Dr. Luke Shoo and a group of amphibian conservation biologists recently published a paper titled "Engineering a future for amphibians under climate change" in the Forum section of the Journal of Applied Ecology. The paper does not present new research, but instead proposes habitat management recommendations for conserving amphibians under conditions of rapidly changing climate. Given that they apply to "amphibians" in the broadest sense, the recommendations are very general. They also entail a rather active level of habitat management, as alluded to by "engineering" in the title.
Among the recommendations is a category of "enhancement and restoration of breeding sites," which, of course, is major component of the rationale for the USC/ESF Vernal Pool Restoration Project. They give a brief summary and assessment of previous efforts to construct or restore amphibian breeding sites, and a few general considerations to improve success. In particular, I was pleased to discover a paper in the journal Hydrobiologia titled "Restoring ponds for amphibians: a success story." The European authors report on an ambitious pool construction and restoration effort in Estonia on behalf of imperiled spadefoot toads and crested newts. Their approach, results, and recommendations are especially relevant to us because of their emphases on building clusters of diverse ponds, and in their explicit consideration of terrestrial habitat conditions.
I agree that such active habitat management recommendations can be helpful in mitigating effects of climate change, but I also suggest that some of them are appropriate for mitigating the more traditional threats to amphibian populations such as habitat loss, emerging infectious diseases, and invasive species. It is surprising that, for the time being, there is such a small number of case studies and success stories in the published literature...
Jim Arrigoni, SUNY ESF
2 comments:
Jim - I agree that the Hydrobiologia paper is promising in that targeted amphibians colonized created ponds, but don't you think that longer-term monitoring of population dynamics needs to occur before the project can be labeled a success?
-E
Thanks for the commment, Elizabeth. Your question points to the most fundemental (and controversial) aspect of wetland restoration: defining success. For example, wetland regulators are likely to have a different (and probably less rigorous) definition than conservation biologists. This point is clearly made relative to our northeastern US vernal pools in Daniel Vasconcelos and Aram Calhoun's 2006 Wetlands (26: 992-1003)paper, "Monitoring created seasonal pools for functional success: a six-year case study of amphibian responses, Sears Island, Maine, USA."
In fact, just as you suggest, their documentation of initial occupancy by vernal pool-associated amphibian species, which satisfied legal compliance, followed by extreme curtailment of wood frog recruitment, makes a strong case for reconsidering "success." Under the legal definition of success, a created pond that is an ecological trap by functioning as demographic sink is fine. But consider that many naturally occurring vernal pools are sinks in many (if not most) years. Thus a longer-term abundance (or larger spatial scale occupancy) perspective is necessary, as you are suggesting.
But you asked what I think, and I think their article stands up well and is a useful contribution to restoration literature, especially considering the very large number of ponds and the great occupancy gains they report. Tracking population dynamics over a longer time period would hamper the dissemination of knowledge they have accrued. Duration of monitoring aside, it is plausible that the project was not successful at increasing populations, but simply reconfigured where they occurred. Even still, I suggest that having the same number of individuals ("eggs) in a greater number of ponds ("baskets") warrents the title's claim of success.
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