Variation Analysis of Spectral Characteristics of Reclamation Vegetation in a Rare Earth Mining Area Under Environmental Stress

Abstract

Large-area hyperspectral remote sensing monitoring of physiological parameters of reclaimed vegetation is a crucial means of environmental supervision in rare earth (RE) mining areas. The variation analysis of reclaimed vegetation characteristics under environmental stress in mining areas provides the necessary foundation for accurate dynamic monitoring of ecological restoration. In this article, the original spectral reflectance of six typical reclaimed vegetations in the RE mining area and their corresponding vegetations in the normal environment are measured. The spectral variations between reclaimed and normal vegetations are then compared and analyzed. To extract more hidden information in spectral features, the original spectrum is transformed using common derivative transform. In addition, wavelet transform (WT) and fractional differential (FD) transform are used to strengthen the detailed information of the original spectrum and explore the spectral features of reclaimed vegetation under environmental stress in RE mining areas. It can be deduced that in the first derivative spectrum, the reclaimed vegetations show a blueshift in the red edge position except for <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Wetland pine</i> . This indicates that reclaimed vegetation is affected by external factors, such as environmental stresses to different degrees in the mining area. WT can extract the original spectral features with a high degree of influence, highlighting the detailed information with obvious changes and sharp fluctuations in spectral information features, in which the reclaimed vegetations and normal vegetations had obvious differences at the d5 scale. These results provide technical support for process management and formulation of reclamation measures of reclaimed vegetation in RE mining areas, and therefore contribute to the ecological reconstruction of RE reclamation mining areas.