关键词: 杉木林, 土壤水分动态, 人为干扰, 蒸降比

Abstract: The dynamic characteristics of soil water were studied in Chinese fir ecosystems un-der different modes of artificial disturbance．Results showed that after clearcutting the storage capacity of forest land decreased，fluctuations of soil moisture increased,varia-tions in soil water content among soil layers became slighter．While after thinning fluctu-ations subsided．Soil water content at depths of O-30cm in the control and thinning wa-tershed was greater than that in the clearcutted watershed，but fluctuations of water content lower；the result turned out contrary at greater depths due to the root system．The greater artificial disturbance，the more similar variation of soil moisture at different depths，which resulted in poor capacity for soil water regulation．Based on standard devi- ation，statistical test of differences of standard deviation and coefficient of vertical varia-tion of soil moisture，the soil profile could be divided into three layers—changeable lay-er，active layre and less active layer．According to the two indicators—the ratio of evapo-transpiration to rainfall and daily mean evapotranspiration，the soil water evolution in a calendar year could be divided into three periods，i．e．，relatively stable period，recharge period and loss period．The fluctuations and vertical variations of soil moisture at differ-ent locations of slope in the three watersheds decreased in the order of hillside>downhill>foothill，and after thinning the effect of soil water regulation at different locations was greater.

Key words: Chinese fir, Soil Moisture, Artificial disturbance, Ratio of evapotran-spiration to rainfall