Reforestation Trials and Secondary Succession with Three Levels of Overstory Shade in the Grand Fir Mosaic Ecosystem

摘要

Grand Fir Mosaic habitats are difficult to regenerate because of pocket gophers (Thomomys talpoides) and successional plant communities dominated by bracken fern ( Pteridium aquilinum) and western coneflower (Rudbeckia occidentalis). This study tested reforestation practices recommended by previous research, tested hypotheses about the effects of overstory shade on regeneration success, and documented secondary succession. Natural regeneration is not a reliable reforestation method on Grand Fir Mosaic sites. Clearcut and planting was the best regeneration method if pocket gophers are controlled. Partial cutting and planting was the best regeneration method if pocket gophers were not controlled. Most gopher-caused seedling mortality occurred the first summer, first winter, and second winter after planting. The clearcut treatment resulted in the loss of shrub species and the dominance of bracken fern and/or western coneflower. In the partial cut treatment, shrubs were retained and there was less bracken fern and/or western coneflower than in the clearcut treatment.