photosynthetically active radiation (PAR) and air temperature. Elevated canopy CO2 concentration resulted in similar patterns in the diel cycle of the temperature-independent component but with different daily average rates in different stages of growing season. We speculate that photosynthesis of the stand is one of the main contributors to this temperature-independent respiration component although more experiments are needed to draw a firm conclusion. We also found that despite its relatively small magnitude compared with the temperature-dependent component, the diel variation in the temperature-independent component can lead to significantly different estimates of the temperature sensitivity of soil respiration in the study forest. As a result, the common practice of using fitted temperature-dependent function from night-time measurements to extrapolate soil respiration during the daytime may underestimate daytime soil respiration.},
doi = {},
journal = {Global Change Biology},
number = ,
volume = 12,
place = {United States},
year = {Sun Jan 01 00:00:00 EST 2006},
month = {Sun Jan 01 00:00:00 EST 2006}
}