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Article: As climate shifts, should we fight it?

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  • Robert Karl Stonjek
    As climate shifts, should we fight it? Disappearing savannas in South Africa s Kruger National Park are forcing scientists to reconsider what conservation
    Message 1 of 1 , Nov 6, 2007

      As climate shifts, should we fight it?

      Disappearing savannas in South Africa's Kruger National Park are forcing scientists to reconsider what conservation means

      Charging elephant

      Elephants and leopards are moving in to the Kruger National Park, South Africa's premier game reserve, while zebras and wildebeest are moving out. They are all possibly victims of global warming. (Tribune photo by E. Jason Wambsgans / January 26, 2007)

      By Laurie Goering Tribune foreign correspondent
      8:08 AM CDT, November 2, 2007
      KRUGER NATIONAL PARK, South Africa - Fourth in a series

      Something unexpected is happening in the grasslands of South Africa's premier game reserve, forcing grazers like zebras and wildebeest to move out of some areas while tree-loving species like elephants and leopards move in.

      The savannas, home to the continent's great grazing herds, are starting to disappear, possible victims of global warming.
      For the first time in eons, fast-increasing levels of carbon dioxide in the atmosphere seem to be giving shrubs and trees a competitive advantage over grass, leaving once-open areas vulnerable to encroaching vegetation.

      Noting the invasion of underbrush with alarm, conservation scientists say climate change is presenting them with a new challenge: to adapt their thinking about an environment that is changing before their eyes. Long trained to protect intact ecosystems, they must now ponder once unthinkable questions, such as whether it is still appropriate to protect every species and manage every terrain, or whether the future of some plant and animal life should be left to the whims of a natural world in flux.

      South Africa's environmental rethink is part of a much bigger shift, an awareness of global warming that was given a dramatic jolt last month when former Vice President Al Gore was given the Nobel Peace Prize along with a UN panel for their roles in educating the public on climate change.

      Businesses, governments and people around the planet are searching for solutions to the vexing problems presented by climate change, including efforts to harness new technologies, accept daily lifestyle changes or, in the case of the African grasslands, reconsider long-standing beliefs.

      "The whole idea of conservation is based around stasis, of things being the way they always were. But that's not a tenable way of doing conservation in the future," said Robert Scholes, a leading systems ecologist and climate specialist in South Africa, which is at the forefront of the international effort to rethink conservation's mission.

      With nature reorganizing itself around the world, "a relaxation of our very purist paradigms about conservation is almost certainly called for," said Scholes, who works for South Africa's Council for Scientific and Industrial Research.

      In South Africa, researchers and park managers are racing to understand the changes under way in some of Africa's best-known nature reserves and to come up with plans to deal with savannas that are quickly coming to resemble thickets more than open plains. What they discover and what they decide will likely guide a new international conservation ethic for an altered age.

      "We've passed the point where we can avoid things being different," said Barend Erasmus, a researcher on climate change and biodiversity at the University of the Witwatersrand in Johannesburg. But "I think we will know enough to do something. I think we can come up with good common-sense solutions."
      Ecosystems being reshaped

      Small climate shifts already are having a dramatic effect on natural areas across the planet. In most places, some species are thriving in altered climate conditions while others falter, a process that is reshaping ecosystems. Butterflies, frogs, antelopes, flowers and other plants and animals are trying to migrate toward more suitable habitat, but many find their way blocked by the boundaries of existing parks or the sprawl of roads and cities.

      Conservation officials, hoping to preserve as much biological diversity as possible, are talking about things they once dismissed as lunacy: gene banks, cloning and even "assisted migration" -- loading plants and animals on trucks to help them get to new, more suitable habitats.

      But worldwide recognition is growing that there are limits to what can be saved. A longtime focus on ensuring no species goes extinct is giving way among some leading scientists to an acceptance that thousands, if not tens of thousands, of species will likely succumb to climate shifts in coming years.

