基于地理探测器的滏阳河流域植被覆盖时空变化与驱动力分析

Spatiotemporal dynamics and control factors of vegetation cover in the Fuyang River Basin based on geographical detector model

滏阳河位于河北省境内,作为子牙河系两大支流之一,流经多座城市和乡村,对流域内的生态环境和经济发展起着重要作用。文章基于2000—2020年月尺度MOD13A1(500 m)遥感数据,采用一元线性回归和Hurst指数法分析了区内植被时空变化趋势,借助Person相关分析方法对降水量和温度与归一化植被指数(NDVI)进行相关性分析,利用地理探测器模型将区内降水量、温度、植被类型、土壤类型和海拔等自然因子,土地利用类型、人口密度和GDP等人为因子进行统计划分,探讨了各驱动因子对NDVI变化的影响程度,利用模型进行了因子探测、交互作用探测和风险区探测,明确了驱动因子与NDVI间的驱动力大小以及利于植被生长的最适因子数值范围或类型,为生态保护和可持续发展提供参考和依据。结果表明:(1)2000—2020年,区内植被覆盖度总体呈现增长的趋势,每年NDVI平均值为0.76,Slope指数平均值为0.000 5,Hurst指数平均值为0.48,据指数空间叠加结果,区内植被覆盖变化以未来改善为主;(2)区内NDVI与降水量之间整体呈现正相关关系,NDVI与温度之间相关性不强,相对而言,NDVI年际变化与降水量关系更密切;(3)区内单个驱动因子对NDVI的影响程度由大到小排序为:降水量>人口密度>GDP>土地利用类型>土壤类型>温度>海拔>植被类型,其中前3个因子的q值均大于0.2,作为影响区内的主要驱动因子;(4)区内双因子组合驱动力明显高于单因子驱动力,因子间的交互作用以双因子增强关系为主,其中NDVI变化受降水量和人口密度的交互作用影响最大,q值为0.59,降水量同其他因子间的交互作用处于主导地位;(5)根据区内风险区探测结果,以降水量464.73~500.03 mm、温度15.14~15.23℃、海拔3~133 m、人口密度551.36~2 059.96人·km^(-2)、GDP 1 756.77~7 507.15元·km^(-2)的数值范围和以栽培植被、初育土、耕地为主要类型的区域,有利于植被的生长。

The Fuyang River—flows through Handan,Xingtai and Hengshui areas of Hebei Province as a tributary of the Ziya River,confluencing with the Hutuo River at Cangzhou—plays an important role in the eco-environment and economic development of the Fuyang River Basin.Based on the 20002020 monthly MOD13A1(500 m)dataset,the spatiotemporal dynamics of regional vegetation cover was analyzed by unary linear regression and Hurst index methods,and Pearson correlation analysis between the normalized difference vegetation index(NDVI)and temperature/precipitation was performed.In combination with geographical analysis by geographical detector method,natural factors such as precipitation,temperature,vegetation type,soil type and elevation,and human factors such as land use type,population density and GDP were evaluated through statistical analysis for their impact on regional vegetation cover.Furthermore,control-factor detection,two-factor interaction detection and risk area detection were carried out.Ultimately,the impact of each control factor on NDVI and the optimal value of each control factor for vegetation growth are calculated,which provided a reference and basis for ecological protection and sustainable development in the region.The results showed that(1)the regional vegetation cover had an overall increasing trend between 20002020,and the NDVI,Slope index and Hurst index annual means were 0.76,0.0005 and 0.48,respectively.According to spatial superposition analysis,the regional vegetation-cover changes were mainly attributed to man-made improvements.(2)There was a positive correlation between NDVI and precipitation annual means,while NDVI interannual trends were more closely related to precipitation than temperature.(3)The control factors were ranked according to their influence on NDVI as precipitation>population density>GDP>land use type>soil type>temperature>elevation>vegetation type.The first three factors,with q values greater than 0.2,were considered the main control factors of regional vegetation cover.(4)The impact of a two-factor combination was significantly higher than that of a single factor,showing a two-factor enhancement effect;the precipitation-population density combination,with a q value of 0.59,had the highest impact,while combinations of precipitation and other factors had dominant effects.(5)Based on risk area detection,areas with precipitation of 464.73500.03 mm,temperature of 15.1415.23℃,altitude of 3133 m,population density of 551.362059.96 people·km^(-2),GDP of 1756.777507.15 yuan·km^(-2),and an eco-environment with cultivated vegetation,nursery soil and cultivated land,were most favorable for vegetation growth.