Research: Shade coffee conserves bee diversity

by on May 22, 2010

ResearchBlogging.orgImpacts of coffee agroforestry management on tropical bee communities. 2010. Jha, S. and J. H. Vandermeer. Biological Conservation 143:1423-1431.

Most people are aware of the importance of bees and other pollinators to functioning ecosystems and agriculture. This study took place in Sococusco, Chiapas, Mexico, and looked at what habitat variables were most important to the abundance and diversity of insect pollinators (bees, in this case). It looked at a number of variables — number of tree species, how many were in flower, canopy cover, etc. — and how important they were at different scales (100 m, 500 m, and 1 km). The study took place in small forest fragments and many small shade coffee farms (13 to 70% shade).

Researchers trapped 46 different bee species in these sites, including both social and solitary bees, and cavity-, wood-, and ground-nesting species. They found that habitat management on farms was more predictive of bee abundance than the forest cover in the surrounding landscape at all the three scales. On these farms, tree diversity — the number of tree species — was the best predictor of bee abundance and diversity. The number of tree species flowering and canopy cover were next.

These results are different than many other similar studies. Often, biodiversity in agricultural areas is dependent on the quality and extent of the surrounding landscape, which acts as a source and provides resources for fauna found on farms. Two factors could be influencing the results of the current study. First, this shade coffee region has farms with high structural diversity, and
low regional forest cover, so resources may be more available on farms
than in forests. Second, bee communities in the study area are small-bodied and thus have shorter foraging ranges. They may react more strongly to local resources.

This study indicates that coffee farmers in Chiapas — and in similar landscapes — can attract pollinators and bolster biodiversity by using diverse shade tree species, allowing trees to mature, creating
light gaps, and creating patches of flowering herbaceous plants. Farmers will also benefit from the ecosystem services provided by the bees which will pollinate supplementary crops on the farm in addition to promoting cross-pollination of their coffee (which improves yield).

The authors conclude that coffee farmers don’t need to rely just on the presence of landscape-level forests to provide pollinator resources. They note, “…most coffee cultivators can only implement land-use changes within their own farms… Our study indicates that local habitat factors, managed within agroforestry systems, can have strong impacts on local bee abundance and diversity.”

Augochlora bee, one of the common genera found in this study, by graftedno1 under a Creative Commons license.

Jha, S., & Vandermeer, J. (2010). Impacts of coffee agroforestry management on tropical bee communities Biological Conservation, 143 (6), 1423-1431 DOI: 10.1016/j.biocon.2010.03.017

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Revised on August 15, 2011

Posted in Coffee and the environment,Research on coffee growing

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