关中五市城市建设用地与热环境的时空演变特征及其相关性研究

A study on spatiotemporal dynamics of urban construction land and its impact on thermal environment in five cities of Guanzhong region

关键词:  城市建设用地  热环境  时空演变  关中地区  景观格局

Key words:  urban construction land  thermal environment  spatiotemporal evolution  Guanzhong region  landscape pattern

摘要:

深入了解建设用地景观格局对热环境的影响机制，对改善城市热环境提高居民生活质量具有重要意义。文章基于MODIS遥感数据产品，利用景观指数分析方法，量化2005—2020年关中五市 （西安、 咸阳、宝鸡、渭南和铜川）建设用地景观格局的时空变化特征及其对城市热环境演变的影响。结果显示： 2005—2020年关中五市建设用地面积呈现稳定增长，且形状不规则程度加深，同时城市地表温度（LST） 缓慢上升 。 相关性分析表明景观类型比例 （PLAND）、 最大斑块指数 （LPI）、 平均斑块面积 （AREA_MN） 以及结合度指数 （COHESION） 均与LST呈显著正相关，而破碎度指数 （SPLIT） 则呈显著负相关。在5个城市中，建筑景观格局的变化对特大城市西安的LST影响最为显著。具体而言，西安白天的LST与COHESION相关性最强，2020年的相关系数为0.591 （P＜0.01）；夜晚的LST与PLAND相关性最强，2020年的相关系数为0.658（P＜0.01）。

Abstract:

Background, aim, and scope Rapid urbanization has led to a series of negative impacts on the regional environment, among which one of the most notable problems is the increasingly prominent urban heat island issue. Understanding the impact of urban landscape change on the thermal environment is of great significance for improving the quality of life for urban residents. Taking five cites (Xi’an, Xianyang, Baoji, Weinan and Tongchuan) in Guanzhong region as the study area, this research explored the spatiotemporal dynamics and correlations between the urban thermal environment and landscape patterns from 2005 to 2020. Materials and methods Sen’s slope estimator and the Mann-Kendall nonparametric test were used to quantify the spatial and temporal changes in urban land surface temperature (LST). Then, the evolution of the urban landscape pattern was analyzed using the landscape index, and the relationship between the urban landscape pattern and LST was investigated by using Pearson correlation analysis. Results (1) From 2005 to 2020, LST in the five cities exhibited a slow rising trend, while the extent of construction land increased steadily. (2) The percentage of landscape (PLAND), largest patch index (LPI), average patch area (AREA_MN) and patch cohesion index (COHESION) of construction land were significantly positively correlated with LST, whereas the splitting index (SPLIT) showed a negative correlation with it. (3) The influence of urban landscape pattern on LST varied greatly among different cities, with the most significant impact in Xi’an. Discussion (1) Large and contiguous construction land had a stronger warming effect than the scattered and fragmented small patches. (2) The warming effect of urban construction land changed more obviously in areas with low urbanization levels, however it was more pronounced in areas with a higher urbanization level. (3) Due to factors such as landscape dominance and patch fragmentation of construction land in different cities, the relationship between individual landscape indices and LST varied regionally. Conclusions (1) Construction land was mainly concentrated in the Guanzhong Plain from 2005 to 2020, with most of these areas having high LST and showing a significant rising trend. (2) During this period, the construction land in the five cities developed from small and scattered patches to large and concentrated ones. (3) Compared with scattered and broken small patches, large area construction land with strong agglomeration and good connectivity had a stronger warming effect. (4) The landscape pattern of construction land in the five cities of Guanzhong had an impact on the surface temperature, among which the influence in Xi’ an was the most significant. Recommendations and perspectives Construction land planning should prioritize the area and shape to avoid negative impacts on the environment, particularly the urban heat island effect. It is recommended that further in-depth research on the relationship among urbanization, landscape patterns, and the thermal environment be conducted in other regions.