中文摘要：

土壤水是联系陆地水文过程与生态过程的纽带，且土壤水分动态表现出明显的随机属性。所以土壤水分随机模拟逐渐成为当前生态水文学研究的一个热点，土壤水分随机模拟研究是土壤-植被-大气连续体（SoilPlant-Atmosphere Continuum，SPAC）水分传输机理的关键。本文系统分析了土壤水分随机模型的内涵。对当前典型的土壤水分随机动态模型进行归纳和总结，包括：Milly模型（step model）、Porporato模型（Linear Model）、Shutfleworth and Ellis模型（Ramp Model）、Rodriguez模型、Laio模型，并对这些模型在土壤水平衡分析中的应用进行了推导和分析。展望了土壤水分随机动态模拟与土壤水平衡研究未来发展方向：加强生态水文学实验研究，特别是加强高分辨率、长时间序列的土壤水分监测；加强理论模型的应用研究，广泛开展土壤水分随机模拟在我国非湿润区的应用；加强土壤水分随机模型在土壤水平衡分析及流域水平衡分析的应用，建立更加完善的基于土壤湿度概率密度函数的流域水平衡模型；加强全球变化、土地利用，土地覆被变化对土壤水分动态影响模拟研究。

英文摘要：

Eco-hydrology is a new discipline combined Ecology with hydrology, which seeks to describe the hydrologic mechanism underlying ecological patterns and processes. Soil moisture is the key link between water cycle and vegetation dynamics at spatial and temporal scale. The temporal dynamics of soil moisture play a very important role in various component of the climate-soil-vegetation continuum. Soil moisture dynamics is extremely complex due to different physical and biological processes and large number variables at spatial and temporal scale （depth and rate of rainfall, soil texture, temperature, vegetation）. Soil moisture determines the partition of rainfall among evapotranspiration, runoff, and deep infiltration in a strongly nonlinear way. Stochastic properties are essential attribute of soil moisture dynamics. Modeling the randomicity of soil moisture dynamics is the core of eco-hydrology. In this paper, the connotation and theories of stochastic soil moisture model are briefly described. Stochastic soil moisture model differs from the traditional bucket model, in which rainfall is simulated as a stochastic process. The integration of stochastic rainfall processes and deterministic evaporation function is the foundation for the stochastic soil moisture modeling. The stochastic representation of rainfall model allows us to calculate soil moisture probability density. The derivation of the equation is to write down the Chapman-Kolmogorov forward function. Several typical and effective soil moisture probability density functions and counterpart water balance models are introduced, which including： Milly model （Step model） ,Porporato model（ Linear Model）,Shuttleworth and Ellis model（ Ramp Model）, Rodriguez model and Laio model and so on. Application of these models to water balance analysis are also deduced. We analyze the trend of soil water balance under variable rainfall rate, which has interesting implications for vegetation productivity and plant growth. It is also pointed out that more res