New Scientist, 5 July 2008
Nature 2.0
Preserving the status quo is no longer an option for conservationists, says Sharon Oosthoek
FOR nearly a decade the forests of British Columbia have been ravaged by an infestation of mountain pine beetles. In March, government experts announced that the pest would soon run out of food. Now comes the hard part – restoring the devastated ecosystem without allowing the beetle to make a comeback. To add to the problem, these forests have been fundamentally altered in recent years by warmer winters, drier summers and polices to prevent fires. Returning them to their former state is not an option – instead conservationists must find a way to create forests that can cope with change.
Their challenge is far from unique. More and more these days, conservationists are struggling like harried triage doctors to protect plants and animals in the face of rapid human-induced changes. This has led some to question the very essence of what they do. Conservation is, by definition, about maintaining the status quo, yet this may no longer be possible, given that pollution, climate change, exotic species invasions, extinctions and land fragmentation are altering almost every ecosystem on the planet.
Earlier this year, ecologist Timothy Seastedt from the University of Colorado and colleagues urged conservationists to reassess their role. “The point is not to think outside the box, but to recognise that the box itself has moved, and in the 21st century, will continue to move increasingly rapidly,” they wrote (Frontiers in Ecology and the Environment, vol 6).
Seastedt is just one voice in a growing chorus of scientists who are recommending a radical shift in thinking about the role of conservation. Rather than trying to preserve nature in aspic, they say we should work with change. We need to focus on optimising genetic and species diversity with an eye towards helping plants and animals adapt, rather than trying to return ecosystems to their historic or natural state.
It may sound like common sense, but some of the practical implications are dramatic. For a start, conservationists should not be afraid to “reassemble” damaged ecosystems to improve them, say some scientists. That may mean introducing non-native or genetically selected species. Others argue we must acknowledge that species will cross-breed to adapt and nurture hybrids as a means of protecting biodiversity and preserving the genes of endangered species.
The approach makes many people nervous, to say the least, and there have been charges that it is tantamount to engineering nature. Susan Lieberman, director of the species programme for the World Wildlife Fund in Switzerland, acknowledges some of the environmental damage caused by human activity may be irreversible, but says she cannot accept the idea of reassembling ecosystems.
“There’s a certain arrogance to thinking we know what we’re doing,” she says. Seastedt counters that we are already engineering nature through our release of greenhouse gases and other pollutants, for example – but with considerably less forethought. He recommends a scientific approach with small-scale experiments, allowing ecologists to compare reassembled ecosystems with controls.
Of course, many conservation groups already factor environmental change into some of their decisions in ways that are not too controversial. The WWF is among those that consider the likely impacts of changing environments before deciding where to direct its efforts. “I look at it as triage,” says Lieberman. “Where are we going to get a return on our investment?” The Nature Conservancy, a worldwide conservation organisation with headquarters in Arlington, Virginia, has gone one step further. “This is so much on TNC’s mind, that we are hiring a scientist to focus on revising our planning tools so we can deal with this pace of change,” says chief scientist Peter Kareiva.
TNC has already started to overlay maps of predicted climate change onto sites where they plan to buy up land for conservation to see if those deals will make sense in the future. So far they have, says Kareiva. In addition, the group has started to target specific lands for conservation because it expects them to become more valuable as the climate shifts. For instance, in the south-eastern US, land slightly in from the coast is valuable for its potential. Rising sea levels may turn today’s nondescript inland habitats into tomorrow’s valuable marshes and wetlands, says Kareiva.
On the flip side, predictions of how environments will change have also left ecologists reluctantly accepting that they won’t be able to save some ecosystems. “Some places will be impossible to protect,” says Jim Harris, an ecologist at Cranfield University in Bedfordshire, UK. “For example, tropical cloud forests may disappear as they move up mountainsides.”
