Ecology and Development Series No. 10, 2003 - ZEF

Current state of knowledgeLianas are not common. However, the lower strata of the forest are often denselypopulated with woody climbers. There is no record of any epiphytic species. The ground ismostly covered with thick litter, and there are apparently very few species of forest floorherbs except Streptogyna crinita.2.1.2 Transitional rain forestThe transitional rain forest is found on the escarpments of the southwestern highlands inWelling, Illubabor and Kufa, between the dry peripheral semi-deciduous Guineo-Congolianforest and the Afromontane rain forest. These forests occur at altitudes between 500 and1500 m, partly in river valleys, and partly in areas with a high water table. The annualtemperature ranges from 20-25 0 C. The mean annual rainfall is about 2000 mm, with rainfalling all year round, the highest amounts falling in September. More detailed informationabout such forests is found in some Italian sources (Friis 1992) and Chaffey (1979). Thetransitional rain forests are similar in physiognomy and composition to the humid broadleavedAfromontane rain forest of southwestern Ethiopia described below, with additionalspecies from the lowland forest described above. However, a few species of forest trees orshrubs known in neither of these two forests appear to be restricted to the transitional forest.A list of these species includes: Aningeria altissima, Anthocleista schweinfurthii,Campylospermum bukobense, Celtis philippensis, Celtis zenkeri, Croton sylvaticus,Dracaena fragrans, Elaeodendron buchananii, Eugenia bukobensis, Ficus exasperata,Garcinia huillensis, Manilkara butugi, Morus mesozygia, Phoenix reclinata, Strychnosmitis, Trichilia dregeana, Trilepisium madagascariense and Vepris dainellii. Friis (1992)noted that this forest type may contain Guineo-Congolian forest species, which are not yetrecorded in Ethiopia. This forest type, therefore, deserves further studies.2.1.3 Afromontane rain forestThese forests occur in the SW highlands and on the Bale Mountains in the SE highlands ofEthiopia. They characteristically contain a mixture of Podocarpus and broad-leavedangiosperm species in the canopy, but Podocarpus becomes gradually more infrequenttowards the southwest of Kafa and Illubabor, while Aningeria adolfi-friederici becomes12