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Title:A Gis-Based Habitat Model Predicting Elk Nutritional Condition in the Pacific Northwest
Author(s):Davis, Ronald W.
Doctoral Committee Chair(s):Warner, Richard E.
Department / Program:Natural Resrouces and Environmental Sciences
Discipline:Natural Resrouces and Environmental Sciences
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Agriculture, Forestry and Wildlife
Abstract:Declining habitat quality has been implicated in population declines in elk (Cervus elaphus) in the Pacific Northwest (PNW) although specific causes are unknown. Nutrition and summer-autumn body condition (percent body fat) have been linked to virtually every aspect of successful ungulate reproduction and productivity; however, many existing habitat evaluations discount the role of nutrition and are unlikely to detect changes in habitat nutritional quality. I applied an algorithm linking the biomass of suitable elk forage (BSF) and dietary digestibility (DD) to model habitat quality for elk at 3 sites in the PNW: 1 in western Oregon (Wendling), 1 in southwestern Washington (Pe Ell), and 1 in northwestern Washington (Nooksack). BSF was best predicted by overstory canopy cover (R2≥0.70) and I developed remote sensing-based maps of canopy cover (accuracy ≥74%) to characterize DD levels at each site. In a GIS, I estimated habitat quality for the overall landscape, and within actual wild elk homeranges. I compared model predictions to autumn fat levels in free-ranging lactating elk. Wendling (DD=55.9%, n=14, SE=0.02) and Pe Ell (DD=55.8% n=19, SE=0.02) afforded only "marginal" habitat quality while Nooksack (DD=61.8%, n=19, SE=0.05) had significantly higher quality (P<0.0001). Fat levels in wild elk corresponded to "marginal" levels at Wendling (10.8% fat, n=10, SE=0.65) and "good" levels at Nooksack (13.6% fat, n=8, SE=0.45). Pe Ell elk (6.1% fat, n=9, SE=0.54) were below "marginal" levels but also had the highest density of wild elk (5 elk/km2) indicating a potential negative feedback between density and condition. I compared BSF/DD predictions to those of 2 forage based and 4 HSI/HEI-type elk habitat models and compared these to wild elk condition BSF/DD models detected marked differences in habitat capacity among sites and accurately predicted elk condition. Forage based models overestimated habitat capacity at all sites (P≤0.001). HSI/HEI-type models did not did not reveal any reliable trends in habitat capacity or wild elk condition at these sites. Hence, habitat evaluation and management focused on road closures, forage-to-cover ratios, or total forage biomass are unlikely to address elk nutritional condition.
Issue Date:2005
Description:117 p.
Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2005.
Other Identifier(s):(MiAaPQ)AAI3202083
Date Available in IDEALS:2015-09-25
Date Deposited:2005

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