Tree age and soil phosphorus conditions influence N2-fixation rates and soil N dynamics in natural populations of Acacia senegal

▶ A. senegal age and site conditions are important factors in the N budget ▶ Soil P positively influenced N2-fixation rates, soil N and C pools ▶ Tree ontogeny directly affected soil N, soil C, and mineralizable N estimates ▶ Soil transplants confirmed soil biological processes are stimulated under mature trees ▶ N2-fixation rates, determined by foliar 15N natural abundance, declined with age.