Editor's Note: The following is an edited and expanded excerpt from Rambunctious Garden: Saving Nature in a Post-Wild World by Emma Marris. Copyright © 2011 Emma Marris.
Jessica Hellmann, an ecologist at Notre Dame University in Indiana, is in the midst of exactly the kind of painstaking study that can help guide those who want to move species. Hellmann works, among other places, on Vancouver Island, studying a kind of oak savanna ecosystem that most people associate with California. The star players of these savannas are called Garry oaks or Oregon white oaks, large trees often gnarled into unique shapes. Under their canopies grow mossy meadows of wildflowers, including buttercups and star- shaped blue camas. For Canadians, this kind of ecosystem is a beloved break from the evergreens that otherwise dominate the landscape. And according to the nonprofit Garry Oak Ecosystems Recovery Team, "approximately 100 species of plants, mammals, reptiles, birds, butterflies and other insects are officially listed as 'at risk' in these ecosystems" in Canada. The range of these Garry oak savannas hugs the Pacific coast from central California to just about halfway up Vancouver Island. These savannas are quite rare in Canada and threatened by land development. Hellmann thinks that British Columbians might be interested in establishing such ecosystems farther north on the island or even on the province's mainland as the climate warms. So one set of questions that her study is asking bears directly on whether such a move would work.
For example, what are the essential components of a Garry oak savanna? Which of these are limiting its range in the North? Will the Garry oak systems be able to move themselves? If so, will the more mobile components of the ecosystem, such as the butterflies, move first? And if one were to move the ecosystem, would it be best to use the organisms from the northern edge of the range to seed the new site, or would organisms from the center of the range fare better? This last question is important because Hellmann expects that the butterflies, oaks, and other constituents of the system will prove to genetically vary as one moves from south to north. The butterflies on Vancouver Island, for example, are genetically different from their cousins on the mainland. "Would you take that whole gradient and scootch everybody?" asks Hellmann.
Getting the answers to these questions all starts with renting a house. Ecological research is a lot of work, and results that can be summarized in a sentence or two represent the hard-won outcome of years of logistical management, grueling days of fieldwork, and caffeine-fueled writing binges. To learn about the dynamics of Garry oak savannas on Vancouver Island, Hellmann had to first get grant money to do the work by putting together a proposal compelling enough to beat out its rivals. Once she got the money, she had to set up a local headquarters, in this case a house in Ladysmith, British Columbia. She then recruited a team, including Caroline Williams, a Ph.D. student from the University of Ontario, and André Burnier, an undergraduate from Brown, to do much of the daily work. With the help of satellite photos and a tour of the island in a rental car, she identified Garry oak sites and sites where Garry oak might conceivably migrate, designed several experiments, bought equipment to collect data and raise butterflies, jerry-rigged the data-collection devices so they would survive out in the field, and procured vehicles for the team. And this is only one of two headquarters. She had to go through the same rigmarole for a team at the center of the Garry oak savanna range in Oregon. The Oregon sites act as controls to which she compares findings at the edges of the range.
As the climate changes, plants like the Garry oaks and animals are suddenly finding themselves outside of their comfort zones. Some are moving. Scientists are documenting range shifts up mountains and towards the poles in creatures from butterflies to trees. Some species will be able to keep up with the changing climate, but others will be too slow, or they will have their path blocked by a valley, a mountain, a city or even a single road. Trapped in their former home, which will, in fits and starts, change into something different, perhaps something hotter and dryer, they will perish.
Conservationists are increasingly considering moving plants and animals in advance of climate change to places where they might thrive in a warmer future. But they are hesitant and nervous; assisted migration is a long way from the conservation many grew up with.
After a lifetime studying the infinitely complex workings of existing ecosystems, the idea of taking a species from one into the other willy-nilly sounds like a terrible idea. The organisms could die, because you don't know exactly what they need to live— some specific soil microbes or microclimatic condition. Or, in a much worse scenario, they could do so well that they become a dreaded "invasive species" that takes over and pushes out native species. And it is one thing when humanity accidentally creates an invasive species. Humanity is dumb. But to do so these days, with all we know, on purpose? For many ecologists and conservation biologists, that is just insanity. But then…to do nothing and watch plants and animals go extinct because of climate change that we caused?
What is interesting about climate change is that it pits two common assumptions against each other: the myth of pristine nature and the myth of a correct baseline for each area. If humans are outside nature and humans caused climate change, then it follows that humans should make good— should make sure that species that would have survived without climate change survive, no matter what— even if it means moving stressed-out organisms to new places where they can thrive under the new climate. But if ecosystems have a correct baseline to which we must return— the second assumption— then we absolutely cannot move species from one area to another. To do so would violate the baseline and be tantamount to willfully creating invasive species. This conundrum has paralyzed many scientists.
Proponents of moving plants and animals threatened by rising temperatures to more hospitable locations are more concerned about the increasing rate of species extinction, while opponents are more worried about the integrity of coevolved ecosystems. But in general, scientists are pretty freaked out by the whole idea.
To find out more, I visited Hellman's northern site. The week I was there, Hellmann was also visiting the team to see that all was well, downloading data from the field, and checking on transplanted oaks. Together the four of us drove up and down the landward side of Vancouver Island, crossing and recrossing the range limit of the ecosystem and visiting sites on military bases, in public parks, on "Crown land" managed for forestry, and on privately owned nature reserves. From the car, the island seemed to be a blanket of conifers, with land carved out for roads and towns. The Garry oak sites were hidden treasures, tucked down winding roads, little patches of flowers, grasses and great gnarled oaks in a sea of Douglas-fir and hemlock. I could see why Canadians found them enchanting. I could also see why they might not be able to move north by themselves.
