Document: MIC-3-99-124

Aspen persistence in the southern greater Yellowstone ecosystem and Rocky Mountain National Park.

BARNETT, D.T.*, M.LEE, M.KAYE, T.J.STOHLGREN and J.BOSSENBROEK

Colorado State University, Fort Collins, CO 80523 USA ¹

Abstract:
We spatially assessed aspen, Populus tremuloides, regeneration in the Southern Greater Yellowstone Ecosystem, WY, and in Rocky Mountain National Park, CO in an attempt to 1.) better understand factors influencing successful stand replacement, and 2.) determine if elk browsing was as ubiquitously damaging as commonly thought. Landscape-scale surveys were used to quantify aspen regeneration across gradients of wintering elk populations using randomly selected 5 by 5 m plots in aspen stands. Sixty-eight stands were sampled in the Southern Greater Yellowstone Ecosystem. Forty-four percent of the stands sampled supported some regeneration. There were no significant differences in aspen regeneration across elk winter range classifications (p = 0.25) or distance from elk feed grounds (p = 0.96). However, a multiple linear regression found that the concentration of elk was one of several important predictors of successful aspen regeneration (p = 0.005, R² = 0.36). In Rocky Mountain National Park, 118 plots were randomly located on both sides of the Continental Divide. Multiple linear regressions were able to explain 47% of the variability of recorded aspen regeneration. Neither elk winter range, nor maps of elk density had an effect on aspen regeneration. Results from both regions suggest that stand-replacing regeneration occurs across the landscape at a variety of elk densities despite some trends of reduced regeneration under greater elk concentrations in Wyoming. We propose that high spatial and temporal variation and scattered patches of successful aspen regeneration characterize aspen persistence between periods of episodic regeneration and recruitment.

Keywords: ASPEN

This abstract is being presented at: 10:30 AM in session:
Poster Session #5: Landscape Ecology.