Abstract

This study was conducted in the Mana-Soda salt crater area in Borana, southern Ethiopia to evaluate the effects of a mineral lick-centered distance gradient on herbaceous species composition and rangeland condition. Samples of herbaceous species were collected along a 12 km transect starting from the edge of the crater. The herbaceous species were clustered into communities and the indicator species of each community were identified. Biomass yields were estimated across the transect and the overall rangeland condition was rated using the ecological index and weighted palatability composition (WPC) methods. A total of 16 grasses, two forbs and sedges were identified. Chrysopogon aucheri was the most abundant grass species, while Aristida adoensis, Themeda triandra and Digitaria naghellensis were among the rarely occurring grass species. Forbs and sedges were also of rare occurrence. Decreaser species increased in abundance as distance from the crater increased. Herbaceous dry matter yield ranged from 408.3 to 2180 kg ha^-1 along the 12 km transect. The biomass produced varied with time of year but generally increased with increasing distance from the salt crater. The ecological index values were 574 and 349 for the main and short rain seasons, respectively. The corresponding WPC values were 44.7 and 5%, respectively. The rangeland was therefore classified as poor to fair. The results showed a high proportion of increaser species leading to the poor to fair rangeland condition.

Key words: Grass yield, indicator species, patch resource, rangeland condition.