高寒草地生长季/非生长季植被盖度遥感反演

植被盖度是刻画陆地生态系统植被覆盖的重要生态参量。以当雄县Landsat-8OLI为数据源,从10种常用植被指数中筛选出适合反演高寒草地生长季/非生长季草地植被盖度的植被指数,引入像元三分法确定端元特征值,通过不同植被指数基于像元二分模型反演植被盖度的对比分析,确定适合生长季/非生长季植被盖度最优植被指数,根据反演结果分析了研究区草地生长季/非生长季植被盖度的时空变化特征。结果表明:1)由可见光-近红外波段构建的植被指数适用生长季植被盖度反演,由短波红外构建的植被指数适用于非生长季植被盖度反演。2)基于MSACRI的像元二分模型适合非生长季植被盖度反演,基于NDVI的像元二分模型则最适用于生长季植被盖度的反演。3)研究区草地植被盖度随海拔增加呈现先增加后减少的单峰变化格局,草地集中分布于海拔4300~5100 m处。生长季植被盖度主要集中于20%~80%,非生长季绝大部分的草地盖度小于40%。研究结果可为草地生态系统碳存储、植被生产力、土壤侵蚀、生态水文等研究提供参考依据。

Evapotranspiration and Removal Performance in the Treatment of High Salinity LandfilI-Leachate Using HSF

In this study, the water budget in the treatment of high salinity landfill-leachate was estimated and the influence of evapotranspiration （ET） on treatment performance was investigated. The salinity of the inside of horizontal subsurface flow constructed wetland （HSF） of the raw leachate inflow was 15.0± 3.4 g.Cl/L which was in the level of the salinity of the survival limit of reed, and that of the double diluted leachate inflow was 9.3 ± 1.9 g.CI7L. There were large differences in the vegetation between HSF of the raw leachate inflow and that of the double diluted leachate inflow. The dense vegetation bed of double diluted leachate inflow during the growing season （April-October） provided a high ET and a large water loss, which made great contributions to the reduction of the outflow load of COD and T-N. The HSF with die-back reeds in the non-growing season （November-March） provided a slight ET and a small water loss and made less of a contribution to pollutant removal compared to the HSF with dense vegetation bed during the growing season. However, the HSF with die-back reeds during the non-growing season exhibited higher removal performance than the unplanted HSF.