| As one of the most important factors in the physical environment of urban residential areas,thermal environment directly affects the quality of life of residents.Urban green space directly or indirectly affects urban thermal environment through transpiration and shading,through photosynthesis and carbon sequestration,and reducing the concentration of greenhouse gas CO2 in the air.As an important part of urban ecosystem,urban green space is the key to alleviate urban heat island effect and improve urban ecological environment.Under the background of global warming,the study of urban green space ecological evaluation based on thermal environment has important practical significance for urban planning and construction.Based on field monitoring and remote sensing data,this paper analyzed the regulatory effect of green space distribution on thermal environment from local and regional scales,explored the impact of land use change,especially urban green space on thermal environment in the process of urbanization from the perspective of time and space,analyzed and studied the relationship between the ecological service and green space pattern of urban green space,and climate regulation function and carbon sequestration function of green space were evaluated.The main conclusions are as follows:1)On the local scale,based on the measured results of temperature and humidity on the underlying surface of the woodland,grassland and non-permeable ground in Xinyi apartment,Shanghai,in summer,the regulating effect of woodland on the surface temperature and humidity near the ground is significantly better than that of grassland.The near surface temperature of woodland is lower than the air temperature almost all day,and the temperature difference is the highest at 11:00 a.m.,reaching 1.8?.at the same time,the grassland temperature is higher than the temperature by 1.5?,and the non-permeable ground temperature 2.6? above air temperature.According to human comfort index,woodland brings the highest comfort to human body.When the non-permeable ground and grassland environment are extremely hot and intolerable,the forest environment is still relatively comfortable.The maximum difference between the human comfort index of woodland t land and that of non-permeable ground and grassland is 2.4(14:00)and 2.6(15:00),respectively.The difference of near surface micro environment between f woodland and non-permeable ground is the most obvious: the difference of near surface temperature between woodland and non-permeable ground is significant(p < 0.05)from 13 o'clock in one day to 8 o'clock in the next day,and the difference of near surface humidity between woodland and non-permeable ground is significant(p < 0.05)almost in the whole day.The results of environmental factor analysis on thermal environment show that: on summer nights,the near surface temperature and humidity are mainly affected by the vegetation coverage rate.For every 10% increase of vegetation coverage rate,the near surface temperature and humidity decrease by 0.15? and increase by 0.93%;in daytime,the near surface temperature and humidity increase by 0.063? and increase by 0.864% for every 10% increase of vegetation coverage rate,except for the influence of sunshine.In addition,on the vertical scale,the impact of green space around the building on the outdoor thermal environment of the building is limited to the first floor and the second floor,with little impact on the third and fourth floors.In autumn,the effect of green space on the thermal environment temperature is reflected in the afternoon and evening.The green space plays a role in heat preservation.The temperature of the first floor is higher than that of the fourth floor,and the maximum temperature is 1.9?(5:00).In summer,the effect of green space on the thermal environment temperature is reflected in the daytime.The green space plays a role in cooling.The temperature of the first floor is lower than that of the fourth floor,and the maximum temperature is 8.6?(15:00).The effect of green land on the thermal environment of different height is also related to its configuration.In summer,the cooling effect of s woodland and shrub is significantly better than that of shrub land: when the green land is configured as shrub,the maximum temperature difference between the first and the fourth floors is 2.2?(16:00),and when the green land is configured as woodland and shrub,the maximum temperature difference between the first and the fourth floors is 8.6?(15:00).2)On the regional scale,the research on the characteristics of land use transfer and the surface temperature of Pudong in Shanghai from 2007 to 2017 shows that in the past ten years,the proportion of green space has decreased from 50.2% to 30.3%,and 93.6% of the total green space transferred out has been transferred to urban land.The average surface temperature of the study area increased by 3.3?,among which the area belonging to the middle temperature area increased by 3%,the area belonging to the weak high temperature area and the high temperature area increased by 1.1%.In 2007,the contribution rate of urban land is 94.63%,which indicates that urban land plays a leading role in urban thermal environment.The contribution rate of green space is 4.1%.The impact of water body and unused land with a small proportion on thermal environment can be ignored.In 2017,the contribution of urban land to the thermal environment reached 99.7%,which played a decisive role in the thermal environment.The contribution of green space to the thermal environment was only 0.2%.3)For the ecological function of carbon sequestration of green space,the carbon storage of green space accounting for 44.1% of the total area of Xinyi apartment is 378.6 Mg.The above carbon storage,below storage,dead carbon storage and soil carbon storage are respectively 1.7%,3.8%,2.6% and 91.9% of the total carbon storage.The forest land carbon storage is about 3.5 times of the grassland,and the carbon density is 49.8 Mg / hm2.The forest land,accounting for 7% of the total area of Pudong,has a carbon sequestration of 1409028 Mg,which is 33.2% of the total carbon reserve of the whole area.The average carbon density of Pudong is 10.2 Mg / hm2.The carbon density of Xinyi apartment residential area in the central city is close to that of Donghai farm with the highest carbon density in Pudong,which is significantly higher than that of street town in the central city within the outer ring road in Pudong.The carbon fixation service function of green space is closely related to its distribution pattern and green space configuration. |
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