Coffee farms and carbon sequestration

by on March 3, 2008

In my post, “Why certifying shade coffee is so complex,” I ended with a comment regarding the upside-down nature of shade (or organic) certification. That is, the burden of certification costs are on the producers who are doing the right thing, rather than on the producers who are damaging the environment. Small producers, who are more likely to preserve forests and grow coffee under diverse shade (both of which enhance biodiversity) and are less likely to use chemicals, are the least able to afford certification.

I’ve been ruminating about this ever since, and wondered if some sort of “cap and trade” system might be helpful. What I had in mind were “credits” for forest or habitat preservation and enhancement small eco-friendly farms could “sell” to naughty sun coffee growers. This was inspired by a similar system: carbon credits. So while I let this idea simmer, it’s worthwhile to briefly discuss the role of carbon credits themselves, and their potential to generate income for farmers practicing sustainable agriculture, including shade coffee.

Quick primer on terrestrial carbon sequestration
Trees (and other plants) sequester carbon by removing it from the atmosphere through photosynthesis and incorporating into their tissues. Existing forests are carbon sinks (or “carbon storage units”) and contain over half of the terrestrial carbon in the world. Carbon remains stored in plant tissues until released, in this case most often by burning and decomposition.  Agroforestry systems, including shade coffee farms, that preserve forest are therefore acting as carbon sinks.

Reforestation also contributes to the sequestration of carbon, although the rate in which carbon is taken up and stored by plants varies among species, as well as where they are grown and if and how they are managed. This means that sun coffee farms converted to shade in which the appropriate tree species are planted and managed have the potential to effectively sequester carbon.

Carbon is also stored in leaf litter and other organic matter in the soil. Sustainable coffee agrosystems frequently rely on fallen leaves from their shade trees as well as the application of coffee skins and other organic matter for soil moisture retention and fertilization, providing another means in which these farms can contribute to carbon sequestration.

How much carbon can coffee farms store?
Although measuring carbon storage is difficult due to the multiple variables involved (even plots in the same region with similar tree species composition can vary in their storage capacity depending on microclimate, soil types, etc.), recent research has revealed some encouraging facts. A few examples:

  • In the tropics, potential carbon sequestration rates for smallholder, sustainable agroforestry systems range from 1.5 to 3.5 megagrams (tonnes) per hectare per year, or 2.1 billion megagrams annually worldwide.
  • It has been estimated that each hectare of sustainable agroforestry in the tropics could potentially offset 5 to 20 ha of deforestation.
  • Models have estimated a 5-year-old coffee farm shaded with two common Latin American tree species (Erythrina poeppigiana and Cordia alliodora) could sequester 5.3 megagrams per hectare.
  • Soil carbon stocks in shade coffee were 60% of that expected in primary forest in Sumatra, versus 45% for sun coffee.
  • In El Salvador, carbon sequestration values for various types of shade coffee management were estimated (in tons per ha per year): 174 for rustic shade to 77 for shade monoculture.
  • A study of carbon stocks in Costa Rican coffee farms calculated aerial (above ground) carbon stocks ranging from 11 megagrams per ha for simple shade (one heavily pruned shade species) to nearly 32 for diverse shade.
  • Using these figures, a farmer with 10 ha in diversified shade coffee could receive a one-time $3000 payment (based on previously carbon transactions for the country), as well as a reduction in expenses from chemical inputs and have timber and fruit for additional income. The payment is over three times greater than would be obtained for the carbon stocks in simple shade coffee systems.

The non-profit TechnoServe is exploring the use of carbon credit trading for promoting sustainable agroforestry, using a Guatemalan coffee cooperative (more here). Small holders in Oaxaca and Chiapas, Mexico, are gaining access to carbon credit funds to pay for sustainable agroforestry there, where a great deal of coffee is grown (more here).

It appears sustainable coffee agroforestry can play a role in helping to mitigate global climate change through carbon sequestration, and in the process also provide additional income and further incentive to growing shade coffee. I have a feeling we’ll be hearing much more about this in the future.

More reading, including sources for the figures above:

  • Smallholder agroforestry projects: Potential for carbon sequestration and poverty alleviation. O. J. Cacho, G. R. Marshall, and M. Milne. 2003.  ESA Working Paper No. 03-06. Agricultural and Development Economics Division, The Food and Agriculture Organizationof the United Nations.
  • Carbon sequestration in tropical and temperate agroforestry systems: a review with examples from Costa Rica and southern Canada. M. Oelbermann, R. P. Voroney, and A. M. Gordon. 2004. Agriculture, Ecosystems and Environment 104: 359-377.
  • Carbon sequestration: An underexploited environmental benefit of agroforestry systems. F. Montagnini and P. K. R. Nair. 2004. Agroforestry Systems 61:281-295.
  • Carbon stock assessment for a forest-to-coffee conversion landscape in Sumber-Jaya (Lampung, Indonesia): from allometric equations to land use change analysis. M. van Noordwijk, S. Rahayu, K. Hairiah, Y. C. Wulan, A. Farida, and. B. Verbist. 2002. Science in China (PDF here).
  • Carbon sequestration in coffee agroforestry plantations of Central America. 21st International Conference on Coffee Science, 2006. Abstract here.
  • Sustainability in the coffee sector: exploring opportunities for international cooperation. U.N. Conference on Trade and Development. 2003. (PDF here)
  • Carbon Storage in Coffee Agroecosystems of Southern Costa Rica: Potential Applications for the Clean Development Mechanism. C. Polzot. 2004. M.S. thesis, York University, Toronto.  Includes excellent cited information on the mechanisms of carbon sequestration in agroforestry systems, and Costa Rica’s Payment for Environmental Services programs.

Photo by Art es Anna; thanks for publishing under a Creative Commons license.

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Revised on March 23, 2014

Posted in Climate change,Coffee and the environment

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