Research on coffee growing

Birds and other biodiversity / Research on coffee growing

Research: Shade coffee important to amphibians

The role of the matrix-edge dynamics of amphibian conservation in tropical montane fragmented landscapes. 2011. Santos-Barrera and Urbina-Cardona. Revista Mexicana de Biodiversidad.

Birds, insects, and occasionally bats are the most frequently studied taxa in shade coffee agrosystems. This paper looked at the diversity and abundance of frogs and salamanders in an area of tropical montane cloud forest, shade coffee farms, and corn plantations in southern Mexico.

The Pygmy Free-fingered Frog (Craugastor pygmaeus) was one of the most common species found in this study, and one which dominated in shade coffee. © 2010 Division of Herpetology, University of Kansas

The study took place near the community of El Molote in the state of Guerrero, part of the Sierra Madre de Sur de Guerrero. Montane forest remnants are embedded in a matrix of other land uses, primarily shade coffee, corn plantations, and areas of cultivated ornamental plants.

Researchers found that the diversity and abundance of amphibians in the forest was highly dependent on what type of land was adjacent to it — coffee or corn. Where shaded coffee plantations bordered forest patches, they helped to buffer the effects of the forest edge, improving the overall quality of the forest interior habitat. Amphibians prefer higher humidity and leaf litter cover which the shade coffee helped preserve, both in the forest and on the farms.

In contrast, where corn bordered the forest, high disturbance and the abrupt change in vegetation had a negative impact on habitat quality. None of the seven amphibian species were found in the corn plantations, and some species, including an endangered endemic frog, the Mourning Treefrog (Plectrohyla pentheter), were never found in the corn/forest ecotone.

The authors recommend that shade coffee farms should be managed to improve habitat and ecological connectivity.

Santos-Barrera, G., & Urbina-Cardona, J. N. (2011). The role of the matrix-edge dynamics of amphibian conservation in tropical montane fragmented landscapes. Revista Mexicana de Biodiversidad, 82, 679-687

Research on coffee growing

Coffee leaf rust: a complex disease

Coffee leaf rust in Bolivia. Photo by Neil Palmer (CIAT).

Coffee rust (Hemileia vastatrix) is fungus that is one of the most devastating coffee diseases in the world. Native to Africa, it is now present in every coffee-growing nation. Infected leaves drop off, weakening the plant. Copper-based fungicides can be effective against coffee rust. However, it must be on the leaf surface to prevent infection, and copper can build up in soils, eventually reaching toxic levels.

The spores of coffee rust are spread by wind or rain, and will only germinate when exposed to one to two days of continuous wetness. Usually humidity is not enough; rain provides the necessary conditions.  Latin America has suffered through more frequent and prolonged rainy periods in recent years as have parts of Asia, thought to be due to climate change. As a result, coffee rust has been having increasing detrimental effects on coffee production.

Aside from fungicide application, there are two lines of defense against coffee rust: planting resistant hybrids, and modifying cultivation methods.

When coffee rust first arrived in the New World, around 1970 in Brazil, nearly all coffee being grown commercially was genetically nearly identical and very susceptible to rust. Thus, the development of rust-resistant hybrids has been an important element in battling this disease. Rust fights back, of course; there are over 40 strains of coffee rust, some of which now attack previously-resistant hybrids.

Colombia has made a large investment in “renovating” the nation’s coffee farms by swapping out older coffee varieties with rust-resistant types. This has been accomplished on a third of Colombia’s coffee lands so far. Some of the resistant varieties include Castillo, Tabi, and Colombia. One thing they all have in common is parentage that includes Hibrido de Timor, which in itself is a natural hybrid between arabica coffee (Coffea arabica) and robusta coffee (C. canephora).

Reliance on selective breeding and fungicides have more or less dominated the fight against rust, because there is debate about which cultivation method, sun or shade, helps mitigate this disease. This is in large part because the various factors that influence the severity of coffee rust outbreaks can be influenced, sometimes dramatically, by microclimate. This makes farm-wide management decisions tricky. Some examples of the quandary:

  • In full sun, plants dry out faster, hindering the germination and spread of rust, and sun may kill the fungus. However, pores (stoma) on the surface of leaves open up at high levels of light intensity, allowing more frequent and deep penetration of rust spores that are present.
  • Coffee grown in sun (especially if generously fertilized, as is usually the case) produces heavy yields. This over-bearing stresses the plants and makes them more apt to succumb to rust and other diseases.
  • Shade increases the life of leaves and their size, so rust spores have more leaf area to colonize and time to be dispersed.
  • Coffee types that are less genetically resistant to rust show lower levels of infection at lower levels of light intensity.
  • Shade trees intercept raindrops in gentle rains, so spores are not dispersed. In heavier rains, however, larger drops of rain accumulate and splash on the coffee, releasing many spores.

One very interesting bit of research suggests that growing coffee under shade can facilitate complex ecological connections that help fight coffee rust in Latin America. Green coffee scale (Coccus viridus) is a small insect that has many hosts, including coffee (on which it is usually more of a nuisance than a pest). Like many scale insects, it has a mutalistic relationship with some species of ants. The ants feed on “honeydew,” a sweet substance exuded by the scale insects. In exchange, the ants defend the scale insects from predators.  Meanwhile, green coffee scale can be infected with a fungus (Lecanicillium [Cephalosporium] lecanii) …which also attacks coffee leaf rust. Researchers have found that where green coffee scales are protected by a particular common species of ant (Azteca instabilis) which nests primarily in the shade trees, the scale insects reach localized population levels that enable the Lecanicillium fungus to attack the coffee rust.

