Data from: Variation in population structure and dynamics of montane forest tree species in Ethiopia guide priorities for conservation and research

The greatest extent of Afromontane environments in the world is found in
Ethiopia. These areas support exceptional biodiversity, but forest cover
and ecological integrity have declined sharply in recent decades.
Conservation and management efforts are hampered in part by an inadequate
understanding of the basic ecology of major tree species. We investigated
population structure and inferred population dynamics from size frequency
distributions of 22 forest tree species encountered in montane forests of
Ethiopia. We collected new empirical data from four sites in the Bale
Mountains, where some of the country’s most extensive and least disturbed
forests remain, and conducted a systematic review and analysis of all such
studies that reported population structure for one or more of these
species in Ethiopia. Thirteen widespread montane tree species showed a
reverse-J size distribution, indicating a relatively stable population
structure. Six other species had size-frequency distributions that
indicate episodic recruitment and/or removal of certain size classes.
Specific causes of these patterns are uncertain: they may involve timber
harvesting, herbivory, fire, or natural disturbances, but patterns were
inconsistent and locality dependent. For three other tree species,
existing data are inadequate for any interpretation of population
structure and dynamics. A species of particular conservation concern that
emerged from this analysis was Hagenia abyssinica, which was found in all
areas to consist only of larger individuals with no recent recruitment.
For management and conservation purposes, the species in most urgent need
of new research are those with inadequate or inconsistent data, and H.
abyssinica..