Zhao Anzhou, Liu Xiaoqian, Zheng Zhoutao
College of Mining and Geomatics, Hebei University of Engineering, Handan, 056038, China.
College of Applied Arts and Science, Beijing Union University, Beijing, 100191, China.
Environ Sci Pollut Res Int. 2023 Jan;30(3):6021-6032. doi: 10.1007/s11356-022-22633-5. Epub 2022 Aug 20.
Vegetation degradation caused by rapid urban expansion is a pressing global challenge. Focusing on the Chinese Loess Plateau (CLP), we use satellite observations from 2000 to 2017 to evaluate the spatiotemporal pattern of urban expansion, and its imprint on vegetation across old urban, new urban, urban, non-urban areas as well as the entire urbanization intensity (UI) gradient (from 0 to 100%). We found a massive increase of urban impervious surface area (UISA) in the CLP from 2000 to 2017, and an uneven expansion of UISA at different urban agglomerations and cities. Less green were found in urban and new urban areas, while old urban and non-urban areas generally showed an improved greening pattern. In addition, the annual maximum EVI (EVI) differences between urban and non-urban areas were - 0.0995 on average from 2000 to 2017. The Guanzhong Plain urban agglomeration (GPUA) witnessed the most significant EVI differences (- 0.120), and the Ningxia Yanhuang urban agglomeration (NYUA) witnessed the lowest EVI differences (- 0.012). The EVI showed significantly decreased trends along the entire spectrum of urbanization gradient for 97.4% (38 of 39) cities and five urban agglomerations. The most significant decrease was found in the GUPA (slope = - 0.0197/10a, p < 0.01), while the smallest drop was found in the NYUA (slope = - 0.011/10a, p < 0.01). This study offered a fundamental support for understanding the vegetation variation along the urban-rural gradient, which may help stakeholders to make better ecological management policies for urban vegetation in ecologically fragile areas.
快速的城市扩张导致的植被退化是一个紧迫的全球挑战。以中国黄土高原（CLP）为研究对象，我们利用2000年至2017年的卫星观测数据来评估城市扩张的时空格局，以及其对老城区、新城区、城市、非城市地区以及整个城市化强度（UI）梯度（从0到100%）上植被的影响。我们发现，2000年至2017年期间，黄土高原城市不透水表面积（UISA）大幅增加，且不同城市群和城市的UISA扩张不均衡。城市和新城区的绿地较少，而老城区和非城市地区总体上呈现出改善的绿化格局。此外，2000年至2017年期间，城市和非城市地区的年度最大增强型植被指数（EVI）平均差异为-0.0995。关中平原城市群（GPUA）的EVI差异最为显著（-0.120），宁夏沿黄城市群（NYUA）的EVI差异最小（-0.012）。97.4%（39个城市中的38个）的城市和五个城市群的EVI在整个城市化梯度范围内均呈现显著下降趋势。下降最为显著的是关中平原城市群（斜率=-0.0197/10年，p<0.01），而下降最小的是宁夏沿黄城市群（斜率=-0.011/10年，p<0.01）。本研究为理解城乡梯度上的植被变化提供了基础支持，这可能有助于利益相关者为生态脆弱地区的城市植被制定更好的生态管理政策。