Although not conclusive, this study suggests that shade coffee systems may provide some level of biological control over coffee leaf rust, and in fact this ant-scale-fungi relationship may be one reason rust was not as devastating in the New World as it was in the Old World. (The ants, scales, and fungi are only part of this very complicated system, which also includes a decapitating fly, wasps, and a lady beetle; see Vandermeer et al. 2010 for more fascinating details.)

Avelino, J., Willocquet, L., & Savary, S. (2004). Effects of crop management patterns on coffee rust epidemics Plant Pathology, 53 (5), 541-547 DOI: 10.1111/j.1365-3059.2004.01067.x

Vandermeer, J., Perfecto, I., & Liere, H. (2009). Evidence for hyperparasitism of coffee rust (Hemileia vastatrix) by the entomogenous fungus, Lecanicillium lecanii, through a complex ecological web Plant Pathology, 58 (4), 636-641 DOI: 10.1111/j.1365-3059.2009.02067.x

Vandermeer, J., Perfecto, I., & Philpott, S. (2010). Ecological Complexity and Pest Control in Organic Coffee Production: Uncovering an Autonomous Ecosystem Service BioScience, 60 (7), 527-537.

Research on coffee growing

Research: Farmers, prices, and shade coffee

Why shade coffee does not guarantee biodiversity conservation. 2010. Tejada-Cruz, C., E. Silva-Rivera, J. R. Barton, and W. J. Sutherland. Ecology and Society 15: [online] http://www.ecologyandsociety.org/vol15/iss1/art13/.

The title of this paper should probably be “Does promoting shade coffee encourage forest conversion?” This question is perfectly legitimate, and has been debated in the literature before [1,2]. I’m not sure, due to methodological and other weaknesses, this paper adds a lot to this debate. It addresses, hypothetically, what coffee farmers might do if coffee prices increased, theoretically due to increased demand created by promotion of shade coffee to consumers.

The authors interviewed 57 coffee farmers inside and outside the buffer zone of El Triunfo Biosphere Reserve in Chiapas, Mexico. Farmers were chosen by the “snowball technique” in which one farmer refers the authors to the next person to be interviewed and so on, so a linkage is assumed between respondents. The authors did not address how this may have biased responses, e.g., shared attitudes regarding forest conservation, risk perception, or coffee production; mutual membership in cooperatives with an organizational slant towards particular farming methods; or similar economic pressures.

The salient question in the interviews for this paper was whether the farmers would convert forested areas on their property to “shade coffee” (not defined) if coffee prices increased. The authors did not specify in their interviews how much of an price increase or how long it would need to continue to influence farmer behavior.

About half of the respondents within the buffer zone said they would be likely to convert forest remnants into shade coffee if prices increased, while this figure was around a third for those outside the buffer zone (where less forest remained to be converted).

This might be instructive, but is missing critical elements. For example: even if the farmers wanted to convert forest, could they? The introduction states that this paper sheds light on “how small-scale coffee growers make decisions on land use when confronted with the choice to switch from conventional to eco-friendly’ labeled coffee.” The authors did not make this explicit in the Methods or survey questions, but given the context of the paper, “eco-friendly labeled coffee” presumably means certified by some agency with environmental standards.

All “eco-friendly” certifying agencies have restrictions on clearing of forest or cultivation in forested areas in their standards, a fact noted in the introduction of the paper. This includes one of the major coffee purchasers in the area, Starbucks. Their C.A.F.E. Practices is not a certification, but a sourcing guideline. One of their mandatory requirements is that there is no conversion of natural forest to agricultural production. Non-compliance would make it difficult if not impossible to become a Starbucks supplier. If farmers were unable to gain “eco-friendly” certification or status, they would be unable to access the increased prices being offered, and the question becomes, in practice, a moot point.

The authors acknowledge conversion is generally not allowed, but that they observed conversion occurring anyway. The circumstances and details were not explained, and it’s unclear from this paper what was going on — whether these farmers were doing so outside a certification system, if they were just not being audited, etc. Without more facts, it’s difficult to ascertain the extent of the problem and what would remedy it.

Within the buffer zone of the reserve, only certain activities are permitted [3]. This includes organic coffee production (which typically requires at least some shade) but not “traditional coffee production” except under certain conditions. It’s worth noting that if coffee prices fell or remained stagnant, farmers might turn to other permitted activities which might not be so eco-friendly, including palm cultivation, organic corn, or cattle management. Some discussion of this would have been helpful in the paper.

The authors report that, according to the farmers interviewed, there has been an increase in the cultivation area, “allegedly at the expense of forest,” although there is no external corroboration.  An accompanying figure graphs the increase in acreage in coffee and decrease in forest patches based on the farmers’ answers; the decade covered was 1991-2001. There is no correlation with coffee prices to provide a link to the theme of the paper. That decade, in fact, was the run-up and commencement of the world coffee crisis, one of (if not the) most volatile periods in modern coffee history. Prices went from a high of nearly $3.00/lb in the mid-1990s to a low of less than $0.50/lb in 2001.

