Human Disturbance, Plant Species Composition, Diversity and Community Types of Kafta-Sheraro National Park, Tigray Region, Ethiopia

Abstract

Background: Ethiopia is rich in woodland natural forest although of increasingly subjected to deforestation and forest degradation with extensive expansion of settlement and agricultural practices. In developing countries like Ethiopia forest is one of the vital resources that determine the livelihood of the local communities. Consequently, woodlands’ of the country’s are under heavy pressure by shifting cultivation and charcoal production. Kafta-sheraro national park is newly established woodland area which lacks documented vegetation diversity and human disturbance on the forest. The study was conducted to quantify plant species richness and diversity along altitude; and identify anthropogenic disturbance on vegetation composition and community diversity of the park. Methods: a Systematic sampling method was used to determine species composition, abundance, and diversity. 161 quadrats each (400 m2) lying 200 m far apart for trees and shrubs while sub-plots (1 m2) for herbs and grasses along transects were established over an altitudinal gradient of 539-1111 m.a.s.l. All vascular plant species were collected and brought to National Herbarium, Addis Ababa University for identification.The degree of disturbance data as (low, moderate and heavy) were visually estimated for each plot. Result: a total of 182 plant species: 63 (34.6%) herbs,46 (25.3%) trees, 38 (20.9%) grasses, 18(9.89%) shrubs, 11 climbers (6.04%), and 6 (3.3%) tree ̸ shrub), belonging to 142 genera and 53 families, were identified. Fabaceae was represented by the highest number of species (37 species; 20.3%) followed by Poaceae (36 species; 19.8%) and Asteraceae, 10 species (5.49%). Three plant communities’ types were identified: Acacia mellifera-Balanites aegyptiaca (1); Hyphaene thebaica-Ziziphus spina-christi (2); Combretum hartmannianum-Terminalia brownii-Boswellia papyrifera (3). Species richness was highest in community 1 (mid-altitude: 607-640 m.a.s.l.).The highest Shannon-Wiener diversity index (H`=2.82) for the forest was in community 2 (low altitude: 539-610 m.a.s.l.) while evenness (J=0.72) was highest in community 3 (high altitude: 674-1111 m.a.s.l.) There was a significant correlation between species richness (p=0.024) and altitude per plot while species diversity was non significant (p>0.05) over altitude. Human activities also strongly correlated with species richness and diversity of specific community type. Conclusion: the site has pronounced floristic composition and diversity. Altitudinal difference and the degree of human disturbance determine variation in species composition and richness among communities. Altitude is significantly correlated with species richness of all community types while it is more strongly correlated with community type1.Crop cultivation, illegal fire, and overpopulation of livestock grazing are the main threats in community types 2 and 3. However, this document is a baseline to vegetation information of the park. detailed study on conservation challenges (anthropogenic disturbance) of the park vegetation and prioritize their mitigation measures should be arranged.