      A key laboratory for this work and worry is Kruger National Park, a 240-mile-long finger of land along South Africa's eastern border with Mozambique.

      Kruger, one of the best-studied conservation areas in Africa is home to Africa's iconic Big Five -- elephants, lions, leopards, Cape buffalo and rhinos -- and draws more than 1.2 million visitors a year. The Wales-size park is also home to dozens of South African and international researchers, who over most of the last century have helped keep meticulous records on everything from the size of the park's elephant population to the water quality of its rivers.

      The park, unlike many in Africa, is intensively managed. Artificial watering holes help support game in some of the driest areas of the park, and controlled fires are used to help weed out brush. Scientists in recent years have developed a management program for the reserve based on "thresholds of potential concern" -- key rises or dips in animal and plant populations or things like river flow as an indicator of impending problems.

      By that standard, Kruger already has major worries. Water flow and quality are declining as development accelerates along the unprotected headwaters of the park's main rivers. A growing elephant population is contributing to the loss of many of the reserve's big trees.

      But park managers in recent years have encountered a new problem as well: bush encroachment, or the invasion of Kruger's open grasslands by woody shrubs and small trees.
      In South Africa, fast-increasing levels of carbon dioxide in the atmosphere are giving an edge to shrubs and trees, which build their woody skeletons out of carbon, while pushing out savanna grasses, which many scientists believe evolved to live in a low carbon dioxide world. In parts of Kruger, slow-growing shrubs and small trees once kept in check by fire and hungry elephants are now shooting up in a tenth of the time it used to take them and turning open grasslands into thickets.

      "Somewhere in the 20th Century, we've created super trees," said William Bond, a University of Cape Town botanist, who has been digging up young acacias in Kruger to study their increasingly hefty roots. "I'm convinced things have changed in an extraordinary way."

      'The end of the savannas'

      Whether those changes extend to the earth's other savannas -- a dominant ecosystem that today covers a fifth of the planet's land surface -- remains in question, because studies in many places have yet to begin or are not yet conclusive. But savannas from northern Australia to South America and the U.S. Midwest potentially could be similarly affected, Bond said.

      So far, bush encroachment hasn't reached the top of the list of Kruger's concerns but Bond thinks that is about to change. Research in several of South Africa's nature reserves and in his lab, in a series of greenhouses where acacias are growing in different carbon dioxide concentrations, has persuaded him that mounting levels of carbon dioxide in the atmosphere mean that savannas are on their way out as one of the earth's dominant ecosystem.

      With hands rough and discolored from days of digging in the soil, he pulls out maps from 2004 that show brush and scrub forest covering 58 percent of another study area in South Africa's Hluhluwe-Imfolozi game reserve, up from 15 percent in 1937. Adjoining privately owned range land and communally held village land, regularly scoured by scrub-eating goats, show similarly impressive jumps. Altogether, a 1989 study shows, 65 percent of South Africa's savannas are now severely encroached by brush.

      "This is a complete biome switch, the end of the savannas," Bond predicted. In South Africa, "we see the same fires, the same rainfall variation, the same animals. But the trees have gone crazy. It looks like a global driver."

      Not everyone agrees with Bond. Many scientists say that while intensifying carbon dioxide in the atmosphere appears to favor trees and brush over grasses, the advantages may be subtle or disappear altogether depending on other factors like rainfall, temperature and soil nutrients.

      Redefining 'natural'

      But if bush encroachment continues, managers at Kruger admit they may soon need to find a way to confront it, whether or not it is "natural" in a transforming climate.

      "Rangers who have been here a long time say it's thicker, that Kruger is changing. Tourists complain they can't see game like they used to, that all they see are thick curtains of bush," said Stefanie Freitag-Ronaldson, science operations manager at Kruger.

