曲靖市马龙区城市林木树冠覆盖与热环境的相关性

Correlation between Urban Forest Canopy Cover and Thermal Environment in Malong District Qujing City

城市建成区是快速城市化的核心,也是热岛效应较为明显的区域。为了探究城市林木树冠覆盖斑块特征与城市热环境的相关性,为整体上改善城市的热环境,提高城市的宜居性提供有益借鉴。以曲靖市马龙区2020年Google Earth全色历史影像和Landsat8 OLI_TIRS卫星影像为基础,利用eCognition Developer 9.0进行土地类型斑块解译和ENVI5.3进行地表温度反演处理,对树冠覆盖斑块降温率与斑块面积、斑块周长、斑块形状指数进行Pearson相关性分析。结果表明:马龙地区树冠覆盖面积为156.91 hm^(2),占研究区总面积25.25%;不透水面温度最高(35.72℃),林木树冠覆盖对地表温度具有降温作用,斑块面积较小且分布零散,容易受到周围大面积不透水面的影响;斑块面积、周长与分别降温率显著相关(P<0.05),面积与降温率的相关性高于斑块周长与降温率的相关性,但斑块周长的增加对斑块内部温度的降低作用强于面积的增加。因此,在未来城市规划设计时,为了更好地发挥其降温效应,首先考虑增大林木树冠覆盖和水体面积,其次可增加潜在树冠覆盖,在独立斑块的基础上,组建有机廊道网,从整体上改善城市的热环境,提高城市的宜居性。

Urban built-up area is one of the core manifestations of rapid urbanization and an area with obvious heat island effect.The current situation of urban canopy coverage is closely related to urban thermal environment and residents’ quality of life.We explored the correlation between the characteristics of urban forest canopy cover patches and urban thermal environment,in order to provide a useful reference for improving the urban thermal environment and improving the livability of the city as a whole.Taking 2020 Google Earth panchromatic historical image and Landsat8 OLI_TIRS satellite images as basis,eCognition Developer 9.0 interpretation was used for land type patch interpretation and ENVI5.3 for surface temperature inversion.The Pearson correlation analysis was conducted on the canopy cover patch cooling rate with patch area,patch circumference and patch shape index.The results show that the canopy coverage area is 156.91 hm^(2),accounting for 25.25% of the study area.The impermeable surface temperature is the highest(35.72 ℃).Forest canopy mulching can cool the surface temperature,but due to the small area and scattered distribution of some patches,it is easy to be affected by the large impervious surface around.Area,perimeter and cooling rate were significantly correlated at the level of 0.05,but the relationship between area and cooling rate was closer than that between perimeter and cooling rate.The mitigation effect of the increase of perimeter on the internal temperature of plaque is stronger than that of the increase of area.Therefore,urban planning and design in the future,in order to better play its cooling effect,can first consider to increase the forest canopy cover and water area,but the tension is the main embodiment of urbanization,urban land can increase the potential canopy cover,on the basis of independent plaques,form an organic corridor network,leading to improve the thermal environment of the city as a whole,and the livability of a city.