Ecological effects of desertification control and desertified land reclamation in an oasis–desert ecotone in an arid region: A case study in Hexi Corridor, northwest China

Desertification around oases is the major obstacle for sustainable development of oases in arid regions of northwest China. An effective way of maintaining the stability of oases is to recover the relatively stable ecological zone between an oasis and desert from the destroyed ecological rift zone. This paper presents a typical case of successful efforts in ecological restoration and desertified land reclamation of oasis–desert ecotone. On the basis of stabilization of mobile dunes and agricultural use of reclaimed land, some successful techniques including established straw checkerboards and planting drought-tolerant indigenous shrubs, leveling sand dunes and drawing water for irrigation, closing dunes for grass reservation were carried out in 1975. In the restoration area, a stable artificial protective forest system had been developed. Pedological analyses indicate that the fine particle fraction (silt and clay content) in 0–10 cm soil surface layer has been increased from 2.6% on the untreated mobile sandy land to 9.3–37.3% in the restoration areas, and correspondingly, soil organic C has been increased from 0.63 to 1.88–9.70 g kg−1 during the 28 years of restoration period. In these 28 years, a 10 cm depth of minero-organic topsoil in the irrigated Picea sylvestris forestland has been developed. It is also observed that sand transportation rate during sandstorm events has been significantly reduced. The increase of vegetation cover indicates a remarkable environmental improvement. Overall, the ecological restoration approach in this study is of practical significance for the rebuilding of rift zone ecosystem and maintenance of the stability of oasis in the arid regions of northwest China.