Hellmann is gathering two species of butterflies, duskywing skippers and swallowtails, at all these sites, and breeding them, so she can look at the differences between the butterflies in different parts of the range. Essentially, she is trying to determine whether the northernmost butterflies are specially adapted to their edge-of-the-range existence, or whether they are in fact more or less miserable and dreaming of California. "I am trying to ask it, 'Where would you like to live?'" she says. If the butterflies would answer, "Ah, northern California, that is the homeland," then one might expect that as the climate warms, the Vancouver Island butterflies will become happier and more fit, reproduce more often, and push north on their own. If they would answer, "Vancouver Island! We are locally adapted," then a warming climate should make them less fit— and they might decline just when they would need a robust population to expand northward. If that is the case, they might need help to move north. Hellmann expects to see more local adaptation in the duskywing than in the swallowtails, as they are more isolated from their southern cousins. The duskywing doesn't fly as well, and it eats oak leaves only as a caterpillar, so many populations may live in particular Garry oak sites like little islands, never breeding with butterflies from the next savanna over.
As I drove up and down the island with Hellmann and her team, I learned that there's another wrinkle to the Garry oak study. Some of the sites they are looking at are probably at least partially anthropogenic. The pre-European residents of Vancouver Island also liked these systems and maintained them with fire. Apart from their aesthetic qualities, the oak meadows were easier to hunt in and provided additional calories in the form of camas bulbs. While the Garry oak meadows on rocky slopes may have looked after themselves, conservation managers have found it difficult to keep conifers from taking over Garry oak savannas on good soils. They've resorted to mowing and chopping down encroaching Douglas fir.
To learn more, I met up with Mark Vellend, a young conservation biologist from the University of British Columbia. Vellend walked me through a few Garry oak sites and told me a story as we strolled single file between slender but ancient and gnarled oak trunks, through buttercups, shooting stars, lomatium, and camas. "Eight thousand years ago the climate was warmer and dryer on Vancouver Island," said Vellend. "Oaks and flowers might have been more widespread back then, and then later were maintained only by people burning."
So, I asked him, if people didn't burn these areas after the climate cooled, would some of the flower species be extinct in Canada? He answered like a true scientist: "That's not an unreasonable hypothesis."
So Garry oak savannas in Canada are a human production, threatened by human activities. And people are worried that it is "unnatural" to save them by having humans move them north? Surely assisted migration of these ecosystems would just be a continuation of the care our species has put into them for thousands of years.
One of Hellmann's sites is a little bare rocky clearing in the woods up near Campbell River, north of the last Garry oak. This site was chosen as an example of the kind of place to which people might move the oak, the butterflies, the flowers, and all the other species that make up the little fairyland savannas. Right now, though, it is already occupied. Exposed rocks were covered with thick pads of acid-green moss interspiked with blades of grass and dotted with balls of elk dung. Small bushes grew from between the rocks; on this late April day their leaves were still tiny red buds, and they were more display stands for various species of lichens. Bears visit this clearing, too, to the mild worry of researchers downloading data. It was a very attractive forest room, with walls of Douglas fir, but it doesn't have a catchy name like Garry oak savanna or a fan club. I felt a bit sorry for it, almost as if the moving trucks were already on the way and the place was scheduled to be turned into a Garry oak savanna that very day. "What makes climate change different from reestablishing from a glaciation is that these northern areas are already full," said Hellmann.
The mood among the team was happy, despite the fact that several of the climate sensors, which looked like oversize watch batteries, had gotten wet and were not recording properly, even though they were carefully duct-taped inside plastic pillboxes. Oaks that they had lugged up to the site were sitting in pots, so Hellmann could see how butterflies that feed on them would do if moved to the clearing. Of course, it would be more like a real migration if the oaks were planted in the ground rather than in pots; every gardener knows that potted plants are more affected by the cold. But Hellmann, despite having permission from the government to stick those oaks right into the ground, could not quite bring herself to personally move the Garry oak past its recorded range.
She's still ambivalent. "Philosophically we are entering an era of interventionism that I am not comfortable with," she says. But on the other hand, "I have not gotten comfortable with this idea of how many species are going to go extinct. There is less stuff than there used to be. That is one thing that we should care about. I am less concerned with how it is configured than that it exists."
While Hellmann and her ilk fret and study, a great uncoordinated, unofficial assisted migration is already underway. A group of citizen scientists has moved north many seedlings of Torreya taxifolia, or Florida torreya, one of the world's rarest evergreen trees, which is currently roasting to death in its tiny range in the US South. Many conservationists predict an explosion of similar efforts by fans of particular species. And an analysis of about 350 native European plants sold at nurseries in Europe has revealed that 73 percent of them are now sold farther north than their native ranges, with a mean shift of about 600 miles. Pretty pink-flowered rock soapwort doesn't occur north of Germany, according to official ranges published by botanists. But you can buy it in Sweden and grow it in your garden. The researchers suggest that these commercial movements might help these species adapt as the climate changes. "While the debate on assisted migration continues," they write, "it is clear that, across the planet, we have already given many species an unintentional head start on climate change."
Undoubtedly true. But there are likely few mosses, lichens or invertebrates in those seed catalogs. People tend to care more about certain kinds of species. And thus, Hellmann says she doesn't think the approach is "a panacea for saving biodiversity under threat from climate change." "There are some species that are very important, and for the species that are really important, people will do it ... but I have a hard time imagining how we would apply it to all the beetles and the microbes, the vast majority of biodiversity. No one is going to pick them up and move them."