The paper states that there was a “steady increase in cultivation area” for this period, which seems unlikely — when prices began to fall after the peak, many farmers didn’t continue to expand their plots, they abandoned them. Perhaps the 2001 end-point was too soon to reflect this. If these interviews were really done around 2001 (the date is not given), when prices were at 30-year lows and farmers were literally starving, it’s hard to imagine farmers not saying they’d convert forest for higher prices. Is this really indicative of what farmer would do in a more stable market? One of the major lessons learned from the coffee crisis is that prices drop when there is an oversupply and this type of overplanting is generally now discouraged.

Without some discussion of what actually happened in this area during this period to these farmers, using this graph as support for the argument that they will convert forest to coffee during an increase in prices makes little sense. There was a follow up question on the survey asking farmers to explain why they would or would not convert their forest to shade coffee. That would surely shed some light on their motivations and experiences, but it was not discussed in the paper.

Some of the discussion surrounding the theme in this paper is worthwhile. But the title of this paper makes quite a definitive negative statement. It is no doubt true under various circumstances,  but the facts in the paper don’t quite back up the claim. Shade coffee, grown under diverse shade — especially when organic and certified using strong, verified standards — is still one of the most environmentally-friendly agricultural alternatives for biodiversity conservation available.

[1] Philpott, S. and T. Dietsch. 2003. Coffee and conservation: A global context and the value of farmer involvement. Conservation Biology 117(6):1844-1846.

[2] Rappole, J. H., D. I. King, and J. H. Vega Rivera. 2003. Coffee and conservation. Conservation Biology 17:334-336.

[3] Castro Hernandez, J. C., R. Hernandez Janapa, S. Nanuez Jimenez, S.R. Rodriquez Alcazar, C. Tejeda Cruz, A. Vazquez Vazquez, K. Batchelder, A.Z. Maldonado Fonseca. 2003. Community-based Conservation Participatory Conservation in Buffer Zone Communities in the Natural Protected Areas of Chiapas, Mexico. The Nature Conservancy, Arlington, VA. 65. pp.

C. Tejada-Cruz, E. Silva-Rivera, J. R. Barton, & W. J. Sutherland (2010). Why shade coffee does not guarantee biodiversity conservation Ecology and Society, 15 (1)

Coffee and the environment / Research on coffee growing

Research: Shade coffee conserves bee diversity

Impacts 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

Birds and other biodiversity / Research on coffee growing

Research: Birds reduce coffee pests in Jamaica, take 2

Pest reduction services by birds in shade and sun coffee in Jamaica. 2010. Johnson, M. D., J. L. Kellermann, and A. M. Stercho. Animal Conservation 13:140-147.

Matt Johnson’s team from Humboldt State University (CA) continues its excellent research on birds and ecosystem services on coffee farms in Jamaica. This study, similar to others, looked at pest reduction on a 18 ha farm, Kew Park Coffee. This farm is about 70% shaded; the other 30% has shade trees too young to provide shade yet. The farm also has one side bordered by dense second growth forest.

Exclosures were placed on some coffee trees to prevent birds (but not insects) from accessing them, and the number of insects on these and control trees were examined. The authors found that on trees where birds had access, there was a 40 to 58% reduction in the coffee berry borer (CBB), or broca (Hypothenemus hampei), the world’s most serious coffee pest.

The most common means of controlling CBB are the nasty pesticide endosulfan (although some are developing resistance), or scent traps. Traps are most effective when female CBBs leave coffee cherries to lay eggs in other cherries; the birds in these studies usually attacked the CBBs as they were entering new cherries. Thus, the birds can provide an extra layer of control even on farms that use traps. The authors determined that the pest reduction by the birds on this small farm amounted to 12% of the value of the crop.

This study did not find that birds were more effective at controlling pests in shade than in sun, but it may have been due to the small size of the farm and the proximity of adjacent forested area. A previous study on four different Jamaican farms by some of the same researchers found that the birds consuming CBBs declined dramatically in abundance as distance from forest patches increased. Birds may have made use of the unshaded portions of the farm in the current study because of the amount of forest and shaded coffee surrounding it. I saw a presentation by another member of this research team at a recent ornithological conference that indicated some of the bird species in question foraged in coffee during the day, but retreated to forest patches to roost at night.

Bird species found in the shaded portion of the farm in good numbers, but not at all in the sun portions, included the national bird of Jamaica, the Red-billed Streamertail (Trochilus polytmus), a hummingbird also known as “Doctorbird”, shown above); another resident hummingbird, the Jamaican Mango (Anthracothorax mango); and the North American migrants the Black-and-white Warbler (Mniotilta varia) and Prairie Warbler (Dendroica discolor), which winter on the island.

Johnson, M., Kellermann, J., & Stercho, A. (2010). Pest reduction services by birds in shade and sun coffee in Jamaica Animal Conservation, 13 (2), 140-147 DOI: 10.1111/j.1469-1795.2009.00310.x

Coffee and the environment / Research on coffee growing

New coffee species from Madagascar

Earlier this year, the news of the “discovery” of a caffeine-free species of coffee from the Cameroon created a bit of a stir. This species was actually first collected in 1983, but remained unstudied and not described to science until 2008 [1], at which point it made headlines when it made a 2009 top ten list of new species. I wrote about it here.

