Early Growth Responses of Lodgepole Pine and Douglas-Fir to Soil Compaction, Organic Matter Removal, and Rehabilitation Treatments in Southeastern British Columbia

Effects of soil compaction, organic matter removal, and rehabilitation on lodgepole pine (Pinus contorta Dougl. ex. Loud.) and Douglas-fir (Pseudotsuga menziesii var. menziesii) were studied after three growing seasons in a long-term soil productivity study established on three calcareous soils in southeastern British Columbia. Effects of soil compaction and organic matter removal on tree growth were site and species specific. Moderate soil compaction increased the diameter and height increment of both species within the stern-only harvest treatment on all three sites, particularly at the coarser textured site (Emily Creek). Compaction tended to reduce tree mortality. Growth of both species was reduced by forest floor removal in the noncompacted soil at Mud Creek and Emily Creek and by whole-tree harvest in the moderately compacted soil at Mud Creek and Kootenay East, possibly due to treatment-induced water limitation. Whole-tree harvest and forest floor removal stimulated lodgepole pine and Douglas-fir growth in the noncompacted soil at Kootenay East. The rehabilitation treatment (established by tilling a heavily compacted soil) reduced lodgepole pine tree mortality on all sites and increased rootcollar diameter and height increment at Mud Creek and Kootenay East. Our findings may provide early growth indication and help assess long-term tree growth trends at these and other long-term soil productivity or related sites. FOR. SCI. 55(3):210-220.