부산대학교 도서관

Populations of Albizia amara, Acacia senegal, Anogeissus leiocarpus, and Balanites aegyptiacawere monitored in five habitats in the Jebel Marra region: clay plains, sand plains, wadis, northern slopes, and southern slopes of the Jebel Marra (mountain) region. The plains and wadi habitat types had been regularly disturbed because of cycles of shifting cultivation. When land was prepared for cultivation, seedlings and juvenile plants were removed, leaving only larger adult plants, and, therefore, unstable tree populations, lacking juveniles, and growing in fallow lands. A. amaraand A. senegalwere more abundant than A. leiocarpusand B. aegyptiaca. The healthiest populations, with more juvenile recruits, were found in the grazing lands at higher elevations. However, A. amaraand A. senegalshowed stable size structure in both grazing and fallow lands. In general, in the four study species, we see a decline in growth and reproduction (with growth measured as tree height and number of branches, and reproduction assessed in terms of number of fruits per tree and dry weight of seeds) along a progression from fallow lands to the grazing lands, and, separately, from lower to higher altitudes. The resilience potential of each species in the fallow lands indicated two distinct population resilience strategies: (1) we saw faster rebound in the case of A. amaraand A. senegaland (2) slow recovery from disturbance in the case of A. leiocarpusand B. aegyptiacawhich showed low juvenile recruitment in fallow lands.