Research on coffee growing

Birds and other biodiversity / Research on coffee growing

Research: Birds and lizards as insect predators in shade coffee

Borkhataria, R. R., J. A. Collazo, and M. J. Groom.  2006.  Additive effects of vertebrate predators on insects in a Puerto Rican coffee plantation.  Ecological Applications 16:696-703.

The authors used an exclosure study to see if birds and lizards had an impact on the abundance of insects in a shade coffee plantation, in particular two that damage coffee (the coffee leafminer and flatid planthopper).  When birds or birds and lizards were excluded, the abundance of larger insects increased.  In particular, planthoppers increased greatly when birds were unable to prey upon them. The leafminers, which are serious pests of coffee and are small insects, increased if lizards were not able to prey on them.   

This study indicates that birds and lizards (which the senior author found more abundant in shade coffee than sun coffee in Puerto Rico, presented in her Masters’s thesis) may help control the numbers of some coffee pests in shade plantations. Another important finding is that neither birds nor lizards interfered with the numbers of other natural insect enemies of coffee pests, parasitoid wasps.

Birds and other biodiversity / Certifications / Research on coffee growing

Research: Biodiversity, yield, and certification

Perfecto, I., J. Vandermeer, A. Mas, and L. Soto Pinto. 2005.  Biodiversity, yield, and shade coffee certification.  Ecological Economics 54:435-446.

The more complex overstory (and thus shade) in a coffee plantation, the higher the diversity.  However, the more shade, the lower the yield (although the relationship is not strictly linear), as coffee grows best in about 35-60% shade.  Therefore, farmers have to be compensated for the lower yields if they preserve shade and biodiversity.  Since a switch to organic farming typically increases yield, while a switch to more shade-dense farming decreases yield, the premiums paid to farmers for growing certified shade coffee must be higher than those for certified organic coffee.

This paper outlines the factors and decisions that have to be taken into account to determine best way to define certification criteria that will effectively preserve biodiversity while keeping yields high enough so that financial premiums paid to farmers are not so high as to discourage consumption. Of course, not all premiums have to be paid by consumers; aid and conservation organizations can absorb some of the costs.  And the authors seem to agree with others that linking shade-grown certification with Fair Trade and organic certification could be effective as long as the premiums are high enough to offset reductions in yield.

Research on coffee growing

Research: Epiphytes in coffee plantations

These two recent papers looked at epiphytes (plants that grow on others, but are not parasitic, such as orchids or bromeliads) in coffee plantations — whether shade coffee plantations preserved epiphyte biodiversity, and whether epiphytes were important to birds. Under shade-grown coffee certification, the pruning or removal of epiphytes is discouraged.

Hietz, P.  2005.  Conservation of vascular epiphyte diversity in Mexican coffee plantations. Conservation Biology 19:391-399.

This study surveyed nine shade coffee plantations in Mexico and found 89 species of epiphytes in the plantations, and 104 in natural forests.  Plantations with smaller trees and less shade had fewer epiphytes.

Cruz-Angon, A. and R. Greenberg. 2005.  Are epiphytes important for birds in coffee plantations? An experimental assessment.  Journal of Applied Ecology 42:150-159.

Plots in which epiphytes were intact and plots in which they were removed were compared in the breeding and non-breeding seasons.  When epiphytes are removed, canopy cover, foraging locations, nest sites, and nest materials are eliminated and microclimate changes.

This study found that plots without epiphytes had less bird diversity. Eighteen forest bird species were significantly more abundant in plots with epiphytes, and resident species that used epiphytes for nesting were more abundant in these plots as well. Three non-forest bird species were more abundant in plots without epiphytes.

Birds and other biodiversity / Research on coffee growing

Research: Shade grown coffee and orchids

Solis-Montero, L., A. Flores-Palacios, and A. Cruz-Angon.  2005.  Shade-coffee plantations as refuges for tropical wild orchids in central Veracruz, Mexico.  Conservation Biology 19:908-916.

This paper in the journal Conservation Biology reports that shade coffee plantations in Mexico provide refuge for orchids from lower montane cloud forest habitats — the most endangered forest type in the country, now comprising only 1% of Mexico’s land.

The magazine of the American Orchid Society published a similar article years ago:

Nir, M.A. 1988. The survivors: orchids on a Puerto Rican coffee finca.  American Orchid Society Bulletin 57:989-995.