Elk summer range habitat, nutritional ecology, and carrying capacity in the Jarbidge Mountains, Nevada

My primary research objective was to develop an elk carrying capacity model to estimate population levels that would not impair rangeland productivity in the Jarbidge Mountains of northeastern Nevada. Fieldwork was critical to obtain baseline data for model parameters such as habitat use and availability, diet composition, and forage nutrient abundance. Ninety-three elk were translocated into the Jarbidge Mountains in the 1990s; this population exhibited high growth rates and is predicted to increase to 1,110 by 2008.; I evaluated production, species richness, and use of herbage standing crop in and outside exclosures across 3 seasons to better understand the effects of grazing by cattle and elk on mountain meadows in northeastern Nevada. Forbs declined throughout summer and total use clipping treatments in early and mid-summer resulted in low regrowth of forbs.; I determined cattle, domestic sheep, elk, and mule deer diets. Summer elk diets were largely composed of forbs. Diet group means did not differ between elk in spring with sheep in summer, elk in summer with deer and sheep, and cattle with sheep in summer. Twelve common forage species formed 44.2 to 85.3% of elk, deer, cattle, and sheep diets.; I estimated crude protein (CP), digestible energy (DE) and macrominerals in 12 common forage species to assess whether nutrient levels met summer seasonal lactating cow elk requirements. Crude protein and DE decreased in herbs and woody browse across summer seasons and CP in lupines and snowbrush ceanothus provided reliably high levels of CP across all seasons. The most limiting nutrient to lactating cows was DE.; Logistic regression modeling provided strong evidence in support of water and forage availability influencing elk habitat selection. I incorporated regression coefficients into resource selection functions (RSFs), or probabilities proportional to elk habitat use. I used RSFs to redistribute economic nutritional carrying capacity (I_NCC) estimates at 2 energetic performance levels for 236-kg lactating cow elk in autumn 1999 and 2000 over the summer range and then accordingly readjusted I_NCC estimates. Unadjusted I _NCC estimates predicted elk use of aspen and sagebrush-herb communities above nutritional resources at both performance levels in both years.