Effect of area closure on selected soil physicochemical properties and woody species diversity in warja watershed, east shewa, ethiopia

Abstract

Land degradation has been a major challenge of environmental problem in highlands of Ethiopia. In East Shewa, as part of the government responses to land degradation, area closure has been mainly implemented to improve land management and the sustainability of environmental resources. This study was initiated with the objective of investigating the effect of area closure on selected physicochemical properties of soils and woody species diversity in Warja watershed, Adami Tulu Jido Kombolcha districts, East Shewa. Systematic sampling method was employed to take vegetation and soil sample. Sampling plot of 20mx20m was established for quantitative data for both vegetation data and soil samples. Sample of woody species, regeneration and soil were taken from both area closure and adjacent open grazing land. The soil samples and vegetation data were taken from 9 plots for each site. Both disturbed and undisturbed soil samples were collected from topsoil (0-30 cm and soil laboratory analysis were done for bulk density, soil texture, soil moisture, soil PH, Av. P, Av. K, total N, CEC, Mg+2, K+, Ca+2, Na + and EC. These data were analyzed by using Excel spreadsheet and SPSS software. Also independent t-test was employed to evaluate the significance level. The analyzed data of all soil physicochemical properties were shown significant differences except soil texture class, Mg+2 and K+. The total density of individuals woody species in the area closure and adjacent open grazing land were 938.75/ha and 352.75/ha respectively. The diversity of all woody species in area closure was greater than in the adjacent open grazing land. The total density of regeneration in study site were 1,056.5 /ha. Out of this, the regeneration species in area closure were 867.75/ha while the density of regeneration in adjacent open grazing land were 197.75/ha. The in area closure total mature trees were greater > seedlings >sapling. Both species diversity and regeneration of vegetation in adjacent open grazing land and area closure revealed significant difference. Therefore, this study comes up with the evidence that the establishment of area closure improved woody species diversity and soil physicochemical properties of degraded land of the study area. Thus, area closure plays a key role to rehabilitate woody vegetation diversity and soil qualities of degraded land. This study did not assess the status of herbaceous plant species diversity and the extent to which enclosures in the study area could reduce soil loss compared to open grazing lands. So other researcher can be to assess area closure will significant or not.