Conservation: Dollars and sense

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  • 2005 Nature Publishing Group

    the rare and endangered or on protectingspecies diversity. Instead, they say, decisionsneed to be made within a rigorous economicframework. Some argue that the key to effec-tive conservation is quantifying and promotingthe economic services that ecosystems providefor people a mantra that has gained momen-tum with the completion this year of the mostcomprehensive survey yet of these benefits, theMillennium Ecosystem Assessment2.

    At the same time, conservationists are beingurged to develop better tools to measure theeffectiveness of their projects, and to sharedata on best practice. In other words, say crit-ics, its time for the organizations involved inconservation to admit that they are fallible,and to learn from past mistakes (see Takingquackery out of conservation, overleaf).

    On the spotIn recent years, the field of conservation biol-ogy has been dominated by the goal of pre-serving biodiversity a slippery concept,which can be defined in various ways. Themost dramatic push came from an article3published in 1988 by Norman Myers, then atCornell University in Ithaca, New York. His

    paper introduced the idea of biodiversityhotspots. To earn hotspot status, Myers said, aregion must contain 1,500 or more endemicplant species, which are found in that area butnowhere else, and it must have lost at least 70%of its original habitat. Myers identified tenareas of tropical forest as hotspots on the basisof these criteria.

    It was a seductive idea: focusing scarceresources for conservation on hotspots offeredmaximum bang for buck. Conservation Inter-national, one of the leading organizations inthe field, adopted the idea as its guiding prin-ciple in 1989. And subsequent analyses byMyers and others extended the concept fromtropical forests to other habitat types and taxo-nomic groups4.

    Conservation International, based in Wash-ington DC, now recognizes 34 hotspots. Theseoccupy just 2.3% of the Earths land surface, yetare the sole home of half the worlds vascularplant species and 42% of terrestrial vertebrates.

    Conservation Internationals maps havebeen an incredible political tool, says IanOwens, a conservation biologist at ImperialCollege London. They made rescuing bio-diversity seem achievable.

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    Approaches to conservation that seek to protect the most endangered species have had onlymixed success. Is it time to move away from biodiversity hotspots and stress the economic valueof ecosystems? Lucy Odling-Smee investigates.

    Dollars and sense

    The Florida panther is living on theedge. Once, these majestic catsprowled throughout the southeast-ern United States. But today, fewer

    than 90 of the creatures cling to fragments ofhabitat in southern Florida. And not everyoneagrees that efforts to save this subspecies makeeconomic or scientific sense.

    Male Florida panthers (Puma concolorcoryi) stalk hunting grounds that average 550square kilometres. Given the exorbitant costof land in the Sunshine State, protecting suffi-cient habitat to support a population viableover the long term is a tall order. Andalthough some argue that protecting the panther will rescue other threatened animalsand plants along the way, this remains littlemore than an article of faith. Even the pan-thers evolutionary heritage has been calledinto question: genetic studies suggest that it isnot as distinct from other subspecies ofmountain lion as was once thought1.

    Attempts to save the Florida panther epito-mize an approach to conservation that isincreasingly coming under fire. A new, hard-headed breed of conservationists say weshould not concentrate exclusively on saving

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  • 2005 Nature Publishing Group

    NATURE|Vol 437|29 September 2005 NEWS FEATURE


    But recently, the hotspot concept has comeunder fire. Analyses have revealed an alarminglack of overlap between hotspots identifiedusing different criteria5,6 (see map, below).And some experts argue that focusing on biodiversity hotspots is fundamentally mis-guided. Its like being a butterfly collector orhaving a zoo in which you protect a tiny sample of the Earth, says Peter Kareiva, a leadscientist for The Nature Conservancy, based in Arlington, Virginia. Meanwhile, you could beignoring ecosystems that are hugely importantto humankind.

