半封闭大棚实验下广州市植被滞尘光谱特征分析

Spectral Characteristics of Dust-Retention Plants in Guangzhou under Semi-Closed Greenhouse Experiment

基于广州市常见的绿化植物,采用高光谱遥感技术,通过设计半封闭的大棚实验方案,探讨了滞尘污染下不同植物叶片的光谱特征,结果表明:1)滞尘时间是影响绿化植物累积滞尘量的一个重要因子,滞尘量随着时间的增加而增加,但达到饱和之后会呈减少的趋势。2)在可见光波段,受叶面尘影响,叶片光谱反射率升高,且随滞尘量的增加而升高;在近红外波段则相反,光谱反射率随滞尘量的增加而降低。3)叶面尘对植物叶片的光谱特征参数具有直接或间接的影响,其中滞尘量与植物的三边位置无关,与归一化植被指数NDVI呈负相关关系,且不同植物的NDVI受叶面尘影响的程度不同,从大到小依次为:朱蕉>红花檵木>金叶榕。文章设计的半封闭大棚实验方案为植物滞尘效应的长时间可持续性研究提供了新思路。

Hyperspectral remote sensing provides highly efficient,convenient,and non-destructive technical means for the quantitative study of the dust retention content of plants.Based on common greening plants in Guangzhou and hyperspectral remote sensing technology,this study designed a semi-closed greenhouse experiment scheme and explored the spectral characteristics of different plants under dust pollution.The research results show that:1)Dust-retention time is an important factor that affects the accumulated dust retention content of greening plants.The amount of dust retention content increases with time but decreases after reaching saturation.There are differences in the amount and time of saturation of different plants,and the order of saturation of dust retention from large to small is:Cordyline fruticosa(L.)A.Cheval>Loropetalum chinensis(R.Br)Oliv.Var rubrum Yieh>Ficus microcarpa L.f.cv'Golden leaves'.In the specific green vegetation screening,Cordyline fruticosa(L.)A.Cheval can be given priority consideration.2)In the visible wavelengths affected by foliar dust,the spectral reflectance of the leaves increases,with increases in the amount of dust retention;in the near-infrared wavelengths,the spectral reflectance is inversely proportional to the amount of dust retention.3)Dust retention content directly or indirectly affects the spectral characteristics of plant leaves and has nothing to do with the three sides of the plant.The dust retention content is directly proportional to the red valley reflectance and green peak reflectance and has no significant relationship with the red valley and green peak positions.There is a negative correlation between the dust retention content and the Normalized Difference Vegetation Index(NDVI).The NDVI values of different plants are affected by dust retention content to varying degrees;in order from large to small,these are:Cordyline fruticosa(L.)A.Cheval>Loropetalum chinensis(R.Br)Oliv.Var rubrum Yieh>Ficus microcarpa L.f.cv'Golden leaves'.The model established by the NDVI and dust retention content can quickly and non-destructively evaluate the dust retention capability of plants,which can provide a scientific basis for urban air quality monitoring.The experimental scheme of the semi-enclosed greenhouse designed in this study provides a new idea for the long-term sustainability study of the dust retention effect of plants.Furthermore,the dust retention effect of plants differs according to their environments,requiring further research.Important future research areas include the inversion band selection of spectral estimation models,the construction of high-precision spectral estimation models,the influence of different plant species on spectral estimation models,and the inversion of dust retention on a large area scale by combining spectral estimation models of dust retention content with the remote sensing images of hyperspectral UAV,satellite,etc.