Spatial variability in soil respiration is poorly understood, yet is being measured at many scales by numerous researchers. Selection of sampling location may strongly influence results, to the point of possibly disproving true hypotheses. The objective of this study is to determine the relationship between soil respiration (including both root and microbial respiration) and the proximity to large deciduous trees in a high elevation watershed in the Potomac Highlands in West Virginia. We hypothesize that soil respiration will be affected by proximity to the stem, within the crown diameter of a tree. As it is known that soil temperature and soil moisture are key controls on soil respiration, we also hypothesize that patterns in temperature and moisture are influenced by the stem proximity, and that soil respiration will follow this pattern. We measured soil temperature, soil moisture, and soil respiration at 12 locations within the crown diameter of three different trees for one year.
Results/Conclusions
We found that soil moisture and soil temperatures associated well with stem proximity, with both increasing with distance from the stem. While observable patterns in soil moisture and temperature exist, we found that soil respiration does not appear to be strongly correlated with stem distance. This finding indicates that local factors other than moisture and temperature may be more important in determining soil respiration than distance from a stem. Such spatially variable factors may include organic matter content, diffusive properties, or micro topography.
