干旱半干旱区山地土壤水分动态变化

Research on Dynamics of Soil Moisture in Arid and Semiarid Mountainous Areas

水分是干旱半干旱区山地植物生长的主要限制因子 ,在这些地区开展土壤水分动态变化研究对农业生产和生态恢复的重要性是不言而喻的。近年来土壤水分测定技术有了很大进步 ,中子水分仪和时域反射仪已成为常规测量仪器 ,新型仪器不断出现 ,总的趋势是仪器的精度和自动化水平不断提高。土壤水分有其时空变化规律 ,一方面土壤水分随季节变化而变化 ,另一方面土壤水分随土壤深度和水平位置的变化发生相应变化。降水是影响干旱半干旱区山地土壤水分的最重要因素 ,气温、太阳辐射等其它气象因子对土壤含水量也用一定影响。此外 ,坡向、坡度、坡位等地形因子以及土壤特性、地表植被、土地利用情况等对土壤含水量空间分布也有重要影响。总之土壤含水量的时空变化是各种环境因子综合作用的结果。目前土壤水分动态变化的研究重点是对其影响因子的研究。就我国而言 ,宜加强干旱河谷区土壤水分动态变化的研究 ,促进土壤水分动态变化研究工作全面深入地开展。

In arid and semiarid areas soil moisture is the most importa nt factor which restricts vegetation growth It is very important to research dyna mics of soil moisture in these areas The technology of measuring soil moisture content has made great progress in these years Neutron Probe and Time Domain R eflectometry have been normal meters of measuring soil moisture content There a re some new instruments to be invented recent years and it is trend that new ins truments become more and more accurate and automatic Temporal and spatial varia bility of Soil moisture content is obvious Change of season influences the dyna mical behavior of soil moisture, and as soil depth and spot different, soil mo isture varies Precipitation is the most important factor which influences soil moisture Other meteorological factors such as air temperature, solar irradiati on have some influence to soil moisture, too Furthermore, Environmental attri butes such as vegetation,land use and topography such as aspect, slope gradien t, hillslope position play controlling roles in the distribution of soil moistu re content So the phenomenon of the temporal and spatial variability of Soil mo isture content is the result of influence of all factors Now the emphasis of so il moisture dynamical study should be factors of influencing soil moisture conte nt Dry valley is a special arid region in our country, but research of soil mo isture dynamics needs lucubrate in these areas