The second impact level focuses onfarm-level effects. Since
most impact studies are limited to plot-level information,
insight into wider farm-level effects is generally limited.
Ruben (2008)registers that certified farms tend to specialize
more on coffee production and may neglect food crops and/
or reduce engagement in off-farm employment. In a similar
vein,Philpotts, Bichier, Rice, and Greenberg (2007)provide
evidence of scarce biodiversity and limited shading on certified
coffee farms, whereasVan der Vossen (2005)shows that certified coffee production competes for labor and nutrients with
other farming activities. While specialization could reinforce
internal economies of scale and scope, net benefits remain limited due to simultaneous reduction of other income-generating
activities. The usually modest and sometimes non-significant
income effects from certification are thus likely to be associated with land and labor substitution