Author: Philip Joseph BurtonPublisher: University of British Columbia Press
ISBN:
Category : Nature
Languages : en
Pages : 80
Book Description
Three replicates of a uniform shelterwood trial were established in even-aged stands dominated by Douglas-fir in the SBSdw1 variant northeast of Williams Lake, B.C., with initial harvesting conducted in the summer of 1991. Treatments consisted of a two-stage shelterwood leaving 50% residual basal area (RBA) after the first entry and a three-stage shelterwood leaving 70% RBA, with overstory thinning achieved by hand-falling or by feller-buncher. Treatment units were 1.4 ha in area, with an uncut control (100% RBA) at each site. Seedfall was monitored using ten 0.37 m 2 seedfall traps in each treatment unit, inspected twice a year from 1992 through 1998. The abundance of different ground surface materials was surveyed in 1990, 1991, and 1993. Controlled germination experiments were conducted in 1994, 1995, and 1996. on four seedbed materials (forest floor, live moss, rotting wood, and mineral soil) across all RBA levels. Surveys of the density of natural regeneration were conducted in 1990, 1991, 1993, 1994, and 1996. ... Results to date suggest that a low residual basal area, combined with a high level of forest floor disturbance, is preferable for enhancing conifer regeneration. It is tentatively recommended that a preparatory cut is not necessary for naturally regenerating Douglas-fir under a shelterwood overstory in this zone, and that the seed cut should leave less than 50% residual basal area.