Ecological Benefits of Integrated Watershed Management: The Case of Sheka Watershed, Ethiopia

Abstract

Watershed degradation through soil erosion is one of the main constraints for agricultural productivity. Integrated watershed management (IWSM) was taken as the basic operational unit to tackle this problem. However, its effectiveness in rehabilitation of degraded watershed was rarely evaluated. Therefore, this research was conducted in Sheka watershed, Ethiopia, with the objective of assessing impact of IWSM on selected ecological benefits. Land map units of treated and untreated sub-watersheds were prepared using Geographic Information System software. Sixteen plots with 20m x 20m were randomly formed in the land map units of the two sub-watersheds for soil and woody plants sampling. The results revealed that there were significantly higher woody plants density and diversity, total nitrogen, soil organic matter, available phosphorous and available potassium contents in the treated sub-watershed than the untreated one. Whereas, in terms of soil pH, soil texture and evenness of woody species, the two areas were not significantly different. Total nitrogen was positively and significantly correlated with soil organic matter, woody plants density and diversity. Therefore, IWSM is not only effective in restoring woody species density and diversity, but also in improving soil fertility status. Thus, it is better to introduce IWSM in to the untreated watershed.

Keywords: Integrated watershed management, woody plants, treated, untreated