Harris also points to a study that suggests more carbon dioxide in the atmosphere will allow trees to invade the grass-dominated ecosystem of Africa’s savanna (Global Change Biology Global Change Biology, vol 6, p 865) If so, restoring the savannas may not be possible either. It is one thing to consider environmental change when it comes to choosing your conservation project, but working with change rather than against it may prove more controversial. Yet this is precisely the approach now being pioneered by some conservationists – including the British Columbian authorities whose task it is to regenerate forests devoured by pine beetles.
The forest covers more than half of the province – around 60 million hectares. It was originally about 20 per cent lodgepole pine – the most commonly logged species – together with a mixture of spruce, fir, hemlock, cedar and deciduous trees. Pine beetles are part of this ecosystem and cold has historically kept them under control, but in the mid-1990s increasingly warmer winters have allowed the pest to prosper. At the same time, mature stands of lodgepole pine – the beetles’ favourite food – increased significantly due to a deliberate policy to keep a tight control over naturally occurring fires. Beetle number soared and now the provincial government estimates that 76 per cent of the merchantable pine in the central and southern interior could have disappeared by 2015.
Not only are these woodlands a valuable source of timber, they also perform other important functions such as filtering water, which dilutes pollutants and reduces erosion. In addition, they absorb carbon dioxide from the atmosphere – although a new study reveals that they are likely to change from a minor carbon sink into a major producer of carbon if the beetle onslaught continues (Nature, 23 April 2008, p 987).
No wonder the British Columbia authorities consider restoration essential – but how to go about it? Clearly, reintroducing cold winters and setting fires that could threaten homes and businesses are not viable solutions: but selecting trees that can cope with the new conditions might just work. With this in mind, the government is already planting lodgepole pine seedlings from its own nurseries chosen because their parents were faster-growing, bigger trees. If loggers can harvest these earlier than in the past, there would be no large stands of mature pines so beloved by the beetles. Government scientists are also studying lodgepoles that have somehow managed to survive the onslaught of beetles. These might have just the right mix of genes to resist attack, says the province’s chief forester Jim Snetsinger. Meanwhile, the province is upping the percentage of native spruce in some replanted areas because these are less susceptible to attack by the pine beetle.
In Australia, conservationists are pondering similar issues. In areas where over-clearing and fragmentation has occurred, researchers are considering how they might reassemble ecosystems, while at the same time making them resistant to the kind of drought that has raged across most of the country since 2003. In the south-west, where two-thirds of the vegetation has been cleared for farming, several NGOs are working to create a wildlife corridor by rehabilitating more than 1000 kilometres ecosystems that used to be connected. These range from the woodlands of the drier interior to the tall wet forests in the far south-west corner.
“People are thinking of bringing species from drier areas. It is being discussed. There are research programmes underway to see if it’s possible,” says Richard Hobbs, a restoration ecologist with Murdoch University in West Australia. “Some would say it’s not nearly as valuable as the original ecosystem, but it is an ecosystem.”
This kind of large-scale rehabilitation raises the question of how conservationists would know when to try active intervention to improve the prospects of a struggling ecosystem. The spectre of rising salinity in south-western Australian farmlands makes a strong case for intervention – replanting deep rooted vegetation will help retain moisture, so reducing salt levels in the soil. But some experts feel that in other ecosystems a more traditional approach to conservation is preferable. “The best way to maintain diversity in the face of change is by protecting places that have all the working parts, that will be more resilient to change and allow species to move across the landscape,” says Jeff Wells, scientific advisor to the Pew Charitable Trust’s International Boreal Conservation Campaign.
The northern boreal forest is a case in point. Consisting of 25 million square kilometres, or 11 per cent of the Earth’s surface, it stretches from Alaska and northern Canada to Norway, Sweden and Finland, into Russia and parts of China, Korea and Japan. Wells and others argue that because this forest is relatively unfragmented, it may become a refuge for climate-stressed species – at least those that can move. Kept intact, it will also continue to act as a massive carbon sink that could slow down the rate of climate change.
