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Soil CO 2 production and surface flux at four climate observatories in eastern Canada
Author(s) -
Risk David,
Kellman Lisa,
Beltrami Hugo
Publication year - 2002
Publication title -
global biogeochemical cycles
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.512
H-Index - 187
eISSN - 1944-9224
pISSN - 0886-6236
DOI - 10.1029/2001gb001831
Subject(s) - environmental science , water content , soil water , context (archaeology) , flux (metallurgy) , soil science , soil horizon , subsurface flow , thermal diffusivity , carbon dioxide , moisture , atmosphere (unit) , atmospheric sciences , hydrology (agriculture) , groundwater , geology , chemistry , geography , meteorology , physics , geotechnical engineering , organic chemistry , quantum mechanics , paleontology
Soils constitute the largest terrestrial source of carbon dioxide to the atmosphere, and in the context of changing global temperature and moisture patterns, it is critical that we understand the climatic controls on soil respiration. We use subsurface CO 2 concentrations, surface CO 2 flux and detailed physical monitoring of the subsurface regime to examine physical controls on soil CO 2 production. Results indicate that subsurface CO 2 production is very sensitive to the subsurface thermal regime, where relationships were robust and also stable across all land use types studied. In contrast, the thermal dependence of surface CO 2 flux was much weaker. We found that soil heat content, rather than soil temperature, was the most descriptive index of the biological processes contributing to soil profile CO 2 production at our study sites. Soil moisture was also found to have an important influence on subsurface CO 2 production, particularly because of the relationship between moisture and soil profile diffusivity. Nondiffusive profile CO 2 transport also appears to be important at these sites where the subsurface controls on transport change regularly and markedly.