Forest Investment Account (FIA) - Forest Science Program
FIA Project Y092244

    Creation of Habitat for Small Mammal Prey and their Predators on Clearcuts: Coarse Woody Debris in Piles and Windrows
Project lead: Sullivan, Thomas (University of British Columbia)
Author: Sullivan, Thomas P.
Subject: Forest Investment Account (FIA), British Columbia
Series: Forest Investment Account (FIA) - Forest Science Program
This proposal outlines a study designed to provide habitat for mustelid predators such as marten, short-tailed and long-tailed weasels, coyotes, and lynx in newly harvested clearcuts and subsequent managed stands through time. A major objective of managing forests for biodiversity is to maintain these predators and their small mammal prey in the forested landscape. Removal of the forest cover by clearcut harvesting has been viewed as a negative effect in terms of loss of thermal and security cover. A major question is: Could post-harvest debris piles and windrows on cutblocks act as "middens" and "corridors:, respectively, for these predators, both initially after harvest, and as the new forest develops? Such habitat attributes at the stand-level may provide den and rest sites and safe passage across clearcuts, thereby linking up forest reserves and riparian buffers. They may also be major sources of small mammal prey.

In the 1990s, there was some interest in the use of post-harvest debris piles to act as potential: 1) cover and resting sites, and 2) source of small mammal prey. Some preliminary work in the Okanagan was done on this subject and suggested that debris piles were used by various wildlife species, but no experimental design and monitoring was conducted. There has been a dearth of follow-up monitoring of habitat management projects and studies. We need a sound experimental design with sufficient replicates (ideally at least n=3), at a real-world (operational scale) to provide a comprehensive database for small mammal prey and predator responses to treatments.

Habitat selection by mustelid predators such as marten appears to be determined by the availability of appropriate food (small mammal prey) and access to nesting and resting sites, particularly in the winter (Spencer et al. 1983; Koehler et al. 1990; Bissonette and Sherburne 1993; Thompson and Curran 1995; Bull 2002). These attributes are essential for population maintenance. Marten are very dependent upon subnivean sheltered sites. Voles (genera Microtus and Clethrionomys), notably red-backed voles, are primary food items of marten and weasels. Resting sites and den sites are associated with large snags, live trees, and downed hollow logs, underground access (especially in winter), and in man-made slash piles. Coarse woody debris (CWD) plays a large role in providing resting sites. While controversy exists over the importance of CWD to small mammals, many studies suggest CWD provides important microhabitat for foraging and cover attributes for these species (Pruitt 1984; Harmon et al. 1986; Hayes and Cross 1987; Loeb 1999; Mengak and Guynn 2003). Provision of debris piles and windrows on clearcuts, and subsequently in young forests, may provide habitat for small mammal prey and their predators.

The project will be installed at newly (2006 and 2007) harvested sites at Upper Trout (Gorman Bros. Lumber Ltd.), at China Valley (Federated Cooperatives Ltd.), and on the Aberdeen Plateau (Tolko Industries Ltd.). Each of these three areas constitutes a replicate block. The experimental design is a randomized complete block with 3 replicates each of: (a) CWD dispersed uniformly over each unit (control); (b) CWD distributed into several small piles (2-3 piles per ha); and (c) CWD distributed into windrows, connecting to a forest edge (either a reserve or riparian buffer).

Responses to treatments by small mammal prey species and terrestrial predators will be monitored through time: live-trapping for small mammals and winter snow tracking for predators.

Related projects:  FSP_Y081244FSP_Y103244


Executive summary (18Kb)

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Updated August 16, 2010 

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