Weather is often accepted as the absolute driver of vegetation responses in semiarid environments; yet, forbs constitute a major portion of white-tailed deer (Odocoileus virginianus) diets in southwest Texas when they are available. Managers in semiarid regions often seek to promote high deer densities while maintaining a sustainable habitat and commonly use supplemental feed to promote their goals. My objective was to determine if increasing deer density, while providing supplemental feed, altered herbaceous plant standing crop and community dynamics under variable weather conditions. I used 6 81–ha enclosures with target populations of 0, 20, 40, 60 or 80 deer. High–quality feed was provided by an ad libitum feeder in all enclosures. In each enclosure, I estimated herbaceous vegetation and subshrub canopy cover. Additionally, I harvested standing crop of forbs and grasses and made monthly observations on the presence of low menodora (Menodora heterophylla) and blackfoot daisy (Melampodium cinereum). Forb and grass canopy cover was not affected by increasing deer densities. Standing crop of forbs and grasses differed among treatments as the potential productivity of harvested plots increased (P < 0.10). Blackfoot daisy presence was affected by deer density treatments (F5, 5.49 = 5.67, P = 0.034). Deer densities and provision of supplemental feed influence vegetation community changes in southwest Texas; however, the magnitude of those impacts may be difficult to detect given the variability in weather patterns.
October 17th, 2016
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