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Soil CO2 efflux in a tropical forest in the central Amazon.

Authors :
Sotta, Eleneide Doff
Meir, Patrick
Malhi, Yadvinder
Nobre, Antonio Donato
Hodnett, Martin
Grace, John
Source :
Global Change Biology; May2004, Vol. 10 Issue 5, p601-617, 17p
Publication Year :
2004

Abstract

This study investigated the spatial and temporal variation in soil carbon dioxide (CO<subscript>2</subscript>) efflux and its relationship with soil temperature, soil moisture and rainfall in a forest near Manaus, Amazonas, Brazil. The mean rate of efflux was 6.45±0.25 SE μmol CO<subscript>2</subscript> m<superscript>−2</superscript>s<superscript>−1</superscript> at 25.6±0.22 SE°C (5 cm depth) ranging from 4.35 to 9.76 μmol CO<subscript>2</subscript> m<superscript>−2</superscript>s<superscript>−1</superscript>; diel changes in efflux were correlated with soil temperature ( r<superscript>2</superscript>=0.60). However, the efflux response to the diel cycle in temperature was not always a clear exponential function. During period of low soil water content, temperature in deeper layers had a better relationship with CO<subscript>2</subscript> efflux than with the temperature nearer the soil surface. Soil water content may limit CO<subscript>2</subscript> production during the drying-down period that appeared to be an important factor controlling the efflux rate ( r<superscript>2</superscript>=0.39). On the other hand, during the rewetting period microbial activity may be the main controlling factor, which may quickly induce very high rates of efflux. The CO<subscript>2</subscript> flux chamber was adapted to mimic the effects of rainfall on soil CO<subscript>2</subscript> efflux and the results showed that efflux rates reduced 30% immediately after a rainfall event. Measurements of the CO<subscript>2</subscript> concentration gradient in the soil profile showed a buildup in the concentration of CO<subscript>2</subscript> after rain on the top soil. This higher CO<subscript>2</subscript> concentration developed shortly after rainfall when the soil pores in the upper layers were filled with water, which created a barrier for gas exchange between the soil and the atmosphere. [ABSTRACT FROM AUTHOR]

Details

Language :
English
ISSN :
13541013
Volume :
10
Issue :
5
Database :
Complementary Index
Journal :
Global Change Biology
Publication Type :
Academic Journal
Accession number :
13104659
Full Text :
https://doi.org/10.1111/j.1529-8817.2003.00761.x