Composition and Structural Diversity of Woody Species in the Wof Ayzurish Forests, the Dry Afromontane Forest of the Northern EthiopiaI

Abstract

Dry Afromontane Forest (DAF) is the largest Afromontane section and plays a fundamental role in preservation of species biodiversity. Despite its biodiversity, DAF is the most altered and threatened in the Ethiopian ecosystem. With the exception of a few isolated pockets left in some sacred places and protected areas of the country, most of forests are inaccessible. The scenario is not different for the present study forest. Therefore, the objective of the present study is to investigate woody species diversity, structure and regeneration status of Wof Ayzurish Forest, which is a dry Afromonatane in North Shewa of Ethiopia. A systematic method was employed whereby 67 quadrats set in 8 parallel lines transecting at 300-meter intervals and quadrats at 150-m distance. All trees and shrubs with diameters of breast height > 2.5 cm and height > 2 m were measured. The results revealed that Wof Ayzurish Forest harbors 76 species of woody plants that belong to 68 genera and 47 families, with Asteraceae, Fabaceae, and Solanaceae displaying the highest diversity. Shrubs had the highest composition than trees. The most abundant plants were Dodonaea viscosa subsp. angustifolia, Carissa spinarum, Juniperus procera, Olinia rochetiana and Olea europaea subsp. cuspidata. Dodonaea viscosa subsp. angustifolia was the most prominent plant, occurring in 98.5 % of all sample plots. The DBH and height classification pattern exhibited that the forest had a classic inverted J-shape, dominated by smaller trees and shrubs, indicating a secondary stage of regeneration. Total basal area (BA) for trees and shrubs DBH > 2.5 cm was 18.03 m2 ha−1. Remarkably, five species accounted for 57.45 % of the basal area, indicating that higher numbers of individuals concentrated in lower DBH classes. By using R software, agglomerative hierarchical cluster analysis and Canonical Correspondence Analysis (CCA) has done to identify plant community types and examine the relationship between plant community types and environmental variables, respectively. Three significantly different (p < 0.05) plant community types were identified. The CCA results showed that species diversity and community composition among community types were significantly influenced by altitude and human disturbance such as expansion of agriculture, cuttings, and grazing. Therefore, it is recommended that community-based methods and awareness creation should be devised in order to implement sustainable forest conservation.