How are floristic structure and community categories in the vegetation of Hamar Tribes at Buska Mountain Range, Southwestern Ethiopia?

Abstract

  The current investigation was conducted in the vegetation of Buska Mountain range, Hamar area, Southwestern Ethiopia. The main goals of the study were investigating plant diversity, community types, vegetation structure, regeneration status, and the major environmental threats to the vegetation.  Accordingly, the required data were collected from 92 quadrats of 20m x 20m (400 m²) for woody species and five subplots of 25 m² for shrubs and five subplots of 4 m² for saplings and seedlings as well as herbaceous plant species within the main plots. The plots were laid out in a systematic manner along eight transect lines that were one kilometer apart. The height and DBH of woody plant species with a height ≥2 m and DBH ≥2.5 cm were measured, and the cover-abundance was estimated. Community classification was conducted using agglomerative hierarchical method(R package version 4.1.3). The Shannon-winner diversity and Evenness indices were used to calculate plant species diversity, richness, and evenness. DBH, basal area, density, height, frequency, and importance value indices were used to describe the vegetation structure. A total of 272 vascular plant species within 202 genera and 77 families were identified. Fabaceae (with 33 species; 12 %) was the most dominant family, followed by the Asteraceae (16 species; 6 %). Shrubs were the most frequent growth habit (43%) in the vegetation. The highest and the least Shannon-Wiener diversity indices were recorded in community types three and two respectively. The result of CCA ordination analysis revealed that the altitude, grazing, slop and aspect were some of the environmental factors influencing the plant species distribution and community types' formation. Despite the arid climatic conditions and fragile characteristics of the study area, it supports a higher variety of plant species. However, there were natural and anthropogenic interventions currently threatening the vegetation. As a result of realized diversity as well as vulnerability, the study vegetation necessitates immediate interventions to mitigate the disturbances.