Bottom-Up Factors Influencing Riparian Willow Recovery in Yellowstone National Park

Riparian willow recovery in Yellowstone National Park's northern range, stymied for decades by elk browsing, has shown uneven progress since wolf reintroduction. Research reveals that tall willow sites (>250 cm) exhibit greater water availability, faster nitrogen mineralization, deeper snow cover, and cooler soil temperatures compared to short sites (<80 cm). These preexisting abiotic factors, not just reduced herbivory, likely drive plant productivity differences. The study contrasts naturally varying willow heights without artificial manipulations, providing insight into the complex interplay between top-down (wolf predation) and bottom-up (soil/water conditions) ecological forces shaping ecosystem recovery.

Tercek, M. T., Stottlemyer, R., & Renkin, R. (2010). Bottom-Up Factors Influencing Riparian Willow Recovery in Yellowstone National Park. Western North American Naturalist, 70(3), 387–399. https://doi.org/10.3398/064.070.0311