While the study found fewer species on farms than in agroforests, and fewer on agroforests than in forests, Şekercioğlu says it doesn't answer a key question: "Does the decline in the number species translate into a decline in individuals providing a given ecosystem service?" If so, farms and agroforests have lost birds that provide important insect-control, pollination and seed-dispersal services.
"It is possible you may lose a lot of species, but some of the remaining species increase in number and compensate and for the decline in ecosystem services by the lost species," he adds. "It's one of the biggest questions in ecology."
The Trend toward Sun Coffee
Noting that the study found forests have more tropical bird species than agroforests, which in turn have more bird species that open farms, Şekercioğlu says: "A lot of threatened species globally are found only in forests, and most of them disappear from agroforests and open agricultural areas."
He says many migratory birds that breed in the United States are in decline even though the nation has a law to protect them and not just because of U.S. environmental problems, "but due to problems in their wintering grounds in Latin America, such as loss of habitat and intensification of agriculture."
"Coffee was originally a mid- to high-elevation African forest understory plant," he adds. "For centuries in Ethiopia and parts of Central and South America, coffee has been grown as an understory plant with shade traditionally provided by native trees."
But fungi can be a problem in humid shade coffee plantations, and growers have come up with varieties that grow well in the sun with less fungus and bigger yields, so in recent decades, there has been a trend toward converting Central and South American shade-coffee forests to open farms, Şekercioğlu says
|Contact: Lee Siegel|
University of Utah