喀斯特山地城市内山体绿地对城市热岛的减温效应——以安顺市西秀区为例

山体绿地是喀斯特山地城市内典型的城市绿地景观类型,其对于改善城市生态环境、提升喀斯特山地城市生态服务功能具有重要作用。以黔中典型喀斯特山地城市安顺市为研究对象,运用2011年和2016年两期热红外遥感影像和城市景观结构空间数据,在反演分析城市热岛效应及其强度时空分布特征的基础上,运用冷热点分析剖析了山体绿地与城市热岛效应冷点分布区的关系,揭示山体绿地对城市热岛的减温效应。结果表明:基于Landsat热红外遥感数据反演地表温度结果显示,2011—2016年,安顺市西秀区平均反演地表温度升高约4℃;主城区一带热岛效应呈现加剧趋势,但总体热岛面积呈下降趋势,绿岛区多分布于水体和山体绿地中,且山体绿地对热岛效应减缓作用逐年增大;热/冷聚集面积呈现上升趋势,约40%~50%的冷聚集区由山体绿地贡献,热聚集区主要由建筑用地和其他用地构成;500 m格网尺度下,山体绿地面积与地表温度呈显著负相关,表现为山体绿地面积占格网比例每增加10%,地表温度将降低0.17~0.27℃。研究结果可为喀斯特山地城市山体绿地管理、城市绿地空间规划和城市热环境缓解提供科学依据。

Cooling effect of mountain greenspace on urban heat island in Karst mountain city:A case study of Anshun City

Mountain greenspace is a typical type of urban green land landscape in Karst mountain cities,which plays a significant role in improving the urban ecological environment and promoting urban ecological service in Karst mountain cities.We analyzed the relationship between mountain greenspace and the distribution of cold points of urban heat island effect in Anshun City,a typical Karst mountain city in central Guizhou Province.We used cold/hot spot analysis and the thermal infrared remote sensing images and urban landscape structure spatial data in 2011 and 2016,based on the inversion analysis of urban heat island effect and the spatial temporal distribution characteristics of its intensity.We further revealed the cooling effect of mountain greenspace on urban heat island.The results showed that the average retrieved land surface temperature in Xixiu District of Anshun City increased by about 4℃ from 2011 to 2016,based on the results of Landsat thermal infrared remote sensing data inversion of surface temperature.The heat island effect in the main urban area showed an increasing trend,whereas the overall heat island area showed a decreasing trend.The green island area was mostly distributed in water and mountain greenspace.The mitigation effect of mountain greenspace on the heat island increased year by year.The cold/hot aggregation area showed an increasing trend.About 40%-50% of the cold accumulation area was contributed by mountain greenspace.The hot aggregation area was mainly composed of construction land and other land-use types.The mountain greenspace area was significantly negatively correlated with the surface temperature at the 500-m grid scale,as indicated by the fact that surface temperature would decrease by 0.17-0.27℃ for every 10% increase in the proportion of mountain greenspace area in the grid.Our results provide a scientific basis for the mountain greenspace management,urban greenspace planning,and urban thermal environment mitigation in Karst mountain cities.