半干旱区草地灌丛化对积雪和融雪的影响及其土壤水文过程

This study focus on the mechanism of action from the shrub invasion on the snow and snowmelt process in a semi-arid grassland of Inner Mongolia Autonomous Region, where the shrubs become more abundant and be confronted with serious grassland degeneration. Compared with the grassland, the snow in shrub patches is both thicker and a greater amounts of drifting snow are trapped and suffer less loss. As a consequence, winter soil surface temperatures are substantially higher, a condition that can promote greater winter decomposition. However, our knowledge on the hydrological cycle and the compensation effect of soil moisture in this transformation is still limited. This study aims to investigate the differences of the snow physical properties between the grassland and shrub as well as the process of snowmelt by a series of field observation and comprehensive experiments, thereby the influence of the shrub on the supplies of winter snow of the ecosystem can be clarified. The results from the investigation could provide a accurate evaluation of ecohydrological effects from shrub invasion in the semi-arid grassland and will also be helpful for the vegetation restoration and ecological construction .

草原灌丛植被斑块对积雪和融雪过程的作用机制、融雪水文循环机理以及土壤水分补偿效应的影响研究是半干旱区生态水文学需要填补的薄弱环节，本研究旨在通过对典型半干旱区灌丛化草地的积雪物理性质、形成过程以及植被影响下的融雪水文过程的综合实验观测研究，阐明灌丛化对草原生态系统冬季积雪补给的影响和作用规律，揭示积雪对半干旱区灌丛化草地的水分补偿机制，为准确评价半干旱区草原入侵灌木的生态水文效应以及植被恢复和生态建设提供理论依据。

草原灌丛植被斑块对积雪和融雪过程的作用机制、融雪水文循环机理以及土壤水分补偿效应的影响研究是半干旱区生态水文学需要填补的薄弱环节。本研究选取位于锡林郭勒盟太仆寺旗境内的“北京师范大学野外试验与教学实习太仆寺旗基地”作为代表样区，对样区内锦鸡儿属灌丛以及草地影响下的积雪/融雪过程、土壤水文效应等进行了系统研究。通过定位实验观测和野外样方调查，获取了不同季节的灌丛高度、直径、覆盖度等植被形态参数，积雪层厚度、融化时间、入渗深度、入渗时间等积雪/融雪水文参数，以及土壤温湿度、容重、养分情况等土壤理化参数，建立了降雪在半干旱退化草地生态系统植被-土壤界面之间的传输转化关系。.研究结果显示：1）灌丛的外围积雪深度要显著高于中心区域，灌丛间的草地是积雪的集聚区，积雪平均深度是灌丛中心的3.2倍左右，灌丛的生长是造成其周围积雪加深的重要因素；2）灌丛中心的土壤含水率显著高于灌丛外围，随着融雪水量增加，灌丛中心和外围的土壤含水率之差增大，增加幅度在4%-8%之间，灌丛聚集了更多的融雪水量；3）相对于草地，灌丛可以更加有效地将融雪水分转移到较深层的土壤中加以储存和利用。.本研究阐明了灌丛化对草原生态系统冬季积雪补给的影响和作用规律，揭示了积雪对灌丛化草地的水分补偿机制，为准确评价半干旱区草原入侵灌木的生态水文效应以及植被恢复和生态建设提供理论依据。