Soil disturbance and aspen regeneration on clay soils: Three case histories

Sustaining forest productivity requires maintaining soil productivity and prompt establishment of adequate regeneration following harvest. We determined effects of commercial, winter-logging of aspen-dominated stands on soil disturbance and development of regeneration on three sites with clay soils. We established transects across each site, recorded pre-harvest stand information, post-harvest site disturbance, and first-year aspen sucker density and height. Use of large logging equipment produced heavy disturbance on 38% of a well-drained site; 45% of the area had no aspen suckers and 82% had less than the recommended minimum of 15 000 (15 k) suckers per ha (6 k ac −1 ). Mean height of dominant suckers was 45 cm (18 in). Hand felling and a small skidder caused heavy disturbance on 12% of a moderately well-drained site. Sucker density averaged 34 k ha −1 (14 k ac −1 ) and height was 97 cm (38 in). Cut-to-length (CTL) equipment produced heavy disturbance on 11% of a somewhat poorly-drained site, mean sucker density of 24 k ha −1 (9.6 k ac −1 ), and height of 101 cm (40 in). These severely disturbed areas essentially are removed from the aspen-producing land base. Retaining the northern hardwood and conifer growing stock would result in less site disturbance and help maintain natural hydrologic and nutrient cycling processes. Key words: aspen management, site disturbance, sustainable management, logging damage, soil rutting, root damage, evapotranspiration, soil aeration, clearcutting with residuals