Dynamics of Woody Species Composition and Diversity as a Result of Conversion of Open Grazing Land to an Exclosure in Northern Ethiopia: The Case of Tigray Lowlands

Abstract

Exclosures have been establishedon open grazing lands to tackle environmental degradation in Ethiopia, particularly in Tigray region. However, little has been know with regard to the effect of establishing exclosures on open grazing lands especially in Lowlands of Tigray region, northern Ethiopia. Hence, this study was conducted to explore the effect of conversion of grazing lands to an exclosure on woody species composition and diversity at Tselemti district, which was taken as testing site to represent the lowlands of Tigray.  To collect data on vegetation, three line transects, parallel to each other and across the slope were laid in the exclosure and open grazing lands systematically at 150 meters interval. Along each transect line, six sample plots measuring 20m×20m were laid down at 100 meters intervals from each other. So, a total of 36 plots (18 from grazing land and 18 from exclosure), measuring 20m*20m, were established along 6 transects for vegetation sampling. 41 and 16 woody species were recorded in the exclosure and grazing land respectively. Shannon diversity, richness, evenness and density were found to be significantly higher (P<0.05) in exclosure than grazing land. It can be concluded that conversion of open grazing lands to exclosures is a viable option to restore degraded vegetation. For this reason, additional exclosures have to be established on previously degraded open grazing lands in the area and areas with similar biophysical setup.