基于“源-匯”理論的海口城市景觀格局與熱島效應響應機制

[摘  要]【目的】城市化引起的土地利用/覆被變化加劇了熱環(huán)境惡化，海口特殊的發(fā)展格局導致其城市熱島具有典型性。【方法】選取2000、2005、2010、2015和2018年5期Landst遙感影像為數(shù)據(jù)源，使用監(jiān)督分類和目視解譯法反演土地利用數(shù)據(jù)，使用單窗算法反演地表溫度；然后基于GIS技術提取研究區(qū)域熱場變異指數(shù)、匯源景觀貢獻度和景觀效應指數(shù)，使用地理空間分析與數(shù)理統(tǒng)計法，分析海口陸域在城鄉(xiāng)梯度上的匯源景觀格局對城市熱環(huán)境的貢獻及其生態(tài)效應。【結果】1）熱島梯度演變集中于西海岸、中心城區(qū)和江東新區(qū)等區(qū)域，導致平均熱場變異指數(shù)在T1～T7較高且遞減T8～21變動則較小。2）不同匯源景觀的平均熱場變異指數(shù)不同，呈“裸地﹥人工表面﹥源景觀﹥灌草地﹥農田﹥匯景觀﹥林地﹥水體”的規(guī)律；五期的匯源景觀貢獻度在T1～T7較大，在T8～T21偏小。3）平均景觀效應指數(shù)在中心城區(qū)段（T1～T7）沿城鄉(xiāng)梯度快速遞減且促進熱島比例大，梯度帶1為第一峰值；在郊區(qū)段（T8～T21）波動上升且緩解熱島比例大，存在第二峰值。【結論】熱源區(qū)面積增加、熱匯區(qū)面積減少是人工表面由中心城區(qū)不斷向周邊擴張的表現(xiàn)；源、匯景觀在中心城區(qū)對熱島貢獻值最大，沿著梯度方向對熱島貢獻度隨之降低；越靠近中心城區(qū)，匯景觀緩解熱島的貢獻度也越大，之后沿遠離中心的城鄉(xiāng)梯度方向逐漸減小。隨著城鎮(zhèn)不斷擴張，在城鄉(xiāng)梯度方向匯區(qū)比例不斷增大、源區(qū)比例不斷減小，導致了熱島的空間轉移與擴散。由此，提出基于區(qū)域景觀系統(tǒng)理論的熱島緩解策略。

[關鍵詞]景觀格局；地表城市熱島；梯度分析；“源-匯”理論；海口市

[中圖分類號] ：Q149     [文獻標志碼]：A     

Research on the relationship between landscape pattern and surface city heat island based on "Source-Sink" Theory of Haikou City

Abstract:【Objective】Changes in land use/coverage caused by urbanization has exacerbated the deterioration of the thermal environment. The unique development pattern of Haikou leads to the typical urban heat island．【Method】Five Landst remote sensing images in 2000，2005，2010，2015 and 2018 were selected as the data source．Invert land uses data using supervised classification and visual interpretation．Utilize a single window algorithm to retrieve the surface temperature．Then，based on the GIS technology, the thermal field variability index，Huiyuan landscape contribution degree and landscape effect index are extracted．Using geospatial analysis and mathematical statistics，the contribution of the Haiyuan land area's Huiyuan landscape pattern on the urban-rural gradient to the urban thermal environment and its ecological effects was discussed．【Result】1）The gradient evolution of heat islands is focused on the west coast，inner urban area and Jiangdong New Area，resulting in a higher and decreasing average thermal field variability index from T1 to T7，and a smaller change from T8 to T21．2）The average thermal field variability index of different Huiyuan landscapes is different，showing the law of “bare land﹥urban and rural construction land﹥source landscape﹥grassland﹥farmland﹥farmland﹥hui landscape﹥forest land﹥water body” The contribution of Huiyuan landscape in the fifth phase is larger from T1 to T7 and smaller from T8 to T21．3）The mediocre landscape effect index decreases rapidly along the urban-rural gradient in the inner city section (T1 to T7 ) and promotes a large proportion of heat islands，with T1 being the highest peak．In the suburban section (T8 to T21)，the fluctuation rises and the proportion of mitigating heat islands is significant，and there is a second peak．【Conclusion】The increase in the area of the heat source area and the decrease in the area of the heat sink area are manifestations of the continuous expansion of the construction land from the dominant urban area to the surrounding area．The source and sink landscapes hold the largest contribution to the heat island in the inner urban area，and the contribution to the heat island reduces along the gradient．The closer to the principal urban area，the greater the contribution of the sinking landscape of the heat island，and then gradually decrease along the gradient of the urban and rural areas away from the center．With the continuous expansion of cities and towns，the proportion of sink areas in the gradient direction of urban and rural areas continues to increase，and the proportion of source areas continues to reduce，resulting in the spatial transfer and diffusion of heat islands．Therefore，heat island mitigation strategy based on the regional landscape system theory is proposed．

Keywords: Landscape pattern；Surface urban heat island；Gradient Analysis；“source-sink” Theory；Haikou