Uneven-aged drybelt interior Douglas-fir (Pseudotsuga menziesii var. glauca) stands have been harvested for over 50 years in British Columbia. Within the Cariboo Forest Region, most drybelt Douglas-fir stands are located in the Interior Douglas-fir (IDF) biogeoclimatic zone. Stands have been partially cut at varying intensities. Natural shelterwoods, based on cutting all trees over a fixed diameter, were common through the 1970ís to the mid-1980ís. This was replaced by the single tree selection silvicultural system to improve the quality of the residual stand, decrease logging damage and improve regeneration establishment on dry sites after harvest.
Despite the number of years in which drybelt uneven-aged Douglas-fir stands have been harvested, very little information is available on post-harvest natural regeneration success and stand basal area growth rates.
In 1995, a retrospective study was initiated to increase understanding of how past harvesting practices have effected natural regeneration establishment and growth within uneven-aged Douglas-fir stands. Stands were selected in three subzones: IDFdk3,
IDFxm and IDFxw. All 31 stands in the study were partially cut between
1980 and 1987, but not spaced. This extension note summarizes the results
from two unpublished reports (Catton 1997; Day 1996). For clarification,
the authors define Stocking as a measure of site occupancy and is
described by basal area, and Density as a measure of spacing, or
competition and is described by stems/ha.
Silvicultural Systems, Research Associate
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