Similiarly, the Royal Botanical Gardens at Kew just announced some recent achievements, among which was the “discovery” of new species in the genus Coffea from Madagascar. Again, these species were not necessarily just discovered but were described in a paper published in 2008[2].  Coffea ambongenis, for example, was first collected in 1841 but not described, was rediscovered in 1999, and is now published as a new species.

There are 103 described species of Coffea in the world, and the Madagascar species are part of the Coffea subgenus Baracoffea, which now stands at 9 species. In addition to species in this subgenus being deciduous rather than evergreen like all other coffee species, some have unusual morphological characteristics. Here is a very brief run-down.

  • C. ambongensis and C. boinensi: Very large fruit, in C. ambongensis often larger than 2.5 cm long. C. boinensi was first collected in 1994.
  • C. bissetiae: Underside of leaves and fruit hairy.
  • C. labatii and C. pterocarpa: Unusual winged fruit. C. labatii, first collected in 1992, has 12 to 18 “wings” per fruit. C. pterocarpa (first collected in 1954) has 16 to 20 wings, and is pictured at right in a photo by Aaron Davis from Kew; an informative accompanying article is here. One theory as to the function of the wings is that it helps the fruit float, and these species occur in regularly-flooded karst limestone habitats.
  • C. namorokensis: First collected in 2000, but not identified as a new species. Also has hairy fruit and leaves.

None of the new species have been tried as a beverage, and it is unlikely they will ever be commercialized.  All are rare: near-threatened to critically endangered, and Madagascar forests are among the most exploited and threatened in the world today.

[1] Stoffelen, P., M. Noirot, E. Couturon & F. Anthony. 2008. A new caffeine-free coffee from Cameroon. Botanical Journal of the Linnean Society 158: 67-72.

[2] Davis, A. P, & F. Rakotonasolo. 2008. A taxonomic revision of the baracoffea alliance: nine remarkable Coffea species from western Madagascar.
Botanical Journal of the Linnean Society, 158 (3), 355-390 DOI: 10.1111/j.1095-8339.2008.00936.x

Coffee and the environment / Research on coffee growing

The water footprint of coffee

The water footprint of coffee and tea consumption in the Netherlands. 2007. Chapagain, A.K., and A. Y. Hoekstra. Ecological Economics 64:109-118.

This is not a newly published paper, but I found it well worth summarizing here.

“Footprint” evaluations — ecological, carbon, or water — determine the amount of a resource needed to produce a unit of a good. This paper calculated the water footprints per ton and per cup of tea and coffee, as well as “virtual” water imports into the Netherlands for each beverage. I’ll only summarize the water footprint of coffee here, but the paper can be downloaded from the publications list at the Water Footprint Network.

The authors measured coffee crop water requirements in different parts of the world. Some regions must irrigate (e.g., Brazil) while others rely on rainfall. Water used in processing, which also varies by region, was then factored in. Much of the world’s coffee (especially arabica) is wet processed, requiring a water source such as a river or groundwater to ferment and wash the coffee prior to drying the beans.

The calculations also took into account the shrinking weight of the product throughout processing — e.g., fresh cherries to pulped cherries to hulled beans, etc.– in order to keep the metric (cubic meters of water per ton of coffee) consistent.

Because of all the variability, from annual crop water requirements (they used FAO estimates) to the number of grams of ground or instant coffee used to make a weak or strong cup, this whole operation is somewhat of an inexact science. However, the authors appeared meticulous in their choices and inclusiveness, and the results seem to at least give us a relative picture between regions and methods, if not numbers that are actually well in the ballpark.

As it turns out, there was little difference whether coffee was wet or dry processed. The water used in wet processing made up only 0.34% of water used to grow the coffee. The summary tables provided figures for wet processing only.

The main results summarized the cubic meters of water used per ton of coffee (for each step from fresh cherry to roasted) for 25 countries.  The two countries with the highest totals were both robusta-producing nations: Togo (49341 m3/ton) and Ghana (47554). In fact, six of the top ten countries grew robusta either exclusively or in addition to arabica. The highest arabica-only country was Panama at 37660 m3/ton.

The average (weighted for world production) “virtual water content” was calculated at 20987 m3/ton. Lowest countries were Vietnam at 6054 and the U.S. (Hawaii and Puerto Rico, 9061). Other countries that grow primarily arabica which were ranked below-average were Ethiopia, Guatemala, Costa Rica, El Salvador, Bolivia, and Colombia.

Finally, the authors calculated that the “average” cup of coffee required around 140 liters of water; several variations were provided. The authors also estimated that if the price of coffee included the economic value of rainwater, it would increase about 20 cents per kilo. This cost increase does not include surface or groundwater used for processing or irrigation water, nor any environmental costs due to erosion or water pollution.

Coffee flotation in Chiriqui, Panama; photo by Darrin O’Brien, used with permission.

Chapagain, A., & Hoekstra, A. (2007). The water footprint of coffee and tea consumption in the Netherlands Ecological Economics, 64 (1), 109-118 DOI: 10.1016/j.ecolecon.2007.02.022

Research on coffee growing

Shade coffee farmers attitudes towards wildlife

Attitudes and knowledge of shade-coffee farmers towards vertebrates and their ecological functions [PDF]. 2009. P. Lopez-del-Toro, E. Andresen, L. Barraza and A. Estrada. Tropical Conservation Science 2:299-318.

