Forest Investment Account (FIA) - Forest Science Program
FIA Project Y071302

    Dry forests and grasslands: stand structures, habitat, and small mammals as indicators of biodiversity
Project lead: Sullivan, Thomas
Author: Sullivan, Thomas P.
Imprint: Vancouver, BC : University of British Columbia, 2007
Subject: Forest Investment Account (FIA), Grassland ecology, British Columbia
Series: Forest Investment Account (FIA) - Forest Science Program
The dry forests of the southern interior of B.C. are represented by three biogeoclimatic zones: Interior Douglas fir (IDF), Ponderosa pine (PP), and the Bunchgrass (BG) zone. Douglas fir and ponderosa pine forests continue to provide an important source of timber for the forest industry. Forests in the IDF are usually harvested by a variety of partial cutting systems (Vyse et al. 1998). Several operational trials were installed in IDF forests in the 1990s and now provide a relatively long-term (10+ years) opportunity to evaluate the effectiveness of residual structures, via variable retention (VR) and green-tree retention (GTR) systems, in these harvested sites to maintain biodiversity. An example is the 'Variable Retention Systems in Mixed Fir-Pine Forest' study initiated in 1996 in the IDF zone west of Summerland (Sullivan et al. 2001). All three zones have varying levels of grasslands and shrublands. To date, 'open range' habitats in these zones have received little attention in terms of maintaining biodiversity. BCs grasslands are most prevalent in the arid valley bottoms which coincide with popular and rapidly growing urban centres such as Penticton, Kelowna, Vernon, Kamloops, and Williams Lake. The B.C. Ministry of Agriculture, Food and Fisheries (2004a) reports that grassland habitats represent less than 1% of BCs landbase, and that this limited habitat is critical to the survival of an estimated 30% of BCs threatened or endangered species. The disproportionate number of rare species found within grasslands, and the loss of habitat and disturbance caused by urbanization, livestock grazing, and farming suggests that careful management of these sensitive ecosystems is essential for the conservation of BCs biodiversity. Grasslands, both open range and in IDF and PP forests, are very important for the ranching industry, which has been grazing livestock within BC since the 1850s. Cattle grazing occurs throughout virtually all areas of the southern interior IDF, PP, and BG zones. In other parts of North America, many studies report that grazing disturbance significantly decreases the overall abundance and richness of small mammal communities compared to ungrazed exclosure habitats (Bock et al., 1994; Rosenstock, 1996; Hayward et al., 1997; Giuliano and Homyack, 2004). In all of these studies, reduced herb cover was reported as the most probable cause for the observed decrease in small mammal abundance and richness following grazing. Unfortunately, there are no published data on small mammals in open range habitats in southern B.C., other than that of Sullivan and Sullivan (2006) investigating orchard and non-crop habitats. What seems clear is that generalist species such as deer mice and chipmunks come to dominate small mammal communities in grazed ranges. It is not clear what communities we would have in relatively ungrazed or protected ranges.
Related projects:  FSP_Y082302FSP_Y093302
Contact: Sullivan, Thomas P., (604) 822-6873,


Executive Summary (92Kb)

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Updated August 16, 2010 

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