中文摘要：

草地是绿地的重要组成部分，耗费巨资的北京“绿色奥运”绿地建设对生态环境的改善作用需定量评估．2005年5月利用涡度相关系统连续观测草地与裸地的水热通量及环境因素并进行分析比较，采用相关分析研究环境因素影响水热通量的权重．结果表明，草地所获得的太阳辐射能量大部分用于植被蒸腾和土壤蒸发，潜热通量约占净辐射的50％，比裸地高20％左右；草地的显热通量占净辐射的比例比裸地低将近30％，草植被下土壤获取的辐射能量低于裸地土壤近一半．白天草地地面温度明显比裸地低，相同时刻的两温度差值最大约10℃，1．5m高度气温也低于裸地近1℃，而相对湿度高于裸地近5％．草地水热通量受多个环境因素的综合影响，净辐射影响最大，其次是下垫面温度与气温差、下垫面温度，再次是相对湿度（仅对潜热）和气温，风速影响相对较弱．草地下垫面温度对水热通量的影响程度明显低于裸地，而下垫面温度与气温差对显热的影响权重明显高于下垫面温度．

英文摘要：

Lawn is the important part of green space. The green space project of Green Olympics was proposed by Beijing municipal government and got large amount of financial investment. However how the project to improve ecological environment needs to be evaluated quantitatively. So it is very significant for us to study water, heat fluxes over lawn quantitatively. The surface energy fluxes and the environmental variables were measured continuously with two eddy covariance systems over wild lawn and bare farmland in the suburb of Beijing on May 2005. Base on the measurements, the different surface fluxes were analyzed and compared in this paper. The influent weights of environmental variables for the fluxes were gotten with correlation analysis. The results show that most of incident solar radiation is changed into the energy in vegetable transpiration and soil evaporation for lawn. Latent heat flux is the major term in energy budget investigation for lawn. On the contrary, sensible heat flux is the dominant consumer of net radiation for bare soil. Latent heat flux occupies about half of net radiation energy over lawn and is about 20% greater than that over bare soil. According to surface energy balance, as latent heat flux consumes most of net radiation energy over lawn, sensible heat flux becomes about 30% less than that over bare soil, and the energy gotten by soil under grass is near a half less than that by bare soil. The ground temperature of lawn is lower than that of bare soil in the daytime, the maximum temperature difference between two surfaces reaches about ten centigrade at the same moment. The atmospheric temperature at the height of 1.5 meter over lawn is about one centigrade lower than that over bare soil. The relative humidity over lawn is about 5% higher than that over bare soil. The fluxes are significantly correlated with several environmental variables such as net radiation, ground temperat .ure, atmospheric temperature, and relative humidity （that is only for latent heat flux）. The most important