河流廊道绿带结构的温湿效应

选择北京北五环清河两侧不同结构类型(内部构成、郁闭度)的绿地作为研究对象,利用小尺度定量测定的技术方法,分析城市河流廊道绿地不同内部构成、不同郁闭度与温湿效应的关系,为河流廊道绿带建设提供科学依据.结果显示:1)温湿影响效应大小为乔-灌-草型＞乔-草型＞灌-草型＞草坪.当绿地内部构成为草坪时,降温增湿效应不明显；当绿地内部构成为灌-草型时,其降温增湿效应较明显；当绿地内部构成为乔-草型和乔-灌-草型时,其降温增湿效果明显.2)绿地的降温增湿效果,随着郁闭度的不断增加而逐渐增强.当绿地郁闭度为0.20～0.40时,绿地具有一定的降温增湿效应,但效应不明显；当绿地郁闭度大于0.40时,绿地降温效应明显；当绿地郁闭度超过0.60时,绿地增湿效应极其明显且趋于稳定.

Effects of the Different Structures of Green Belts on the Temperature and Humidity in River Corridors

In order to understand scientific basis for constructing green belts in river corridors,the effects of the different structures(internal constitution,canopy closure density) of green belts on the temperature and humidity were analyzed by the small-scale quantitative measurement.In this paper,four-green belts with different internal constitutions including tree-shrub-herbage mixture,tree-herbage mixture,shrub-herbage mixture and lawn and five-green belts with different canopy closure densities including 0-0.20,0.20-0.40,0.40-0.60,0.60-0.80 and 0.80-1.00 along the Qinghe river in Beijing were investigated in July of 2010.The air temperature and relative humidity in the green belts were measured in two hour interval from 8:00 to 18:00 for continuous seven days.The results showed:1) the effects of different belts on the temperature and humidity were ranked in an order of tree-shrub-herbage > tree-herbage > shrub-herbage > lawn.The green belt with internal constitution of lawn had no significant effect on temperature and humidity.The shrub-herbage green belt had a moderate effect on temperature reduction and humidity increase,and an obvious and stable effect was found with the green belts of tree-herbage and tree-shrub-herbage.Based on Duncan’s Post Hoc Tests(P = 0.05),it was concluded that the tree-herbage and tree-shrub herbage of urban green belts had obvious effects on the temperature decrease and humidity increase(width of green belt must be about 45 m).2) The temperature and relative humidity benefits increased with the canopy density of the green belt.The green belt with canopy density of 0.20-0.40 had a slight effect on the temperature decrease and humidity increase;The density of over 0.40 had an obvious effect,and an extremely obvious and stable effect was found with canopy density of over 0.60.