Wild Side : Resilience
By Matt Pelikan
Published: October 9, 2008
Vineyarders should be proud of the conservation successes achieved here over the last century: we've protected a lot of land and learned how to manage it properly, helping preserve not just biodiversity but clean water, scenic and recreational opportunities, fish, shellfish, and game populations, and pollinators that support agriculture.
Much of this work has been guided by a basic, widely shared assumption: that the goal of conservation is to keep things the same. But on Martha's Vineyard and elsewhere, two newly emerging forces are changing the rules. The first of these new risks is climate change, the rising temperatures, altered storm and precipitation patterns, and rising sea levels that have been touched off by the "fossil-fuel economy." The second is the unprecedented mobility for wildlife and microbes that have emerged as an unintended consequence of global trade. These problems affect the whole globe. But because of their isolation and finite dimensions, islands (including our own) face particular risks.
Temperature and the availability of water, for example, exert enormous control over where wild species can survive. If the predicted warmer climate and longer droughts emerge, some species will surely go extinct on Martha's Vineyard, and because this is an island, it will be difficult for other species to arrive by natural means to take their place. Global warming, in other words, appears certain to erode Martha's Vineyard's native biodiversity over time.
Meanwhile, exotic plants, animals, and diseases will be carried here by human activity, and some of these, separated from the predators or parasites that constrain them in their natural range, will burgeon out of control. The likely consequence will be declining native biodiversity and steadily increasing dominance by a small number of wildly successful, non-native generalist species. In short, we are entering a new era in which extreme but unpredictable changes are likely in the basic dynamics of our natural systems.
Traditional conservation thinking - the notion that preserving the status quo is the goal - doesn't suffice to address the resulting uncertainty. Investing resources to protect a particular species, for instance, is risky because some species - we just don't know which ones - are already doomed. Likewise, trying to preserve a particular habitat type runs the risk that the habitat will be unsustainable in spite of our best efforts. How should Islanders respond?
A new concept is rapidly gaining currency among conservationists, here and elsewhere: the notion of resilience. In the context of biology, the term means the ability to absorb a shock and still continue to function. A resilient system, that is, tends to resist invasion by exotic species. A resilient system, struck by a severe drought, bounces back into a viable ecosystem rather than devolving into desert. The system may change as a result of the disturbance, but it remains functional and productive.
Two factors that tend to create resilience are high biodiversity and large tracts of land. Where a wealth of native biodiversity is present, the odds are good that the loss of one species will create new opportunities for others. And chances are increased that any arriving invasive species will meet its match in the form of a native competitor or predator. Larger tracts of protected land, meanwhile, hold larger and therefore more secure populations of wildlife, and provide larger areas for vital processes like the filtration of water. Large, diverse tracts may change over time, but they are likely to remain diverse and functional.
To a great extent, then, promoting resilience means doing the same things Vineyard conservationists have been doing all along - protecting land and preserving biodiversity - only doing it more and better. But we can take new, additional steps to promote resilience. The key is thinking of Martha's Vineyard as a whole as a single system. For example, ensuring connectivity among our network of individual protected areas can help wildlife move about the entire landscape, avoiding inbreeding and permitting recolonization of areas from which a species has been lost.
While "ensuring connectivity" may entail expensive steps like establishing protected wildlife corridors or making infrastructure changes such as wildlife underpasses under roads, much smaller measures can still help link conservation areas. For example, landscaping with native plants and minimizing highly altered habitats like lawns can turn a developed area from a complete barrier into an area that is permeable to the movements of at least some wild species.
I don't know what the sandplain or the hills of Chilmark will look like in 200 or 500 years, but something will be growing there. And if we shift our focus to enhancing the resilience of the entire Island now, we can give our descendents a better chance of having a functional landscape that, whatever mix of species it contains, still performs the many vital tasks of a healthy natural ecosystem.
