Grizzly Bears Use Large Cutblocks in Central British Columbia: Implications for Natural Disturbance-Based Forest Harvesting and Salvage Logging

Posted on Dec 12, 2014


Lana M. CIARNIELLO, Douglas C. HEARD, Dale R. SEIP

Correspondence: Lana M. Ciarniello, Aklak Wildlife Consulting, 3021 Jody Lynne Way, Campbell River, British Columbia, V9H 1N3, Canada. Email:

Received 14 June 2014 – Accepted 12 December 2014


In central British Columbia, Canada, large-scale logging and salvage operations to control an outbreak of the spruce bark beetle (Dendroctonus rufipennis) occurred in the late 1980s and early 1990s.  In the mid to late 1990s, a mountain pine beetle (D. ponderosae) epidemic killed extensive areas of lodgepole pine (Pinus contorta) trees and widespread salvage logging ensued.  We utilized GPS and VHF location data on 28 (16 females, 12 males) grizzly bears (Ursus arctos), 1998-2003, to determine how bears would respond to the resulting reduction in mature pine forests and increase in the number and size of cutblocks.  Grizzly bears used pine stands less than expected and cutblocks more than expected, selecting for cutblocks in spring and summer but not in fall.  Cutblock size inluenced selection by bears during the spring and summer but not in fall with grizzly bears being 4 times more likely to select for very large cutblocks (6,600-7,000 ha) than smaller blocks.  In spring, the best predictors of grizzly bear use of individual cutblocks were higher greenness values and larger block sizes.  In summer, bears selected for larger cutblocks with higher greenness values, at higher elevations, and where the risk of human-caused mortality was greater.  In fall, bears remained closer to block edges and used younger stands.  Bears spent a signiicantly greater fraction of their time in cutblocks during the night than during the day and during ‘active’ versus ‘resting’ periods in all 3 seasons.  Selection for large blocks suggests that bears may respond positively to a harvest regime that mimics the size of natural disturbances.

Key Words: Cutblock, Forestry, Grizzly Bear, Habitat Selection, Salvage Logging, Ursus artcos.



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