UW Aquatic & Fishery Sciences Quantitative Seminar

Kristin Marshall

Northwest Fishery Science Center (NRC post-doc)

Wolves, elk, and willows: have trophic cascades restored riparian ecosystems on Yellowstone's northern range?

Abstract

The reintroduction of wolves to Yellowstone National Park 17 years ago provided a rare opportunity to study whether the effects of predation could restore an ecosystem degraded by herbivory. My research describes how the top-down effects of predation and herbivory interact with the bottom-up effects of resource availability in riparian areas. I studied the role of landscape heterogeneity on willow height and growth along small streams during 2008 to 2010, and reconstructed willow canopy cover, height, growth, and establishment over the past four decades. I modeled spatial and temporal variation in willow responses using Bayesian hierarchical methods. Results from my research show that wolf reintroduction has not uniformly restored riparian areas along small streams on the northern range. Instead, water table depth, topography, and climate drivers influence willows more strongly than herbivory or wolves.