In western North America, forests of Ponderosa pine or Douglas-fir as pure stands or mixtures with other species such as larch, grand fir or lodgepole pine are widespread from Mexico to southern British Columbia. Over the past 50 years, numerous reports have examined and debated the role of fire and fire suppression in these ecosystems (Leopold 1924, 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), and this is being reflected in local Land and Resource Management Planning documents (e.g. see drafts of the Okanagan-Shuswap and Lillooet LRMP). These documents accept the hypothesis that frequent, low severity fires were in recent history the main disturbance agent in dry forests and grasslands, and that fire suppression has led to unnatural and ?unhealthy? forest conditions.
There is little doubt that low severity fires were common in many areas dominated by coniferous forests in western North America (Agee 1993), with some of the strongest evidence for frequent low severity fires from the dry Ponderosa pine forests in the southwestern United States (e.g. Covington and Sackett 1989). However, there is mounting evidence that supports the concept of a mixed severity fire regime, especially on more mesic sites and at northern latitudes (Shinneman and Baker 1997, Veblen et al. 2000, Noss et al. 2006) with fire effects ranging from low to high severity in a complex mosaic within a single fire and across the landscape. For example, Wong (1999) found evidence to support the mixed-severity model in her study in the Stein Valley in southern British Columbia. Her work on the age structure of stands suggests only about 25% of the fires in her study area were low severity underburns. Shinneman and Baker (1997) also reported a mosaic of forest types in the Ponderosa pine forests in the Black Hills of South Dakota. Xeric sites had more open stands that would reflect periodic low severity fires, while mesic sites in valleys and northerly aspects often supported old forests in dense stands that likely arose from stand replacing fires. Similarly, studies by Taylor and Skinner (1998) in northern California report similar evidence for a mixed severity fire regime in some areas of dry conifer forests. These results, coupled with the diverse habitats encompassed by the NDT4 designation and the complex topography in BC suggests that the frequent low severity fire disturbance hypothesis should be carefully examined prior to initiating costly programs to ?restore? ecosystems.
The project involves work to update and complete a review of the published literature on the management of dry forest ecosystems, some of which are the focus of extensive restoration initiatives (e.g. see Blueprint for Action, Rocky Mountain Trench Ecosystem Restoration Steering Committee 2006; www.for.gov.bc.ca/drm/ ). Previous work by Klenner et al. (2001, ?A strategy for managing dry-belt ecosystems of the Kamloops Forest Region?, see www.for.gov.bc.ca/ftp/RSI/external/outgoing/NDT4/) prepared an extensive draft review of the literature relating to likely historic natural disturbances, and the likely consequences of implementing different management strategies. Historic photographs and accounts, an analysis of lightning and weather data, and fire scar analyses suggested a mixed severity fire regime, along with episodes of widespread and intensive insect attack likely shaped many of the dry forest ecosystems in the Southern Interior. Current interest in manipulating forest structure in the context of ecosystem restoration, the current widespread mortality of Ponderosa pine across extensive areas resulting from mountain pine beetle (Dendroctonus ponderosae) and western pine beetle (Dendroctonus brevicomis) attack, and recent perspectives on fuel management (Filmon 2004, Forest Practices Board 2006) indicate a tho ...
Forest Investment Account (FIA). 2009. Extension - Options for the landscape-level management of dry NDT4 ecosystems in the Southern Interior Forest Region. Forest Investment Account (FIA) - Forest Science Program. Forest Investment Account Report. FIA2009MR408
Topic: FLNRORD Research Program
Keywords: Forest, Investment, Account, (FIA), British, Columbia
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