Nâng và núi lửa trong Miocen và thời gian địa chất Oligocene (giữa 38 và 7 triệu BP) trong bao gồm tất cả những tảng đá nằm bên dưới và hình thành các vùng núi Đông Phi, phần còn lại như hòn đảo trên các ngọn đồi xung quanh và đồng bằng. Những quần đảo Afromontane này được phân phối trên cả hai mặt của thung lũng Rift Đông Phi. Dãy núi Bale nằm ở phía đông nam của vùng cao nguyên Ethiopia, khoảng 850 km phía bắc của đường xích đạo. Đỉnh cao nhất trong Bale, Tulu Dimtu, là. | Part II Effects of Fire on Mountain Biodiversity Copyright 2006 Taylor Francis Group LLC 2 Diversity of Afroalpine Vegetation and Ecology of Treeline Species in the Bale Mountains Ethiopia and the Influence of Fire Masresha Fetene Yoseph Assefa Menassie Gashaw Zerihun Woldu and Erwin Beck INTRODUCTION Uplift and volcanism in the Miocene and Oli-gocene geological periods between 38 and 7 million BP resulted in the covering of all the underlying rocks and the formation of the East African mountains that rest like islands on the surrounding hills and plains. These Afromon-tane archipelagos are distributed on both sides of the East African Rift Valley. The Bale Mountains lie in the southeastern part of the Ethiopian highlands about 850 km north of the equator. The highest peak in Bale Tulu Dimtu is the second highest peak in Ethiopia and the seventh in Africa see Figure . The East African mountain nearest to the Bale mountains is Mt. Kulal 550 km south in the Turkana Depression. The vegetation of the Bale Mountains has been the subject of studies by a number of botanists and ecologists. A full account of the history of botanical exploration of the Bale Mountains has been provided by Miehe and Miehe 1994 . In a series of publications Hedberg 1975 1986 made important analyses of the vegetation and ecology of Afroalpine regions in Ethiopia. Weinert 1981 Weinert and Mazurek 1984 and Uhlig 1988 also conducted ecological research on the vegetation of the Bale Mountains. Miehe and Miehe 1994 presented a detailed study on ericaceous vegetation and on the plant communities within the ericaceous zones of the Bale Mountains. The present study attempts to provide a description of plant communities in the entire altitudinal range of the Afroalpine and ericaceous zones. The ericaceous belt of the Bale Mountains is a region most seriously affected by the progressive increase of human activities. Cattle and horses put heavy pressure on the vegetation especially at the lower .
