Research on coffee growing

Research on coffee growing

Research: Shade coffee buffers against climate change

Agroforestry management as an adaptive strategy against potential microclimate extremes in coffee agriculture. B. B. Lin.  2007. Agriculture and Forest Meteorology 144:85-94. DOI:10.1016/j.agrformet.2006.12.009.

A few months ago I wrote a detailed post on coffee growing and climate change. Climate change poses a significant threat to coffee growing, as arabica coffee grows best in temperatures around 20C (68F).  As this paper reiterates, the photosynthesis of coffee decreases markedly at temperatures between 20 and 24C (68-75F), and grinds to a halt at 34C (93F) and above. At the same time, the fruit ripens at an accelerated rate above 23C, reducing quality, as the best-tasting coffees come from cherries that have ripened slowly, intensifying and concentrating flavor.

This study looked at shade cover at farms in the Soconusco region of southern Chiapas, Mexico (Finca Irlanda, Finca Hamburgo, and Rancho Alegre) and how the amount of shade impacted temperature, humidity, and soil moisture. Although this has long been suspected, this study confirms that the fluctuations in microclimate decrease as shade level increases. Increased shade in coffee agrosystems can help mitigate the effects of climate change by buffering the coffee from climate variability.

Nearly 4 million Mexicans depend on coffee production. Farmers have already noticed changes in the climate, particularly longer dry seasons.  What will happen if farmers have to abandon their plots? As during the coffee crisis, many head north.

Birds and other biodiversity / Research on coffee growing

Research: Birds in shade coffee favor plant diversity

Dietsch, T.V., I. Perfecto, and R. Greenberg. 2007. Avian foraging behavior in two different types of coffee agrosystem in Chiapas, Mexico.  Biotropica 39:232-240.
Other studies have documented that structural diversity is important in coffee farms — it is the complexity of multiple layers of vegetation in shade coffee systems that are so important and attractive to birds and other organisms. This study looked at Finca Irlanda in Chiapas, a 290 hectare shade coffee farm, during both summer and winter seasons. Forty of those hectares are being further restored by additional plantings of native plants in order to qualify for Smithsonian Bird-Friendly certification. At the time of the study, the structural diversity of the entire farm was similar, but the 40 ha under restoration had a wide variety of plants.

Eighty-eight bird species were observed, and more species were found foraging in the restoration plot than the rest of Finca Irlanda. The study revealed the importance of plant diversity in addition to structural diversity. These diverse plants provide varying resources throughout the year — from nectar to insects to fruit — that are critical to birds.

Rogers Family Company is Finca Irlanda’s roaster in the U.S., but I was unable to determine which one of their brands or coffees uses beans from this farm. One expects it would be used in the Audubon coffee line, but as noted in our review of the Audubon Breakfast Blend, there is no information on the origin of those coffees; specific information is lacking on most Rogers Family coffees. You can also buy Finca Irlanda coffee from Cafe Altura.

Research on coffee growing

Research: Beneficial fungi in wild Ethiopian coffee forests

Composition of coffee shade tree species and density of indigenous arbuscular mycorrhizal fungi (AMF) spores in Bonga natural coffee forest, southwestern Ethiopia. Muleta, D., F. Assefa, S. Nemomissa, and U. Granhall. 2007.  Forest Ecology and Management 241:145-154.

Mycorrhizal fungi have mutualistic associations with plants. They benefit coffee plants by enhancing growth and tolerance to nematodes, increasing phosphorus and zinc uptake in young plants, and increasing overall survival. This study looked at which shade trees were associated with the highest levels of AMF in a wild coffee forest.  Four tree species were dominant: Millettia ferruginea, Olea welwitschii, Schefflera abyssinica, and Phoenix reclinata. Millettia are legumes, and thus fix nitrogen in the soil, an added benefit.  Higher mean counts of AMF were found under leguminous shade trees compared to non-legumes. This healthy ecosystem is considered to have high potential for conservation of the wild coffee gene pool.

Research on coffee growing

Research: Leaf-cutting ants do not harvest coffee leaves in shade farms

Varon, E. H., S. D. Eigenbrode, N. A. Bosque-Perez, and L. Hilje. 2007. Effect of farm diversity on harvesting of coffee leaves by the leaf-cutting ant Atta cephalotes. Agriculture and Forest Entomology 9:47-55. Leaf-cutting ants, which are common in the tropics, cut pieces of live leaves and carry them to underground burrows where they are used to raise a fungus, which is the food of the ants.

