Effects Of Different Urban Green Structure And Plant Communities On Temperature Reduction And Humidity Increase In Beijing

With the rapid development of the city,the city problem has attracted wide attention.The phenomenon of urban heat island is becoming more and more serious,which gradually affects the quality of life of urban residents,and even endangers people’s health.Numerous studies have shown that urban green space can alleviate the heat island effect,and green space plays an important role in improving the quality of life and livability of residents.The current research takes different urban green structure and plant as the object by using small-scale quantitative measurement method in Beijing,measuring the air temperature and relative humidity of the sample,to explore the relationship between green structure and plant and temperature and humidity effect.This experiment concluded that:(1)The type of green structure have a significant correlation with air tempera ture and relative humidity,the order of average temperature-humidity effect for different types of green structure daily in summer is Tree-shrub-herbage>Tree-herbage>Shrub-herbage>Lawn Bare.8:00～18:00,except 18:00,the order of the temperature-hu midity effect for different types of green structure in each period is consistent with the effect of daily average.The effects of temperature-humidity for different types of green structure reach the maximum at 14:00,Tree-shrub-herbage can decrease t he air temperature with an average of 4.50℃ and increase the relative humidity by 7.45%,Lawn bare can increase the air temperature with an average of 0.25℃ and decrease the relative humidity by 0.45%.The order of human comfort index for d ifferent underlying surface is nearly Tree shrub herbage>Tree herbage>shrub herbage>Lawn Bare>land,the same as temperature-humidity effect.(2)The temperature of the 10 green plant show a single peak change with ti me,but humidity changes in the opposite direction.All of the 10 green plant have t he effect of temperature and humidity,which are different from others.In the cooling effet : 8:00～18:00,the 10 green plant have obvious cooling effect during the daytime,they can decrease the air temperature with an average of 8.42%～11.60%,and the cooling effect in the high temperature period was more signif icant.The type of plant have a significant correlation with air temperature,the results of order and cluster analysis of the cooling effect of the 10 green plant can be seen.The cooling effect of Robinia pseudoacacia,Sophora japonica,Fraxinus chine nsis,Koelreuteria paniculata and Salix matsudana is strong,while Ginkgo biloba,S alix matsudana,Populus tomentosa,Ailanthus altissima and Pinus tabuliformis is w eak.In the humidifying effet : 8:00～18:00,the 10 green plant have obvious humidif ying effect during the daytime,they can increase the relative humidity with an avera ge of 2.28℃～3.18℃,and the humidifying effect in the high temperature period w as more significant.The type of plant have a significant correlation with relative humidity,the results of order and cluster analysis of the cooling effect of the 10 green plant can be seen.The cooling effect of Sophora japonica,Salix matsudana,Ginkgo biloba,Fraxinus chinensis and Koelreuteria paniculata is strong,while Robi nia pseudoacacia,Ailanthus altissima,Pinus tabuliformis,Salix matsudana and Popu lus tomentosa is weak.In the human comfort index : 8:00～18:00,the order of human comfort index for 10 green plant daily in summer is Salix matsudana > Robinia pseudoacacia > Sophora japonica > Koelreuteria paniculata > Fraxinus chinensis > Populus toment osa > Ailanthus altissima > Salix matsudana > Ginkgo biloba > Pinus tabuliformis,the same as temperature-humidity effect in general.