Soil-water characteristics and hydrologic implications following forest soil disturbance: The relative influence of organic residue and soil compaction on permeability and moisture capacity. A study on Cohasset soil in the Sierra Nevada mixed conifer zon

Physical and chemical environmental parameters were monitored to describe soil and plant characteristics on an artificially disturbed forest soil in the western Sierra Nevada Mountains, California. USFS Long Term Soil Productivity (LTSP) Research Program disturbance treatments were assessed in order to characterize the impacts of forest removal, soil compaction and the removal of organic residue on soil moisture characteristics and related physiological processes as related to soil water uptake and site hydrology. The initial study (1997) measured soil hydrologic characteristics over ten soil disturbance treatments; soil water potential in the upper 30 cm of the soil profile was highly correlated with organic residue level. Heavy soil compaction significantly reduced soil sorptivity in all cases. The primary investigation (1998–1999) assessed a broader range of soil-water characteristics following forest removal and mechanized soil disturbance in order to determine the relative influence of organic residue and soil compaction on soil permeability and moisture capacity. In-situ volumetric soil moisture content was monitored throughout the 1998-growing season and soil moisture characteristics were evaluated in the laboratory from soil water retention data. The results demonstrate that soil disturbance typified by soil compaction and organic matter removal decisively influences the seasonal soil moisture regime and plant available water. Significant changes in soil porosity and the depth of organic residue were found to directly affect infiltration potential, soil water content, soil water potential and availability, soil temperature, soil aeration and leaf water potential.; A soil moisture balance for the 5 soil disturbance treatments (REF, OM-0 C-0, OM-2 C-0, OM-0 C-2, and OM-2 C-2) was modeled using available soil moisture parameters established during the 1998 summer sampling period. The results reveal that losses in soil porosity following soil disturbance resulted in reduced plant available soil moisture late in the growing season within near surface soils and similarly resulted in reduced potential for translocation of moisture to deeper subsurface zones. (Abstract shortened by UMI.)...