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Handle with care

Ecologists must research how best to intervene in and preserve ecosystems.

For many people — including many scientists — 'nature' is defined by a negative: it exists where people do not. Nature lies outside the urban and agricultural realms, in regions of Earth where natural processes are unimpeded. Nature is where fallen logs rot and acorns grow, wildfires turn woodlands into meadows, and barrier islands shift with the currents — all without human interference. By extension, this definition suggests that nature is best protected by keeping humans far away, so that it can continue to run itself.

But there is a serious problem with this view. If nature is defined as a landscape uninfluenced by humankind, then there is no nature on the planet at all. Prehistoric peoples changed their surrounding ecosystems, whether by installing orchards in the Amazon or — according to one increasingly accepted theory — by hunting many large mammals to extinction in North America. And modern humans are changing the global environment even more profoundly, whether through planet-wide climate change, or by the worldwide movement of synthetic chemicals through the food chain. Today there is no place untouched by man — a point made by environmentalist Bill McKibben as early as 1989 in the starkly titled The End of Nature.

Nature doesn't have to end if we stop defining it by humankind's absence. Humans prize natural spaces because they are historic, culturally significant, aesthetic and scientifically interesting — and, increasingly, because they have been recognized as providing essential services such as filtering water, ameliorating storm surge, providing fish, game and timber, and sequestering carbon. Ecosystems that are valuable for one or more of these reasons can be identified by quantifiable biological traits, such as the presence of certain key species or processes. In the Białowieża forest of eastern Europe, which has a long history of human activity, for example, one could cite the presence of European bison and of a large amount of dead wood as characteristics worth preserving (see page 277).

“Scientific research on the best ways to manage natural ecosystems needs to become a much higher priority.”

Retaining such characteristics takes more than the absence of active destruction. It is precisely because of humanity's pervasive influence that even the least changed ecosystems need help surviving in the future. Białowieża's core is so small that the dynamic processes that once drove its mosaic of different micro-ecosystems probably can't operate as they once did. Some of its large mammals are extinct. Many new species have arrived through human agency. And climate change is altering the seasonal timing and hydrological cycles of the forest.

The only alternative is proactive management — by humans. Already, conservationists in some forests set small fires to burn out underbrush before it reaches levels that could produce catastrophic fires. They shoot prey species whose populations are out of control because the top predators have been exterminated. And they have begun to control water flows into wetlands where the natural flow has been disrupted. In the future, as climate change takes hold, management may become even more radical. Some ecologists are beginning to talk about moving slowly dispersing plants and animals pole-wards or upslope to keep them in climates they can thrive in, or introducing non-native 'functional equivalents' in some ecosystems to play certain key roles.

Such talk will undoubtedly raise hackles among those ecologists for whom intervention in natural ecosystems is anathema. Yet our species' all-pervasive impact on this planet has already doomed that hands-off approach to failure.

Unfortunately, would-be managers of natural regions still know very little about how to save natural places without continuing Homo sapiens' legacy of destruction. Ecologists have conventionally studied the workings of intact ecosystems, but have focused much less attention on how to keep them intact. Scientific research on the best ways to manage natural ecosystems needs to become a much higher priority.

Meanwhile, economists, ecologists and ethicists need to seek ways to bring natural ecosystems into the economic system, instead of just assuming that they exist outside of or in opposition to economics. If nothing else, this will require continued research on how to put a fair economic value on ecosystems that provide humankind with services — a classic example being wetlands that absorb storm run-off and help prevent flooding — while not dooming ecosystems such as deserts and tundras that contribute in a less obvious way.

For now, the custodians of Białowieża are letting the never-logged core area alone, even going so far as to prohibit entry to tourists except when accompanied by a guide. But the day may come when hands-off means waving goodbye. Will science know how to save Białowieża when that day comes?

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Handle with care. Nature 455, 263–264 (2008).

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