Plant community types and species compositional variations of the forest patches in Wolaita zone, Southwest Ethiopia

Forests in Ethiopia are of high ecological value, but their area is declining at an alarming rate due to various anthropogenic pressures. We identified and characterized plant communities, species diversity, and their determinants in forest patches in Wolaita, Southwest Ethiopia. We recorded the number of individuals of plants, species cover-abundance, and environmental factors in 126 (20 m x 20 m) quadrats. We sampled soils from three layers of 10 cm depth each and took air-dried composite samples to soil laboratory of Arba Minch University for analyses. The plant community-environment relationship was determined using canonical correspondence analysis. We used various diversity indices to compute species diversity. Species composition resemblance between the plant communities was determined using Sorensen's similarity coefficient. We identified five distinct plant communities using hierarchical agglomerative clustering. Diospyros abyssinica-Combretum collinum community was rich, while Combretum molle-Ficus vasta community was poor in species. Juniperus procera-Olea europaea community and Cordia africana-Prunus africana community showed the highest species similarity. D. abyssinica-C. collinum community had the maximum Shannon entropy (H = 4.19), while C. molle-F. vasta community had the minimum (H = 3.17). Shannon entropy was high in the study area (H = 3.75; Evenness = 0.86; Number of effective species = 41.7). J. procera-O. europaea community was dense (1014 individuals' ha-1), whereas C. molle-F. vasta community was sparse (762 individuals ha-1). Altitude, pH, EC, total nitrogen, sand, and clay explained most of the variations among community types. In general, low level of disturbance was detected in the study areas. Anthropogenic pressures, such as livestock grazing, and browsing, tree cutting for construction material and fuelwood, and mowing of grasses for livestock feed and roof cover may expose the soil to erosion and can alter the composition and structure of the forest patches in the study area. The low disturbance value, the high Shannon entropy, and other metrics show that these communities are of high natural value; thus, their preservation is of utmost importance. Monitoring and conservation intervention are necessary to sustain the importance of forest ecosystems.