城市景观格局影响地表热环境的多尺度分析——以上海市为例

Multi-scale Analysis of the Influence of Urban Landscape Pattern on Land Surface Temperature: ACase Study of Shanghai

关键词:  风景园林  景观格局  地表热环境  尺度效应  上海市

Key words:  landscape architecture  landscape pattern  land surface temperature  scale effect  Shanghai

摘要:

全球气候变化背景下，城市地表热环境恶化已成为生态环境治理的重大挑战，而景观格局变化对地表温度(land surface temperature，LST)有重 要影响。基于上海市1998、2007和2017年的Landsat TM/TIRS影像数据，探讨城市景观格局与LST的变化特征和影响机制，并对其相关性进行多尺度分 析。结果表明：1)热岛区域由中心城区的“聚合状”转为“扩散式”，不同土地覆盖类型LST差异较大，建设用地LST最高，而水域、林地和草地较低；2)在景 观水平层面，城市景观格局在不同尺度下具有空间变异性，总体上在2 700~5 400 m范围内相对稳定，可视为适宜尺度域；3)建设用地与LST呈显著正相关 (P <0.01)，耕地、林地和水域为负相关，水域、林地构成的蓝绿空间在3 500~4 500 m尺度上的抑温作用更强；4)不同土地覆盖类型的景观格局与LST的相关 性具有尺度效应，耕地、建设用地的面积占比和聚集度对LST影响显著，而大范围整体连片式、形状复杂的蓝绿空间更有助于缓解城市热岛效应。通过城市景观 格局和LST相关分析，为制定缓解高温热浪的规划策略提供参考。

Abstract:

In the context of the intensification of global climate change, the escalating frequency of extreme weather events, recurring heatwave onslaughts, and heightened urban vulnerability have markedly intensified pressures on urban habitation environments and resilience infrastructure systems. This paradigm has resulted in progressively amplified adverse impacts on urban ecological integrity and public health security, while the deteriorating urban thermal environment - as manifested through land surface temperature (LST) anomalies - has emerged as a critical bottleneck in ecological governance frameworks, posing a formidable challenge to sustainable urban environmental management. Following the accelerated urbanization phase, megacities and super-large cities have undergone profound transformations in their urban landscape morphology and land use configurations. This transformation process has revealed that alterations in urban landscape patterns exert substantial impacts on LST, while scale as a central research focus in landscape ecology has emerged as an indispensable determinant in understanding urban surface thermal environment mechanisms. To investigate the variation characteristics and influencing mechanisms of urban landscape patterns and LST in the spatiotemporal dimension, based on the Landsat TM/TIRS image data of Shanghai in 1998, 2007, and 2017, the study used a multi-scale analysis method to conduct an in-depth study on the correlation between urban landscape patterns and LST. The results show that: 1) the urban heat island area gradually changes from the "aggregation" distribution in the central urban area to the "diffusion" distribution, and the urban heat island area gradually spreads to the whole area, and the LST of different land cover types is significantly different, with significant LST disparities among land cover types - built-up land exhibited the highest LST, while the water area, forests, and grassland had lower LST, indicating aggregated built-up areas intensify heat island effects whereas blue-green spaces regulate and improve land surface thermal environments; 2) at the landscape level, urban landscape pattern exhibited spatial variability at different scales but remained relatively stable in the range of 2,700-5,400 m in general, which could be regarded as the optimal scale domain for urban landscape pattern research in the study area; 3) built-up land has a significant positive correlation with LST (P<0.01), indicating its greater contribution to urban heat island formation, while cropland, forests and water area have a negative correlation with LST. The blue-green space composed of water area and forests exerted stronger cooling effects on the scale of 3,500- 4,500 m. This indicates that blue-green space is more efficient in alleviating the urban heat island effect on small and medium scales; 4) the correlation between landscape pattern and LST of different land cover types showed a scale effect, in which the area proportion and aggregation degree of cropland and built-up land had a significant impact on LST. Therefore, to avoid the continuous increase of heat island area, urban construction should avoid largescale continuous development and utilization of construction land space. A large range of integrated contiguous blue and green space with complex shapes is more conducive to alleviating the negative impact of the urban heat island effect. The findings highlight the importance of establishing a climate-resilient urban landscape framework, and urban planning and design should prioritize decentralized, diverse networks of blue-green Spaces rather than single urban sprawl. Under the severe situation of climate warming, the study is expected to provide important references for optimizing urban landscape pattern, scientifically delineating blue-green space scope, and accurately formulating planning strategies for alleviating heat waves.