William J Ripple

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Until recently, large apex consumers were ubiquitous across the globe and had been for millions of years. The loss of these animals may be humankind's most pervasive influence on nature. Although such losses are widely viewed as an ethical and aesthetic problem, recent research reveals extensive cascading effects of their disappearance in marine,(More)
Large carnivores face serious threats and are experiencing massive declines in their populations and geographic ranges around the world. We highlight how these threats have affected the conservation status and ecological functioning of the 31 largest mammalian carnivores on Earth. Consistent with theory, empirical studies increasingly show that large(More)
Quaking aspen (Populus tremuloides) biomass has declined in Yellowstone National Park (YNP) in the past century. We installed permanent belt transects (plots) for long-term monitoring of aspen stands both within and outside of established wolf pack territories on YNP’s northern range to determine if reintroduced wolves are influencing elk browsing patterns(More)
We conducted an analysis of aspen (Populus tremuloides) overstory recruitment on the northern range of Yellowstone National Park (YNP) using information provided in a monograph published by Warren (Warren, E.R., 1926. A study of beaver in the Yaney region of Yellowstone National Park, Roosevelt-Wildl. Ann. 1, 1±191), increment cores collected from riparian(More)
We explored multiple linkages among grey wolves (Canis lupus), elk (Cervus elaphus), berry-producing shrubs and grizzly bears (Ursus arctos) in Yellowstone National Park. We hypothesized competition between elk and grizzly bears whereby, in the absence of wolves, increases in elk numbers would increase browsing on berry-producing shrubs and decrease fruit(More)
To investigate the extent and causes of recent quaking aspen (Populus tremuloides) recruitment in northern Yellowstone National Park, we measured browsing intensity and height of young aspen in 87 randomly selected aspen stands in 2012, and compared our results to similar data collected in 1997-1998. We also examined the relationship between aspen recovery(More)
“Predation risk” and “fear” are concepts well established in animal behavior literature. We expand these concepts to develop the model of the “landscape of fear”. The landscape of fear represents relative levels of predation risk as peaks and valleys that reflect the level of fear of predation a prey experiences in different parts of its area of use. We(More)
While patterns from trophic cascade studies have largely focused on density-mediated effects of predators on prey, there is increasing recognition that behaviorally mediated indirect effects of predators on prey can, at least in part, explain trophic cascade patterns. To determine if a relationship exists between predation risk perceived by elk (Cervus(More)
By the early 1900s, Euro-Americans had extirpated gray wolves (Canis lupus) from most of the contiguous United States. Yellowstone National Park was not immune to wolf persecution and by the mid-1920s they were gone. After seven decades of absence in the park, gray wolves were reintroduced in 1995–1996, again completing the large predator guild (Smith et(More)
We studied young riparian cottonwoods (Populus spp.) and associated woody plants along Soda Butte Creek and the Lamar River in northeastern Yellowstone National Park (YNP) to examine the potential influence of wolf/elk interactions upon plant growth. After a period of approximately 70 years without wolves in YNP, they were reintroduced in the winter of(More)