Islands and introduced herbivores: conservation action as ecosystem experimentation

نویسندگان

  • C. JOSH DONLAN
  • BERNIE R. TERSHY
  • DONALD A. CROLL
چکیده

1. Overgrazing by exotic herbivores has a widespread impact on plant communities. We used the removal of exotic European rabbits, goats and donkeys from the San Benito Islands, Mexico, as an experimental manipulation to examine the importance of top-down and bottom-up processes in the impact and recovery of an island plant community. 2. Using a paired approach, we removed herbivores from one island, while they remained temporarily on an adjacent, similar island. We combined this large-scale manipulation with smaller-scale mechanistic experiments: herbivore food-preference trials and herbivore exclosures on the control island. 3. El Niño-related precipitation dominated vegetation dynamics early in the study. Differences in plant community structure due to selective herbivory between the experimental and control islands were detectable in the second year. Results from food-preference trials accurately predicted changes in the perennial plant community. When herbivores were removed from the experimental island, the abundance of their preferred plants increased while unpalatable species decreased. On the control island (herbivores present), we observed the opposite trend. However, we saw no recovery of vegetation inside the exclosures on the control island, constructed after the El Niño rains, probably due to the absence of rainfall. 4. While the relationship between herbivore food preference and changes in plant cover is strong evidence of a top-down effect by exotic species, the influence of El Niño precipitation highlights the importance of bottom-up factors, such as water availability, in the recovery of arid plant communities from long-term disturbance.

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

منابع مشابه

Islands, Exotic Herbivores, and Invasive Plants: Their Roles in Coastal California Restoration

The Pacific islands off southern California, U.S.A. and Baja California, Mexico hold potential for the conservation and restoration of California Mediterranean coastal ecosystems. However, the presence of exotic herbivores and invasive plants pose threats to these systems. Here, we use introduced herbivore removal as a large-scale experimental manipulation to examine the importance of topdown a...

متن کامل

Species–environment interactions changed by introduced herbivores in an oceanic high-mountain ecosystem

Summit areas of oceanic islands constitute some of the most isolated ecosystems on earth, highly vulnerable to climate change and introduced species. Within the unique high-elevation communities of Tenerife (Canary Islands), reproductive success and thus long-term survival of species may depend on environmental suitability as well as threat by introduced herbivores. By experimentally modifying ...

متن کامل

Conservation action in the Gal apagos: feral pig (Sus scrofa) eradication from Santiago Island

Introduced mammals are major drivers of extinction and ecosystem change. As omnivores, feral pigs (Sus scrofa) are responsible for wholesale adverse effects on islands. Here, we report on the eradication of feral pigs from Santiago Island in the Gal apagos Archipelago, Ecuador, which is the largest insular pig removal to date. Using a combination of ground hunting and poisoning, over 18,000 pig...

متن کامل

Feral Goat Eradications on Islands

Introduced mammals are major drivers of extinction. Feral goats (Capra hircus) are particularly devastating to island ecosystems, causing direct and indirect impacts through overgrazing, which often results in ecosystem degradation and biodiversity loss. Removing goat populations from islands is a powerful conservation tool to prevent extinctions and restore ecosystems. Goats have been eradicat...

متن کامل

Galapagos Islands: Managing Introduced Species in an Endangered Ecosystem

Species introduced through development for fishing and tourism are destroying the native ecosystem on the Galapagos Islands, Ecuador. To address this problem, introductions must stop, and species already introduced should be removed or reduced. This paper analyzes the “species introduction” problem and makes recommendations to improve conservation efforts. The problems with management to date i...

متن کامل

ذخیره در منابع من


  با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

عنوان ژورنال:

دوره   شماره 

صفحات  -

تاریخ انتشار 2002