"A uniform shelterwood trial in interior Douglas-fir (Pseudotsuga menziesii var. glauca) leading stands, within the Dry Warm Sub-Boreal Spruce biogeoclimatic subzone (SBSdw) in the central interior of British Columbia, was thinned from below twice (1991, 2001) before the final harvest in 2011. Mean merchantable volume and basal area growth rates for all species and the Douglas-fir component were not significantly different among three residual basal area (RBA) treatments (30, 40, and 60 m²/ha) in 10- and 20-year periods from 1990 to 2010 or among five RBA treatments (15, 20, 30, 40, and 60 m²/ha) from 2001 to 2010. For all species and Douglas-fir, merchantable volume growth rate was higher in the 60 m²/ha RBA treatment in the first growth period but was higher in the 30 m²/ha RBA treatment in the second period. The 20-year yield was highest in the 30 m²/ha RBA treatment (102 m³/ha), followed by the 60 m²/ha RBA treatment (97 m³/ha), and they exceeded the other RBA treatments (83-93 m³/ha). In the 40 and 60 m²/ha RBA treatments in the second period, the growth rate was reduced due to mortality of lodgepole pine (Pinus contorta var. latifolia) caused by mountain pine beetle (Dendoctonus ponderosae); the lower RBA treatments were less affected because pine had been preferentially harvested. Stand growth accrued onto the large Douglas-fir trees in the lower RBA treatments but across a wide range of tree sizes and species in the higher RBA treatments. Large Douglas-fir trees are highly valued for products such as plywood and house logs. The excessive tree- fall that occurred in a few locations may have been reduced by conducting a pre-harvest assessment of soil conditions, altering the thinning intensity, and modifying the adjacent stand harvesting intensity or timing. A shelterwood sys- tem can be used to add volume to the mid-term timber supply in the short term because, for 10 to 20 years, the growing space is occupied by large trees that are adding merchantable volume, whereas the same growing space occupied by a clearcut does not."-- Abstract, page iii.