Symposium Schedule >

Ecosystem effects of wind and salvage-logging disturbance in a subalpine forest

Cristina M. Rumbaitis-del Rio (1) and Carol A. Wessman
Cooperative Institute for Research in Environmental Sciences
Campus Box 216, Boulder, CO 80309, USA

Compound disturbances have the potential to fundamentally alter an ecosystem structure and function. This study compares the effects of a natural disturbance and a compounded natural and anthropogenic disturbance on soil properties, biogeochemical cycles, and ecosystem reorganization in a windblown and salvage-logged ecosystem in northwestern Colorado. Areas of intact forest are used as a control to compare the disturbance effects. Results of this three year study indicate that soils in the salvage-logged areas are significantly warmer, denser, andcontain less organic matter than soils in blowdown or control areas. Significant amounts of erosion and mechanical soil compaction in the salvage-logged areas may have produced these results. Furthermore, total soil nitrogen is lower in salvage-logged soils than in blowdown soils. By contrast, nitrogen availability and net nitrogen mineralization rates are significantly higher in blowdown areas than in control areas. Seedling density, herbaceous cover, and plant species diversity are greatest in blowdown areas, and least in salvaged-logged areas. Of particular interest is the low abundance of spruce seedlings in salvage-logged areas. This finding suggests that a shift in species composition may occur in these areas.. The results of this study indicate that the mitigation effects of salvage logging significantly alter ecosystem functions and delay the rate of recovery when compared to unlogged blowdown areas.