The types of leaves these ants harvested were studied on Costa Rican coffee farms which varied in the diversity of tree species present.  In sun coffee monocultures, the proportion of coffee leaves harvested was highest, at 40% of total biomass.  It was under 1% in farms with complex shade, and the ants preferred shade tree species over coffee when given the choice in trials.

Leaf-cutting ants can consume 12 to 17% of leaf production in an area,and can defoliate coffee plants if there are not preferred alternatives. Damage to coffee plants by these ants is minimized by the availability of a diversity of shade trees.

Photo of Atta cephalotes by Scott Bauer. USDA Agricultural Research Service.

Birds and other biodiversity / Research on coffee growing

Endangered coffee

I previously discussed the important species and varieties of coffee. An understanding of these varieties can be of great help to consumers looking for sustainable coffee, as different types are typically grown under shade or sun conditions.  The species and varieties of coffee familiar to consumers, however, are just a tiny part of the coffee family tree.

Rather astonishingly, no comprehensive monograph on the taxonomic status of coffee has been published since the 1940s.  That was recently remedied by a lengthy paper published in the Botanical Journal of the Linnean Society.* It details 103 species in the genus Coffea: 41 species in Africa, 59 in Madagascar, and three in the Mascarene Islands; no naturally-occurring Coffea species are found outside of these three areas, and no species is shared between the three areas.

While most of the paper is of interest only to botanists, one aspect is quite striking.  Over 70% of coffee species can be categorized as threatened using World Conservation Union (IUCN) Red List definitions:

  • 14 species (13.6%) are Critically Endangered,
  • 35 species (33.9%) are Endangered, and
  • 23 species (24.2%) are Vulnerable.
  • An additional 13 species (13.7%) are Near Threatened.

The majority of the most threatened species are from Madagascar, an island with a high level of endemism and deforestation. The authors note there is virtually no in situ preservation of coffee genetic resources, and there are difficulties in conserving coffee genes ex situ because of its general lack of suitability for placement in seed banks (see also my post on The value of wild coffee). Habitat loss is the single most important threat to rare coffee species. The photo shows dramatic erosion on deforested areas in western Madagascar, courtesy of Rhett Butler’s excellent Wild Madagascar web site, where you can read more about this country’s environmental issues.

*Davis, A. P., Govaerts, R., Bridson, D. M., and Stoffelen, P.  2006. An annotated taxonomic conspectus of the genus Coffea (Rubiaceae). Botanical Journal of the Linnean Society. 152:465-512.

Birds and other biodiversity / Research on coffee growing

Research: Biodiversity and profitability in coffee agrosystems

Gordon, C., R. Manson, J. Sundberg, and A. Cruz-Angon.  2006. Biodiversity, profitability, and vegetation structure in a Mexican coffee agrosystem. Agriculture Ecosystems & Environment 118:256-266.

This study looked at coffee grown in various types of shade in central Mexico, and any correlation between biodiversity (in birds and mammals) and profits. The conversion of plantations to sun coffee is generally believed to increase yield (and therefore profits), while the preservation of shade and forest tree species is thought to be costly in terms of decreased yield.  However, the additional costs of chemical inputs and labor in sun coffee may offset any increases in yield.  This study sought to examine this purported trade-off.

They found no support for a trade-off between biodiversity and profitability. Biodiverse, large shade plantations were highly profitable under all price scenarios, even profit calculations did not include any price premiums, such as those received if a farm is certified organic.  The authors concluded that farms and the environment both stand to gain…

“…by dispelling the notion that high-input, low biodiversity and sun and specialized shade coffee cultivation systems are the most economically sensible ways to grow coffee.”

Sites that were shade monoculture (or “specialized shade”) — with a low diversity and density of shade trees — were indistinguishable from sun coffee in terms of abundance and diversity of forest birds.  This emphasizes the point that not all shade coffees preserve biodiversity. These farms have shade trees, could market their coffee as “shade grown,” and may appear to non-biologists as having a lot of birds (which tend to be common, open-area generalists like grassquits and sparrows), but really do not preserve the diversity of species that were present before the native forest was cut down.

