Research on coffee growing

Research on coffee growing

Research: Tree species diversity in Veracruz coffee farms

Tree species diversity and vegetation structure in shade coffee farms in Veracruz, Mexico. A. M. LÁ³pez-GÁ³meza, G. Williams-Linera, and R. H. Manson. 2008. Agriculture, Ecosystems and Environment 124:160-172. 10.1016/j.agee.2007.09.008

Fifteen shade coffee farms, under different types of shade management, and two forest reserves in the Coatepec-Huatusco region of Veracruz were compared. Some of the results were as expected, e.g., there were fewer tree species in shade monocultures and the most tree species in diverse polycultures; some of these diverse polyculture farms actually had more species than the two forest reserves sampled.

One of the most interesting revealations in this paper was that the proportion of native tree species was similar across all farms, regardless of management type, at around 79%. Many of these species (71%) were rare, found on only one or two farms. This highlights the importance of coffee farms for preserving native species diversity in this important coffee-growing area, which is becoming highly fragmented and losing forest rapidly. One of the authors found in a previous study that 27 native tree species were no longer found in regional forests, but still existed on shaded coffee farms.

The authors noted that high tree species richness and functional diversity is linked to the fates of many other plant and animal taxa, and that further multi-taxa studies are needed to better evaluate the role of coffee farms in biodiversity preservation. They also suggested that it is imperative for shade coffee agrosystems be explicitly included in regional conservation strategies.

Birds and other biodiversity / Research on coffee growing

Research: Mammals in coffee plantations in India’s Western Ghats

The mammalian communities in coffee plantations around a protected area in the Western Ghats, India. A. Balia, A. Kumarb, and J. Krishnaswamy. 2007. Biological Conservation 139: 93-102.
This study looked at the number of mammal species found in 15 coffee plantations around the Bhadra Wildlife Sanctuary in the Western Ghats of India, and any correlation between the number of species and distance from the park or vegetation characteristics.

First, a bit of background. Climate conditions in India — monsoon seasons followed by long dry periods — require coffee to be grown under a protective canopy of shade trees, usually under a three-tier system. Although coffee plantations have replaced much of the mid-elevation moist deciduous and evergreen forests in India, coffee has at least traditionally used native forest tree species for shade, such as Ficus glomerata (Doomar, Gular, or Cluster Fig), Dalbergia latifolia (Rosewood), Sapindus laurifolius (Soapnut), and Artocarpus integrifolia (Jackfruit tree).

More recently, non-native species have been used in Indian coffee plantations. In the lowest layer, nitrogen fixing species such as Erythrina lithosperma (Dadap; native to the Philippines and Java) and Gliricidia maculata/sepium (native to Mexico and Central America) are planted. The middle layer, trees that shed their leaves in the monsoon and maintain a dense canopy during the summer, are often native Ficus species. For the canopy layer of hardwood, many coffee farmers are now planting a fast-growing, sparse shade timber species from Australia, Grevillea robusta, often called silver oak although not related to North American oak species.

Twenty-eight species of mammals were recorded in the plantations; this included a number of large carnivores (e.g., tigers and leopards) and herbivores (e.g., elephants and deer). Not surprisingly, more species were found in plantations nearer to the sanctuary. The authors concluded that coffee estates act as a buffer around the park for large mammals, protecting them from the direct effects of more intensive agriculture and higher-density human settlements.

The study did not find any negative correlation with Grevillea abundance, but the fact that the estates with the highest proportion of Grevillea were the closest to the sanctuary may have diluted the effect. The percentage of Grevillea was about 30%; a high percentage of this species is usually avoided, because they drop their leaves during the monsoon, a situation which can cause rot.

Nonetheless, the authors noted that the non-native timber species provide few or no resources for resident wildlife and cautioned that “Such conversions not only lead to the loss of biodiversity values of these plantations, but also severely affect the integrity of the adjoining protected areas.”

Certifications / Research on coffee growing

Research: Evaluating benefits of coffee certification programs


Field-testing ecological and economic benefits of coffee certification programs. S. M. Philpot, P. Bichier, R. Rice, and R. Greenberg. 2007. Conservation Biology 21:975-985.

This study looked at the ecological (vegetation, ants and birds) and economic (yield, revenue) aspects of coffee growing for eight cooperatives in Chiapas, Mexico. Farms were certified organic, organic and Fair Trade, or uncertified. None were certified shade-grown, so farms were examined to see if they would meet shade certification criteria.

The authors found no significant differences in vegetation, bird or ant diversity, or percent of forest fauna on farms based on what type of certification they had. While none of the farms had the necessary complexity of vegetation layers that shade certification required, but the other vegetation criteria met by those farms nonetheless corresponded with higher ant and bird diversity. I think this emphasizes the importance of the specific criteria known as “vertical stratification,” or the percent of leaf volume in each of the three layers of vegetation in shaded coffee. I’ll talk a bit more about this in a follow-up post.

Organic farms had a higher number of tree species, and shared more tree, bird, and ant species with forests than uncertified farms or (curiously) those that were certified both organic and Fair Trade.

There was no difference in yield based on certification, contradicting a common perception that without chemical pesticides and fertilizers, yield will decrease.

Farmers with organic or organic and fair trade certification did not always have higher revenues than uncertified farms. Partly this was due to the costs associated with certification programs. Another factor was the differing market prices between the two years of the study. When market prices increased, the premiums for organic coffee rose, but the premium for Fair Trade coffee did not. This can dilute the relative increase for farmers in Fair Trade co-ops, and exposes a previously-discussed weakness in the Fair Trade model. I think the overall lack of substantially higher revenues in certified organic coffee also illustrates the need for some type of a) reform in the cost of certifications and/or b) an increase in the premiums paid to farmers for sustainable coffee — which would require willingness by consumers to pay more.

Research on coffee growing

Research: Ants eat more coffee borers on shade farms

Testing ant predation on the coffee berry borer in shaded and sun coffee plantations in Colombia. I. Armbrecht and M. C. Gallego. Entomologia Experimentalis et Applicata 124:261-267.

The study took place in Apia, Colombia (Risaralda dept.). Prior to the 1990s, this was primarily a shade coffee region, but outside owners came converted farms to sun coffee. Annually about 5% of the crop is lost to the coffee borer or broca, Hypothenemus hampei, an African pest which arrived in Colombia in 1988.

Three shaded and three sun coffee plantations were examined. Canopy cover averaged 79% with 302 shade trees per hectare in shade farms, and 29% and 33 trees per ha in sun farms. A previous study in the same farms found a higher leaf litter ant
diversity in shaded farms than sun farms (32.3 species per square meter
versus 24.3). Although most of the life of the broca is spent inside the coffee cherry, fallen infected cherries are an important source of infestation, so studying the impact of ground ants is relevant. Previous studies in Colombia have also found that ants feed on broca at all their life stages.

More ant species (16) were attracted to broca in shade farms than sun farms (12). More broca adults were removed from traps by ants in shade farms (30.5%) than in sun farms (15.5%).  This provides strong evidence that native ground-dwelling ants are attracted to and feed on broca adults, and that shade management has a positive effect on this biocontrol. The introduction of the broca in Colombia has led to a dramatic increase in pesticide use, which may also be negatively impacting ant biodiversity.

The two shade plantations that had greater than 10 species of shade trees and used no pesticides in this study are la Playita and la Esperanza (not to be confused with the better-known Esperanza estate from Huila, Colombia, H on map). I did not find any sources of coffee from these specific farms, so they may only be contributing to a cooperative.