Variability in growth of Vachellia nilotica provenances tested in the Sudano-Sahelian zone of Niger

A provenance trial of Vachellia nilotica (Acacia nilotica) was conducted in Niger in order to assess variability in growth among 10 provenances from Africa (subsp. adstringens from Niger, Senegal and Cameroun) and outside the continent (subsp. indica from Pakistan and Yemen). Tree height, diameter at breast height and crown diameter were measured 15 years after trial establishment. Comparison of blocks located at slightly different elevation showed that trees had better survival and growth at the lower sites. The African provenances had better survival and total basal area than provenances from Yemen and Pakistan. Within the African provenances, origins from Niger and Senegal were performing better than the provenance from Cameroun. There were indications that the performance could be correlated to precipitation at origin, but since the correlation was driven by the poor performance of subsp. indica provenances our data are not conclusive.