Maintenance of long-term forest productivity is of concern to the scientific community, forest managers, the public, and the international marketplace. Forest productivity depends on maintaining the diversity and function of the belowground (soil) and aboveground ecosystems. Inherent site productivity is a function of off-site factors such as climate, landscape-level factors such as ecological diversity, and on-site factors such as soil productivity. Soil properties that affect productivity are broadly grouped into three classes: physical, chemical and biological. Some of these properties are fixed, e.g. soil texture and soil mineralogy. Forest management can, however, alter the majority of soil properties. Powers et al. (1990) proposed a model of soil productivity that relates alterable soil properties to two factors - soil porosity and organic matter (OM). There are numerous direct, indirect and interactive effects of OM and soil porosity, e.g. decompacted landings may recompact without organic matter addition and removal of OM affects biological activity, which may alter soil structure.
Timber harvesting and site preparation affect soil porosity and site OM. Harvesting removes OM and nutrients in trees and may displace forest floor during road and landing construction. Site preparation may lead to a loss of OM (burning) or its displacement (scalping). The adverse effects on tree growth caused by landing compaction are well documented but the effects of compaction caused by skid trails, random ground skidding and site preparation have not been clearly demonstrated. The effects of soil compaction may only appear some time after plantation establishment and may be confounded by regional climate and soil texture. Strategies for minimizing soil degradation during harvesting and site preparation have been developed, but we need solid research to back up these strategies. Although it is clear that soil productivity must be conserved, it is also clear that each additional requirement imposed on the forestry industry add costs, so regulations and guidelines must be relevant to specific forests and soils.
In BC, there are few long-term trials of soil productivity. For regulation and management to be truly science-based, real data derived from long-term monitoring of forest sites is needed. To avoid the difficulties inherent in chronosequence studies, designed studies that are established prior to treatment are required. Data from planned, long-term studies will be used by industry and government to evaluate and adjust forest practices and regulations (e.g. Forest and Range Practices Act).
For these reasons, Powers et al. (1990) proposed a full rotation-length research project called the Long Term Soil Productivity (LTSP) study with an experimental design involving a 3x3 factorial of soil compaction and soil OM removal. The LTSP is the world?s largest coordinated effort to understand how soil disturbance affects long term forest productivity. From the inception, BC soil scientists have been involved in the development and implementation of this study. Installations based on this design have been established in the United States, Ontario and British Columbia.
The present proposal requests a continuation of support for the LTSP study. Results from BC to date have addressed seedling growth response (Fleming et al 2006, Kabzems & Haeussler 2005, Kranabetter et al 2006, Stone & Kabzems 2002), seedling physiology (Choi et al 2005, Kamaluddin 2005), soil physical, chemical and biotic responses (Battigelli et al 2004, Kranabetter & Chapman 2004, Mariani et al 2006, Page-Dumroese et al 2006, Sanchez et al 2006, Tan et al 2005), and vegetation responses (Haeussler & Kabzems 2005).
Battigelli, J, J Spence, D Langor, and S Berch. 2004. Short-term impact of forest soil compaction and organic matter removal on soil mesofauna density and oribatid mite diversity. Can J For Res 34:1136-1149
Choi, W, S Chang, M Curran, and H Ro. 2 ...
Berch, Shannon M., Chapman, Bill K.; Curran, Mike P.; Dubé, Stephane; Hope, Graeme D.; Kabzems, Richard; Kranabetter, J. Marty; Hannam, Kirsten; Macadam, Anne; Osberg, Marty; Sanborn, Paul T.; Trowbridge, Rick. 2009. Long Term Soil Productivity Study. Forest Investment Account (FIA) - Forest Science Program. Forest Investment Account Report. FIA2009MR356
Topic: FLNRORD Research Program
Keywords: Forest, Investment, Account, (FIA), British, Columbia
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