I recently reviewed a paper, Field-testing ecological and economic benefits of coffee certification programs, that included a nifty summary table of the criteria used for shade certification by Rainforest Alliance, and Smithsonian Migratory Bird Center (under the “Bird-Friendly” trademark). I thought it would be useful to post a summary here, with a little commentary. Note that SMBC’s criteria are mandatory, while RA has no required criteria for shade management — the standards below are one of the optional criteria (more on the RA standards and scoring can be found here).
|No. tree species||>10||>12/ha*|
|No. trees/ha (mean)||na||>70*|
|% allowed to be Inga trees||<60||na|
|% shade cover||>40||>40*|
|No. of shade layers||3||2|
|% leaf volume in each shade layer|
|….. >15 m (emergent)||>20||na|
|….. 12 to 15 m (backbone)||>60||na|
|….. <12 m (understory)||>20||na|
*As of April 2009, standards were modified from the previous version, February 2008. In the old standards, one requirement was for at least 12 native tree species and at least 70 trees per hectare; now it is an average of 12 native tree species, with no minimum number of trees per hectare. Previous criteria stated a minimum of 40% shade cover, now the standard specifies this minimum only on cultivated land.
As noted in the previous post, the criteria having to do with vertical stratification — the number of layers of vegetation and the leaf volume in each — are critical components for preserving a rich mix of species. Many ecological studies support the key role of structural diversity (sometimes referred to technically as floristic heterogeneity) in increased biodiversity — of many types in many ecosystems well beyond the realm of coffee growing. This is the classic schematic illustrating the various coffee production systems and their layers of shade diversity, from a paper by Patricia Moguel and Victor Toledo .
As you can see from the table above, Rainforest Alliance requires (if this criteria is used) only two layers of shade, while Smithsonian requires three. RA has no standards for leaf volume in the shade layers. In short, RA certified farms that use these criteria would have still have structurally-simpler habitats (closer to commercial polyculture) that would likely not support as much biodiversity as farms that met SMBC criteria (closer to traditional polyculture).
A further note. SMBC inspectors visit farms and set up a number of plots and measure various vegetation parameters following methods used in typical ecological studies. The aforementioned paper reports that “Rainforest Alliance inspection auditors rely heavily on data provided by farm managers” (who are not ecologists), and confirm data provided during visits by various estimates and extrapolations.
As an ecologist myself, I am more comfortable that SMBC offers the more stringent, reliable assurance that coffee is grown sustainability if one is comparing certification schemes. And not to beat a dead horse, but the usual caveats apply: there are pros and cons of certification, and many uncertified farms grow coffee sustainably, meeting or exceeding the strongest criteria.
 Biodiversity Conservation in Traditional Coffee Systems of Mexico. 1999. Conservation Biology 13:11–21.