Author : Charles Kay
Publisher :
ISBN 13 :
Total Pages : 12 pages
Book Rating : 4.:/5 (13 download)
Book Synopsis Browsing by Native Ungulates by : Charles Kay
Download or read book Browsing by Native Ungulates written by Charles Kay and published by . This book was released on 1995 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: Long-term grazing exclosures were used to compare browsed versus unbrowsed shrubs in the Greater Yellowstone Ecosystem. Deciduous shrubs protected from wild ungulates exhibited significantly greater canopy-cover, height, size, and volume than unprotected plants. Browsed shrub populations were dominated by significantly smaller plants than were unbrowsed populations. Protected shrubs increased in canopy-coverage and size while browsed plants remained static or declined. Ungulate browsing in recent times has virtually eliminated shrub seed production in areas frequented by wintering elk. Shrubs measured inside exclosures produced up to 20,000 times more berries than unprotected plants. Individual unprotected shrubs with a few stems beyond the reach of ungulates displayed a similar pattern. Stems above the browse height (2.5 m) produced an abundance of berries while none were produced on that portion of the plants exposed to browsing. Old photographs and historical journals indicate that tall shrubs and berries were common prior to park establishment, so the present lack of berries and the browsingstunted shrub growth form were not the conditions prevailing in pre-European times. The virtual elimination of shrub seed production over much of the ecosystem suggests that ungulate populations are not in equilibrium with their food resources, as required under the ?natural regulation? paradigm. These circumstances are not unique to Yellowstone. Similar situations exist in other Western States where wild ungulate numbers are at historical highs. At many locations, large populations of native ungulates are having dramatic impacts on shrub growth and seed production. Without adequate seed production and recruitment, existing plants are not replaced when they die, and plant populations cannot be in long-term equilibrium with herbivores or the environment. By reducing or eliminating seed production, native ungulates may render long-term shrub restoration ineffective. The impact of native ungulates should be carefully considered in the planning and implementation of all shrub revegetation projects.