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Evaluation of woody vegetation changes with distance from a salt crater was conducted in the semi-arid rangelands of southern Ethiopia. Data on live woody plants were collected over three seasons at 0, 1, 4, 6, 9 and 12km from the salt crater. The density and diversity of woody plants differed significantly (p<.01) along the distance gradient. Six woody plant families were identified of which Fabaceae and Burseraceae were the dominant families. Acacia drepanolobium, Acacia nilotica, Commiphora africana and Acacia mellifera were among the severely encroaching woody species. There were high proportions of seedlings and saplings recorded closer to the salt crater showing a vigorous recruitment by woody plants. Woody plant encroachment along the 12-km transect ranged from a low to severe encroachment, which could be translated into poor rangeland condition. Changes in soil characteristics increased grazing pressure and sedentary settlement around the salt crater, and the breakdown of traditional institutions seems to be major contributing factors to these vegetation changes. We suggest that severely encroached areas could be improved through a combination of methods such as bush clearing, prescribed fire, browsing animals and proper grazing management.

Resume Nous avons realise une evaluation des changements de la vegetation avec la distance par rapport a un cratere salin dans les etendues semi-arides du sud de l’Ethiopie. Nous avons recolte des donnees sur des plantes ligneuses vivant a 0, 1, 4, 6, 9 et 12km du cratere salin. La densite et la diversite des plantes ligneuses differaient significativement (p<.01) le long du gradient de distance. Six familles de plantes ligneuses ont ete identifiees, parmi lesquelles les Fabaceae et les Burseraceae etaient les familles dominantes. Acacia drepanolobium, Acacia nilotica, Commiphora africana et Acacia mellifera comptaient parmi les especes ligneuses les plus gravement envahissantes. Il y avait de fortes proportions de jeunes plants et d’arbustes plus pres du cratere, ce qui montre un recru vigoureux de plantes ligneuses. L’envahissement des plantes ligneuses le long des 12km de transect allait de faible a severe, ce qui peut se traduire par un etat mediocre de l’habitat. Les changements des caracteristiques du sol, une pression plus intense du paturage et les installations permanentes autour du cratere salin, ainsi que la disparition des institutions traditionnelles semblent etre les principaux facteurs de ces changements de la vegetation. Nous suggerons d’ameliorer les zones les plus gravement envahies grace a une combinaison de methodes telles que l’elimination des broussailles, un regime de feux volontaires, l’introduction d’animaux qui mangent ces broussailles et une gestion correcte des paturages.