An ecological study of the vegetation of Gambella Region, Southwestern Ethiopia

Abstract

The vegetation of Gambella Region, southwestern Ethiopia, has been studied through five field trips made between October 14, 1995 and October 10, 1996. Systematic sampling method was used to select homogenous vegetation stands. Cover/abundance data was recorded for all plants from a total of 58 relevès. For each relevè, environmental data on topographic factors (altitude and slope), and soil from a depth of 0—10 cm (topsoil) and 40—50 cm (subsoil) were collected. The soil samples were analyzed for pH, texture, cation exchange capacity, organic carbon, total nitrogen, available phosphorus, exchangeable potassium and sodium. The species and relevès were classified using a fortran computer program twinspan and seven major plant communities were described. Five plant communities were found to have phytogeographical affinity to the Sudanian vegetation type while two are affiliated to the Guineo-Congolian vegetation type of Africa. Comparison of the community types was made using anova to find whether there are statistically significant variations in environmental factors.

SINET: Ethiopian Journal of Science Volume 24, No. 2 (December 2001), pp. 213-228



Key words/phrases: Ethiopia, Gambella Region, phytogeographic affinity, phytosociology, plant communities