Abstract:

The question of how to extrapolate point measurements of soil CO₂ processes to coarser scales remains unanswered because we know little about the spatial and temporal variability in the CO₂ concentration of soil air. In this work, we describe a series of simple physically-based models that simulate soil temperature, soil tension, and soil CO₂ processes. We apply these models to simulate the spatial and temporal dynamics of soil CO₂ concentrations throughout a small catchment in the Virginia Blue Ridge. Output from the simulations is compared with field measurements. We find that despite some model deficiencies, we are able to simulate the gross patterns through space and time of soil air CO₂ concentration. During the growing season when soil temperature is high, we find that soil water status is the limiting control on soil respiration and CO₂ concentration. We also find that soil CO₂ concentration can be high despite low respiration values due to decreased soil diffusivity as moisture fills pore spaces.

Keywords: Carbon dioxide; Catchment; Physically-based model; Spatial variation

Document Type: Research article

DOI: 10.1023/B:BIOG.0000049350.24911.e9

Affiliations: 1: Department of Environmental Sciences, University of Virginia, P.O. Box 400123, Charlottesrille, VA 22904, USA; Department of Geography, Frostburg State University, Frostburg, MD 21532, USA (( dwelsch@frostburg.edu; phone: +1-301-687-4891;, Fax: +1-301-687-4495)), Email: dwelsch@frostburg.edu 2: Department of Environmental Sciences, University of Virginia, P.O. Box 400123, Charlottesrille, VA 22904, USA