The authors of this study interviewed 36 Mexican shade coffee farmers regarding their knowledge and resultant perception and attitudes of the wildlife on their farms. Farmers were members of a cooperative, and some of them had also attended environmental workshops, which included wildlife-related topics, sponsored by the cooperative. In general, this study found that:

  • All farmers liked having birds on their farms, and they were viewed positively.
  • Farmers thought most snakes were poisonous, and only a third knew they ate rodents and/or could be beneficial in pest control.
  • Most farmers had a very utilitarian view of non-flying mammals (everything from squirrels to ocelots), being largely indifferent except towards those used for food.
  • Bats were the least understood, with most farmers not knowing what bats feed on or what ecological role they fulfilled.
  • Most farmers knew that seed dispersal was an important ecological function, and identified birds as seed dispersers. Few knew mammals could also disperse seeds.
  • Few farmers perceived pollination as being important, or understood the process well.
  • Farmers that had attended educational workshops gave an
    “environmentally friendly” answer to questions for the majority of the
    questions, compared to the farmers who had not. The authors acknowledge this could either be due to what the farmers learned in the workshops, or inherent interest or knowledge by the farmers attending, since the sessions were voluntary.

These results are not particularly surprising, but serve to illustrate a point. I think most First World coffee drinkers, if they think about coffee farmers at all, envision a Juan Valdez-like farmer. There is some romantic notion of the peasant who lives close to the land, full of indigenous knowledge and in tune with nature. This study presents something much closer to reality: for the average small coffee farmer, the land is there to support a family. The flora and fauna have to aid in that goal. There are no field guides or textbooks (or, in many cases, the level of literacy to comprehend them). No binoculars or microscopes.

These are the people we expect to conserve and protect tropical biodiversity for us. We think they should grow their coffee a certain way, without cutting down trees, using chemicals, or harming animals. Further, we would like them to pay someone to prove this to us, by way of some type of certification. And we’d like them to do this with little or no compensation.

There is no such thing as “cheap coffee.”

Coffee farmer by Neil Palmer (International Center for Tropical Agriculture, CIAT).

Lopez-del-Toro P., Andresen, E., Barraza, L., & Estrada, A. (2009). Attitudes and knowledge of shade coffee farmers towards vertebrates and their ecological functions. Tropical Conservation Science, 3 (2), 299-318.

 

Coffee and the environment / Research on coffee growing

Climate change and coffee pests

Jaramillo, J., A. Chabi-Olaye, C. Kamonjo, A. Jaramillo, F. E. Vega, H.-M. Poehling, and C. Borgemeister 2009. Thermal tolerance of the coffee berry borer Hypothenemus hampei: Predictions of climate change impact on a tropical insect pest. PLoS ONE 4(8): e6487. doi:10.1371/journal.pone.0006487.

A paper just published in the journal PLoS ONE explores the impact of climate change on the life history and distribution of the world’s worst coffee pest, a minute beetle called the coffee berry borer (CBB), Hypothenemus hampei.

The study modeled potential changes in mortality, number of generations per year, and developmental rate, among other traits, under eight different temperature regimes. The model indicated that CBB successfully develop at 20-30°C, and the intrinsic rate of increase (rate at which a CBB population increases in size) is highest, and the population doubling time lowest, at about 25-26°C (around 77°F).

As mean seasonal temperatures in coffee-growing countries move toward the optimum development temperatures for CBB, these areas become more vulnerable to increasing pest pressure from CBB. This could be especially problematic in Colombia, where multiple flowering of coffee plants means nearly year-round availability of coffee cherries.

The predicted optimal temperature for CBB increase is higher than that which is best for arabica coffee, which prefers a temperature range of 18-21°C (above which yields are reduced), while robusta coffee thrives at temperatures several degrees higher. Climate change is already predicted to reduce area suitable for coffee production. This is probably an even more pressing threat to coffee than changing pest dynamics.

As far as mitigation of the effects of higher temperatures on CBB and coffee production in general, the authors state:

A proven strategy to alleviate the potentially negative effects of climate, especially warmer temperatures, on coffee production is the introduction of shade trees in coffee plantations.

They point out that shade trees can lower temperatures around coffee by up to 4°C at low altitudes (<700 m) and 2°C higher up (>1100 m), that shaded farms harbor more CBB enemies which can provide bio-control of these pests, and that coffee cherry weight and quality is higher when grown under shade, thus offsetting lower yields.

A number of the authors are associated with the International Center of Insect Physiology and Ecology.

Update, March 2011: James Hoffman did an overview of the CBB with some links to climate change research.
Update, September 2011: Further follow-up research by the authors is summarized here.

Photo of a female CBB entering an unripe coffee cherry, part of Figure 1 from the PLoS paper, photo by Gonzalo Hoyos of CENICAFE. Don’t discount small enemies.

