Response of Vegetation Cover Change to Drought at Different Time-scales in the Beijing-Tianjin Sandstorm Source Region,China

Dominated by an arid and semiarid continental climate,the Beijing-Tianjin Sandstorm Source Region(BTSSR)is a typical ecologically fragile region with frequently occurring droughts.To provide information for regional vegetation protection and drought prevention,we assessed the relations between vegetation cover change(measured by the Normalized Difference Vegetation Index,NDVI)and the Standardized Precipitation Evapotranspiration Index(SPEI)at different time-scales,in different growth stages,in different subregions and for different vegetation types based on the Pearson's correlation coefficient in the BTSSR from 2000 to 2017.Results showed that 88.19%of the vegetated areas experienced increased NDVI in the growing season;48.3%of the vegetated areas experi-enced significantly increased NDVI(P<0.05)and were mainly in the south of the BTSSR.During the growing season,a wetter climate contributed to the increased vegetation cover from 2000 to 2017,and NDVI anomalies were closely related to SPEI.The maximum correlation coefficient in the growing season(Rmax)was significantly positive(P<0.05)in 97.84%of the total vegetated areas.In the vegetated areas with significantly positive Rmax,pixels with short time-scales(1-3 mon)accounted for the largest proportion(33.9%).The sensitivity of vegetation to the impact of drought rose first and then decreased in the growing season,with a peak in July.Compared with two subregions in the south,subregions in the north of the BTSSR were more sensitive to the impacts of drought variations,especially in the Xilingol Plateau and Wuzhumuqin Basin.All four major vegetation types were sensitive to the effects of drought variations,especially grasslands.The time-scales of the most impacting droughts varied with growth stages,regions,and vegetation types.These results can help us understand the relations between vegetation and droughts,which are important for ecological restoration and drought prevention.

Spatiotemporal changes in terrestrial water storage in the Beijing-Tianjin Sandstorm Source Region from GRACE satellites

The Sandstorm Source Control Project in and around the Beijing-Tianjin region was one of the most important ecological projects in China.Terrestrial water storage(TWS)has important impacts on the ecological construction,agriculture,industry,and resident's lives.Based on the Gravity Recovery and Climate Experiment(GRACE)data,meteorological and Moderate Resolution Imaging Spectroradiometer(MODIS)data,etc.,this paper analyzed spatiotemporal characteristics of TWS,groundwater storage,and precipitation,and explored the influencing factors of regional TWS combined with land use and land cover(LULC),social and economic data.The most important results were as follows:(1)From 2003 to 2016,TWS in the Beijing-Tianjin Sandstorm Source Region showed a decreasing trend with a rate of 3.14 mm yr-1.(2)The TWS decline was caused mainly by groundwater overexploitation,but not pre-cipitation variation.(3)Spatiotemporal variations of TWS were related to LULC.The area with the most serious decrease of TWS was mainly located in the southwestern part of the region,where farmland percentage and population density were greater.(4)Reducing the percent of farmland and tree planting,and adding the shrub and grass planting,could be a viable choice for the Beijing-Tianjin Sandstorm Source Control Project.These results provide a scientific basis for regional water resource and ecological management.

Introducing Seawater from Bohai Sea to West China for Sustainable Development in the Area

Sustained and profound aridization process in north west China in Tertiary and Quaternary period and time of mankind history are discussed. The rain creased function of 3 set high mountain condensation systems in north west China is recognized once more. A sandstorm happened on 20th March 2002 in Alasan and Ejinaqi areas was very strong and arrived in Japan and Korea. For saving Alasan area from sandstorm a way of introducing sea water from Bohai to Alasan has been proposed. Four problems are replied in this paper. It is concluded that introducing sea water from Bohai to west China is the best way for sustainable development of west China.

Examining the efficacy of revegetation practices in ecosystem restoration programs:insights from a hotspot of sandstorm in northern China

Retrospectively evaluating the efficacy of revegetation practices is helpful in planning and imple-menting future ecosystem restoration programs(ERP).Having a good understanding of how human activities can affect vegetation cover,both before and after ERP,is particularly important in sandstorm hotspot areas.The Beijing-Tianjin Sandstorm Source Region(BTSSR)is one such area.We conducted an investigation into vegetation dynamics within the BTSSR.This was done using remote sensing data in conjunction with climate data sets and land use data spanning the 1982-2014 period.The relationships between climatic factors(such as precipitation and temperature),and vegetative change were modeled using a neural network method.By a process of residual analysis,the proportions of human-induced vegetative change both before and after the ERP were established.Our results show that:1)before the ERP(1982-2000),40.96%of the study area exhibited significantly progressive vegetation changes(p<0.05).This proportion decreased to encom-pass only 20.23%of the study area in the period following the ERP(2001-2014).2)89.55%of the study area showed signs of human-induced vegetation degradation before the ERP.Between 2001 and 2014 however,following ERP,this figure fell to only 27.78%.3)ERP implementation led to visible improvements in vegetative conditions within the BTSSR,especially in areas where ecological restoration measures were directly and anthropogenically applied.These results highlight the benefits that positive human action(i.e.,revegetation initiatives implemented under the framework of an ERP)have brought to the BTSSR.