基于MODIS时序数据的秦巴山区生态环境质量动态监测及驱动力分析

Dynamic Monitoring and Driving Forces of Eco-Environmental Quality in the Qinba Mountains Based on MODIS Time-Series Data

生态环境质量评价是开展秦巴山区生态环境保护和生态文明建设的重要基础。现有研究多利用统计数据或者单一指标探讨秦巴山区生态环境状况,但难以揭示研究区内部生态系统的复杂性和整体性。本文选取2002—2020年的MODIS系列遥感数据,借助主成分分析法提取遥感生态指数并探究秦巴山区生态环境质量的时空分异特征,综合地理探测器和相关性分析方法对影响该区域生态环境质量的驱动力进行量化分析。结果表明:(1)绿度、热度、湿度以及干度的第一主成分贡献率均高于50%,说明基于第一主成分提取的遥感生态指数能够较好地表征秦巴山区的生态环境状况。(2)2002—2020秦巴山区的生态环境质量总体呈现波动上升的趋势,地域差异明显,呈“中间高四周低”的空间特征;区域内生态环境质量存在轻微退化和轻微改善并存现象,其中轻微退化主要分布在东部和中部地形较平坦地区,轻微改善主要集中在大巴山和龙门山地区。(3)生态环境质量随高程和坡度变化均呈现先变好再变差的趋势,且阶段性变化特征显著,与气温、降水具有显著的相关性;人为因子对生态环境质量的影响主要表现在退耕区的生态环境质量明显高于未退耕区和全区整体水平,说明生态恢复工程有利于改善区域生态状况。本研究可为山区生态环境质量的评估和改善提供实践参考和理论支撑。

Eco-environment quality evaluation is a prerequisite for environmental protection and ecological civilization construction in the Qinba Mountains.Past researches on the Qinba Mountains mostly were conducted by statistical method,which only used single index to discuss its eco-environmental quality,but it was difficult to fairly reveal the complexity and integrity of the internal ecosystem in the Qinba Mountains.To address this issue,Principal Component Analysis(PCA)was used to extract remote sensing ecological index based MODIS time-series data from 2002 to 2020,to explore the temporal-spatial characteristics of eco-environmental quality in Qinba Mountains.Driving forces influencing eco-environment quality were determined by a combination of comprehensive geographic detectors and correlation analysis.Findings are as follows:(1)The contribution rate of NDVI,Land surface temperature(LST),WETNESS and DRYNESS on the first principal component was higher than 50%,suggesting that remote sensing ecological index based on the first principal component could well characterize ecological environment in the Qinba Mountains.(2)From 2002 to 2020,eco-environmental quality in the Qinba Mountains presented a fluctuating and upward trend.Regional differences were significant,characterized as“high in the middle and low in the surroundings”.Both slight degradation and slight improvement existed in the region.The slight degradation was mainly distributed in the eastern and central areas over relatively flat terrains,and the slight improvement was mainly distributed in the Daba and Longmen Mountains.(3)Eco-environmental quality initially improved and then deteriorate along the gradient in elevation and slope,which indicated periodic changes and significantly correlated with temperature and precipitation.With respect to the impact of human activity,much higher eco-environmental quality was observed in the returned farmland,compared to non-returned and the whole region,which indicated that ecological restoration project greatly contributed to improve ecological environment in the region.These findings provide a scientific basis for the evaluation and improvement of eco-environmental quality in the Qinba Mountains and similar regions.