Using net primary productivity (NPP) as an indicator to desertification driving factor and expansions is one of the importance tools in the assessment of the contribution of climate change and human activity in desertification. In this study we used three types of net primary productivity; the actual NPP, Potential NPP and HNPP (human appropriation of NPP) to discriminate the relative role of climate change and human activities in desertification from 2000 to 2008 in Northern Kordofan province-Sudan. The results showed, 63.75% of the study area experienced desertification expansion. Within which, 67.32% was induced by Human activities compared with 32.03% caused by climate change and 0.65% caused by a combination of the two factors. By contrast, climate change is the dominant factor of desertification reversion, 2.3% of desertification reversion caused by human activities compared with 97.7% induced by climate change and there isn’t interaction between climate change and human activities in reversion area. The largest area of expansion and reversion occurred in northeast and western parts of the study area respectively. We developed two propositions in the study area. First, the desertification expansion was induced by human activities, whereas desertification reversion was induced by climate change as typified in north south part, central part and western part. Second, both desertification expansion and reversion was induced by climate change as typified in northeast part of study area.

Climate change scenarios project that several regions, especially in dryland areas of sub-Saharan Africa, will undergo increasing aridity and, subsequently, expanding land degradation. The study aims to investigate the effect of two drying treatments on establishing and growing Hashab (Acacia senegal) and Boabab (Adansonia digitata) in nursery conditions. Through a 2×2 factorial experiment, seedlings grown in a mixture of silt and sand soil (2:3) were treated by irrigation intervals of one or two liters every three days for 14 weeks to simulate rainfall fluctuation patterns. Seedling germination rate, leaf number, stem height, and diameter were measured weekly; taproot length, shoot, and root dry weights were also assessed. The results showed that neither drying treatment significantly affected A. senegal and A. digitata seedling growth parameters. However, an interaction effect was found in the height and diameter for A. senegal and shoot dry weight for A. digitata. The study concluded that A. senegal and A. digitata seem tolerant to drying treatment. Therefore, the two species are recommended for afforestation programs in areas with relatively harsher conditions. Also, exposing the seedlings of these studied species to similar, extended periods of simulated drought (e.g., 6 – 12 months) is recommended for future studies.