基于无人机遥感的采动影响区冬小麦生物量分布特征

Biomass distribution law of winter wheat in mining-affected area based on UAV remote sensing

  • 摘要: 为了监测煤矿采动影响下耕地损毁范围和程度,探索地表沉陷与植被长势之间的响应关系,以河南新郑种植的冬小麦为研究对象,利用无人机(Unmanned Aerial Vehicle, UAV)激光雷达结合实时动态定位技术(Real-Time Kinematic, RTK)监测采煤沉陷情况,并验证地表高程与沉降数据的精度,基于UAV多光谱影像提取植被指数及纹理特征,采用皮尔逊相关性分析法筛选数据,结合田间同步实测生物量数据,构建决策树回归(DTR)、随机森林回归(RFR)以及支持向量回归(SVR)的生物量反演模型,通过决定系数(R2)和均方根误差(RMSE)筛选出最佳模型,以确定研究区冬小麦生物量的空间分布反演结果。结果表明:① 所选植被指数(VIs)与纹理特征(TFs)均与生物量显著相关,与单一变量相比,植被指数和纹理特征结合作为输入变量,模型估算精度最高,且采用SVR模型预测精度最高;② 研究区生物量在Ⅲ级(414~661 g/m2)和Ⅳ级(662~822 g/m2)的区域占整体的66.4%,表明大部分样本的生物量集中在中高范围,生物量低于414 g/m2的小麦区域占25.93%,说明植被长势受采动影响严重;③ 采动影响下从返青期到拔节期的下沉值与拔节期冬小麦生物量之间存在明显的负相关关系,即随着下沉值的增大,冬小麦生物量减小,在冬小麦返青期到拔节期下沉量大于2.1 m,生物量等级为Ⅰ级。研究结果为制定精确的土地复垦和生态修复策略提供了依据,为煤粮复合区耕地产能提升提供技术支撑。

     

    Abstract: In order to monitor the scope and extent of cultivated land damage caused by coal mining, the relationship between surface subsidence and vegetation growth was explored, and winter wheat planted in Xinzheng, Henan Province was selected as the research object. Unmanned Aerial Vehicle(UAV)laser radar combined with RTK technology was used to monitor coal mining subsidence, and the accuracy of surface elevation and subsidence data was verified. Vegetation indices and texture features were extracted based on UAV multi-spectral images, and Pearson correlation analysis was used for screening. Biomass inversion models were constructed using decision tree regression (DTR), random forest regression (RFR), and support vector regression (SVR) based on field-synchronous biomass data. The best model was selected based on the coefficient of determination (R2) and root mean square error (RMSE). The final spatial distribution inversion results of winter wheat biomass in the study area were obtained. The results show that: ① The selected vegetation indices and texture features were significantly correlated with biomass, and the combination of vegetation indices and texture features as input variables achieved the highest estimation accuracy. The SVR model had the highest prediction accuracy. ② Biomass in regions III (414–661 g/m2) and IV (662–822 g/m2) accounted for 66.4% of the total, indicating that most samples concentrated in the middle and high biomass range. The area with wheat biomass below 414 g/m2 accounted for 25.93%, indicating that vegetation growth was severely affected by mining. ③ Under the influence of mining, a significant negative correlation was found between the subsidence value from the regreening to the jointing stage and the biomass of winter wheat at the jointing stage. The biomass of winter wheat decreased with the increase of subsidence values. When the subsidence of winter wheat from the regreening stage to the jointing stage exceeded 2.1 m, the biomass grade was grade I. The results of the study provide an important basis for the development of precise land reclamation and ecological restoration strategies and provide technical support for enhancing arable land production capacity in the coal-grain composite area.

     

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