Reduced cottonwood recruitment following extirpation of wolves in Yellowstone's northern range
Reduced cottonwood recruitment following extirpation of wolves in Yellowstone's northern range
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DOI：
10.1890/04-0964
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发表时间：
2005-02-01
期刊：
影响因子：
4.8
通讯作者：
Beschta, RL
中科院分区：
文献类型：
--
作者：
Beschta, RL
美洲黑杨（Populus spp.）代表了北方黄石公园麋鹿（Cervus elaphus）群冬季活动范围内河岸植物群落的重要树木组成部分，但年轻的三角叶杨对有蹄类动物来说非常可口。为了评估潜在的草食动物的影响与野生有蹄类动物的灰狼（犬），长期的棉白杨招聘和立场动态进行了研究。虽然结果表明，建立年轻的三角叶杨是一个持续的过程中，在黄石公园的北方范围，他们相对较小的身材和对冲的外观表明高浏览压力的野生有蹄类动物，主要是麋鹿。在五个研究地点，测定了所有>= 5 cm的三角叶杨树的胸径;还获得了生长量核心，以建立树龄与胸径的关系。在拉杜克春天和魔鬼幻灯片网站，这是代表避难所网站，因为麋鹿有限的访问（由于当地的地形条件和文化发展），三角叶棉白杨招聘一直发生在过去的半个世纪，表明气候因素并没有阻止棉白杨招聘在这段时间。然而，在同一时期，在苏打山和拉马尔山谷内的地点不再发生三角叶棉白杨的招聘。在这些地点的棉白杨招聘的整体下降发生在20世纪20年代从黄石国家公园灭绝狼。在布法罗牧场，布法罗[野牛]（野牛野牛）的牧场和与麋鹿扑杀相关的活动是集中的，三角叶棉白杨招聘在狼消失后继续进行，但在20世纪60年代末这些设施的有蹄类动物管理活动减少后停止了。综上所述，本文所报告的五个地点的数据沿着其他研究的结果提供了令人信服的证据，表明北方黄石公园没有狼对三角叶棉白杨和其他木本浏览物种的招募产生了重大影响。
Cottonwoods (Populus spp.) represent an important tree component of riparian plant communities within the winter range of the northern Yellowstone elk (Cervus elaphus) herd, yet young cottonwoods are highly palatable to ungulates. To assess potential herbivory impacts associated with wild ungulates following the removal of gray wolves (Canis lupus), long-term cottonwood recruitment and stand dynamics were studied. While results indicated that the establishment of young cottonwoods is an ongoing process in Yellowstone's northern range, their relatively small stature and hedged appearance were indicative of high browsing pressure by wild ungulates, principally elk. At five study sites, the diameter at breast height (dbh) of all cottonwood trees >= 5 cm was determined; increment cores were also obtained for developing tree age vs. dbh relationships. At the La Duke Spring and Devils Slide Sites, which represent refugia sites since elk have limited access (due to local terrain conditions and cultural developments), cottonwood recruitment has been occurring during the last half century, indicating that climatic factors have not prevented cottonwood recruitment during that time. However, over this same period cottonwood recruitment no longer occurred at sites within the Soda Butte and Lamar Valleys. The overall decline in cottonwood recruitment at these locations occurred following the extirpation of wolves from Yellowstone National Park in the 1920s. At the Buffalo Ranch Site, where ranching of buffalo [bison] (Bison bison) and activities associated with culling of elk were centered, cottonwood recruitment continued after the loss of wolves but stopped following the curtailment of ungulate management activities at these facilities in the late 1960s. Taken together, data from the five sites reported herein along with the results of other studies provide compelling evidence that the absence of wolves in the northern Yellowstone has had a major impact on the recruitment of cottonwood and other woody browse species.