Browsing by native ungulates: effects on shrub and seed production in the Greater Yellowstone Ecosystem
Kay CE. 1995. Browsing by native ungulates: effects on shrub and seed production in the Greater Yellowstone Ecosystem. Pages 310-320. In Roundy BA, McArthur ED, Haley JS, Mann DK (ed): Proceedings: Wildland Shrub and Arid Land Restoration Symposium. Las Vegas, NV. October 19-21, 1993. U.S. Department of Agriculture: Forest Service--Intermountain Research Station. Ogden, UT. General Technical Report INT-GTR-315
In the Greater Yellowstone ecosystem, covering NW Wyoming, S. Montana and NE Idaho, the effects of grazing by Cervus elaphus, Odocoileus hemionus, Antilocapra americana, Ovis canadensis and Bison bison on Amelanchier alnifolia, Prunus virginiana, Shepherdia canadensis and Purshia tridentata were examined. Deciduous shrubs protected from wild ungulates exhibited significantly greater canopy-cover, height, size, and volume than unprotected plants. In exclosures the canopy of shrubs increased but the canopy of browsed plants remained static or declined. Seed production of the browsed plants in areas frequented by wintering elk was virtually nonexistent, whereas in the exclosures seed output was 20,000-fold higher than that of unprotected plants; individual unprotected plants with a few stems beyond the reach of elks displayed a similar pattern. Prior to the area becoming a park, tall shrubs and berries were common which indicated that there were now too many elk for the ecosystem. Without adequate seed production and recruitment, existing plants were not being replaced when they died and plant populations were not in long-term equilibrium with the herbivores or the environment. It was suggested that the impact of native ungulates should be considered in the planning and implementation of all shrub revegetation projects.
- Type
- Conference Proceeding Paper
- Authors
- Kay, Charles
- Units
- YELL
- Keywords
- Animal Studies, Plant Studies, Rangeland Management, Seeds, Vegetation Survey