Forest bees ‘can boost coffee crops’

Conserving tropical forests could increase profits for coffee farmers in developing countries, according to research to be published next week in the Proceedings of the National Academy of Sciences. The study shows that the closer coffee bushes are planted to patches of forest, the more and better quality beans they produce because of greater pollination by wild bees.

The researchers, from the World Wide Fund for Nature, Stanford University and the University of Kansas, studied a Costa Rican coffee farm bordered by patches of intact forest. They selected five coffee plants at increasing distances from the forest patches. On each plant, two branches were pollinated by hand, and two were left to be pollinated naturally.

By comparing yields from each branch, the scientists were able to measure the contribution of wild insect pollinators, and how this varied with distance from the forest. They found that coffee plants within one kilometre of a forest patch had yields that were 20 per cent higher than plants further away. The plants close to the forest also had 27 per cent fewer ‘peabodies’, or misshapen seeds.

The explanation, suggest the scientists, is that the forest patches provide nesting sites for bees, which pollinate the coffee plants while foraging for nectar.

According to the researchers’ calculations, the extra pollination that bees provide increased the farm’s income by about US$60,000 in the 2002-2003 coffee season. This corresponds to seven per cent of the farm’s total income for that year.

The figure is similar to the total that could be earned in a year if the same area of forest were used as pasture for beef cattle or to grow sugar cane. If other ‘ecological services’, such as carbon storage and water purification, were included, the estimated value of conserving forest patches would increase.

“Policies that allow landowners to capture the value of pollination and other services could provide powerful incentives for forest conservation in some of the most biodiverse and threatened regions on Earth,” concludes the study.

The researchers also point out that the income provided by insect pollination is nearly ten times what farmers would be paid to maintain the same area of forest under Costa Rica’s Environmental Service Payments (ESP) Project, a scheme that provides financial incentives for conservation.

“The ESP program in Costa Rica is a great idea, and should be considered elsewhere,” says Taylor Ricketts of the World Wide Fund for Nature, who led the study. “Based on our results, though, it vastly underestimates the value of the services that conserved forest provides. Payments ideally should reflect this real value, as that is the ‘efficient’ economic result, but payments at almost any level are certainly a start.”

Ricketts believes the research findings are potentially applicable in most places coffee is grown. But he says that different varieties of Coffea arabica — the species of coffee grown in Costa Rica — grown worldwide may differ in their response to pollinators.

“The other coffee species, C. robusta, has a very different pollination ecology,” says Ricketts. “But studies on both species on several continents have consistently shown that bee activity declines with distance from native habitats.”

The researchers’ next steps will be to develop an outreach strategy based on their results, making recommendations to governments and coffee cooperatives in Costa Rica and elsewhere, Ricketts told SciDev.Net.

“I would also like to see whether a diverse, natural shade canopy can provide native pollinators right in the farms themselves,” says Ricketts. “This would help farmers be in more direct control of the pollination services on their farms.”