**3. Methods**

120 Sustainable Forest Management – Case Studies

particularly interested in understanding natural wildfire disturbances in order to maintain the ecological patterns and functions of these forests (Parminter, 1998; Kimmins, 2000; Wei et al. 2003). In these areas, wildfire disturbance is part of natural ecosystem processes, and its functions are, from a long-term perspective, part of natural variability. Lodgepole pine forest (*Pinus contorta ssp. latifolia* Engelm. ex S. Wats.) is a major type of forests in the central interior of BC, and concerns have been expressed over potential impacts of intensive timber

Both timber harvesting and wildfire disturbances can vary substantially in size, intensity, severity, frequency and internal heterogeneity, greatly complicating comparisons of the effects of different disturbance types. The differences relate to differences in forest type, topography, timing of the disturbance, local management methods, and management objectives (Lertzman and Fall, 1998; Parminter, 1998). From a nutrient perspective, a major difference between timber harvesting and wildfire disturbance is the biomass of woody

WD, particularly coarse woody debris (CWD), has been shown to be an important structural and functional element in many forested ecosystems (Lambert et al., 1980; Sollins, 1982; Harmon et al., 1986; Spies et al., 1988). It provides a key habitat component (especially large logs) for many forms of wildlife (Reynolds et al. 1992). Studies by Harvey et al. (1981) and Harvey et al. (1987) showed that organic materials, especially humus and buried residue in the advanced stage of decay, are excellent sites for the formation of ectomycorrhizal root tips. Graham et al. (1994) used ecotomycorrhizal activity as a primary indicator of a healthy forest soil. Further, CWD may play a significant role in long-term nutrient cycling; it can be an important site for asymbiotic nitrogen fixation, and it acts as a source of slow nutrient

This paper summarizes a series of our research and publications in lodgepole pine forests in the sub-boreal regions of British Columbia, Canada. The objectives of this study are: (1) to quantify the difference in the mass and nutrients of woody debris remaining immediately following harvesting and wildfire disturbances; (2) to evaluate long-term implications of those differences in site productivity; and (3) to determine the management strategies for achieving

The study area is located west of Williams Lake in the Chilcotin plateau of interior British

March. Average annual precipitation is 464 mm, of which 195 mm is snow. Soils are well drained brunisols and luvisols of sandy or sandy loam texture. Soil parent material is primarily glaciofluvial or morainal. The forest is relatively pure lodgepole pine with trembling aspen (*Populus tremuloides* Michx) in some of the newly disturbed stands. White spruce (*Picea glauca* (Moench) Voss) is the theoretical climax tree species over most of the SBPS. In the very dry and cold SBPSxc subzone area, however, the abundance of pine regeneration and the virtual absence of spruce regeneration on zonal sites suggests that lodgepole pine is the climatic climax tree species (Steen and Demarchi, 1991). Lodgepole pine grows relatively slow under such a dry and cold subzone. Average diameter and

Spruce biogeoclimatic zone (SBPSxc). Average monthly temperatures range from -13.8-

W) in the very dry and cold subzone of the Sub-Boreal Pine

C in July. The mean daily temperature is below 0oC from November to

C in

sustainability of long-term site productivity in lodgepole pine forests in the BC interior.

harvesting on long-term site productivity (Kimmins, 1993; Wei et al., 1997).

debris (WD) left in the ecosystem, and the quantity of nutrients removed.

release during its long period of decay.

**2. Study area** 

Columbia (52-

January to +11.6-


N, 123-


height are 17.8 cm and 14.4 m in mature stands, respectively.

A combination of field investigation with ecosystem modeling was used for this study. The purpose of the field survey is to quantify the differences immediately following wildfire disturbance and harvesting, while the ecosystem modeling is to evaluate the long-term implication of those differences in site productivity. The ecosystem model FORECAST, or its forerunner FORCYTE, has been used as a management evaluation tool in several types of forest ecosystems (Sachs and Sollins, 1986; Kellomäki and Seppälä, 1987; Wang et al., 1995; Wei and Kimmins, 1995; Morris et al., 1997; Wei et al., 2000; Seely et al., 2002; Welham et al., 2002). The model was specifically designed to examine the impacts of different management strategies or natural disturbance regimes on long-term site productivity. A brief description of the FORECAST model approach is presented in the next section; details are found in Kimmins (1993); Seely et al., (1999); and Kimmins et al., (1999).