Jaramillo, J., Chabi-Olaye, A., Kamonjo, C., Jaramillo, A., Vega, F., Poehling, H., & Borgemeister, C. (2009). Thermal Tolerance of the Coffee Berry Borer Hypothenemus hampei: Predictions of Climate Change Impact on a Tropical Insect Pest PLoS ONE, 4 (8) DOI: 10.1371/journal.pone.0006487

Birds and other biodiversity / Research on coffee growing

Research: Andean shade coffee quality habitat for birds

Bakermans, M. H., A. C. Vitz, A. D. Rodewald, and C. G. Rengifo. 2009. Migratory songbird use of shade coffee in the Venezuelan Andes with implications for the conservation of the cerulean warbler. Biological Conservation 142:2476-2483. doi:10.1016/j.biocon.2009.05.018

Most studies of birds in shade coffee have concentrated on numbers, species composition, and foraging dynamics, but none has looked at whether birds using shade coffee improve in body condition during the winter months. Body condition is strongly correlated with annual survival, and thus a crucial metric.

This study took place in Venezuela’s northern Andes near La Azulita in the state of Merida. This region is not very well represented in the literature (either coffee-growing or bird ecology research), yet it is an important wintering site for many North American bird species. These include various flycatchers and thrushes (Contopus and Catharus sp.), and a number of warblers including Cerulean Warbler (Dendroica cerulea). This species, which I have written about before, has declined an estimated 83% in the last four decades. The shade coffee farms examined ranged from 3 to 5 ha with 38 to 63% canopy cover. Nearby primary forest was also included in the study.

The four most common North American migrant species found, all warblers, were American Redstart, Blackburnian Warbler, Cerulean Warbler, and Tennessee Warbler. These species were three to fourteen times more common in shade coffee than in primary forest, even when detectability was factored in (because coffee farms are more open, birds can often be easier to detect, which would introduce bias if not accounted for).

Body condition was measured using various parameters in the five most common species of birds captured for banding in the shade coffee farms. Body condition improved over the winter for three species, including Cerulean Warblers, and was maintained in the other species. Nearly 30% of the individuals of the 15 species of migrants banded were recaptured, meaning they stayed in the coffee farms for prolonged periods of time throughout the season. These are all indications that the shade coffee provided quality habitat for these species.

In addition, 65% of Cerulean Warblers banded the first winter were recaptured or resighted the next winter, a remarkable return rate. Faithfulness to wintering sites is advantageous in that birds are familiar with resources such as food and cover, which can improve survivorship. However, it is also quite risky for birds wintering in areas experiencing high rates of habitat loss. Venezuela has seen nearly 40% of its shade coffee converted other types of agriculture — the authors state that they witnessed several shade coffee farms turned into cattle pasture during the two year duration of this study.

Just noting the sheer numbers, or even diversity of birds, in a particular habitat doesn’t tell the whole story. They may be present, sometimes only briefly, depending on the availability of resources in the larger landscape. This study not only showed that migrant birds were very common in shade coffee even in a region with primary forest, but also demonstrated site fidelity and improvement in body condition — adding  a critical component to the story of the value of shade coffee.

Cerulean Warbler photo by Petroglyph under a Creative Commons license.

Bakermans, M., Vitz, A., Rodewald, A., & Rengifo, C. 2009. Migratory songbird use of shade coffee in the Venezuelan Andes with implications for conservation of cerulean warbler Biological Conservation DOI: 10.1016/j.biocon.2009.05.018

Research on coffee growing

Research: Coffee as an invasive plant in India

Brewing trouble: coffee invasion in relation to edges and forest structure in tropical rainforest fragments of the Western Ghats, India. A. A. Joshi, D. Mudappa, and T. R. Shankar Raman. 2009. Biological Invasions 11:2387-2400.

While invasive plant species receive a lot of attention, the focus is often on weed species that compete with crops — not the potential invasiveness of the crops themselves. Coffee is native to Africa, but of course is widely planted in tropical regions worldwide. Both varieties of coffee, Coffea arabica and C. canephora (commonly called robusta) are grown in India.  In the Western Ghats of India, a biodiversity hotspot, coffee is often planted adjacent to fragmented forest reserves. This study looked at the spread of coffee into forest fragments at four sites that adjoined coffee farms, but varied in degree of disturbance.

Both coffee species were found in all the forest fragments, with whatever species that was cultivated in the adjacent farms being the most abundant. Stem density generally decreased as the distance from the the plantation edge increased for the coffee species planted in the adjacent farms. Stem density of arabica increased with disturbance level of the fragment. Robusta did not show such a pattern, and stem density was many times higher than arabica in fragments adjoining robusta farms, including the least disturbed, protected forest fragment. Further, there was a negative relationship between robusta invasion and native shrub density.

Robusta coffee growing in the forest, Anamalais, Tamil Nadu, India. Kalyan Varma, used with permission.

The main consumers and dispersers of coffee in India are the Asian Elephant, Lion-tailed Macaque (Macaca silenus), Sloth Bear (Melursus ursinus), and Brown Palm Civet (Paradoxurus jerdoni). Yet in this study the pattern of dispersal in one fragment, which was separated from the farm by a stream, and the sharp decline of coffee densities beyond 100 meters hints that small mammals might be important agents for dispersal in these systems. Larger mammals have bigger ranges, and the stream would not have acted as a barrier for them.

The authors concluded robusta may have a greater impact as an invasive species than arabica in this region. Whether this has to do with robusta being more adaptable, or just more fecund (robusta coffee plants can produce four times more fruits than arabica plants) needs further study.

I’ve not seen any similar research on the spread of coffee into forest fragments in Latin America. This may be because of a more limited number of potential animal dispersers, and, at least in many parts of Central America, less cultivation of robusta coffee.

