农田和灌丛生态系统蒸散发过程及水分利用效率研究

发布时间：2018-05-06 04:34

本文选题：农田 + 灌丛　；参考：《中国科学院教育部水土保持与生态环境研究中心》2016年博士论文

【摘要】：水资源短缺已成为干旱、半干旱地区农业生产和生态环境建设的关键问题。揭示干旱、半干旱区农田和灌丛生态系统蒸散耗水规律及水分利用效率,对农田和灌丛生态系统的管理及水资源的可持续利用具有重要的指导意义。本研究以黑河中游绿洲春小麦农田和黄土高原北部灌丛(柠条和长柄扁桃)生态系统为研究对象,利用涡度相关法测定农田和灌丛生态系统碳、水、热通量过程,并分析水分利用效率变化特征,在此基础上探讨两种灌木林地条件下蒸散发及水分利用效率的影响因素及其环境响应机制,主要得出以下结论:(1)农田和灌丛生态系统条件下,各辐射通量分量和热存储通量分量均表现出明显的季节和日变化规律,其变化规律在不同植被类型条件下存在较大的差异。感热通量和潜热通量是净辐射的主要消耗项。0-5 cm土壤热存储通量在净辐射中所占的比重在两种生态系统条件下均最大;大气感热存储通量在农田生态系统中占净辐射的比重较大,而在灌丛生态系统中所占的比重较小。(2)农田和灌丛生态系统存在明显的能量不闭合现象,考虑热存储通量项后能显著提高生态系统的能量闭合度。土壤热存储通量对能量闭合度的贡献最大,其值介于9.04%-13.73%之间;大气潜热存储通量在农田生态系统的贡献度可达2.96%,而在灌丛生态系统则平均降低了0.06%的能量闭合度。(3)农田和灌丛生态系统蒸散发及水分利用效率具有明显的季节和日变化规律,不同植被类型下差异明显。净辐射、大气温度、0-60 cm平均土壤温湿度、饱和水汽压差和叶面积指数均对蒸散发和水分利用效率产生不同程度的影响,其影响程度在不同植被条件下表现出很大的变异性。(4)降水后蒸散发量显著增加但具有一定的滞后性,蒸散发量的增加幅度及滞后天数受降水量大小和降水时长的影响和限制;降水量的时空分布决定了灌木林地蒸散发量的大小和季节分配模式。(5)农田生态系统大约有273.41 mm的水分用于补给0-60 cm土层以下深层土壤水分或地下水;柠条林地蒸散发量高于降水量,水分处于严重亏缺状态;长柄扁桃林地蒸散发量低于降水量,水分能够满足长柄扁桃生长的需求。
[Abstract]:Water shortage has become a key problem in agricultural production and ecological environment construction in arid and semi-arid areas. It is of great significance to reveal the evapotranspiration and water use efficiency of farmland and shrub ecosystem in arid and semi-arid areas, which is of great significance to the management of farmland and shrub ecosystem and the sustainable utilization of water resources. In this study, spring wheat field in the middle reaches of Heihe River and shrub ecosystem (Caragana korshinskii and almond) in the northern Loess Plateau were studied. The carbon, water and heat fluxes in farmland and shrub ecosystem were measured by vorticity correlation method. On the basis of analyzing the change characteristics of water use efficiency, the influencing factors of evapotranspiration and water use efficiency and their environmental response mechanism under two kinds of shrub land conditions were discussed. The main conclusions were as follows: 1) under the condition of farmland and shrub ecosystem, The radiative flux components and heat storage flux components showed obvious seasonal and diurnal variations, and there were great differences in the variation of the radiation flux components and the heat storage flux components under different vegetation types. Sensible heat flux and latent heat flux are the main consumption of net radiation. 0-5 cm soil heat storage flux accounts for the largest proportion of net radiation under both ecosystem conditions. The sensible heat storage fluxes in the atmosphere account for a large proportion of net radiation in the farmland ecosystem, while the proportion in the shrub ecosystem is smaller. 2) there is an obvious energy unclosure phenomenon in the farmland and shrub ecosystem. Considering the heat storage flux term, the energy closure of the ecosystem can be improved significantly. The contribution of soil heat storage flux to energy closure was between 9.04- 13.73%. The contribution of atmospheric latent heat storage flux to farmland ecosystem was 2.96, while in shrub ecosystem, the energy closure was decreased by 0.06% on average.) the evapotranspiration and water use efficiency of farmland and shrub ecosystem had obvious seasonal and diurnal variation laws. There were significant differences under different vegetation types. Net radiation, average soil temperature and humidity from 0 to 60 cm, saturated water vapor pressure difference and leaf area index had different effects on evapotranspiration and water use efficiency. Under different vegetation conditions, the amount of evapotranspiration increased significantly but had a certain lag. The increase of evapotranspiration and the number of days behind were influenced and restricted by the amount of precipitation and the duration of precipitation. The spatial and temporal distribution of precipitation determines the magnitude of evapotranspiration and seasonal distribution model of shrub land. The farmland ecosystem has about 273.41 mm water to recharge the deep soil water or groundwater under 0-60 cm soil layer. The evapotranspiration of Caragana woodland was higher than that of precipitation, the water was in a serious deficit state, and the evapotranspiration of longstalked almond forest land was lower than that of precipitation, and the water content could meet the needs of the growth of longstalked almond.
【学位授予单位】：中国科学院教育部水土保持与生态环境研究中心
【学位级别】：博士
【学位授予年份】：2016
【分类号】：Q948

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