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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, it’s 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 article3

published in 1988 by Norman Myers, then atCornell University in Ithaca, New York. His

paper introduced the idea of biodiversity‘hotspots’. 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 Earth’s land surface, yetare the sole home of half the world’s vascularplant species and 42% of terrestrial vertebrates.

“Conservation International’s 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-ther’s 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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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. “It’s 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 Kareiva’s 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 theworld’s biodiversity hotspots is “like fixing theantenna on your car when the engine’s broken”,Possingham quips.

Possingham and his colleagues argue thatspending money on those areas containing themost species at risk of extinction isn’t 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 Possingham’sanalyses 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 world’s lung’, this habitat is animportant carbon sink, providing a naturalbrake on the greenhouse effect, and it isarguably the planet’s 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 theworld’s media and politicians. “If you went outand said we’ve 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 aren’t 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 don’t 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 where people gettheir water from. The goal is to produce aseries of maps that can convince governmentsof the merits of conserving habitats thatinclude economically important watersheds.

The practical difficulties of making sucharguments work, however, are daunting.Andrew Laurie is chief technical adviser to awetlands biodiversity project in China fundedby the United Nations Development Pro-gramme and the Global Environment Facility.As well as providing diverse habitats for ani-mal and plant species endemic to China, the

wetlands that Laurie is trying to protect act aswater purifiers, floodwater and climate regula-tors, and suppliers of grass and reed buildingmaterials. Although the overall cost–benefitanalysis gives a strong economic case for con-servation, the equation is different for localfarmers, who would lose the opportunity toconvert wetlands for their own use. Devisingspecific financial mechanisms to reward thesefarmers will be key to success.

In Laurie’s wetlands, there is at least a strongoverlap between protecting biodiversity andpromoting ecosystem services. Elsewhere, thisisn’t necessarily the case. Boreal forests, forinstance, fare poorly on standard measures ofbiodiversity. And economic arguments relat-ing to ecosystem services can, in some cases,usurp the goal of conserving wildlife. “You cancut down a mountain-top forest that has a lotof rare endemics, plant eucalyptus and proba-bly get the same watershed benefit from the

introduced exotics as you would from nativeplants,” Dinerstein admits.

Indeed, many conservation biologists areconcerned that giving natural habitat a mon-etary value risks losing sight of the ethicaland spiritual dimensions of conservation —driving forces in campaigns such as those tosave the Florida panther.

“We mustn’t rely only on an ecosystem-services approach because it misses out somuch,” says Laurie. “The argument that onlyby instilling respect for life are we going to getanywhere with conservation still carries a lotof weight.”

But against the backdrop of environmentaldevastation now gripping the planet, and thescant resources devoted to conservation,there is a growing realization that economicarguments must become a key weapon in themovement’s arsenal. “If conservation is tohave any chance of being relevant in the nextcentury,” warns Kareiva, “it will only bebecause we have figured out how to protectecosystem services at the same time as weprotect biodiversity.” ■

Lucy Odling-Smee is a subeditor for Nature.

1. Culver, M., Johnson, W. E., Pecon-Slattery, J. & O’Brien, S. J.J. Hered. 91, 186–197 (2000).

2. Ecosystems and Human Well-Being: Synthesis Report —Millennium Ecosystem Assessment (Island Press,Washington DC, 2005).

3. Myers, N. Environmentalist 8, 187–208 (1988).4. Myers, N., Mittermeier, R. A., Mittermeier, C. G.,

da Fonseca, G. A. B. & Kent, J. Nature 403, 853–858 (2000).5. Possingham, H. P. & Wilson, K. A. Nature 436, 919–920

(2005).6. Orme, C. D. L. et al. Nature 436, 1016–1019 (2005).7. Dahdouh-Guebas, F. et al. Curr. Biol. 15, R443–R447 (2005).8. Ricketts, T. H., Daily, G. C., Ehrlich, P. R. & Michener, C. D.

Proc. Natl Acad. Sci. USA 101, 12579–12582 (2004). 9. Sutherland, W. J., Pullin, A. S., Dolman, P. M. & Knight, T. M.

Trends Ecol. Evol. 19, 305–308 (2004).

TAKING QUACKERY OUT OF CONSERVATIONMichael Wright knows he isn’tbeing told the whole truth. Thedirector of conservation andsustainable development for the Chicago-based MacArthurFoundation, Wright says he “fallsout of his chair” if any of hisgrantees admit that their planshave misfired. “You get aproposal that says, ‘Here are thethings we want to do in the nextthree years’, and then you get areport that says everything wentaccording to plan,” he says.

The true picture cannot bequite so rosy, Wright argues. But,in a field dominated by a fewlarge organizations that rely ongoodwill from foundations andthe public to keep the moneyflowing, few conservationists arebrave enough to admit to failure.“As much as fear of donors, it’sinstitutional egos betweenorganizations,” says Wright.

In the past few years, effortshave been launched to makeevaluation more rigorous andtransparent. The three-year-oldConservation MeasuresPartnership, for instance, drawstogether big players in the field tocreate a common framework fordeciding whether a project hassucceeded. One goal is toharmonize terminology: forexample, what ConservationInternational calls ‘pressures’ ona habitat or species, the WWFcalls ‘threats’.

But measuring the effectivenessof a particular project is only thestart — the data must bedisseminated to be useful. Oneattempt to do this is the websiteConservationEvidence.com, runby William Sutherland of theUniversity of East Anglia inNorwich, UK. The site acceptsvarious accounts of how

interventions have gone, fromjournal articles to reports fromwildlife managers. Severalaccounts of an issue are reviewedby an expert and encapsulated inan easy-to-read summary.

“I became increasingly uneasy about the fact thatconservationists just makepronouncements about what is ‘the right way’,” explainsSutherland. He surveyed thepeople in eastern England whodo the real work of conservation,such as park managers, andfound that they get only 2.4% oftheir information from primaryscientific literature9. His idea, he says, is to emulate theevidence-based medicinerevolution launched in the 1970s,in which doctors began switchingfrom tradition and intuition — and sometimes ineffectivequackery — to remedies that

had been shown to work byscientific review.

The Centre for Evidence-BasedConservation at the University ofBirmingham, UK, has similargoals. Since its launch in 2003,the centre has put out reviews on such topics as whethercontrolled burning of uplandheaths helps to maintain floraldiversity. “Conservation hasstood still,” complains AndrewPullin, who heads the centre.“We’re still making the samemistakes. Until we can get criticalappraisal of our own actions, andmake it available, we are notgoing to advance.”

Nevertheless, both he andSutherland are optimistic thattheir approach will eventuallyprevail. “I think we will cause ashift in the way conservation isdone,” Pullin predicts.

Emma Marris

“The hotspot approach protects a tiny sample of the Earth.

Meanwhile you could be ignoringecosystems that are hugelyimportant to humankind.”

— Peter Kareiva

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