You can find a summary of the paper at the Nature Conservation Foundation web site.

Thanks to Kalyan Varma for use of his photo of robusta

Joshi, A., Mudappa, D., and Raman, T. 2009. Brewing trouble: coffee invasion in relation to edges and forest structure in tropical rainforest fragments of the Western Ghats, India Biological Invasions DOI: 10.1007/s10530-009-9423-6

Research on coffee growing

Research: Coffee and sacred groves in India

Comparing tree diversity and composition in coffee farms and sacred forests in the Western Ghats of India. 2009. S. Ambinakudige and B. N. Sathish. Biodiversity and Conservation 18:987-1000.

The Western Ghats of India is a global biodiversity hotspot with high endemism. And like many other tropical montane regions, a lot of coffee is grown there. This study took place in the Kodagu (a.k.a. Coorg) district of Karnataka state, where both arabica (Coffea arabica) and robusta (C. canephora) coffee are grown. It’s one of the most densely forested areas remaining in India.

There are several types of land tenure and timber rights in the coffee lands of India. On unredeemed land, the coffee farmer owns the land, but the government owns the rights to the trees; tree rights belong to the farm owner on redeemed lands; and sacred groves are forest patches with little human impact used for communal activities that are the most pristine forests left in the region. The study was straightforward: comparing the diversity and abundance of trees in each category of land ownership.

The results regarding tree diversity were unsurprising, with sacred groves containing the more species (62) and more unique species (51) than either of the land tenures planted in coffee. The most common species in the sacred groves was Dimocarpus longan, a native fruit tree.

Redeemed and unredeemed lands had nearly the same number of species (38 and 39), but examination of dominant species showed the influence of government regulations on timber rights. On unredeemed coffee lands, where the government owned the tree rights, rosewood (Dalbergia latifolia), was most common. A high-value native timber tree, it can only be harvested under special license. On redeemed coffee lands, the most common tree was Grevillea robusta. This Australian tree is commonly used as a shade tree in Indian coffee farms. It grows quickly, straight and tall, so it is used as a living trellis for a common companion crop (pepper vines) before it is harvested for timber.

Species composition in these plots is not static, and highlights the ironic destructive nature of laws designed to protect native tree species in this region. In interviews with coffee farmers that were part of this study, it was found that growers were concerned about coffee prices and wanted to plant timber trees to hedge against low prices. Grevillea was not only planted in redeemed lands for this reason, but farmers were also planting it in unredeemed lands because it is easier to get permission to harvest non-native trees (Grevillea is apparently totally unregulated). This is encouraging the planting of Grevillea, where it is supplementing or (more often) replacing native species.

Not only does this diminish tree biodiversity, but diversity of other species as well. Birds, for instance, that depend on insects to eat find fewer insects adapted to feed on non-native vegetation. In another study, an increase in Grevillea from 33% to 55% was associated with 91% reduction in the abundance of one restricted-range, endemic species, the Malabar (Crimson-fronted) Barbet (Megalaima malabarica), shown above.

This has implications for any type of shade certification scheme that might be used in India, as encouragement of “shade” without adjustment to regulations regarding harvesting native species will only further serve to promote planting of more non-native trees, especially Grevillea.

Photo of barbet, taken in Karnataka, by Shiva Shankar. Used by permission.

Research on coffee growing

Coffee-related deforestation in Sumatra

Three decades of deforestation in southwest Sumatra: effects of coffee prices, law enforcement and rural poverty. 2009. D. L. A. Gaveau, M. Linkie, Suyadi, P. Levang, and N. Leader-Williams. Biological Conservation 142:597-605 .

I’ve written in the past about Sumatra’s problems with illegal coffee growing, particularly in Bukit Barisan Selatan National Park. A 2007 World Wildlife Fund investigation revealed that the robusta coffee grown illegally in the park was threatening the integrity of tiger, elephant, and rhino habitat and was purchased by such large companies as Kraft and Nestlé. A year later, I posted an update that noted Nestlé was still buying coffee originating in the park.

This study revisited this on-going situation, examining how deforestation can be curbed by law enforcement efforts, and how deforestation rates are driven by coffee prices.

Over the last 34 years, the main driver of deforestation in and around the park has been production of low-grade robusta coffee, the kind used in cheap grocery store blends and instant brands. In 2005, more than 85% of the forested areas in the park that had been converted to agriculture was planted with coffee, and the yield was a remarkable 4% of Indonesia’s entire annual robusta production.

The was a complex interplay of changing laws, local coffee prices tied to currency valuation, and low wages in the coffee-growing regions that drove the coffee-related deforestation, nicely analyzed by the authors. Active law enforcement did curtail the encroachment in the park in the 1980s. It has rebounded since the late 1990s; the departure of President Suharto has seen a decline in the emphasis on law enforcement, and a change in the governing philosophy towards conservation and rural workers, explain the authors.

The authors did not give a lot of cause for optimism that the coffee-related deforestation can be easily addressed. For example, eco-certification has been suggested to help provide premiums to farmers that grow coffee outside of the park under sustainable guidelines. But according to the authors, buyers and roasters are unwilling to manage the costs of certification. I doubt that the premiums wouldn’t be sufficient to discourage farming inside park boundaries (consumers would be unwilling to absorb additional costs for low-quality robusta).