    Hotspots are questions waiting foranswers, concludes Hugh Possingham, amathematician and conservation biologist atthe University of Queensland in Brisbane,Australia. He echoes Kareivas call for empha-sis on the importance of ecosystems to people,and wants conservation biologists to embracethe tools of decision theory. This theory iswidely used in planning by engineers andfinancial advisers to work out how their funds

    should best be allocated. Mapping more of theworlds biodiversity hotspots is like fixing theantenna on your car when the engines broken,Possingham quips.

    Possingham and his colleagues argue thatspending money on those areas containing themost species at risk of extinction isnt neces-sarily the best strategy. Often, these are areas inwhich there is a small chance of success because of overwhelming development pressure or official corruption, for example. Inmany cases the future of areas with fewerthreatened species can be secured more easilyand cheaply, he says.

    In their current work, as yet unpublished,Possingham and his colleagues are using deci-sion theory to lay economic factors over themaps of priority areas used by major conser-vation organizations. After plugging in thecost of action which depends on factorssuch as land prices and human populationdensity their algorithms churn out an opti-mized strategy for allocating a limited pot of

    conservation funds. Kareiva sees Possinghamsanalyses as an early sign of a much-neededshift in thinking. The whole conservationmovement needs to deal more with people andwith ecosystem services, he says. If it did so,he suggests, greater emphasis would be givento habitats such as the vast tracts of boreal for-est that stretch from Russia to Canada. Nick-named the worlds lung, this habitat is animportant carbon sink, providing a naturalbrake on the greenhouse effect, and it isarguably the planets most important nitrogen-fixing ecosystem. Yet boreal forests are not apriority for several major international con-servation groups.

    Service not includedNatural ecosystems provide a wide variety ofresources that have a social and economicvalue. These include services, such as cleanwater, stable soils and protection against nat-ural catastrophes, and potential benefits, suchas a storehouse of biodiversity from whichdrugs might be discovered. But studies toquantify these benefits, especially the financialcosts and gains attached to protecting them,are only just beginning to gain momentum.

    Preliminary results are eye-opening. Recentresearch indicates that the catastrophic loss oflife seen in the Asian tsunami of 26 December2004 could have been lessened had the clear-ance of Sri Lankan mangrove forests been prevented7. In Costa Rica, experiments haveshown that maintaining a patch of forest, andso a supply of pollinators, near coffee planta-tions increases coffee yields by 20% an economic gain that easily matches revenuesobtained by converting the forest to farmland8.

    At least now there is a solid base on which tobuild further analyses of the costs and benefitsof protecting specific ecosystems: the Millen-nium Ecosystem Assessment. Requested byUnited Nations secretary-general Kofi Annan,

    Counting costs: humans need vast forests (above), but these may be ignored if conservationists focus on the Florida panther (left) or hotspots in Peru (right).

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    it has been drawn up by more than 1,300researchers from 95 nations over four years. Itreviews the state of 24 different ecosystem services from easily measured benefits,such as the provision of food, to elusive ones,which include the regulation of air quality andclimate. Of these 24 services, 60% are beingdegraded, and fast2.

    Those involved in the assessment are disap-pointed with the response so far from theworlds media and politicians. If you went outand said weve looked at 24 indicators of eco-nomic well-being, and only four of them areimproving, and of those four, one is about tocrash, the world would panic, says GeorginaMace, a conservation biologist with the Zoo-logical Society of London. The problem, shesuggests, is that people arent yet used to think-ing about the environment as an economicresource.

    Capital ideasNevertheless, the message is being picked upby influential figures within the conservationmovement. Among the converts is Eric Diner-stein, chief scientist with the WWF, formerlythe World Wide Fund for Nature, in Washing-ton DC. I dont think conservationists havesufficiently exploited the value of certain habi-tats that maintain services essential for humanlife and welfare, he says.

    Eager to capitalize on this approach, theWWF is planning a scheme called hydro-sheds. This will use climate and hydrologicalmodels to identify the places w