Spacial patterns of soil temperature and moisture across subalpine forest-clearcut edges in the southern interior of British Columbia

Abstract

To investigate if timber harvesting influences spatial patterns of soil micro climate, forest floor soil temperature and moisture were examined across forest-clearcut edges. Transects were sampled during the 2000 growing season across a 1-ha clearcut at a subalpine forest site in the southern interior of British Columbia, Canada. Forest floor temperature measurements were made twice, once under sunny and once under overcast conditions. Moisture status, measured under wet and dry conditions, was expressed as gravimetric and volumetric moisture content and matric potential. Wavelet analysis was used to detect and compare the location of edges in soil properties, and variance partitioning was used to examine the environmental and spatial sources of variability in temperature and moisture. Based on the wavelet analyses, the transition zone, in both temperature and moisture between forest and clearcut occurred at 7–15 m into the clearcut from the south edge and at 8–18 m into the forest from the north edge. Spatial patterns were consistent between clear and overcast conditions and wet and dry conditions. Distance from the edge was a minor source of spatial variability in temperature and moisture relative to the strong contrast between forest and clearcut conditions. The edge influences may have implications for nutrient cycling, plant available water and forest regeneration. Key words: Soil temperature, soil moisture, forest floor, subalpine forest, wavelet analysis, edge effects