Divergent patterns of riparian cottonwood recovery after the return of wolves in Yellowstone, USA
Divergent patterns of riparian cottonwood recovery after the return of wolves in Yellowstone, USA
复制标题
美国黄石公园狼群回归后河岸杨木恢复的不同模式
DOI：
10.1002/eco.1487
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发表时间：
2015
期刊：
影响因子：
2.6
通讯作者：
W. Ripple
中科院分区：
文献类型：
--
作者：
R. Beschta;W. Ripple
了解顶端捕食者可能通过营养级联对河岸植物群落产生的潜在影响，是落基山脉生态系统中的一个重要研究挑战。在黄石国家公园北部有蹄类的冬季山脉，灰狼(Canis Lpus)在历史上曾出现过，消失了70年，最近又重新引入。我们的目标是评估棉白杨(Pillius spp.)为拉马尔河谷的两个毗邻河段招募人员。结果表明，当狼在历史上存在时，两个河段的招募都很常见，但在20世纪初狼被灭绝后，由于麋鹿(Cervus Elaffus)强烈的食草性，招募的数量减少了。到了20世纪70年代，这两个地区的白杨树招聘基本上已经停止。狼在20世纪90年代中期被重新引入，到2012年，大约4,660只年轻的棉杨≥2 m的高度(麋鹿的一般上层觅食水平)已经在2公里长的拉马尔上游研究河段内建立起来，这与重建包括狼、麋鹿和棉杨的三营养级联一致。然而，在8公里长的拉马尔下部研究范围内，由于高度草食，特别是野牛(野牛)的高度，只有22名年轻的棉杨达到了≥2 m的高度。涉及狼和麋鹿的自上而下的营养相互作用，以及河段特征和野牛的觅食，似乎解释了最近在黄石公园北部正在进行的河岸棉杨招募的强烈对比模式--一个河段代表着正在恢复的河岸生态系统，另一个河段代表着另一种稳定的状态，河岸植被和航道条件发生了很大的变化。版权所有©2014 John Wiley&Sons，Ltd.
Understanding the potential effect apex predators may have on riparian plant communities, via a trophic cascade, represents an important research challenge in Rocky Mountain ecosystems. In the northern ungulate winter range of Yellowstone National Park where grey wolves (Canis lupus) were historically present, absent for seven decades, and recently reintroduced, our objective was to evaluate patterns of cottonwood (Populus spp.) recruitment for two adjacent reaches of the Lamar Valley. Results indicated that recruitment was common in both reaches when wolves were historically present and declined because of intensive herbivory from elk (Cervus elaphus) after wolves were extirpated in the early 1900s. By the 1970s, cottonwood recruitment along both reaches had essentially ceased. Wolves were reintroduced in the mid‐1990s, and by 2012, some 4660 young cottonwoods ≥2 m in height (the general upper browse level of elk) had become established within the 2‐km‐long upper Lamar study reach, consistent with re‐establishment of a tri‐trophic cascade involving wolves, elk, and cottonwoods. However, within the 8‐km‐long lower Lamar study reach, only 22 young cottonwoods had attained a height of ≥2 m because of high levels of herbivory, especially from bison (Bison bison). Top–down trophic interactions involving wolves and elk, as well as reach characteristics and browsing by bison, appear to explain the strongly contrasting patterns of recent riparian cottonwood recruitment currently underway in the northern Yellowstone – one reach represented by a recovering riparian ecosystem and the other an alternative stable state with highly altered riparian vegetation and channel conditions. Copyright © 2014 John Wiley & Sons, Ltd.