Establishment of Long-term Soil Productivity Studies on Acidic Soils in the Interior Douglas-fir Zone

A clear understanding of the impacts of forest practices on long-term soil productivity is required to maintain the productivity of forest soils while forests continue to be managed for timber production. Although current regulations governing soil conservation in British Columbia are partially based on historic and ongoing research, there are few clear and unambiguous long-term results. The need for these results led to the development of a Long-term Soil Productivity (LTSP) project by a group of U.S. Forest Service researchers (Powers et al. 1990). The study focuses on soil organic matter retention and compaction. The LTSP project is the world’s largest co-ordinated effort to understand how soil disturbance affects longterm forest productivity. The effort has resulted in the establishment of more than 62 major research installations across a broad range of forest types in the United States and Canada. The British Columbia Ministry of Forests (MOF) was a major collaborator during the inception of the LTSP, and MOF staff have established sites in the British Columbia Interior covering the boreal, sub-boreal, interior cedar-hemlock, and interior Douglas-fir forests (see http://www.for.gov.bc.ca/hre/ltsp/ for a description of the British Columbia project). Ultimately, this research will lead to a better understanding of soil sensitivity and resiliency to disturbance, and help develop specific management recommendations for different forest and soil types. In the Southern Interior of British Columbia, the dry Douglas-fir forests (the Interior Douglas-fir biogeoclimatic zone, or IDF zone) were of particular interest because, compared with other forests in the region, they have more sensitive soils, less organic matter reserves, more partial cutting, and more harvesting in the spring and early summer when soils are most susceptible to compaction. In the IDF zone, three sites were established near Kamloops and three sites near Invermere. The Kamloops sites are on slightly acidic soils that are representative of the Interior Plateau area, whereas the Invermere sites are on calcareous soils that are representative of the East Kootenay. The LTSP project is designed to provide long-term (rotation length) information on the effects of organic matter removal and compaction on soil and site productivity. However, the trial and related studies will also provide answers to short-term questions. This note summarizes the establishment of the project in the IDF zone near Kamloops, and offers short-term information on soil and microclimate changes after treatment, vegetation response, and early seedling survival and growth.