基于遥感的河岸带生态修复效应定量评估—以辽河干流为例

物理结构完整性(PSI)是河岸带生态系统的基础特征。通过定量分析PSI的动态变化,可以有效评估河岸带生态修复效应。以辽河干流河岸带为研究对象,选取植被覆盖率、河宽比和人工干扰程度等作为监测指标,利用遥感(RS)和地面实测方法分别评价2010年和2016年的PSI,将其作为评价指标对河岸带生态修复效果进行定量评估。同时,利用Getis-Ord Gi*统计量对PSI值进行空间自相关分析,通过冷点与热点的空间分布来识别河岸带稳定及脆弱区域。研究结果表明,基于RS的河岸带物理结构评价方法与地面实测的结果一致,河岸带生态修复前后的PSI平均值由63.47提升至72.07,处于亚健康状态的河岸减少了189.5 km(97.1%)。辽河干流27.5%河岸带的修复效应显著,结构稳定性状况得到明显改善,整体上达到了生态修复的预期目标。修复后的PSI存在5个统计学意义上的显著热点和冷点,局部空间自相关性较强,其中冷点为低值聚集的河岸带脆弱区,与河岸带生态修复效果不理想的区域在空间上存在一致性。研究结果在评估河岸带生态修复效应的同时指明下阶段治理工作的方向,为我国北方平原河流的生态修复评估提供科学参考,尤其对于缺少实测资料的修复工程具有重要的应用价值。

Quantitative evaluation of riparian ecological restoration in Liao River based on remote sensing

Physical Structural Integrality (PSI) is a fundamental feature of riparian ecosystem. Riparian eco-logical restoration effect is able to be evaluated by quantitatively analyzing PSI''s variation. This study is ad-dressed to evaluate riparian ecological restoration of Liao River conservation area using PSI value in 2010 and 2016. PSI value is calculated through evaluation indicators, e.g., vegetation percent cover, water level width and human disturbance derived from remote sensing (RS) data and validated by field measurements. The variation and clusters of PSI values were calculated by Hot and Cold Spots Analysis (Getis-Ord Gener-al Gi Statistics) to discriminate stable and weak area of riparian zones. The results indicated that there was no significant difference between evaluation results based RS and field measurements. The average value of PSI increased from 63.47 to 72.07 after the riparian ecological restoration, and the length of riparian zone under the sub-healthy condition decreased 189.5 km which accounted for over 97.1% of 2010. The riparian zone achieved significant restoration effect accounted for over 27.5% of the entire riparian zone of Liao Riv-er,then the structural stability was obviously improved. The riparian PSI value in 2016 existed five statisti-cally significant hot and cold spots, on which local spatial autocorrelation was strong. The cold spots with low-low clusters of PSI values were in the vulnerable riparian zone, which was consistent to the riparian zone with poor ecological restoration effect. The research results can provide reference for plain rivers in northern China to evaluate riparian ecological restoration effect and indicate restoration position in the fu-ture, which are of particularly important application value for the ecological restoration projects lacking field measurements.