城市带状绿地宽度与温湿效益的关系

Effects of the different width of urban green belts on the temperature and humidity

带状绿地是城市绿地系统中的重要组成部分,其对城市绿地的建设和城市生态环境的改善起到其他绿地不可替代的作用。选择北京市西四环旁侧6块不同宽度带状绿地作为研究对象,利用小尺度定量测定的技术方法,分析城市带状绿地宽度与温湿效益的关系,为城市带状绿地建设提供科学依据。每天8:00—18:00,每2h分别对6块不同宽度带状绿地和对照处的温度、相对湿度进行同步测定,连续测定7d。结果显示:(1)当城市绿地宽度为6m时,绿地内部具有一定的增湿效应,但降温效果不明显;当绿地宽度为16—27m时,绿地内部的降温增湿效果较明显;当绿地宽度为34m时,绿地内部的降温增湿效果明显;当绿地宽度超过40m时,绿地内部的降温增湿效果极其明显且趋于稳定。经SPSS方差分析,6块绿地与对照间的温、湿度差异均达到显著水平,通过Duncan’S两两比较(P=0.05),认为城市园林绿地可以明显发挥温湿效益的关键宽度为34m左右(绿化覆盖率约80%),此时绿地已经表现出较佳的温湿效益;可以显著发挥温湿效益的关键宽度为42m左右(绿化覆盖率约80%)。(2)绿地对旁侧人行道的增湿降温效应存在一定影响,但由于其受周边环境影响较大,规律不明显。(3)根据3d内6块绿地平均温湿度值进行相关性分析,作出夏季带状绿地温、湿度关系的回归方程Y(相对湿度)=184.721-4.038x(温度),温度每升高1.0℃,相对湿度降低约4.0%。

As a very important part of urban green space system,green belt plays an irreplaceable role in the construction of green space and improvement of ecological environment.In order to provide scientific basis for the construction of urban green belts,the effects of the different width of urban green belts on the temperature and humidity were analyzed by the small-scale of quantitative measurement.In this paper,six-green belts with different width including 6 m,16 m,27 m,34 m,42 m,80 m along the west fourth ring road of Beijing were investigated in July of 2009.The air temperature and relative humidity in six-green belts were measured once every two hours from 8： 00 to 18： 00 every day for continuous seven days.The results show：（1）The temperature and relative humidity benefit increases as the width of six-green belts rises.The green belt of 6 m width has a little effect on the decrease of temperature and unobvious effect on the increase of humidity;It has an comparatively obvious effect with the width of 16-27 m;an obvious effect with the width of 34 m;an extremely obvious and stable effect with the width of more than 40 m.Analysis of variance shows that the differences of air temperature and humidity between six-green belts with different width and control group reach significance level.Based on Duncan′S Post Hoc Tests（P = 0.05）,it can be concluded that the critical width of urban green belt for the obvious effect on the decrease of temperature and the increase of humidity is around 34 m（green cover percentage must be about 80%）,as the effect is better,and the optimum width is around 42 m（green cover percentage must be about 80%）.（2）There is a certain effect of green belts on surrounding byway,but this effect dose not reach significant level because the temperature and relative humidity of byway is affected by the surrounding environments.（3）Regression equation Y（humidity） = 184.721-4.038x（temperature） is built based on regression analysis between the temperature and humidity in six different width green belts,which indicates that the relative humidity decreased by 4.0% with every 1.0 ℃ rise.