Too often, ecologists focus on attaining an ideal that's no longer possible. An excerpt from the new book, Rambunctious Garden.
We have lost a lot of nature in the past three hundred years--in both senses of the word lost. We have lost nature in the sense that much nature has been destroyed: where there was a tree, there is a house; where there was a creek, there is a pipe and a parking lot; where there were passenger pigeons and Steller's sea cows, there are now skins and bones in dimly lit museum galleries. But we have also lost nature in another sense. We have misplaced it. We have hidden nature from ourselves.
Our mistake has been thinking that nature is something "out there," far away. We watch it on TV, we read about it in glossy magazines. We imagine a place, somewhere distant, wild and free, a place with no people and no roads and no fences and no power lines, untouched by humanity's great grubby hands, unchanging except for the season's turn. This dream of pristine wilderness haunts us. It blinds us.
Many ecologists spend their lives studying the most pristine places they can find, and many conservationists spend their lives desperately trying to stop wilderness from changing. We cling to fragments of "virgin" or "old growth" forests, to the "last great places," the ever-rarer "intact ecosystems," but they slip through our fingers. Like slivers of soap, they shrink and disappear. And we mourn. We are always mourning, because we can't make more of such places. Every year there are fewer of them than the year before.
Yes, nature is carefully managed national parks and vast boreal forest and uninhabited arctic. But nature is also the birds in your backyard; the bees whizzing down Fifth Avenue in Manhattan; the pines in rows in forest plantations; the blackberries and butterfly bushes that grow alongside the urban river; the Chinese tree-of-heaven or "ghetto palm" growing behind the corner store; the quail strutting through the farmer's field; the old field overgrown with weeds and shrubs and snakes and burrowing mammals; the jungle thick with plants labeled "invasive" pests; the carefully designed landscape garden; the green roof; the highway median; the five-hundred-year-old orchard folded into the heart of the Amazon; the avocado tree that sprouts in your compost pile.
Many conservationists are opening up their definitions of nature and embracing a whole suite of possible goals beyond the familiar "pristine wilderness" goal. They find that when they do, they can use all sorts of new tools and approaches. But even those who are interested in expanding their conception of nature run into problems. The notion of a stable, pristine wilderness as the ideal for every landscape is woven into the culture of ecology and conservation--especially in the United States. Take the baseline. Virtually every scientific study of environmental change uses or assumes a baseline. Baselines are reference states, typically a time in the past or a set of conditions, a zero point before all negative changes. In the past, a place's default baseline was often before Europeans arrived. Today, as we learn more about how indigenous inhabitants of places from Australia to the Americas changed their surroundings, it is sometimes set to before any humans arrived. For many conservationists, restoration to a prehuman or pre-European baseline is seen as healing a wounded or sick nature. For others, it is an ethical duty. We broke it; therefore we must fix it. Baselines thus typically don't just act as a scientific before to compare with an after. They become the good, the goal, the one correct state.
But ecosystems are slippery, and setting a baseline is not straightforward. The Hawaiian islands are some of the remotest islands in the world, home to hundreds of species that live nowhere else, many of which are rare and at risk for extinction. Earlier ecologists might have used 1778, the year Captain James Cook landed in Hawaii, as the baseline date for the island chain. But restoring the islands' ecosystems to the way they were in 1777 would be restoring them to a state very much shaped by the Polynesians who had been living there for at least one thousand years: a semidomesticated landscape filled with species the Polynesians brought with them, including taro, sugarcane, pigs, chickens, and rats, and missing others, including at least fifty species of birds, who were hunted out by the first arrivals.
But if we set a date thousands of years back, safely before any humans arrived, we run into another problem. Ecosystems are always changing, whether humans are involved or not. Ancient forests with trees thousands of years old may feel timeless to us. We are a short-lived species with a notoriously bad grasp of timescales longer than a few of our own generations. But from the point of view of a geologist, a paleoecologist, or some other expert with "deep time eyes," ecosystems are in a constant dance, as their components compete, react, evolve, migrate, and form new communities. Geological upheaval, evolution, climatic cycles, fire, storms, and population dynamics see to it that nature is always changing. On Hawaii, volcanic activity wipes the slate clean on any given slope every few hundred years, and occasional new arrivals to the islands, washed ashore or drifting in on the wind, adapt to their new home and find a place for themselves in its ecosystems.
Once we pick a date from amid this muddle, another problem emerges. Even when we use all the scientific tools available to look backward in time, from fossil pollen records to the climate information enshrined in tree rings, we don't always know what places looked like thousands or even hundreds of years ago.
The final and perhaps most vexing issue with prehuman baselines is that they are increasingly impossible to achieve--either through restoration or management of wild areas. Every ecosystem, from the deepest heart of the largest national park to the weeds growing behind the local big-box store, has been touched by humans. We have stirred the global pot, moved species around, turned up the thermometer, domesticated a handful of plants and animals, and driven extinct many more. We have definitively changed the entire planet, and it is getting increasingly difficult to undo all these changes at any one place.