Many farmers have the erroneous belief that epiphytes parasitize shade trees, and they remove them. Biodiversity and profitability could immediately increase if farmers stopped this practice (called “destencho”). See this post on the value of epiphytes in coffee farms. Compared to intact forest, even the shaded farms lacked a number of bird and mammal species, in particular those that utilize the understory and ground level.  These are the layers most managed and disturbed in coffee farms.  Diverse shade coffee farms are best at preserving species that live in the upper layers and canopy.

Birds and other biodiversity / Research on coffee growing

Research: Nesting birds in shade coffee

Gleffe, J.D., J. A. Collazo, M. J. Groom, and L. Miranda-Castro.  2006.  Avian reproduction and the conservation value of shaded coffee plantations.  Ornitologia Neotropical 17: 271-282.

Most of the research on birds and coffee farms focuses on migrant birds which breed in North America and winter in the tropics.  This is the first study to examine the nesting success of resident birds in shade coffee plantations compared to secondary forest.  The study took place in north-central Puerto Rico, and the shade coffee farms were in the Ciales area (map).

The majority of bird nests (72%) were found in shade coffee, and 26 species were recorded in coffee, versus 22 in secondary forest. Six species were found only in coffee, two only in forest.

Thirty-two different plant species were used as nest sites in coffee, with the two most common plants used for nesting Inga vera and Andira inermis.  Coffee trees themselves were host to 26% of the nests, many of which were of the Bananaquit (Coereba flaveola), shown here at right. However, it was the canopy trees that were the most important and harbored most of the bird species in both the coffee and forest habitats. The stunning Puerto Rican Woodpecker (Melanerpes portoricensis), an endemic species, is one example of a bird that needs mature canopy trees for nesting. These canopy trees, of course, would not be present in sun coffee plantations, and the authors emphasize that it is the value of shade coffee plantations for preserving birds depends on the shade canopy layer, not the coffee itself.

The study also looked at reproductive success, and discovered that it was similar between coffee and forest, an important finding.  The authors suggest restoration of native shade canopy in existing and new coffee farms to conserve avian diversity in Puerto Rico.  This is especially important because Puerto Rico is experiencing both deforestation due to urban sprawl and development, and the majority of coffee grown there (59%) is sun coffee, with more being converted.  Consumers should choose their Puerto Rican coffee very carefully.  One source I found from the area where the study took place was Finca Cialitos (web site in Spanish, store in English).

Birds and other biodiversity / Research on coffee growing

Research: The value of wild coffee

Hein, L. and F. Gratweiler. 2006.  The economic value of coffee (Coffea arabica) genetic resources. Ecological Economics 60:76-185.

This fascinating paper is not about the sort of ecological research I usually summarize here, but absolutely keeps with the theme of preserving biodiversity, as well as the recent Ethiopian thread that has come up here lately.

First, the authors introduce the importance of ancestral/wild genetic resources in agricultural crops, since careful breeding can impart in existing cultivars genes that can increase yields, confer disease resistance, and improve quality.  Wild coffee, and therefore its genetic resources, are only found where the species originated, in the highland forests of Ethiopia.  The paper highlights two urgent facts:

  • These forests are disappearing at an alarming rate, a rate at which, if it continues, will eliminate the forests in fewer than ten years.
  • Unlike many other plant seeds, coffee seeds are sensitive to cold and maintain their germination potential for only a couple of months.  Therefore, wild varieties are not candidates for seed banks. They must be preserved growing in the wild.

Although the benefits of preserving genetic resources is widely acknowledged, putting a monetary figure on these resources is difficult. The authors of this paper examined the potential economic benefits of preserving the genetic resources of coffee by looking at several characteristics that are known to occur in wild Ethiopian coffees: resistance to three major coffee pests/diseases, a variety with a lower caffeine content, and a higher yield variety.

They concluded that the economic value of Ethiopian coffee genetic resources is between US$420 million up to $1.45 billion (the variation reflects uncertainty in the coffee markets over the period of time it would take to incorporate wild genes into cultivars).  This does not take into account other beneficial characteristics that might be found in wild coffees, such as heat resistance that will be needed in the face of global climate change.

