whitebark pine stand condition, tree abundance, and cone production as predictors of visitation by clarks nutcracker就站条件,树丰富,锥生产预测探视克拉克的胡桃夹子.pdfVIP

Whitebark Pine Stand Condition, Tree Abundance, and Cone Production as Predictors of Visitation by Clark’s Nutcracker 1 1 1 2¤ Lauren E. Barringer , Diana F. Tomback , Michael B. Wunder *, Shawn T. McKinney 1 Department of Integrative Biology, University of Colorado Denver, Denver, Colorado, United States of America, 2 National Park Service Inventory and Monitoring Program, Sierra Nevada Network, El Portal, California, United States of America Abstract Background: Accurately quantifying key interactions between species is important for developing effective recovery strategies for threatened and endangered species. Whitebark pine (Pinus albicaulis), a candidate species for listing under the Endangered Species Act, depends on Clark’s nutcracker (Nucifraga columbiana) for seed dispersal. As whitebark pine succumbs to exotic disease and mountain pine beetles (Dendroctonus ponderosae), cone production declines, and nutcrackers visit stands less frequently, reducing the probability of seed dispersal. Methodology/Principal Findings: We quantified whitebark pine forest structure, health metrics, and the frequency of nutcracker occurrence in national parks within the Northern and Central Rocky Mountains in 2008 and 2009. Forest health characteristics varied between the two regions, with the northern region in overall poorer health. Using these data, we show that a previously published model consistently under-predicts the proportion of survey hours resulting in nutcracker observations at all cone density levels. We present a new statistical model of the relationship between whitebark pine cone production and the probability of Clark