Mountain pine beetles and emerging issues in the management of woodland caribou in Westcentral British Columbia

Deborah Cichowski,Patrick Williston

doi:10.7557/2.25.4.1775

Abstract

The Tweedsmuir—Entiako caribou (Rangifer tarandus caribou) herd summers in mountainous terrain in the North Tweedsmuir Park area and winters mainly in low elevation forests in the Entiako area of Westcentral British Columbia. During winter, caribou select mature lodgepole pine (Pinus contorta) forests on poor sites and forage primarily by cratering through snow to obtain terrestrial lichens. These forests are subject to frequent large-scale natural disturbance by fire and forest insects. Fire suppression has been effective in reducing large-scale fires in the Entiako area for the last 40—50 years, resulting in a landscape consisting primarily of older lodgepole pine forests, which are susceptible to mountain pine beetle (Dendroctonus ponderosae) attack. In 1994, mountain pine beetles were detected in northern Tweedsmuir Park and adjacent managed forests. To date, mountain pine beetles have attacked several hundred thousand hectares of caribou summer and winter range in the vicinity of Tweedsmuir Park, and Entiako Park and Protected Area. Because an attack of this scale is unprecedented on woodland caribou ranges, there is no information available on the effects of mountain pine beetles on caribou movements, habitat use or terrestrial forage lichen abundance. Implications of the mountain pine beetle epidemic to the Tweedsmuir—Entiako woodland caribou population include effects on terrestrial lichen abundance, effects on caribou movement (reduced snow interception, blowdown), and increased forest harvesting outside protected areas for mountain pine beetle salvage. In 2001 we initiated a study to investigate the effects of mountain pine beetles and forest harvesting on terrestrial caribou forage lichens. Preliminary results suggest that the abundance of Cladina spp. has decreased with a corresponding increase in kinnikinnick (Arctostaphylos uva-ursi) and other herbaceous plants. Additional studies are required to determine caribou movement and habitat use responses to the mountain pine beetle epidemic.

Highlights

Five woodland caribou (Rangifer tarandus caribou) (Abies lasiocarpa) on moist sites
Low elevation forests consist primarily while forest harvesting is the primary anthropogenic of lodgepole pine (Pinus contorta) with hybrid white disturbance (Cichowski et al, 2001a,b)
With increased average winter temperatures and fewer cold weather extremes predicted, there is potential for a northern migration of mountain pine beetles as winter temperatures become insufficient to maintain populations at endemic levels (Ministry of moderate and severe attack in northern Tweedsmuir Park, and the strategy of prescribed burning in pro¬ tected areas and forest harvesting in commercial for¬ ests for mountain pine beetle management was aban¬ doned (Cichowski et al, 2001a; 2001b)

Summary

Introduction

Five woodland caribou (Rangifer tarandus caribou) (Abies lasiocarpa) on moist sites. Woodland caribou populations are found in Westcentral British Colum- in the area typically calve and summer in moun¬bia (BC): Tweedsmuir—Entiako, Telkwa, Itcha—Ilga- tainous habitat and winter primarily in lower eleva¬chuz, Rainbow and Charlotte Alplands (Northern tion forests or on windswept alpine slopes, and to a Caribou Technical Advisory Committee, in prep.). lesser extent, in subalpine forests (Cichowski, 1993; Much of the area consists of low elevation flat to Telkwa Caribou Standing Committee, 1999; Young gently rolling terrain, gradually rising to mountain¬ & Roorda, 1999; Young et al, 2001).ous plateaus of the Itcha, Ilgachuz, Rainbow, FawnieFire and forest insects are the main natural distur¬and Quanchus ranges, and to the Coast Mountains bance factors affecting forest dynamics in the region, in the west. Lished on the effects of mountain pine beetles or other tain pine beetle spot attacks within a 720 ha area major forest insect pests on caribou or lichens.

Results

Conclusion