作 者 ：王晓学,李叙勇*,莫菲,江燕
期 刊 ：生态学报 2010年 30卷 20期 页码：5491~5500
关键词：元胞自动机；森林水源涵养量；水文响应单元；森林水文模型；
Keywords:cellular automata, forest water conservation, hydrological response unit, forest hydrological model,
摘 要 ：模型方法是定量评价森林水源涵养的重要途径。根据元胞自动机的基本理论，结合森林水源涵养效应的多尺度特征，提出了一个新的基于元胞自动机的森林水源涵养量计算模型。该模型将森林“水文响应单元”网格化作为元胞空间的基本单元，邻域定义为摩尔（Moore）型，元胞“水库”水量状态变化范围定义在一个连续的实数空间上。将元胞单元对不同降雨事件的响应分为不产生径流和产生径流两种情况，通过对蒸散发、邻域元胞间水量传输、深层渗漏等制定转换规则，模拟森林在不同尺度上的水源涵养动态特征。这种新模型方法将为森林水源涵养由小尺度（水文响应单元）向流域、景观尺度上推提供有效的定量研究途径，从而进一步推动森林水源涵养功能研究的深入。
Abstract:As forest water conservation has become one of critical ecosystem service issues in context of global water shortage, the exploration for its quantitative methods has increasingly gained more attention. The relationship between forests and water is complex. Different geographical characteristics and forest types have various effects on the interception of rainfall redistribution in forest, surface runoff and evapotranspiration. There exist interactions among the complex hydrological and ecological processes in forest ecosystems, thus causing the spatial and temporal variations in water cycles and water balance at the watershed and landscape scales. However, the dominant factors and driving mechanisms of forest water conservation key processes at these different scales are not yet clear，making it difficult to evaluate forest water conservation at these scales and develop a scale-up method for quantifying forest water conservation. The modeling method is an efficient route towards quantitative evaluation of forest water conservation. Over the past decades, most of the quantitative researches concerning forest water conservation have focused on one dimension methods (e.g. methods of water balance, soil water storage capacity, precipitation storage, canopy interception surplus and so on). Scaling-up remains as a challenging issue in quantifying forest water conservation. In this study,the author employes the basic theories of cellular automata to developing a new modeling method for quantifying forest conservation. The model, we integrate the hydrological characteristics of rainfall redistribution by canopy, water retention of litter and water conservation of soil and define a cell as an elementary spatial unit that is rasterized from a hydrologic response unit, with every cell interior having relatively consistent characteristics of the vegetation, soil and terrain attributes. A cell neighborhood is defined as the Moore type. The range of quantitative change of water is measured in continuous real numbers. The water quantity in each cell is affected by neighboring cells and status of the previous time step. Based on the response characteristics of the underlying surfaces on different rainfall intensity and duration, the cellular responses to different rainfall events is classified by two scenarios: generation of runoff and without generation. The transformation rules of forest hydrological processes are also defined, including evapotranspiration, intercellular water transmission and deep seepage. And the hydrological processes with both horizontal and vertical directions are also considered. Taking main factors affecting forest water conservation and its spatial heterogeneity into consideration, the model overcomes the defects of most traditional methods which focus on one dimension. This new modeling will provides a useful way for solving forest water conservation scaling-up issues from small-scale (hydrological response unit) to watershed, or landscape scale; and thus improves quantitative evaluation of forest water conservation at different spatial scales. The model also provides an effective quantitative way of quantifying forest water conservation with different spatial distribution patterns of different forest types. This paper is the theoretical framework of the model described above. A case study will be presented in a follow-up paper.
全 文 ：