Shade-grown coffee preserves native tree diversity
Jeremy HanceDecember 23, 2008
Shade-grown coffee protects more than birds and bats
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"Shade coffee farms allow birds and bats to move and disperse seeds throughout the coffee landscape, promoting plant gene flow," said Shalene Jha, a graduate student whose interests in insects led her to studying shade-grown coffee farms. "This is unlike most agricultural systems, which do not provide habitat for seed dispersers, and thus limit the distance plant seeds can move. By supporting important seed dispersal processes, shade coffee farms maintain plant population gene flow across fragmented habitats."
When a habitat is fragmented, as is the case of many tropical habitats near agricultural regions, gene flow from one population of plant species to another becomes increasingly difficult. If gene flow is constricted it can lead to inbreeding and even extinction.
 Coffee bush. |
"More than 60 percent of the earth's surface is managed by humans as agriculture or pasture, and these landscapes provide us with a great opportunity to support native biodiversity," Jha said. "Many studies have shown that conserving native biodiversity in agricultural systems can actually benefit crops—by preventing pest outbreaks and providing native pollinator services. Our study shows that agricultural crops can also benefit native trees living across the landscape."
Shade coffee farms have a production life of around a century, after the production life ends the farm can become a key place for reforestation projects, since the area already has a jump start toward second-growth forests with a number of native trees and wildlife.
Despite the ecological importance of shade-grown coffee, many farmers are feeling pressure to change traditional farms into coffee monocultures because of increasing demand for coffee. "A lot of the rustic coffee farms are turning into sun-intensive operations, where farmers cut down the overstory and try to level out the fields so it's easier to get machines in," Jha said.
A prior study showed that traditional farms in Mexico retain about 94-97 percent more bird species than industrialized monoculture farms. In addition, monoculture farms require large amounts of pesticides and fertilizers in order to remain viable. While monoculture farms produce more coffee than traditional ones, Jha believes that shade-grown coffee is imperative to ensuring habitat and long-term sustainability.
"It's more essential than ever to pay attention to the ecological benefits shade coffee farms provide,” she explains.
Shalene Jha and Christopher Dick. Shade coffee trees promote genetic diversity of native trees. Current Biology, Volume 18, Issue 24, December 23rd, 2008.
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