Natural regeneration of Douglas-fir and associated species using modified clear-cutting systems in the Oregon Cascades.

Clear cutting is the standard harvesting system in old-growth Douglas-fir (Pseudotsuga menziesii) forests in the Pacific Northwest. Usually these clear cuts are in "staggered settings" of 15 to 80 acres with the surrounding stand left uncut to provide seed and serve as a firebreak. However, satisfactory natural regeneration of Douglas-fir does not always develop on such cuttings. The erratic and infrequent occurrence of abundant Douglas-fir seed crops and high surface soil temperatures appear to be major deterrents in many areas. Consequently, some modified clear cuts were tried in old-growth Douglas-fir in the western Oregon Cascade Range in 1954 and 1955 to determine their effect on natural regeneration. Cutting was in small patches and in strips of various widths and orientations. One trial of the seed-tree method was included. Cuttings were designed to leave residual trees in patterns that would reduce surface soil temperatures by providing shade and also improve distribution of natural seed fall. Resultant regeneration was examined in the summer of 1959.