Forest Investment Account (FIA) - Land Base Investment Program
FIA Project 9095004

    Occurrence of Den Trees for Fisher (Martes pennanti),in the Sub Boreal Pine-Spruce Biogeoclimatic Zone in the Chilcotin Area of British Columbia
Project lead: West Fraser Mills
Subject: Forest Investment Account (FIA) - Land Base Investment Program
Series: Forest Investment Account (FIA) - Land Base Investment Program
The central interior of British Columbia (B.C.) encompasses a significant amount of fisher habitat that is experiencing an epidemic of mountain pine beetle (MPB) in pine dominated landscapes. There is a requirement for more information regarding fisher reproductive denning ecology in pine dominated areas, and increasing our knowledge on the characteristics of reproductive structures used by fisher will enable improved forest management for this species. We examined site factors leading to the development of trees suitable for use in reproductive denning by fisher (den trees), and obtained density estimates for the occurrence of these trees in the Sub-boreal Pine Spruce (SBPS) very dry cold (xc) biogeoclimatic (BEC) subzone near Alexis Creek, B.C. Suitable trees require 3 features to potentially be used for fisher den trees. First, the tree needs to grow large enough to support a cavity of sufficient size to house a female and kits (Tier 1). Second, the tree needs to develop sufficient advanced decay in the stem or butt for a cavity to form (Tier 2). Third, an entrance that a female fisher can use, but which excludes larger predators, must develop through the hard sapwood into the cavity (Tier 3). We recorded the presence of Tier 1, 2 and 3 trees in three structural stages (age classes) across wetter (04/05) and drier (01/02) site series. Tier 1 trees are classified as lodgepole pine trees .35 cm diameter at breast height (dbh), trembling aspen trees .40 cm dbh or Douglas-fir trees .55 cm dbh. Tier 2 trees met the above tree species and size requirements and had advanced decay in the stem or butt. Tier 3 trees met the above species and size and decay requirements and had an existing entrance 5 . 10 cm wide at narrowest axis leading to advanced decay.
Contact: Mauro Calabrese, (250) 392-1331,

Updated August 16, 2010 

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