Current inventories of the genetic diversity in Ethiopian forests are inadequate to determine how much forest needs to be preserved in order to maintain the coffee gene pool, conclude the authors.  Certainly, we do not need to be replacing native forest and wild coffee with large plantations of nursery-grown plants. This paper provides significant economic evidence that preserving Ethiopian forests, and their wild coffee resources, are nearly priceless.

Climate change / Coffee and the environment / Research on coffee growing

Coffee growing and climate change

Coffee (Coffea sp.) requires quite specific growing conditions.  It grows in subtropical regions that have distinct wet and dry seasons.  Although plants can live and produce fruit for decades, drought or heat in summer can diminish production and quality.  And while coffee requires a dry period in the spring, heavy rains in this season can disrupt flowering.

This sensitivity to climatic variables means that global climate change is likely to have profound impacts on coffee growing and production.  An upcoming article in the journal Climatic Change (1) modeled what could happen to coffee production in Veracruz, Mexico if observed trends in climate change continue and coffee prices remain steady.  The report concludes that coffee production will not be economically viable in Veracruz by 2020 due to lowered yields and many current areas becoming unsuitable for coffee growing.

Although there is some work being done on breeding coffee varieties that are more heat-resistant, it will do little to prevent losses due to the climatic instability brought on by global warming (droughts and floods, unusual cold spells) or the pests whose ranges will also change as temperatures rise.

Farmers will be left with few choices.  Areas at higher latitudes (which although too cool now to grow coffee will become warmer) could be used. However, most small holders do not have the money or credit to buy property, even if it is available to purchase; most land is already under ownership that is passed down in families.  If land upslope is turned into coffee farms, it means some conversion and clearing of existing forest, and the old coffee farms will be converted to other crops, none of which is likely to be as environmentally friendly as shade coffee.  This means a loss of biodiversity, and the deforestation of new and old coffee farms will exacerbate and accelerate warming trends, since trees help sequester carbon and buffer temperature changes.

We all have a great deal at stake as the planet warms. Unfortunately, the poor in developing countries, such as coffee growing nations, often bear a large burden.  Even growers of more heat-tolerant lowland robusta coffee, where it is indigenous, stand to lose their livelihoods, as this graphic illustrates.

The authors of the Veracruz report recommend supporting farmers to move into specialty coffee to help to provide some financial security. Purchasing shade coffee and providing incentive for farmers to plant trees rather than cut them down will also help.  As the Fresh Cup article notes,

In the past several decades, roughly half of the world’s coffee plantations have cut down their trees, or cut down forest to plant unshaded coffee. This decreases the ability of vegetation to counteract global warming by absorbing carbon dioxide, and it also raises local temperature.

All the more reason to stay away from corporate technified sun coffee, and enjoy the superior taste of environmentally-friendly coffee.  I’ll be following the research on climate change and coffee, and report further news and suggestions.

(1) Gay, C., F. Estrada, C. Conde, H. Eakin, and l. Villers. 2006. Potential impacts of climate change on agriculture: case study of coffee production in Veracruz, Mexico.  Climate Change 79:259-288.

Birds and other biodiversity / Research on coffee growing

Abstracts on presentations at the NAOC

Here are some very brief summaries of research that had to do with coffee growing that were presented at North American Ornithological Conference. I also put together a page with full abstracts, and author contacts.

  • Cerulean Warbler (Dendroica cerulea) foraging behavior in the western Andes of Colombia. This species (which I’ve written about before) was common in shade coffee plantations, and only fed in the shade canopy.
  • Population ecology of Cerulean Warblers on breeding and wintering grounds. This study concluded that shade coffee farms in the Venezuelan Andes were critical wintering habitat for this species, with density in the farms higher than in the surrounding forest.
  • Coffee certification as an economic incentive for bird conservation. Discusses the shade coffee farms of central Veracruz, Mexico, many shaded by cloud forest tree species.
  • Certification and birds: the importance of shade coffee plantations for species diversity in the Cuetzalan region, Puebla, Mexico. 182 species were recorded in this area, and while not as rich as primary forest, shade coffee still maintains a high diversity of birds.
  • Traditional coffee plantations: suitable habitat in the anthropogenic matrix for Neotropical resident and migratory birds. A study that complements the previous Puebla study, quantifying the different types of birds found in shade coffee.
  • Neotropical insectivorous birds as pest control of the coffee berry borer (Hypothenemus hampei) on Jamaican Blue Mountain coffee farms.  More on Matt Johnson’s work in Jamaica.
  • Birds, shade grown coffee, and community outreach in Ecuador. Self explanatory.
  • Sensitive bird species in shade coffee plantations. In southern Mexico, shade coffee with high levels of structural diversity (many layers of shade trees) may be good for conservation purposes; however, shade coffee may only be important for forest species which are sensitive to deforestation and disturbance when close to intact forest.

