Dry Douglas-fir forests extend over several million hectares in the Southern Interior Forest Region (SIFR) and represent a valuable resource from an economic, social and ecological perspective. The proximity of these forests to urban centers, lumber mills and valley-bottom ranches highlights the need for effective fuels management to reduce the risk of uncontrolled wildfire, and value to the timber and livestock industry. The ecological value of these sites is similarly high due to less severe temperatures and lesser snowpack in winter than at higher elevations. Concerns have been raised about management practices in dry forest habitats (Ponderosa pine and Interior Douglas-fir) grouped as Natural Disturbance Type 4 in BC (see BC Ministry of Forests and BC Ministry of Environment 1995). These dry forests generally occur at low elevations (under 1200m), often have a lower canopy closure than forests on more mesic sites, and have traditionally been characterized by the historic role of frequent low severity, ?stand maintaining? fires. Over the past 50 years, numerous reports have examined and debated the role of fire and fire suppression in these ecosystems (Leopold 1924, Weaver 1951, Cooper 1960, 1961, Covington and Moore 1994). In the last decade, there has been an increasing concern regarding the shortcomings associated with current fire suppression activities (Daigle 1996, Gayton 1996, Rocky Mountain Trench Ecosystem Restoration Steering Committee 2000, 2006), and this is being reflected in local Land and Resource Management Planning. Although the reintroduction of fire is usually identified as a key requirement to returning these ecosystems to a condition within their former range of natural variability (Landres et al., 1999; Allen et al., 2002; Baker et al., 2007), uncertainty remains regarding the long-term efficacy of these treatments, the likelihood of achieving ecological objectives, and the effect of treatments on a range of forest values including the plant community, fuels, forage production and timber.
At higher elevations and more northern latitudes across the range of Ponderosa pine and in mixed stands that include Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) or lodgepole pine (P. contorta Dougl.), the historic range of natural variability for dry forests is far less certain. Shinneman and Baker (1997), Baker and Ehle (2001), Heyerdahl et al. (2001), and Sheriff and Veblen (2007) document spatially and temporally complex fire regimes in Ponderosa pine dominated forest. The occurrence of such mixed- or moderate-severity fire regimes (Agee, 1993, 1998; also termed variable severity fires in Baker et al., 2007) in more productive habitats or topographically complex areas creates uncertainty in both the need for and the nature of restoration practices. Forests that historically experienced mixed- or high-severity fire regimes are not likely to be in a structural condition that is outside the historic range of natural variability (Baker et al., 2007), and it is likely that mixed Ponderosa pine and Douglas-fir forests fall into this category (Sheriff and Veblen, 2007). However, regardless of the historic disturbance regime and the questions surrounding the need for ?ecosystem restoration? in dry forests in BC, it is clear from resource planning initiatives that open forest conditions are desirable and may well be necessary to achieve a number of resource management expectations (e.g. ladder and crown fuel management, forage for native ungulates and livestock, etc.).
Historically, many of the low elevation, accessible dry forests have experienced repeated and often different harvesting treatments over the last century (Klenner and Vyse 1998, Klenner et al. 2001). A variety of harvesting practices have been applied, ranging from the unregulated selection of desired stems for specific needs, to diameter limit partial cutting or patch cutting. The primary objective of most prescriptions has been to remove t ...
Forest Investment Account (FIA). 2009. Harvesting and site preparation treatments to develop and maintain open canopy conditions in dry-belt Douglas-fir forests: the Isobel Project. Forest Investment Account (FIA) - Forest Science Program. Forest Investment Account Report. FIA2009MR309
Topic: FLNRORD Research Program
Keywords: Forest, Investment, Account, (FIA), British, Columbia
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