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 stategy 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 unmanipulated 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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