Trophic consequences of postfire logging in a wolf-ungulate system

M. Hebblewhite, R. H. Munro, E. H. Merrill

Research output: Contribution to journalArticlepeer-review

43 Scopus citations

Abstract

Controversy surrounds postfire logging, often because of negative effects on snag-dependent wildlife species. Few studies, however, have examined effects on early-seral species that may benefit from postfire logging, nor effects on trophic relationships. We studied the effects of postfire logging on trophic dynamics between wolves (Canis lupus), three ungulate species and ungulate forage biomass during the first 3 years in a large burn in the Canadian Rockies, Alberta, Canada. We examined plant biomass and ungulate responses to two treatments (post- and prefire logging) compared to a burned but unlogged area (control). We evaluated resource selection for the three treatments by elk (Cervus elaphus) using radiotelemetry and for deer (Odocoileus spp.), moose (Alces alces), and, secondarily, elk using pellet counts. Elk resource selection was modeled as a function of the trade-off between wolf predation risk and herbaceous forage biomass to test for trophic impacts of postfire treatments. Postfire logging had transient effects on total herbaceous biomass; while forb biomass was reduced, increases in graminoid biomass more than compensated by the third year. Prefire logging areas were dominated by a few species, but had generally higher forage biomass by the third year. Ungulates avoided postfire and prefire logged areas despite greater herbaceous biomass. Only when we considered elk resource selection as a function of both forage and wolf predation risk was the extent to which trophic interactions affected by postfire logging revealed. Wolves selected proximity to roads and the higher forage biomass associated with postfire logging in open logged areas. This translated to the highest predation risk for elk in postfire logged areas. Thus, ungulates avoided postfire logged areas because of human alteration of top-down predation risk despite enhancements to bottom-up forage biomass. Managers should consider trophic consequences of postfire logging on the interactions among species when gauging logging effects on terrestrial ecosystems. Making use of existing roads, minimizing the construction of new roads, and managing road removal following postfire logging will help mitigate the negative effects of postfire logging on terrestrial ecosystems.

Original languageEnglish
Pages (from-to)1053-1062
Number of pages10
JournalForest Ecology and Management
Volume257
Issue number3
DOIs
StatePublished - Feb 10 2009

Funding

The following funding agencies provided funding for this research: ACA Challenge Grants in Biodiversity, Foothills Model Forest-Chisholm-Dogrib Fire initiative grants, Parks Canada, Sundre Forest Products LTD., Canon National Parks Science Scholarship for the Americas, and University of Alberta. We thank Rick Smee, Darren Labonte, and James R. Allen, Alberta Sustainable Resource Development (AB-SRD), Tom Daniels and Barry McElhinney from Sundre Forest Products Ltd., Dr. Wayne Strong and Dr. Cormack Gates from University of Calgary, and Cliff White, Ian Pengelly and Darrel Zell from Parks Canada for assistance. We thank the Ya Ha Tinda ranch staff, particularly ranch managers Johnny and Marie Nylund and Rick and Jean Smith for logistical support. Final thanks are reserved for field technicians, in particular Shari Clare, Joe Litke, Mark Lindberg, Cedar Mueller, Judith Wheeler, and Robin Whittington. We thank R. Hutto, D. Dellasala, and D. Lindenmayer for helpful comments on an earlier version of this manuscript.

FundersFunder number
Alberta Conservation Association
University of Alberta

    Keywords

    • Fire
    • Forage
    • Habitat selection
    • Postfire logging
    • Salvage logging
    • Trophic cascade

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