Preserving water supplies can alleviate poverty. Credit: M. OSTERGAARD/PANOS

World leaders will gather at the United Nations in New York next week to discuss progress on two goals said to be complementary: saving species and lifting people out of poverty. Conservationists often claim that efforts to preserve biodiversity can also benefit the people who rely on natural resources for food and income, and since 2002, the UN Convention on Biological Diversity has linked its conservation plans to poverty alleviation.

Yet despite many small-scale, often anecdotal studies, the evidence for a link is inconclusive. Many studies have simply shown that poverty frequently overlaps with areas that are a high priority for biodiversity conservation.

Disappointing progress on two of the UN's Millennium Development Goals — stemming the loss of biodiversity by 2010, and lifting half of the world's poorest people out of poverty by 2015 — has focused high-level political interest on potential synergies between the two. So researchers are now tackling wider studies. These projects are finding that although conservationists' optimism is sometimes borne out, synergy can't be taken for granted.

Last year, Will Turner, a researcher at Conservation International, a non-profit agency headquartered in Arlington, Virginia, and his colleagues completed a global assessment of the question, drawing on maps illustrating the extent and function of 17 different ecosystem services, such as water supplies from rivers and streams. The team used the maps to pin down who benefits from the services, and whether conserving these resources was likely to have a marked effect on poverty.

One set of maps drawn up by the international conservation group WWF, headquartered in Gland, Switzerland, used data collected during NASA's Shuttle Radar Topography Mission in 2000 to depict global water networks. Onto these, Turner and his colleagues overlaid LandScan data from the US Department of Energy's Oak Ridge National Laboratory in Tennessee, which uses satellite monitoring of indicators such as roads and land cover to estimate population. Using child malnutrition as a proxy, they estimated the poverty levels of the populations living along rivers shown on the maps.

The researchers then calculated how many people depended on the rivers for their water, whether they had access to other water sources, and how poor they were. They used this to assess whether conservation projects to protect these rivers could also improve people's livelihoods — for example, whether paying for upstream conservation would have knock-on benefits for everyone living along the river.

Saying it can’t be done is like saying we can’t achieve peace. ,

The study, as yet unpublished, showed that water conservation projects could aid poverty alleviation. The 16 other ecosystem services they assessed, including crop pollination by insects and waste treatment, showed similar results. "This suggests we should continue to push for biodiversity conservation and sustainable development where these synergies exist," says Turner.

But a study published last month by the International Institute for Environment and Development, a non-profit research organization based in London, offered less certainty. Linking Conservation and Poverty Alleviation: the Case of Great Apes ( reviewed existing projects to protect apes in Africa, and used follow-up interviews and other methods to assess whether these are helping to reduce the poverty of local communities.

"We can say that under some circumstances tourism generates lots of money," says co-author Chris Sandbrook, a conservation scientist at the University of Cambridge, UK. But the study was unable to clarify whether the money reaches the poorest people and genuinely leads to a reduction in poverty levels. One problem was the lack of good-quality socio-economic data about the conservation projects, he adds.

A UK-funded programme to catalogue and assess conservation and poverty reduction projects in Africa, South Asia, China and the Amazon should help unpick some of the confusion. The seven-year Ecosystem Services for Poverty Alleviation programme, announced at the end of last year, is being funded with more than £40 million (US$62 million) from the UK government's Department for International Development, the Natural Environment Research Council and the Economic and Social Research Council. The first call for projects will come in the next few weeks.

Bill Adams, who studies conservation and poverty at the University of Cambridge, says that conservation and poverty alleviation are not natural bedfellows, not least because development usually goes hand in hand with greater consumption of natural resources. "They are not in principle incompatible, but most ways of doing poverty alleviation are not good for the environment," he says.

Political leaders must be prepared to make tough choices about where to focus efforts to alleviate poverty, even if there are negative impacts on biodiversity, he adds. But that should not stop them from seeking ways to achieve both. "Saying it can't be done is like saying we can't achieve peace," says Adams. "Maybe we can't stop biodiversity loss and lift people out of poverty at the same time, but we have to try to make it work."