基于改进遥感生态指数的干旱内流区生态质量评价--以阴山北麓塔布河流域为例

Ecological index evaluation of arid inflow area based on the modified remote sensing ecological index:a case study of Tabu River Basin at the northern foot of the Yin Mountains

干旱-半干旱地区生态环境脆弱,开展多要素、长时序生态质量动态变化研究,可为干旱-半干旱区生态建设与区域可持续发展提供科学依据。在遥感生态指数RSEI基础上,根据干旱-半干旱地区特点,耦合了绿度(NDVI)、湿度(WET)、热度(LST)、干度(SI)和盐度(SI-T)五个指标,提出适应干旱-半干旱区域生态质量评价的mRSEI模型,对1986—2022年间塔布河流域生态质量进行动态评价。利用Mann-Kendall突变检验、Theil-Sen(T-S)分析联合Mann-Kendall趋势分析法探究生态质量时空变化;引入欧洲中期天气预报中心发布的第五代再分析数据集(ERA5)的气象数据,在逐像元层面探讨了气候因素与mRSEI的相关关系。研究表明:(1)相较于RSEI而言,mRSEI能更好集成各生态分量包含的信息,且模型更加稳定可靠;(2)mRSEI受到的负面影响主要来自于盐度指标(SI-T),相关系数均值为-0.922,其影响力大于干度、热度指标,表明引入盐度指标对干旱-半干旱区生态质量评价具有重要意义;(3)研究时序内mRSEI介于0.179—0.423,生态质量总体呈下降趋势(Slope=-0.0014,P<0.05);(4)趋势分析结果表明,塔布河流域84.37%的区域生态质量未发生变化,另外15.63%中,生态质量退化面积占比远高于生态质量变好的区域,研究区生态质量总体呈退化趋势。(5)气候因素与mRSEI相关分析结果表明,降水与mRSEI呈正相关(r=0.411—0.807),年均气温与mRSEI呈负相关(r=-0.824—-0.398);时序相关分析结果表明,气温是研究区生态质量的主控因子。(6)人文因素虽然会对塔布河流域生态质量产生扰动,但并不起决定作用。基于改进的遥感生态指数mRSEI,能够科学监测干旱-半干旱区生态质量空间分布、准确把握生态质量变化趋势,可为干旱-半干旱地区生态保护提供理论支撑。

The ecological quality of arid and semi-arid regions is fragile,and research on multi-factor and long-term dynamic change of ecological quality can provide scientific basis for the ecological construction and regional sustainable development in arid and semi-arid regions.Based on the remote sensing ecological index(RSEI),according to the characteristics of arid and semi-arid regions,five indexes of greenness(NDVI),humidity(WET),heat(LST),dryness(SI)and salinity(SI-T)were coupled,and the modified remote sensing ecological index(mRSEI)model was proposed to dynamically evaluate the ecological quality of the Tabu River Basin from 1986 to 2022.Mann-Kendall mutation test,Theil-Sen(T-S)analysis,and Mann-Kendall trend analysis were used to explore the temporal and spatial changes of ecological quality.Then,ERA5 meteorological data was introduced to explore the correlation between climatic factors and mRSEI ecological indicators at pixel by pixel level.Results showed that:(1)Compared with RSEI,mRSEI could better integrate the information contained in each ecological component,and the model was more stable and reliable.(2)The negative influence of mRSEI mainly came from the salinity index(SI-T),and the average correlation coefficient was-0.922,which was greater than that of the dryness index and the heat index,indicating that the introduction of salinity index was of great significance for the ecological quality evaluation in arid and semi-arid areas.(3)The mRSEI was between 0.179 and 0.423 in the study time series,and the ecological quality showed a downward trend(Slope=-0.0014,P<0.05).(4)The results of trend analysis showed that 84.37%of the ecological quality did not change in the Tabu River Basin,and in the other 15.63%,the degraded area accounted for much more than the area with improved ecological quality.On the whole,the ecological quality of the study area showed a trend of degradation.(5)The correlation between climatic factors and mRSEI showed that precipitation was positively correlated with mRSEI(r=0.411—0.807),and average annual temperature was negatively correlated with mRSEI(r=-0.824—-0.398);Besides the results of temporal correlation analysis showed that temperature was the main controlling factor of ecological quality in the study area.(6)Although human factors may disturb the ecological quality of the Tabu River Basin,they do not play a decisive role.Based on the mRSEI,it can scientifically monitor the spatial distribution of ecological quality in arid and semi-arid areas and accurately grasp the trend of ecological quality change,which can provide theoretical support for ecological protection in arid and semi-arid regions.