Sunday, October 12, 2008

Shade Coffee and Climate Change

Many environmentalists have been promoting shade-grown coffee as a way to protect important migratory bird habitat in Latin America. (Shade plantations, with their layered vegetative structure, have much higher bird diversity than sun plantations.) This growing arrangement, which is actually the traditional way of farming coffee, may also benefit coffee producers. Shade coffee plants appear to survive extreme weather events in much better condition than their sun-grown counterparts.

In the October edition of the journal BioScience, three U-M researchers say shade-growing also shields coffee plants during extreme weather events, such as droughts and severe storms. Climate models predict that extreme weather events will become increasingly common in the coming decades, as the levels of heat-trapping carbon dioxide gas continue to mount.

The U-M scientists warn Latin American farmers of the risks tied to "coffee-intensification programs"---a package of technologies that includes the thinning of canopies and the use of high-yield coffee strains that grow best in direct sunlight---and urge them to consider the greener alternative: shade-grown coffee....

The livelihoods of more than 100 million people worldwide are tied to coffee production. In Latin America, most coffee farms lack irrigation---relying solely on rainwater---which makes them especially vulnerable to drought and heat waves.

Shade trees help dampen the effects of drought and heat waves by maintaining a cool, moist microclimate beneath the canopy. The optimal temperature range for growing common Arabica coffee is 64 to 70 degrees Fahrenheit.

Shade trees also act as windbreaks during storms and help reduce runoff and erosion.
Another benefit is that shade coffee plants often have higher yields because more pollinators are available for fertilization.