导　　师： 孙向阳

学科专业： 083002

授予学位： 博士

作　　者： ;

机构地区： 北京林业大学

摘　　要： 应用SPAC系统理论，研究了宁夏盐池沙地中间锦鸡儿和油蒿混交灌木林地的植物个体水分生理特征、水分利用效率及群体的耗水量；沙地土壤的水分特性；灌木林地的水量平衡，以及SPAC中水势的变化规律及水分运移。从而阐明沙地土壤水分承载量与植物需水特性的关系。结果表明： 沙地土壤表层存在一个干土层，对较深土层的水分保持有一定的作用。总体而言沙地土壤含水量低。经验方程θ=A·S~/(-B/)在＜1.5MPa吸力段对该地区的土壤水分特征曲线具有良好的模拟性，土壤的有效水上限为0.01MPa吸力所对应的土壤湿度，易效水与难效水的吸力界点以0.1MPa为宜。 中间锦鸡儿和油蒿有着适应干旱生境的水分生理特征，但避旱的具体方式不同。中间锦鸡儿属于低蒸腾植物，油蒿属于高蒸腾植物。两种植物的水分生理指标受环境因素影响。 沙地植物受到水分胁迫时水势最低值出现的时间前移。干旱沙地，水分从土壤到植物，由树叶扩散到大气中的阻力较大。土壤水势的变化受降雨、土面蒸发和林木蒸腾的共同影响；灌木的叶水势与土壤含水量、降雨相关；大气水势受气温和相对湿度影响。大气水势、叶水势和土壤水势之间具有一定的相关性。水势梯度明显，时空变异规律明显。SPAC系统中水势梯度比约为：中间锦鸡儿1：14：355；油蒿1：13：355。前者的水势临界值大于后者，提高了水流运移的驱动力，使吸水能力增强。 植物蒸腾和土面蒸发是林地的主要耗水形式。在植物生长季节，林地土壤水分增量处于负值，说明林地蒸散高于降雨量，植被密度过大，应减小植被覆盖度，留出一定面积的沙地。 Water physiological characteristics of the two desert plants, that is, Caragana intermedia Kuang et H.C.Fu and Artemisia ordosica Krasch, water consumption of the individual and colony, the soil water characteristics, water balance of the mixed forest and the variation of water potential in SPAC were systematically studied in Sandy Land Shrab Garden, Yanchi County, Ningxia. The research results are as follows: The study shows that a dry layer forms under the surface, which is beneficial to the water conservation of the deeper layers. Water content of the soil is comparatively low in the area. It is found that the empirical equation θ = A·S~/(-B/) can well simulate the water characteristic curves of the soil during the low and medium suction /(<1.5MPa/). The study also demonstrates that the upper limit of available water is the soil moisture content corresponding to soil suction 0.05MPa and it is suitable to take 0.1 MPa as the dividing line of soil suction for readily available water and resistant available water. Both plants possess the physiological characteristic of adapting to the arid region. But their approaches to resist the aridity are different. Artemisia ordosica Krasch has higher transpiration rate. The water physiology indices of the two plants are affected by the environmental factors. When the plant is under the stress of drought the lowest leaf potential appears in advance. The resistance of water distribution in SPAC is high. The distinctly seasonal change of soil moisture is the common result of rainfall, evaporation from the forest floor and transpiration of the shrubs. The variation in leaf water potential is related with soil water content and rainfall. The pertinence between the atmosphere water potential, temperature and relative humidity is notable. The water potential gradient and space-time- variation are evident. The SPAC water potential gradient of Caragana intermedia Kuang et H.C.Fu is 1:14:355; that of Artemisia ordosica Krasch is 1:13:355. Ev

关 键 词： 土壤水分特性曲线 沙生植物 水量平衡 土壤 植物 大气连续体

领　　域： [农业科学]