Managing an ecological paradox: Balancing wildfire risk and mule deer habitat in antelope bitterbrush of Central Oregon.
Riegel, Gregg*,1, Lovtang, S1, Busse, M2, Ramsey, M1, Ganzhorn, S1, Ardt, G3, Lowrie, J4, Babb, G5, 1 USDA Forest Service, Bend, OR, USA2 USDA Forest Service3 Oregon Department of Fish and Wildlife4 USDA Forest Service5 The Nature Conservancy
ABSTRACT- Antelope bitterbrush (Purshia tridentata) is the dominant understory shrub and most important browse species for mule deer (Odocoileus hemionus) throughout much of the east-side pine forests (Pinus ponderosa and P. jeffreyi) of Oregon and California. Historically, frequent, low intensity fires kept fire sensitive bitterbrush abundance and cover low while favoring herbaceous vegetation, primarily perennial grasses. Fire suppression and exclusion policies have more than doubled bitterbrush cover on many sites causing a great concern for fire managers. Land management practices that encourage bitterbrush abundance while reducing fuel hazards and wildfire risk are urgently needed. To solve this ecological paradox, our primary objective was to develop an interactive model that predicts bitterbrush response to prescribed fire, understory mowing, overstory thinning, and wildfire. Data from physiographically-distinct experimental studies on the Deschutes, Winema, and Modoc National Forests were used in the Stella model platform to predict bitterbrush cover as a function of: 1) site characteristics and burn conditions related to changes in vegetation production and composition, 2) relationships between small mammal abundance, and bitterbrush cover, 3) plant age structure, volume, height, and density, and 4) disturbance frequency and intensity. Our ultimate goal is to integrate the predictive responses of the Stella Bitterbrush Growth Model into a time and space explicit mid-scale model so the results of all vegetation and fuel treatments as well wildfires can be tracked. The anticipated result is a reduction in unforeseen cumulative effects from treatments and wildfires on mule deer browse, hiding cover, and winter range at the stand and landscape scales.
Key words: historic range of variation, ecosystem assessments, species at risk, ecosystem management
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