【作者】 陈方敏；

【导师】 李俊祥；

【作者基本信息】 华东师范大学 ， 生态学， 2010， 硕士

【摘要】 城市热岛效应(Urban Heat Island Effect简称UHI)是指城市气温高于郊区的现象(Oke,1987),是城市气候最明显的特征之一,也是城市化的环境后果之一。城市热岛不仅改变了城市的局部气候特征(气温、湿度、对流、降水格局),还有影响动植物生理、物候、生态系统功能、居民身心健康乃至生命安全,加重污染,增加能耗等多种生态环境效应。城市绿地系统是城市生态系统的重要组成部分,城市公园作为城市绿地系统的主要组分,可以有效缓解城市热岛效应,改变城市热场分布。但是城市公园如何在多个时空尺度上对城市热岛产生影响,却很少有系统的研究。本文采用小气候定位观测、流动观测、遥感数据反演、景观格局分析等方法,从植物群落、公园景观斑块、公园、社区(公园+周边复合商住区)、城乡样带多个尺度上,研究城市公园绿地如何缓解城市热岛效应,定量分析了城市公园绿地(面积、斑块属性)及其结构的热环境效应,探讨了公园绿地周边的景观格局变化对公园降温效应的影响。得出的主要结论如下：(1)秋冬季的公园绿地的温度明显低于周围环境,作为较明显的“冷岛”,仍能有效缓解城市热岛效应。(2)城市公园绿地对热岛效应的缓解与其斑块特征有关：气温与公园面积呈显著负相关(R2=0.817,P<0.05),两者满足对数函数关系；内部气温与公园的周长呈负相关(R2=0.7473,P<0.05),两者呈幂指数关系,公园内气温与形状指数(周长面积比)呈显著正相关(R2=0.844,P<0.01),两者满足对数函数关系,即公园边界越复杂,内部气温越高。公园绿地内部平均地表温度与公园面积负相关,但不显著；地表温度与公园的周长存在负相关关系(R2=0.2792,P<0.01),两者满足幂指数关系；地表温度与周长面积比无显著相关关系。周围环境地表温度的差异与绿地斑块特征无明显相关性。(3)不同绿地景观类型的热环境效应不同。所有绿地类型的温度在白天和夜间均低于铺砌地面,乔灌草和乔草复合型绿地的降温增湿效应优于草地类型绿地。乔灌草类型比草地类型在白天和夜间降温效果分别高1.71%、0.8%,增湿效果分别高8.95%、2.34%；乔草类型比草地类型在白天和夜间降温效果分别高5.93%、0.18%,增湿效果分别高12.61%、3.41%。复合类型的林地降温增湿作用白天强于夜间；草地类型降温作用夜间强于白天,草地在夜晚明显增加空气湿度,白天反而略降低空气湿度。(4)公园绿地周围环境温度与周边景观格局有关,与距离公园的远近无明显的相关关系。高层的商业区和住宅比低层的住宅区温度稍低。公园微风扩散经高层建筑区达到低层建筑区时温度明显升高,而经过低层建筑区达到高层建筑区的时温度明显降低。(5)公园绿地的热环境效应在城乡梯度上随城市景观格局而变,城市绿地的温度效应与城市化水平有关。城市化程度较高的中心城区公园绿地的温度比城市化水平较低的区域明显较低,即随着城市用地结构的比例提高,绿地的降温作用增加。更多还原

【Abstract】 Urban heat island (UHI) effect was defined as the temperature difference between urban and rural area (Oke,1987). UHI is one of the hot topics in urban climate research, and also one of the environmental consequences of urbanization. UHI not only alters the local microclimate conditions in urban area, but also influences the physiological activities, phenology of plants and animals living in urban area, ecosystem functions, and health even life of urban habitants. UHI can deteriorate urban pollution, increase the energy consumption. Urban green space, an essential component of urban ecosystem, can markedly mitigate urban heat island effect. The effect of urban park on urban heat island has been well documented, but how urban park mitigates urban heat island at multi-scale has not been well addressed.In this thesis, methods of microclimate in situ observation, mobile observation, land surface temperature retrieval from remotely sensed imagery, and landscape pattern analysis were employed to study how urban park mitigate urban heat island effect in Shanghai, to quantitatively analyze how urban park (e.g. area, patch characteristics) and their structure affect urban thermal environment, to explore how the adjacent urban landscape pattern influence the cooling effect of urban park. My findings are as followed:(1) The temperature of urban park was clearly lower than that of the ambient environment in the autumn and winter. Urban Park, as cool island, could effectively mitigate of urban heat island effect.(2) The mitigation effect of urban park on UHI could be correlated to characteristics of park patch. Air temperature was negatively correlated to park area and fitted well with logarithmic function (R2=0.817, P<0.05). Air temperature was negatively correlated to park perimeter, and fitted well with power function (R2=0.7473, P<0.05). Air temperature was positively correlated to park shape index and well fitted with logarithmic function (R2=0.844, P<0.01). That is to say, the more complex the patch perimeter was, the higher the air temperature within the park would be. The land surface temperature was negatively correlated to park area, but no significance. But it was negatively correlated to park perimeter and could be fitted well with power function (R2=0.2792, P<0.01). Surface temperature difference between park and ambient environment could not be correlated to park patch characteristics.(3) The various plant community structure of the park showed different thermal effects on air temperature, land surface temperature and relative humidity. The effect of decreasing temperature and increasing humidity of all plant community was remarkable better than that of sealed surface. Arbor-grass and Arbor-shrub-grass type were better than grass type in regulating microclimate. The cooling effect of arbor-shrub-grass was higher than that of grass type by 1.71% in the day and 0.8% at night. Humidification effect of arbor-shrub-grass type was better than that of grass type by 8.95% during daytime and 2.34% during nighttime. The cooling effect of arbor-grass was higher than that of grass type by 5.93% during daytime and 0.18% during nighttime. Humidification effect of arbor-shrub-grass type was higher than that of grass type by 12.61% during daytime and 3.41% during nighttime. The cooling and humidification effect of compound community type was stronger in daytime than that at night. Cooling effect of grass was weaker in daytime than that at night. Grassland could increase relative humidity at night but decrease relative humidity in daytime.(4) The ambient temperature of the park could be correlated to landscape pattern but not be correlated to the distance to urban park. Temperature in commercial and residential areas with high-rise buildings was lower than that in residential area with low-rise buildings. The air temperature decreased sharply when park wind blew from high-rise to low-rise building area, but increased when from low-rise to high-rise building area.(5)The thermal effect of urban park varied with landscape pattern along urban-rural gradient which was affected by urbanization degree. Both air and surface temperature of parks in the area with higher urbanization were lower than that with lower urbanization. The mitigation effect of park on urban heat island increased with patch coverage of urban land use.更多还原