Plant diversity and communities along environmental, harvesting and grazing gradients in dry Afromontane forests of Awi Zone, northwestern Ethiopia

Afromontane forests support diverse species and provide numerous ecosystem goods and services. There are few studies examining the role of dry Afromontane forests in biodiversity conservation, thus motivating our assessment of plant diversity and communities in five dry Afromontane forests. The objective of the study was to determine plant diversity and communities along environmental, harvesting and grazing gradients. Vegetation data were collected systematically in 80 quadrats (400 m(2)) with subplots for shrubs and herbaceous species. Biodiversity models and multivariate analyses were employed to determine diversity and community types. Cluster and Redundancy Analyses (RDA) were employed for classification and ordination. The result showed that the forests contained 153 species belonging to 63 families of which six species were endemic. Shannon-Weiner index (H') and its effective number of species in five forests were 2.4 and 11.11, respectively. Modeling diversity and evenness exhibited a declining trend along with an increase in elevation. The harvesting index and grazing intensity correlated negatively with richness and diversity. A cluster analysis coupled with indicator species resulted in four community types. RDA showed that the cumulative variance explained by the first four axes accounted for 14.4% of the species variation. The environmental factors that contributed most to explaining species-environment variation included elevation (37.3%), total nitrogen (13.3%), soil pH (12.2%) and grazing intensity (11.8%). In conclusion, dry Afromontane forests contained considerable endemic species, diversity and community types. However, environmental factors, harvesting and grazing intensity showed significant impacts on diversity and community types. Therefore, an effective management plan is needed for the conservation of biodiversity in the forests.