Gable Thomas D, Johnson-Bice Sean M, Homkes Austin T, Windels Steve K, Bump Joseph K
Department of Fisheries, Wildlife, and Conservation Biology, University of Minnesota, 2003 Upper Buford Circle, St. Paul, MN 55801, USA.
Department of Biological Sciences, University of Manitoba, 50 Sifton Road, Winnipeg, Manitoba R3T 2N2, Canada.
Sci Adv. 2020 Nov 13;6(46). doi: 10.1126/sciadv.abc5439. Print 2020 Nov.
Gray wolves are a premier example of how predators can transform ecosystems through trophic cascades. However, whether wolves change ecosystems as drastically as previously suggested has been increasingly questioned. We demonstrate how wolves alter wetland creation and recolonization by killing dispersing beavers. Beavers are ecosystem engineers that generate most wetland creation throughout boreal ecosystems. By studying beaver pond creation and recolonization patterns coupled with wolf predation on beavers, we determined that 84% of newly created and recolonized beaver ponds remained occupied until the fall, whereas 0% of newly created and recolonized ponds remained active after a wolf killed the dispersing beaver that colonized that pond. By affecting where and when beavers engineer ecosystems, wolves alter all of the ecological processes (e.g., water storage, nutrient cycling, and forest succession) that occur due to beaver-created impoundments. Our study demonstrates how predators have an outsized effect on ecosystems when they kill ecosystem engineers.
灰狼是食肉动物如何通过营养级联效应改变生态系统的一个典型例子。然而，狼对生态系统的改变是否如之前所认为的那样剧烈，这一问题越来越受到质疑。我们证明了狼是如何通过捕杀正在扩散的海狸来改变湿地的形成和重新定殖的。海狸是生态系统工程师，在整个北方生态系统中创造了大部分湿地。通过研究海狸池塘的形成和重新定殖模式以及狼对海狸的捕食情况，我们确定，84%新形成和重新定殖的海狸池塘在秋季之前一直有人占据，而在狼杀死在该池塘定殖的扩散海狸后，0%新形成和重新定殖的池塘仍然活跃。通过影响海狸对生态系统进行工程改造的地点和时间，狼改变了所有因海狸建造的蓄水设施而发生的生态过程（如蓄水、养分循环和森林演替）。我们的研究表明，当食肉动物杀死生态系统工程师时，它们对生态系统会产生巨大影响。
