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For forest ecosystem management to be effective, explicit understanding of the species diversity-environmental relationship along elevation gradient is crucial. This study aimed at identifying and describing plant communities and also documenting their species diversity. Evaluation of relationships between selected environmental variables and species diversity was another objective of this study. Systematic sampling techniques were used to collect vegetation data in a total of forty two sample plots (size=20×20 m). Within main plots, four sub-plots of 5×5 m were established at four corners and – one sub-plot of the same size in the center. These plots were used for shrub and herb diversity assessment. Within each sample plot, all plant species were documented and their scientific names were identified. Environmental variables, such as: elevation, aspect and slope, were also recorded for each main plot. Species diversity was determined using Shannon-Wiener diversity index and evenness in R statistical software. Agglomerative hierarchical clustering method was used for plant community classification. The total of 44 plant species belonging to 30 families was documented. Four plant community types were identified with different diversity, evenness and species richness. These plant communities were: Afrocurpus falcatus-Ficus sur, Maesa lanceolata-Bersama abyssinica, Vernonia myriantha-Urera hypselodendron and Croton machrostachus-Tecleanobilis occurring at average elevation of 2521, 2429, 2329, and 2364 m asl, respectively. Maesa lanceolata-Bersama abyssinica community type exhibited the highest species diversity and evenness followed by Croton machrostachus-Teclea nobilis community type showing the fact that median elevation ranges were rich in species. Elevation and slope gradient explained significant variation in species richness in the studied forest. For effective conservation of biodiversity and sustainable management of the forest ecosystem, further research on the impacts of anthropogenic disturbances and soil properties is recommended as a result of this study. [ABSTRACT FROM AUTHOR]

Abstract: Aim: Past land use legacy effects—extinction debts and immigration credits—might be particularly pronounced in regions characterized by complex and dynamic landscape change. The aim of this study was to evaluate how current woody plant species distribution, composition and richness related to historical and present land uses. Location: A smallholder farming landscape in south‐western Ethiopia. Methods: We surveyed woody plants in 72 randomly selected 1‐ha sites in farmland and grouped them into forest specialist, generalist and pioneer species. First, we investigated woody plant composition and distribution using non‐metric multidimensional scaling. Second, we modelled species richness in response to historical and current distance from the forest edge. Third, we examined diameter class distributions of trees in recently converted vs. permanent farmland. Results: Historical distance was a primary driver of woody plant composition and distribution. Generalist and pioneer species richness increased with historical distance. Forest specialists, however, did not respond to historical distance. Only few old individuals of forest specialist species remained in both recently converted and permanent farmlands. Main conclusions: Our findings suggest that any possible extinction debt for forest specialist species in farmland at the landscape scale was rapidly paid off, possibly because farmers cleared large remnant trees. In contrast, we found substantial evidence of immigration credits in farmland for generalist and pioneer species. This suggests that long‐established farmland may have unrecognized conservation values, although apparently not for forest specialist species. We suggest that conservation policies in south‐western Ethiopia should recognize not only forests, but also the complementary value of the agricultural mosaic—similar to the case of European cultural landscapes. A possible future priority could be to better reintegrate forest species in the farmland mosaic. [ABSTRACT FROM AUTHOR]

Striga hermonthica, a root hemiparasitic Orobanchaceae, severely constrains grain production in sub-Saharan Africa. Host specificity and geography may play important roles in shaping the population structure of S. hermonthica, with the Rift Valley potentially presenting a significant barrier to dispersal. Genetic diversity was assessed in 12 S. hermonthica populations from locations in Ethiopia. Of these, seven populations were parasitic on sorghum, two each on tef and maize, and one on finger millet. Genetic variation was detected using four amplified fragment length polymorphism (AFLP) primer combinations. After correcting for repeatability, 385 fragments were detected across all primer combinations. The percentage of polymorphic loci was relatively high, ranging from 53.2% to 76.4%. Expected heterozygosity ranged from 0.168 to 0.279. Genetic differentiation between populations was relatively high, and all populations were significantly different from each other . FST values ranged from 0.032 to 0.293 and averaged 0.146. Genetic differences between populations could not be attributed to host specificity. Instead, geography was the main determinant of population structure. There was a correlation between geographic and genetic distance. A significant portion of the genetic variance could be apportioned on either side of the Rift Valley (5%; P = 0:001). Also, a significant geographic barrier was identified in the southern portion of the sampled region. [ABSTRACT FROM AUTHOR]