Research on coffee growing

Research on coffee growing

Research: Meta-analysis of biodiversity loss in coffee farms

Biodiversity loss in Latin American coffee landscapes: review of the evidence on ants, birds, and trees. 2008. Philpott, S. M. et al. Conservation Biology 22:1093-1105. doi:10.1111/j.1523-1739.2008.01029.x

At a recent ornithological conference I attended, I saw a presentation on this paper by one of the authors, my friend Tom Diestch. The authors examined multiple studies of biodiversity impacts of shade coffee management in Latin America (excluding the Caribbean). They wanted to see if there were any patterns to biodiversity loss in these systems. Their results were not surprising. For all taxa (trees, ants, and birds), there was a loss in the number of species as shade management went from rustic to highly-managed shade monoculture or sun coffee.

Compared to forests, there are losses of ant and bird species in most coffee systems, with the exception of rustic shade coffee farms, which had equal or greater ant and bird species richness (number of species) than nearby forests. Most sensitive to habitat changes of the three taxa were ants.

Resident birds, and species specialized in foraging in the canopy or understory, were more impacted by increased management (e.g., less shade) than were migratory species or those that are able to forage in multiple strata. Thus, the diversity of tree species and vegetation characteristics associated with less intense shade management — higher tree density, more vegetation layers, height of canopy and understory — were very important to birds.

The authors made several recommendations:

  • Since species are lost whenever forest is managed, remaining forest patches should be preserved.
  • Rustic coffee should be encouraged — but not to the point where forest is being cut down or substantially disturbed to grow coffee.
  • Sun coffee and similar intensively managed farms should be restored to multi-story canopies with more diverse shade to provide more habitat, and native trees should be included in the restoration.

Many farmers believe that shade coffee results in a lowering of coffee yield. Studies have indicated however that optimum yields come in at around 40-60% shade, and that shade actually helps farmers due to decreased pests (if predators are present) and increased pollination services.

The authors speculate that low production in rustic shade might actually be due to a lack of attention to the crop, and measures can be taken to increase yield without removing vegetation. If there is lowered yield and farmers do take an economic hit, then consumers or other funding mechanisms (e.g., a “payment for ecosystems services” program) should pay a premium to farmers who grow coffee under rustic conditions.

You get what you pay for. I know I’m willing to pay a little more to preserve biodiversity.

Research on coffee growing

Research: Higher beetle diversity in shade coffee, more pests in sun

Simplification of a coffee foliage-dwelling beetle community under low-shade management. C. E. Gordon, B. McGillb, G.Ibarra-NÁºÁ±ezc, R. Greenberg, and I. Perfecto. 2008. Basic and Applied Ecology, in press. doi:10.1016/j.baae.2008.04.004

This study looked at beetle abundance and diversity in coffee farms with high shade or low shade in the Soconusco region of the state of Chiapas in southern Mexico. Farms with low shade systems had lower or equal number of individual beetles, but fewer and more similar species than high shade systems. One beetle species, the dreaded coffee berry borer, la broca (Hypothenemus hampei), however, was far more abundant in the low shade farms (201 total on the low shade farms versus 23 on the high shade farms).

Another example of how shade may help reduce costs to the farmer, in this case, pest control.

Research on coffee growing

Research: Shade coffee = more pollinators = higher fruit set

Pollinator diversity increases fruit production in Mexican coffee plantations: The importance of rustic management systems. C. H. Vergara and E. I. Badano. 2009. Agriculture, Ecosystems & Environment 129: 117-123.

Although arabica coffee is self-pollinating, it can benefit from the activity of insect pollinators. This study looked at pollinators in coffee farms in Veracruz, Mexico that used various types of shade management. Rustic shade had the highest number of pollinating species (12), closely followed by polyculture shade (11). Sun and specialized shade (shade monoculture) had the least number of species (5 and 4).  The more shaded farms also had significantly higher fruit set, which was positively related to the diversity of pollinators.

This has important economic implications. Coffee farmers need to see the economic advantages to any change in their management practices. It is often believed that shade results in lower yields. In this case, we see that increased shade (especially diversity in the shade management) encourages a wider diversity of pollinating insects, which in turn leads to higher fruit set in the coffee and thus higher yields.

Photo of bee pollinating coffee by Ganesh Subramaniam.

Research on coffee growing

Research: migratory birds provide pest control, increase profit, in Jamaican coffee farms

Ecological and economic services provided by birds on Jamaican Blue Mountain coffee farms. 2008. Kellermann, J. L., M. D. Johnson, A. M. Stercho, and S. C. Hackett. Conservation Biology 22:1177-1185.

There have been several good papers published lately on coffee farming that I will be summarizing, but this was the most interesting to me, as I have seen the data presented at recent ornithological conferences.

This study looked at the benefits birds provide by preying on coffee berry borers at four coffee farms in Jamaica’s Blue Mountain region: Clifton Mount, Wallenford, McGraham, and Rowan’s Royale. Rowan’s Royale is the only certified organic coffee farm in Jamaica. All others used the pesticide endosulfan four months before this study began. To see if birds were eating coffee berry borers, the authors excluded birds from some coffee plants to look at the rate birds were preying upon coffee berry borers.

Coffee trees in which birds had no access had higher rates of borer infestation and greater damage. Unprotected trees had rates of infestation that were up to 14% lower, and the declines were determined to be due to birds preying on the borers.

Seventeen bird species preyed on coffee borer beetles; eleven were North American migrants wintering in Jamaica. The decline of the borer infestations on coffee trees accessible to birds coincided with the arrival of migrant birds to the island. Three migrant species did most of the work: Black-throated Blue Warbler, American Redstart, and Prairie Warbler (right).

The authors calculated that the value of pest control provided by birds (via increased yield) to farmers averaged US$75 per ha of coffee, not a small sum considering there are 10,000 ha of coffee in Jamaica and the per capita gross income in the country is US$3400. This figure did not include any additional economic benefits such as reduction of other pests, the potential for savings in pesticide reduction, or additional environmental benefits of not using highly toxic endosulfan.

One important component to this study was the finding that these bird species increased with close proximity to native forest patches, and declined steeply on coffee plots that were further than 40 to 50 meters from a habitat patch. In order for farmers to receive these ecological services and economic benefits from the birds, they need to provide habitat for them! Preserving native forest is a win-win situation for the farmers and the birds.

Black-throated Blue Warbler photo by yours truly; American Redstart by my talented friend Steve Hamilton; Prairie Warbler by Scott A. Young.

J. L. Kellerman, M. D. Johnson, A. M. Stercho, S. C. Hackett. (2008). Ecological and economic services provided by birds on Jamaican Blue Mountain coffee farms. Conservation Biology, 22 (5), 1177-1185 DOI: 10.1111/j.1523-1739.2008.00968.x