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Evolution of the Afroalpine Flora

Olov Hedberg
Biotropica
Vol. 2, No. 1 (Jun., 1970), pp. 16-23
DOI: 10.2307/2989783
Stable URL: http://www.jstor.org/stable/2989783
Page Count: 8
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Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Evolution of the Afroalpine Flora
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Abstract

The alpine enclaves of the high East African mountains provide a number of geographically and ecologically isolated temperate islands, inhabited by an afroalpine flora which is poor in species and peculiarly adapted to the extreme diurnal climate. Phytogeographically this afroalpine flora is of complex derivation. Its high degree of endemism indicates that its enclaves have long been isolated from each other and from other temperate areas. The high mountams harboring it have evidently stood isolated from each other since their origin, and Pleistocene climatic changes cannot have enabled direct contacts between the different alpine enclaves. Intermountain migration has probably occurred by independent long-distance dispersal. The frequency of apparent adaptations to different vectors is given in table 1. Establishment of newly dispersed afroalpine plants has necessitated climatic preadaptation and may have been facilitated by the occurrence of open habitats with weak competition. The vicarious plant communities occurring on the mountains appear to have been synthesized on each mountain separately after independent long-distance dispersal of the constituent species. The distribution of afroalpine plant communities seems to depend mainly on edaphic differences, and below the foreground of the glaciers there are few signs of regular successions.

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