Ultimately the authors suggested that prohibiting local use of the park would have to be reconsidered, including, perhaps, some type of sustainable-use policy and community conservation projects.

Photo of a Sumatran Tiger by g-na under a Creative Commons license.

Research on coffee growing

Research: Coffee certification and bird conservation in Ethiopia

Ethiopian coffee cultivation — Implications for bird conservation and environmental certification. 2008. A. D. Gove, K. Hylander, S. Nemomisa, and A. Shimelis. Conservation Letters 1:208-216.

Common Fiscal (Lanius collaris), a shrike relative that favors shrubland found almost exclusively in the farm plots.

This is probably the first peer-reviewed paper specifically about coffee growing/shade coffee and birds in Ethiopia. It reveals that the relationship between coffee management and bird diversity is different in Ethiopia than it is in Latin America, where shade coffee criteria were developed, and these differences need to be taken into account in certification criteria.

The study took place in southwestern Ethiopia near Bonga, where coffee is harvested from within existing forests, and also grown in mixed systems with other crops under isolated shade trees. The study area is a mosiac of forest and agriculture, and authors compared birds present in 19 forest sites with 19 farm sites — all representing a range of tree and coffee densities.

Many of the 106 bird species recorded were found in both the forest and farm plots, but forest bird assemblages were distinct from those found on farms.

The Red-chested Cuckoo (Cuculus solitarius) is a woodland species that was found in both farm and forest plots, but more often in forest.

Tree density on farms had a positive influence on the number of forest and woodland bird species. In this way, coffee cultivation, with its associated shade trees, improves habitat for birds by increasing
habitat complexity in these largely open degraded lands. The
coffee plots with their isolated tree patches would not qualify as “shade coffee” under most current criteria. But since coffee is native to Ethiopia, even these little plots could be considered rehabilitation of cleared land. Further, although isolated, the shade trees in coffee farm plots acted as “stepping stones” through inhospitable habitat, and, if plots were abandoned, as valuable sources of seeds that could regenerate forests. The authors concluded coffee cultivation on these small farms was a plus for bird habitat.

On the other hand, most of the forest plots would qualify as shade coffee under current criteria, which emphasize canopy structure. However, it is not uncommon for forest plots to be manipulated for increased coffee density; these plots had complex canopy but simplified understories. This change in forest structure decreased the number of bird species. Encouraging this type of “shade” coffee farming would actually have an overall negative impact on birds and bird habitat. These situations need to be taken into account in future certification schemes in Ethiopia, and perhaps elsewhere in Africa.

A forest specialist, the African Hill Babbler (Pseudoalcippe abyssinica) was found nearly exclusively in forest plots.

Finally, the authors emphasized that “Ensuring that coffee farmers receive a reasonable price for the commodity is perhaps most important.” Under low prices, farmers anticipate clearing forest for cereal, corn, or khat crops, or large government-sponsored sun coffee farms, threatening habitats of all types.

Top: Common Fiscal photo by Lip Kee. Middle:  Red-chested Cuckoo photo by Johann du Preez. Bottom: African Hill Babbler photo by Veli Pohjonen, East Usambara Conservation Area Management Programme, Bugwood.org.

A. D. Gove, K. Hylander, S. Nemomisa, A. Shimelis (2008). Ethiopian coffee cultivation — Implications for bird conservation and environmental certification. Conservation Letters, 1, 208-216.

Research on coffee growing

Research: Ethiopian garden coffee preserves epiphyte biodiversity

Home garden coffee as a repository of epiphyte biodiversity in Ethiopia. 2008. K. Hylander and S. Nemomissa. Frontiers in Ecology and the Environment. 6:524-528.

Nearly all the work that’s been done examining the relationship between shade coffee and biodiversity has taken place in Latin America, so it’s good to see studies like this coming out of Africa.

This study looked at the diversity of epiphytes and bryophytes (mosses, liverworts) in home coffee gardens and forest patches in southwestern Ethiopia near Bonga. People often grow coffee under shade trees in their gardens, and this study not only compared the gardens versus the forest, but also the epiphytes growing on the coffee shrubs and shade trees.

Six to 27 species of epiphytes were found growing on coffee shrubs in home gardens, and only liverworts were more diverse on forest coffee shrubs. Eleven to 33 species were found on shade trees in home gardens. Overall, epiphyte/bryophyte diversity was higher on forest shade trees, but there was a lot of overlap and many garden shade trees had richer diversity than those in the forest. It was also noted that heavily pruned coffee in more intensively managed farms did not host many epiphytes.

The authors concluded that coffee shrubs and shade trees in home gardens are important hosts of epiphytes and bryophytes, helping to preserve the biodiversity of these plants. They also felt that epiphytes and bryophytes likely provide nest material, nest sites, and food sources for birds as has been proven in Latin America. Shaded home coffee gardens also had the added benefit of providing resources such as honey and firewood, and environmental services such as erosion control.

The tree depicted on the stamp, Bicoloured waterberry, Syzygium guineense, is a common canopy tree in the region of Ethiopia examined in this study.

K. Hylander, S. Nemomissa. (2008). Home garden coffee as a repository of epiphyte biodiversity in Ethiopia. Frontiers in Ecology and the Environment, 6 (10), 524-528 DOI: 10.1890/080001