Soil respiration is a major contributor to atmospheric CO2, but accurate landscape-scale estimates of soil CO2 flux for many ecosystems including shrublands have yet to be established. We began a project to measure, with high spatial and temporal resolution, soil CO2 flux in a stand (11 x 25 m area) of big sagebrush (Artemisia tridentata Nutt.) at the Logan, Utah, Forestry Sciences Laboratory. Beginning on Nov. 1, 2009, hourly soil CO2 flux measurements were made at a single location in the stand using the Li-Cor LI-8100 soil CO2 flux instrument and 20-cm long-term chamber. Beginning in April, 2010, monthly soil CO2 flux measurements were made on a grid of 11 locations within the stand using the LI- 8100 equipped with the 20-cm survey chamber. Hourly soil temperature (10-cm depth) and volumetric soil water content data were also collected. Soil CO2 flux, temperature, and water content were highly temporally and spatially variable in the sagebrush stand. Mean (std dev) soil CO2 flux, temperature, and water content for the measurement period (November 1, 2009 - October 31, 2010) were 0.96 (0.81) umol m-2 s-1, 10.59 (10.11) deg C, and 0.101 (0.062) m3 m-3, respectively. Calculated annual soil CO2 flux obtained by summing all the hourly measurements was 328 g C m-2 y-1. For semi-arid or arid sites where precipitation is less than evapotranspiration, measured total annual soil CO2 flux will be less than the potential maximum because of dry season suppression of soil respiration when soil water content is very low.
Amacher, Michael C. and Mackowiak, Cheryl L.
"Seasonal Soil CO2 Flux Under Big Sagebrush (Artemisia tridentata Nutt.),"
Natural Resources and Environmental Issues:
Vol. 17, Article 27.
Available at: http://digitalcommons.usu.edu/nrei/vol17/iss1/27