      "If by 2020 or 2050, what is natural is uniform thicket across Kruger, we might try to find a way to flout that," added Harry Biggs, Kruger's expert on adaptive biodiversity. "One of our values is the park should be natural. But what is natural is a hard question anymore."

      Kruger's managers are gradually coming to accept that some of the coming changes may be unstoppable. For reasons they don't fully understand, the park's populations of roan and sable antelope have plunged in recent years despite costly attempts to rebuild the herds. The handsome grazers may soon simply be allowed to go extinct in the park.

      Most of the world's conservation efforts over the last century have focused on setting aside key pieces of land to preserve ecosystems and help ensure no species goes extinct. But as the Earth's climate changes, a growing flood of extinctions are inevitable, many scientists say. A 2004 study, "Extinction Risk from Climate Change," published in the journal Nature by some of the world's top conservation climate experts estimates that by 2050 between 15 percent and 37 percent of species in the world's most biologically rich habitats will be on the path to extinction if the climate alters even moderately.

      That could be reduced if nations quickly and dramatically cut greenhouse gas emissions -- something most people now agree is unlikely -- or if conservation reserves can be added or expanded to give species fleeing new climate stresses somewhere to go.

      Competition for land is increasingly intense, and conservation will have to compete with other political priorities.

      Still, efforts are under way in some places. With warming oceans fast destroying coral reefs worldwide, conservation organizations are racing by year's end to set up some of the world's first marine parks designed to buffer the effects of climate change. The parks, in the Indian Ocean, will set aside areas where natural up-wellings of cold water offer the potential to protect fragile coral, said Lee Hannah, a climate specialist with Washington-based Conservation International, and one of the authors of the paper on predicted extinctions.

      New conservation arguments

      South Africa similarly has expanded nature reserves in the direction that some highly endangered members of its unique Cape floral kingdom are migrating. And Kruger itself has in recent years taken down fences on its border with neighboring Mozambique conservation areas to create a bigger new "trans-frontier" park with more room for animals to move.

      But a growing number of scientists believe the future success of conservation efforts will be determined by how well plants and animals are protected outside parks. As species migrate in response to climate stresses, some will inevitably move onto private land, where their reception may determine their ultimate survival.

      Around Kruger, conservationists used to convincing the reserve's neighbors of the economic benefits of having wildlife next door are now trying to convince them of the benefits of having wildlife on their own land. Citrus farmers, forest plantation owners and villagers around the park are being urged to try no-till farming, use fewer pesticides and leave natural corridors for plants and animals moving in response to climate stresses, all part of an effort to create a broader "matrix" of habitat where pressured species can survive.

      Persuading governments and wildlife groups to abandon old ideas about conservation in favor of a new ethic won't be easy. Kevin Rogers, a University of the Witwatersrand ecologist who helped write Kruger's adaptive management plan, predicts the rise of a new era of "greenies and bunny huggers" virulently opposed to allowing species to slip into extinction. Even pragmatic nature lovers may wince at the idea that emblematic species like the blue crane -- South Africa's endangered national bird that nests in grasslands -- may no longer have a place in an altered world.

      Of course it's possible that species may ultimately prove more adaptable than scientists think. While the most fragile, sensitive and specialized likely will perish, their demise will leave openings for competitors to exploit, Rogers said. The Earth's plants and animals have evolved in changing climate conditions over thousands of years, and may still retain hidden abilities to adapt.

      At Kruger, rethinking old models is already the new way of doing business. In essence, park managers recognize that ecosystems and the processes that affect them, including climate change, are more complicated and unpredictable than scientists previously imagined.

      Nature is "in a continuous state of flux and not in balance," Rogers said. With Kruger managers now thinking along those lines, "they're as well set up as anywhere, if not better than anywhere" to respond, he said.

      "We're still in Act 1 of this play," Biggs said, pausing in a hallway at the park's headquarters. "We can hear the big monster coming, but we're still getting the chairs arranged on stage."
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      Robert Karl Stonjek
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