Ecological and Floristic Study of Hirmi Forest, Tigray Region, Northern Ethiopia

Abstract Background: The Dryland area in Ethiopia contributes large vegetation resources. However, the landmass has received less attentioneven if it has high ecological, environmental and economic importance. The present study was conducted in Hirmi forest, which is one of the dry forest in Northwestern, Ethiopia; to study the floristic composition, plant community types, community-environment relation, vegetation structure and regeneration status of the forest.Method: Vegetation and environmental data were collected from 80 sampling plots having equal size of 25m×25m were designated as the main plots. Within the main plot, five 2mx2m subplots were laid to record seedlings, saplings, and herbaceous species. Furthermore, within each subplot, soil samples were collected to analyze the relationship of edaphic parameters with the plant community. DBH, height, BA, density, vertical structure and frequency were computed. Floristic diversity and evenness were computed using Shannon diversity and Evenness indices. The plant community types and vegetation-environment relationships were analyzed using classification and ordination tools in R package (ver. 3.6.1), respectively.Result: A total of 171 vascular plant species belonging to 135 genera and 56 families were recorded. About 5.85% of the species were endemic/near endemic to Ethiopia. Woody species (48%) were dominant over herbs (45.6%) and liana (6.4%). The highest number of species was recorded in plant families of Fabaceae (16.37%) and Poaceae (11.7%) followed by Asteraceae (7.02%) and Combretaceae (3.5%). Five plant communities were identified and positively correlated with altitude, slope, sand, silt, soil organic matter, total Nitrogen and disturbance. Vegetation structure reveals that, large number individual species were categorized in the lower class of DBH, BA, frequency and height. The highest Shannon diversity index and evenness values of the study area were 4.21 and 0.95, respectively. Anogeissus leiocarpa, Combretum hartmannianum, Ziziphus mucronata, Terminalia macroptera, Acacia polyacantha were the species with high important value.Conclusion: the study shows Hirmi forest has high species diversity, richness, and endemism. However, due to various disturbances, it is under poor regeneration status that requires urgent conservation measures. Integrated forest management, monitoring, applying restoration techniques by considering the significant environmental factors associated with the species diversity, IUCN threat and regeneration status of the species is recommended to preserve the study forest.