Relationship between frequency of sandstorms and air humidity as well as plant phenology: a case study from the Minqin desert area Rooting in the Sustainable Utilization of Rangeland Resources for Sandstorm Prevention Contributions of aboveground litter to soil respiration in coniferous and deciduous plantations An analysis of the potential impacts of ecological restoration on frequency and disaster reductions of sandstorm in the arid regions of the middle Ningxia The spatiotemporal changes of vegetation cover in Beijing-Tianjin sandstorm source control region during 2000-2012