Conservation often seems to boil down to preserving the environment versus economic opportunity. If a given patch of land is saved, then a farmer will go hungry. If a marine reserve is created, then fisherfolk will lose their jobs. But two new studies demonstrate that intact ecosystems offer a variety of economic benefits, and preserving the environment may do more economic good than bad.

Robin Naidoo and Taylor Ricketts of the World Wildlife Fund (WWF) performed a classic cost-benefit analysis of the Mbaracay Forest Nature Reserve in eastern Paraguay, part of the disappearing Atlantic woods of South America. In the past 30 years this protected region has lost 34 percent of its tree cover to agriculture and cattle ranching as well as timber harvesting. The researchers rated the economic benefits derived from five ecosystem services: sustainable bush meat hunting; timber harvest; bioprospecting for pharmaceuticals; carbon storage; and so-called existence value, or the intrinsic value of nature "as a source of wonder and inspiration," the researchers write in the paper presenting their finding published yesterday in PLoS Biology. As for costs, the researchers calculated this as the agricultural value the land would have provided if deforested.

These costs ranged widely, as they were based in part on the probability that a given parcel of land would be converted to agriculture, but they reached as high as $927 per hectare in the easternmost portion of the reserve where soybean farming is present and profitable. On average, the overall cost hit $60 per hectare. The value of ecosystem services ranged widely as well: from $2 to $1,045 per hectare. Storing the carbon associated with global warming proved the most remunerative of the ecosystem services, providing roughly $378 of value over every hectare--despite a relatively low assumed price of carbon of $2.50 per metric ton. Bioprospecting delivered little benefit.

In the same issue of PLoS Biology, Kai Chan of the University of British Columbia and his colleagues examined the overlap between preserving ecosystem services, such as providing water or pollinating crops, and preserving overall biodiversity in the central coast region of California. They found that saving various ecosystem services would not preserve species--mostly because of the negative effects on crop pollination and forage production. But focusing on carbon storage, flood control, outdoor recreation and water provision as well as biodiversity protection delivered the least loss of species, according to the model. And preserving biodiversity would largely protect critical ecosystem services. "This [research] will help maximize the impact of scarce conservation dollars, allowing diverse partners to build common ground," Chan says.

Already, the Nature Conservancy, WWF and Stanford University have partnered to form the Natural Capital Project, an attempt to definitively assess the value of ecosystem services in the Sierra Nevada of California, the upper Yangtze River basin in China and the Eastern Arc Mountains of Tanzania. By knowing the value of the natural world, the researchers hope it will become worthwhile to save it. "Efforts to save wildlife often play out within a win-lose framework that pits conservation against economic opportunity," Chan adds. "The management of both land- and sea-scapes will produce far greater benefits for people when we analyze ecosystem services in a systematic fashion."