京津冀地区近20年NDVI时空变化特征

健康稳定的自然生态系统是保障城市发展的重要基础。了解京津冀城镇快速发展过程中自然生态系统的变化,有助于该区域城镇绿色协调可持续发展。植被指数NDVI时空变化特征可反映地区自然生态系统状况及其演变规律。基于MOD13Q1和Landsat遥感影像数据,利用一元线性回归趋势分析法分析近20年(2000—2019年)京津冀地区不同功能区和北京市NDVI的时空变化特征。功能区划分参考《京津冀协同规划纲要》和《北京城市总体规划(2016—2035年)》。结果表明,(1)近20年京津冀地区NDVI略有增加,但增速缓慢,仅为0.025/(10 a),前4年(2000—2004年)增长明显,随后基本保持不变,略有波动,其中西北部生态涵养区NDVI最高且增长最多,但张家口市NDVI低于其他地区。(2)NDVI变化趋势数据结果显示,近20年,植被改善的区域占京津冀地区总面积的88.09%,退化的区域仅占11.91%。前10年(2000—2009年)植被改善的区域占京津冀地区总面积的95.13%,退化的区域面积仅占4.87%;后10年(2010—2019年)植被改善的区域略有减少,占总面积的92.88%,退化的区域增加,占7.12%。改善的区域主要分布在中部核心功能区和南部功能拓展区,退化的区域主要分布在西北部生态涵养区的张家口市和承德市。(3)北京市近20年NDVI波动增长,增长幅度深山区>浅山区>平原区。京津冀地区近20年采取的生态保护工程改善了植被状况。

Spatiotemporal Variation of NDVI in Beijing-Tianjin-Hebei Region in the Past 20 Years

A stable and healthy natural ecosystem is an important factor for supporting urbanization.Understanding the changes of natural ecosystem during the rapid urbanization of Beijing-Tianjin-Hebei region is helpful to the green,coordinated and sustainable development of cities and towns in this region.The spatiotemporal variation of NDVI can reflect the status and evolution of local natural ecosystems.Based on the MOD13Q1 and Landsat data,the spatiotemporal variation of NDVI were analyzed by means of univariate linear regression in different functional areas of Beijing-Tianjin-Hebei region and Beijing,which was divided according to the Beijing-Tianjin-Hebei Collaborative Planning Outline and Beijing Overall City Planning(2016?2035),in recent 20 years(2000?2019).The results show that:(1)NDVI in Beijing-Tianjin-Hebei region has increased slightly in recent 20 years,with a growth rate of only 0.025/(10 a).It increased obviously in the first four years(2000?2004),and then remained almost unchanged and fluctuated slightly.NDVI in Northwest Ecological Conservation Region was the highest and increased the most,but it in Zhangjiakou City was obviously lower than that in other areas.(2)The NDVI change results showed,in the past 20 years,the area with improved vegetation accounted for 88.09%of Beijing-Tianjin-Hebei region,and the area with degraded vegetation only accounted for 11.91%;in the first 10 years(2000?2009),the area with improved vegetation accounted for 95.13%of Beijing-Tianjin-Hebei region,while the area with degraded vegetation only accounted for 4.87%.In the last 10 years(2010?2019),the area with improved vegetation decreased slightly,accounting for 92.88%,while the area with degraded vegetation increased,accounting for 7.12%.The vegetation improved areas are mainly distributed in Central Core Functional Region and South Functional Development Region,while the degraded areas are mainly distributed in Zhangjiakou City and Chengde City in Northwest Ecological Conservation Region.And(3)in recent 20 years,NDVI in Beijing has fluctuated and increased,growth in high mountain area>low mountain area>plain area.In general,Environmental engineering measures taken in Beijing-Tianjin-Hebei region in recent 20 years have improved the ecological conditions.The environmental measures taken have improved the vegetation status in Beijing-Tianjin-Hebei region in recent 20 years.