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Impacts of Glyphosate Application on Grizzly Bear Forage Production in the Coastal Western Hemlock Zone

Author(s) or contact(s): A.N. Hamilton, C.A. Bryden, and C.J. Clement
Source: Research Branch
Subject: Wildlife
Series: FRDA Report
Other details:  Published 1991. Hardcopy is available.


The impacts of glyphosate on grizzly bear forage availability in coastal British Columbia were investigated. Emphasis was on floodplain ecosystems. Impacts were examined at three scales: 1) regional - occupied grizzly bear habitat in the coastal Western Hemlock (CWH) zone; 2) local - one watershed representative of operational use; and 3) site-specific-plots in 22 cutblocks. Changes in percent cover and fruit production of bear forage species were monitored following foliar and individual stem treatments. Total cover of fruit producing shrubs declined an average of 63% 1 year after operational foliar treatments. Recommendations for the integrated management of grizzly bears and forestry-related glyphosate use include: 1) using the biogeoclimatic ecosystem classification system to structure integrated management prescriptions; 2) assessing proposed treatments in the context of habitat supply within the watershed; 3) using application rates no higher than required to meet silvicultural obligations; 4) avoiding bear forage species not directly competing with crop trees; and 5) assessing alternative silvicultural methods. Integrated resource planning on floodplain site associations should consider the likelihood of silvicultural success, the ecosystems of harvest and reforestation, and bear habitat values overtime.

FRDA Research Report 165 (2753 KB)

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Updated July 24, 2015