Can large carnivores change riparian ecosystems via a trophic cascade? Yellowstone wolf reintroduction study suggests yes.

Link to study: https://onlinelibrary.wiley.com/doi/abs/10.1002/eco.2048

Abstract: Large carnivores were persecuted in Yellowstone National Park, WY, USA, during the late 1800s and early 1900s, leading to extirpation of gray wolves (Canis lupus) and cougars (Puma concolor). Soon thereafter increased herbivory of riparian plant communities by Rocky Mountain Elk (Cervus elaphus) became widespread in the park’s northern ungulate winter range, or “northern range.” Wolves were reintroduced in 1995‐96, again completing the park’s large carnivore guild. In 2004 and 2017 we sampled Geyer willow (Salix geyeriana), a commonly occurring tall willow, along the West and East Forks of Blacktail Deer Creek in the central portion of the northern range. Results indicated high levels of elk herbivory in the late 1990s not only continued to keep willows short, generally <52 cm in height, but resulted in stream widening and incision, leading to “oversized” channel cross‐sections and a drastically reduced frequency of overbank flows. However, by 2017 willow heights...

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