摘要:城市园林绿地由于自然环境条件、天气气候条件、绿地类型、绿化树木种类、树冠郁闭度以及面积大小等的不同，其降温增湿效应是不一样的。本试验选择了北京四环以内绿化覆盖率相当、面积不同的8块园林绿地，进行了绿地面积与温湿效益之间关系的探究。研究表明：当城市绿地面积为1~2hm2时，其具有一定的增湿效应，但降温效果不明显；当绿地面积为3hm2时，其降温增湿效果较明显；当绿地面积为5hm2时，其降温增湿效果极其明显；当绿地面积大于5hm2时，其降温增湿效果极其明显且恒定。因此可以认为：城市园林绿地可以明显发挥温湿效益的最小面积为3hm2(绿化覆盖率80%左右)，最佳面积为5hm2(绿化覆盖率80%左右)。

Abstract:The lowering temperature and raising humidity effect of urban green space is discrepant due to different natural environment, weather and climate, types of greenbelt, kinds of trees, crown density and area. Eight urban green spaces of different areas and same green coverage ratio in the Fourth Ring Road in Beijing were selected for this test. The relationship between urban green spaces of different areas and the temperature and humidity benefit was studied in this paper. The results indicate that it has a little effect of lowering temperature and unobvious effect of raising humidity when the area of urban green space is 1~2hm2; an comparatively obvious effect with the area of 3hm2; an extremely obvious effect with the area of 5hm2; an extremely obvious and stable effect with the area of more than 5hm2. Therefore, it can be taken that the minimum area of urban green space producing temperature and humidity effect is 3hm2 (green cover percentage is about 80%), and the optimum area is 5hm2 (green cover percentage is about 80%).