民勤10种典型荒漠植物冠层光谱与含水率的特征分析

Analysis of the canopy spectrum and water content of desert plants

植物体内水分是影响植物光合作用、呼吸作用、生物量及其他生理生化指标的主要因素之一,植物含水率的调查是植被研究的重要内容,利用高光谱进行典型荒漠植物含水率与冠层光谱的关系研究对荒漠区植被遥感监测具有重要意义。本研究借助ASD便携地物光谱仪实地测定了10种典型荒漠植物的冠层光谱曲线,并采用相关系数法和植被指数法,分析了不同荒漠植物光谱特征及其与冠层含水率的关系,结果显示:1)荒漠植物反射光谱曲线具有绿色植物在可见光-近红外波段的普遍特征,有明显的"绿峰"特征和"红边效应"。2)在954-973,1 184-1 198和1 440-1462 nm三个波段,荒漠植物存在明显的水分吸收谷。其中,1 440-1 462 nm波段的光谱反射率与含水率相关系数大于0.8,二者具有很强的线性相关性。3)WBI(Water Band Index)、NDWI(Normalized Difference Water Index)、NDII(Normalized Difference Infrared Infrared Index)、MSI(Moisture Stress Index)与植物含水率显著相关(P<0.05),冠层水分含量指数与植被水分实测值具有较高的一致性,可以反映荒漠植被含水率变化。

Plant water is one of the main factors affecting plant photosynthesis,respiration,biomass,and other physiological and biochemical indices. Investigation of the water content of plants is an important part in vegetation research.Study of the relationship between water content and canopy spectrum of typical desert plants is of considerable significance to remote sensing monitoring of vegetation in desert areas. In this study,the canopy spectral curves of 10 desert plants were determined using ASD portable terrestrial spectrometers. Correlation coefficient and vegetation index methods were used to analyze the spectral characteristics of different desert plants and their relationship with canopy water content. The following results were obtained,1) The reflectance spectrum of desert plants had the general characteristics of green plants in the visible-near infrared band,and had an obvious "green peak"and "red-edge effect. "2) The three bands of 954-973,1 184-1 198,and 1 440-1 462 nm showed an obvious water absorption valley in desert plants.In the 1440-1462 nm band,the spectral reflectance and water content correlation coefficient is greater than 0. 8,and the two parameters showed a strong linear correlation. 3) There was significant correlations between water band index,normalized difference water index,normalized difference infrared index,moisture stress index,and plant water content( P < 0. 05),and the canopy water content index was consistent with the measured value of vegetation water,which could reflect changes in the water content of desert vegetation.