However, just 10 per cent of the boreal forest is protected and the rest is under growing pressure from developers. What’s needed here, according to Wells, is not ecosystem engineering but governments moving swiftly to protect species diversity. Although Wells favours traditional conservation methods, he admits that the future will bring novel challenges. “Climate change is going to cause new combinations of species and communities that haven’t been seen in recent human history,” he says. “The question is how to develop conservation with the recognition that things are changing more rapidly than in the past.”
At least conservationists can all agree on one thing – the need to preserve the diversity of both species and genes. Not all species will survive higher temperatures or more precipitation but, when it comes to maintaining functional ecosystems, diversity provides an insurance policy. “It’s like a diversified stock portfolio. The more variety you have, the more likely you’ll be able to withstand a major shift in the environment,” says Brad White, a wildlife geneticist at Trent University in Peterborough, Canada.
Yet, even though this would seem uncontroversial the implications are dividing conservationists, as White’s research makes clear. A decade ago, he was the first to use genetic testing to show that all eastern wolves in Ontario’s 7630-square-kilometre Algonquin Park have some coyote DNA. Today, the wolves are designated as “of special concern” because the 2000 or so individuals left in Canada could easily become endangered. A federal management plan for eastern wolves is in the works, and should be ready later this year. The trouble is that the outcome will partly depend on whether officials consider that the hybrids are as worthy of protection as a pure-bred species.
White, for one, is in no doubt that they are. He points out that most North American wolves carry some coyote DNA and argues that hybrids are a natural consequence of environmental change. Instead of trying to prevent cross-breeding between endangered and non-endangered species we should allow them to evolve along with the changing habitats to which they are better suited, he says.
Genetic mixing between eastern wolves and coyotes began more than a century ago after settlers cut down forests to plant crops. Coyotes, who like open spaces, arrived in traditional wolf territory just as wolf populations were plummeting due to gun-toting settlers and deforestation. With so few of their own kind left to mate with, eastern wolves turned to the next best thing – coyotes.
More recent human-induced change is sure to create new hybrids too, as species change their habits in attempts to adapt. Some wildlife experts, for example, suggest that warmer temperatures in northern Canada could be prompting grizzlies to spend less time hibernating and more time roaming outside their traditional range, so coming into contact with polar bears more often.
In April 2006, an American sports hunter shot the first documented cross of a polar bear and grizzly in the Northwest Territories. Bear hybrids are not nearly as common as wolf/coyote crosses, nevertheless, this single “grizzlar” has provoked discussion among members of the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) who have to come up with a recommendation for dealing with hybrids.
The group – made up of experts from universities, NGOs and government – expects to send its report to the federal government later this year. Marco Festa-Bianchet, a biologist at the University of Sherbrooke in Quebec, who heads the group, describes the task as “godawfully complicated”. Hobbs agrees, but adds: “to say you shouldn’t think about it is like putting your head in the sand.”
Accepting hybrids as an inevitable consequence of ecosystem change and worthy of protection would be a new departure for conservationists. Nevertheless, Festa-Bianchet is wary of redefining conservation. The problem with focusing on adaptation rather than keeping things the way they are is that it becomes a “free-for-all”, he says. “It just becomes an excuse not to act.” Wells agrees. “People could say, ‘We have a lot of invasive species and things are missing from ecosystems, so let’s not worry about it.’ It could be translated into corporate policies that impact the environment with scientific approval.”
Others are more sympathetic to the idea that conservation should work with change rather than try to prevent it. Young Choi, an expert in botanical restoration at Purdue University in Indiana, likens the approach to a prosthetic leg: its purpose is to allow someone to walk rather than to restore the original flesh and bone. “Taking this analogy to our profession, a complete replica of the predisturbance ecosystem is not realistic because much of the damages in our environment are irreversible. All we can do for now is to rehabilitate certain ecological functions,” he writes (Restoration Ecology vol 15, page 351).
This rings true for Seastedt too. He stresses that he is not advocating a revolution in conservation, but instead pointing out that radical change may well be the only viable option given the damage we have already inflicted on the Earth. The status quo is not working, he says.
Sharon Oosthoek is a freelance writer based in Toronto