Rats on Islands: Direct and Indirect Effects on Plant Communities

世界各地的老鼠入侵岛屿，给当地的动物，特别是鸟类、哺乳动物和爬行动物带来了毁灭性的后果。最近，一些岛屿上的老鼠已经被根除，以努力恢复当地动物的数量。然而，老鼠做的不仅仅是杀死动物：它们还吃植物的部分(种子、幼苗、水果和树皮)，从根本上改变植被。此外，许多被老鼠入侵的岛屿也是大群海鸟的筑巢场所，这本身就对植被和土壤产生了很大影响(通过挖洞来产卵)。这个项目有两个目标。首先，我们将研究老鼠如何影响植被和土壤，其中有多少是由于海鸟数量的变化。其次，我们将评估灭鼠后岛屿从老鼠效应中恢复到什么程度，以及这是否取决于海鸟的数量。我们将通过比较新西兰海岸外的三组岛屿来做到这一点：一组从来没有老鼠，一组有老鼠，还有一组在过去十年里老鼠被移走了。如果灭鼠后植被和土壤不能恢复(或需要很长时间才能恢复)，那么如果不进行额外的恢复工作，恢复当地动物种群的努力可能就不会成功。这项工作的结果将使人们更好地了解老鼠的影响，以及如何在世界各地的岛屿上逆转这些影响。

Lay abstract, proposal # 0317196 (Mulder)Throughout the world rats have invaded islands with devastating consequences for local fauna, particularly birds, mammals and reptiles. Recently, rats have been eradicated from a number of islands in an effort to restore populations of native animals. However, rats do more than just kills animals: they also eat plant parts (seeds, seedlings, fruit and bark) and radically change the vegetation. Furthermore, many of the islands invaded by rats also served as nesting grounds for large colonies of seabirds, which themselves had large effects on the vegetation and soils (by digging burrows in which to lay their eggs). This project has two goals. First, we will examine how rats affect the vegetation and soils, and how much of this is due to changes in seabird populations. Second, we will evaluate to what extent islands recover from rat effects after rats are eradicated, and whether this depends seabird population sizes. We will do this by comparing three groups of islands located off the coast of New Zealand: one which has never had rats, one which has rats, and one from which rats have been removed during the past decade. If vegetation and soils fail to recover (or take a long time to recover) following the eradication of rats, then efforts to bring back native animal populations may not be successful without additional restoration work. The results of this work will give a better understanding of the effects rats have and how to reverse them on islands everywhere.