. Regeneration in mixed conifer partial cuttings in the Blue Mountains of Oregon and Washington. . Exceptions are the negative correlation of mineral soil to regeneration in the grand fir type and the positive correlation of animal damage to regeneration in both communities. The negative correlation of mineral soil to regeneration was not expected because studies have shown mineral soil to be the most favorable seedbed for natural regeneration (Seidel and Cooley 1974, Seidel 1979a). Al- though mineral soil is an excellent seedbed for natural regeneration, many seedlings (especially true fir) d
. Regeneration in mixed conifer partial cuttings in the Blue Mountains of Oregon and Washington. . Exceptions are the negative correlation of mineral soil to regeneration in the grand fir type and the positive correlation of animal damage to regeneration in both communities. The negative correlation of mineral soil to regeneration was not expected because studies have shown mineral soil to be the most favorable seedbed for natural regeneration (Seidel and Cooley 1974, Seidel 1979a). Al- though mineral soil is an excellent seedbed for natural regeneration, many seedlings (especially true fir) do become established in light to medium litter layers (one-fourth to one-half inch deep). Also, light amounts of slash provide a favorable environment for seedling establishment because of the protection offered against temperature extremes. Therefore, it is neither necessary nor desirable to com- pletely remove all litter and slash from the seedbed. Generally, enough disturbance is caused by logging and slash disposal to provide a receptive seedbed, except possibly in areas of continuous heavy pinegrass sod. A positive correlation of animal damage and regeneration also was not expected, although disturbance as a result of livestock and big game activity may have resulted in a more favorable seedbed. Consumption of understory vegetation (especially grass) by animals could also reduce competition for water and nutrients and thus increase survival of seedlings. Similar to stocking in shelterwood units in the Cascade Range, stocking of regener- ation decreased as grass cover increased in both plant communities (fig. 2). Al- though the equations relating milacre stocking to grass cover were highly significant (P<) for both com- munities, there was still too much un- explained variation for use as prediction equations. The equations do indicate, however, that heavy amounts of grass can reduce the chance of successful establishment of tree seedlings. Residual Stand Density and
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