Saturday, December 27, 2008

Shade Grown Coffee: Delicious and Better for the Planet

There's news out today about the big differences in coffee quality, and how some of the very best coffees in the world come from what are called "shade coffee farms." These farms grow coffee under a canopy of multiple tree species, and they not only harbor native birds, bats and other beneficial creatures, but the farms also also maintain the genetic diversity of native tree species. 

Researchers are now showing how these shade coffee farms can act as focal points for tropical forest regeneration. The findings come from a study published by University of Michigan researchers Shalene Jha and Christopher Dick in the Dec. 23 issue of the journal Current Biology.

Typical of many coffee farms in the area, the three farms in this study were clear-cut and burned in the late 1930s and immediately replanted with coffee bushes and canopy tree species, including nitrogen-fixing legumes and fruit trees. Since then, farmers have allowed local trees such as Miconia to invade because they help prevent soil erosion. These trees spread into the farms when birds and bats carry their seeds from "mother trees."

"We found that clustered trees in the forest were highly related to one another, suggesting that the seeds are not moving far from the mother trees," said Jha. "In the coffee farms, however, even in close clusters, the trees were very distinct from one another genetically, indicating that the seeds came from multiple mothers." The difference likely occurs because small, forest-dwelling birds like the chestnut-sided warbler are the main seed carriers in forested areas, while large, ubiquitous birds like the clay-colored thrush spread seeds throughout coffee farms.

Lower genetic diversity is a concern in agricultural areas because increasingly fragmented landscapes isolate native plant populations. But this study shows that shade coffee farms, by being hospitable to the right kind of birds, support widespread dispersal of native trees. What this has done, in effect, is to actually connect patches of surrounding forest. These farms have the potential of sewing up the forest -- from a fragmented state into a place of genetic diversity and healthy growth.

In addition, shade coffee farms may serve as reservoirs for future forest regeneration, as the farms typically fall out of production in less than a century. Given that potential---as well as their roles in connecting habitat patches, preserving genetic diversity and sheltering native wildlife---it is important to encourage this traditional style of agriculture.

In spite of the trendiness of shade coffee, the enormous demand for java is pressuring some farmers into converting their traditional farms to intensive, industrialized plantations.

"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," said Jha. "It's more essential than ever to pay attention to the ecological benefits shade coffee farms provide."

Please ask for "shade grown coffee" the next time you are at the market.


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