Birds and other biodiversity / Research on coffee growing

Research: American Redstarts in Jamaica

Johnson, M.D., T.W. Sherry, R. T. Holmes, and P.P. Marra.  2006.  Assessing habitat quality for a migratory songbird wintering in natural and agricultural habitats. Conservation Biology 20:1433-1444.

This study examined American Redstarts (Setophaga ruticilla) in natural and agricultural habitats in Jamaica.  Redstarts are beautiful warblers that nest in North America and winter in the tropics (see map).

Four natural habitats were compared with two agricultural habitats: citrus groves and shade coffee plantations, which were shaded primarily by Inga vera, with understories of varying densities.

Measures of habitat quality for redstarts on the coffee farms was generally intermediate between the best and worst natural habitats.  Two measures, body mass and overwinter survival, were very similar in shade coffee and the best natural habitat. Body mass is especially important.  It indicates that enough food is available, and maintaining body mass is critical for later survival, even after departure from the wintering grounds.  This study estimated that a loss of 0.1 grams (a very tiny amount!) over the winter corresponded with a 6.8% reduction in annual survival probability.

The authors provide two caveats: First, this study focuses on a single species in a single region.  And importantly, there is no similar data to compare the quality of present coffee farms with the habitat from which they were carved. Although shade coffee farms can provide habitat for some species, they do not possess the complete suite of species or ecosystem functions as the original habitat.

The paper named the three shade coffee farms/areas that were used in the study.  None were in the eastern Blue Mountain region. One was in the western growing region, in James Hill, Westmoreland Parish.  Two were in the central highlands in Manchester Parish, Coleyville Farm and Baronhall Farms.  Most coffee is pooled and single estates are hard to find, but Baronhall (formerly Broomhall Estate) is apparently an exception.  I have been able to find various roasters offering this coffee.  Here is a review of Jamaica High Mountain, Baronhall Estate at Coffee Review.

Research on coffee growing

Research: Ants on Colombian coffee farms

Armbrecht, I., I. Perfecto, and E. Silverman. 2006. Limitation of nesting resources for ants in Colombian forests and coffee plantations.  Ecological Entomology 31:403-410.

Ants are popular research subjects in coffee farms because they are abundant and important components of tropical forest ecosystems (summaries of other research here). This study looked at ants that nest in leaf litter and those that nest in twigs to see if these nest sites are limited in different coffee farm types — sun, monogeneric shade, polygeneric shade, and in forest.

The response of the ants to the type of coffee farm depended a great deal on the species, elevation, and predatory ant assembleges.  Major findings include that there were more species of litter-nesting ants in the shade systems than in sun coffee, and there were more ant colonies in the monogeneric system (one species of shade tree) than in the polygeneric (multiple species of shade trees) or sun systems.  This was an intriguing finding, I thought, and the authors thought that in part it might be due to the fact that the polygeneric shade farms were also organic, and used coffee pulp as a mulch — generally placed right where the ant plots used in the study were located.  Caffeine in the pulp could have depressed the number of ants in these plots (the number of species was very high, however).

The farms were in the Apia municipality, and the sun farms were La Felisa, La Maria, and La Estrella.  This is not the same La Estrella farm that placed in the 2006 Cup of Excellence program (that one is in Huila “state” while Apia is in Risaralda).  La Clarita, one of the polygeneric farms in the study, is Rainforest Alliance certified.

Birds and other biodiversity / Research on coffee growing

Research: Biodiversity in wild coffee farms in Ethiopia

Senbeta, F. and M. Denich. 2006. Effects of wild coffee management on species diversity in the Afromontane rainforests of Ethiopia. Forest Ecology and Management 232:68-74.

