Floristic composition and environmental factors characterizing coffee forests in southwest Ethiopia

Afromontane rainforest stands in Ethiopia with a high frequency of wild populations of Coffea arabica are commonly known as 'coffee forests'. These forests are important for the conservation of the genetic diversity of wild Arabica coffee, and for subsistence coffee production. This study analyses the floristic composition and environmental factors of such coffee forests, using the Yayu forest as a case. Fifty-eight plots of 20 m x 20 m were assessed, and a total of 220 plant species, representing 73 families, were recorded, of which 71 were trees, 28 shrubs, 27 climbers and 94 herbs. A cluster analysis, coupled with indicator species analysis, revealed three plant community types, which can designated as C. arabica-Cassipourea malosana, Argomuellera macrophylla-Celtis africana and Dracaena fragrans-Teclea noblis communities. The C. arabica-C. malosana and D. fragrans-T noblis communities occur at relatively higher altitudes (1450 and 1435 m on average) on gentle and steep slopes, respectively, while the A. macrophylla-C. africana community occurs on steep slopes at lower altitudes (1380 m on average). C arabica is one of the most frequent species in the Yayu forest, and its abundance is strongly negatively correlated with slope. These habitat differences, together with the predominance of Coffea in the understorey, support the floristic circumscription of a coffee forest. Forests commonly known as "coffee forests" have, therefore, to be viewed as a complex mosaic of different plant communities, which needs to be taken into consideration in the designation of conservation areas and differential management planning. The plant species composition of Yayu forest is predominantly Afromontane rainforest type, with several dry peripheral semi-deciduous Guineo-Congolian forest type species. Hence, Yayu forest can best be described as transitional between these lowland and montane forest types. (C) 2008 Elsevier B.V. All rights reserved.