中国重要生态系统保护和修复工程区域植被覆盖时空变化研究

Spatiotemporal changes in vegetation cover of the national key ecosystem protection and restoration project areas,China

植被覆盖变化是气候变化和生态环境变化的双重指示器,如何量化全国尺度植被变化、评估生态修复成效,成为当前陆地表层生态系统研究领域共同的科学问题。利用2000—2020年的植被覆盖度(FVC)数据,采用增幅变化分析、Theil-Sen Median趋势分析、稳定性分析方法,对中国六大重要生态系统保护和修复工程区域的自然植被覆盖度本底和时空变化特征进行了研究,并对不同区域植被覆盖度变化与气温、降水的相关性进行了分析,以期掌握我国生态系统保护和修复“家底”。结果表明:(1)2020年,六大区域平均植被覆盖度为27.66%,2000—2020年,黄河重点生态区、北方防沙带和青藏高原生态屏障区增幅分别为54.4%、34.6%和21.8%,是全国范围平均植被覆盖度增幅的1.04—2.59倍;长江重点生态区、东北森林带和南方丘陵山地带增幅分别为18.0%、13.7%和12.9%,均低于全国增幅,我国西北方较南方改善更明显。(2)2000—2020年,六大区域植被覆盖度变化总体呈增加趋势。黄河重点生态区、东北森林带、南方丘陵山地带和长江重点生态区增加区域面积占比均超过60%,北方防沙带和青藏高原生态屏障区植被增加区域面积占比相对较低,分别为24.9%和17.6%,植被变化受人类活动影响较明显。(3)六大区域自然植被覆盖度变化相对稳定,主要变异区域位于青藏高原生态屏障区、北方防沙带和黄河重点生态区的生态环境敏感脆弱区,受气候、地质灾害等自然因素影响较大。(4)不同修复区域植被覆盖度变化与降水和温度的相关性有差异。青藏高原生态屏障区、长江重点生态区和南方丘陵山地带FVC与年降水量相关性不显著,但与年均温度显著相关;北方防沙带植被覆盖度变化与年降水量显著相关,与年均温度相关性不显著;黄河重点生态区和东北森林带植被覆盖度变化与年均温度和年降水量相关性均不显著。

Vegetation cover change is a dual indicator of climate change and ecological environment change,How to quantify vegetation cover change at the national scale and evaluate the effectiveness of ecological restoration has become a common scientific issue in the current field of terrestrial surface ecosystem research.This article used vegetation coverage(FVC)data from 2000 to 2020,the methods of incremental change analysis,Theil Sen Median trend analysis,and stability analysis to study the background and spatiotemporal changes of natural vegetation coverage in six national key ecosystem protection and restoration project areas in China.The correlation between vegetation coverage changes in different regions and temperature and precipitation was also analyzed.The results showed that:(1)In 2020,the average vegetation coverage of the six major regions was 27.66%.From 2000 to 2020,the growth rates of the key ecological area of the Yellow River,the northern sand prevention zone,and the ecological barrier area of the Qinghai Tibet Plateau were 54.4%,34.6%,and 21.8%,respectively,which was 1.04 to 2.59 times of the national average vegetation coverage growth rate;The growth rates in the key ecological area of the Yangtze River,the northeast forest belt,and the southern hilly mountain zone were 18.0%,13.7%,and 12.9%,respectively,which were lower than the national growth rate.The improvement was more obvious in the northwest of China than in the south.(2)From 2000 to 2020,the overall vegetation coverage changes in the six major regions showed an increasing trend.The proportion of increased areas in the key ecological areas of the Yellow River,northeast forest belt,southern hilly mountain zone,and Yangtze River exceeded 60%.The proportion of increased vegetation in the northern sand prevention zone and the ecological barrier area of the Qinghai Tibet Plateau was relatively low,with 24.9%and 17.6%,respectively,vegetation change was significantly affected by human activities.(3)The changes in natural vegetation coverage in the six major regions were relatively stable,with the main variation areas located in the ecological barrier area of the Qinghai Tibet Plateau,the northern sand prevention zone,and the key ecological area of the Yellow River,which were more influenced by natural factors such as climate and geological disasters.(4)There were differences in the correlation between vegetation coverage changes and precipitation and temperature in different restoration areas.The correlation between FVC and annual precipitation was not significant in the ecological barrier area of the Qinghai Tibet Plateau,the key ecological area of the Yangtze River,and the southern hilly mountain zone,but it was significantly correlated with annual average temperature.The vegetation coverage change in the northern sand prevention zone was significantly correlated with annual precipitation,but not with annual average temperature;There was no significant correlation between the vegetation coverage changes in the key ecological area of the Yellow River and the northeast forest belt and the annual average temperature and precipitation.