Traditional coffee management in Ethiopia ranges from harvesting cherries in relatively undisturbed forest, to reducing tree and shrub density in semi-forest systems. This study looked at plant species diversity in these two systems in the southeast (Bale Zone of Oromia) and southwest highlands (Bench-Maji Zone) of Ethiopia.

In the forest system, coffee plants made up less than 25% of the plant density versus greater than 88% in the same size class in the semi-forest system.  Continuous management of coffee in the semi-forest system suppresses tree regeneration, reduces tree density, and eventually leads to the disappearance of forest plant species.

This management is leading to a tall tree canopy with no intermediate layer, effecting not only diversity of plants but the structural diversity needed for other wildlife.  In some plots, not even young coffee trees were allowed to regenerate, which means coffee production will end up being affected.  Another way the production of coffee may suffer is that the lack of native forest plants species may also result in a decline of bees and other pollinators. Other studies have shown that coffee fruit set is strongly influenced by the abundance of pollinating insects.

The authors note that “Traditional wild coffee management methods are not based on systematic analysis, and hence opinions among the farmers vary on how to manage the forest.” With a higher demand and stronger market for Ethiopian coffee, farmers
in these areas tend to focus on seed production rather than
preservation of the natural regeneration of coffee trees.  The authors recommend a strategy that will strike a balance between plant diversity (and hence pollinator diversity, which contributes to coffee production, as well as other biodiversity) and coffee production.

They conclude that biodiversity conservation spots are crucial to maintain and enhance biodiversity, including acting as repositories for plant and animal diversity, and genetic resources of wild coffee populations — which are under increasing threat from deforestation — which can prove invaluable in developing new strains.

I consider this an important paper, as most of the emphasis on coffee and biodiversity has been on farming methods in the New World, while African coffees are usually considered “wild” and grown in an un-manipulated manner.  As the Ethiopian and African coffee industries gain momentum, we will have to see how management methods develop, and no longer take for granted that the coffees we purchase from these regions are always sustainable.

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Birds and other biodiversity / Research on coffee growing

Research: Bat diversity in different types of shade coffee

Garcia Estrada, C., A. Damon, C. Sanchez Hernandez, L. Soto Pinto, and G. Ibarra Nunez.  2006.  Bat diversity in montane rainforest and shaded coffee under different management practices in southeastern Chiapas, Mexico.  Biological Conservation 132:351-361.

Southeastern Chiapas is Mexico's primary coffee-producing region.  Very little of the original montane rainforest remains.  Originally, coffee was grown under polyshade, or trees of various species found in the original forest.  Incentives have resulted in many farms using Inga trees for shade; these are native, hardy, fast-growing, deep-rooted, and fix nitrogen (however, production is not increased with Inga, there tend to be more weeds and soil erosion, so replacing forest with Inga doesn't offer many advantages).

This study looked at the diversity of bat species in shade coffee farms that use polyshade; or monoshade (Inga or Inga and bananas) with high, low, or no chemical inputs.  While unaltered montane rainforest had the highest number of species (37), all the others had 23-27 species.  Species composition was different, though, with more fruit and nectar eating bats found in farms with high chemical inputs, which had fewer insect-eating bats.  Application of pesticides decreases insect diversity for these species, especially insect families important to rare bat species. 

Birds and other biodiversity / Research on coffee growing

Research: Shade coffee farms as habitat for monkeys

Williams-GuillÁ©n, K., C. McCann, J.C. MartÁ­nez SÁ¡nchez, and F. Koontz.  2006. Resource availability and habitat use by mantled howling monkeys in a Nicaraguan coffee plantation: can agroforests serve as core habitat for a forest mammal? Animal Conservation 9: 331-338.

The incredible contact roars of Mantled Howler Monkeys (Alouatta palliata) are a frequent wake-up call to visitors to the New World tropics.  They were studied in a Nicaraguan shade coffee plantation, which had a diverse (60+ species) canopy which insured that preferred foods were available to the monkeys year-round. The monkeys did not avoid areas of coffee plantations, but stuck to the larger trees. The authors concluded that shade coffee can serve as alternate wildlife habitat and corridors between forest fragments for howling monkeys and possibly other forest mammals.