Estimation Modelling of Nitrogen Content of Wetland Plants in Dian-chi Lake Basin Using Hyperspectral Technology
The study area is Dianchi Lake Basin,the spectral reflectance of 4 typical wetland plants,includ-ing Phragmites australis,Zizania latifolia,Typha orientalis and Cyperus involucratus,was acquired by S-R3500 spectrometer,nitrogen content of wetland plant leaves was determined by model A3 3 of continuous flow analytic-al instrument,the most sensitive spectral bands and spectral transformation formal parameters in leaves of 4 wet-land plants with nitrogen contents were selected,and the nitrogen contents estimation models of wetland plants were established with hyperspectral data.The results revealed that the spectral curves of 4 wetland plants were consistent with those of the healthy green plants,there are differences in the wavelength of 800-1350 nm and 1650-1 800 nm,the spectral characteristics of 4 wetland plants can be more highlighted through transformation of spectral includ first-order differential,second-order differential and"three-edge"parameters;the highest absolute correlation coefficient between wavelength and nitrogen content is found in the second-order differential band spectrum of P.australis(1,836nm),the first-order differential band spectrum of Z.latifolia(1264 nm),the second-order differential band spectrum of T.orientalis(881 nm),the second-order differential band spectrum of C.invol-ucratus(1 665 nm).The correlation of the"three-edge"parameters that ratio of red-edge and blue-edge area and the normalized value of red-edge and blue-edge area of Z.latifolia,the red-edge amplitude,red-edge area,the ra-tio of"green peak"and"red valley"reflectance and ratio of red-edge area and blue-edge area of T.orientalis with the nitrogen contents were the largest and significantly correlated(P＜0.01);the accuracy of nitrogen content es-timation models of wetland plant leaves based on spectral second-order differentiation was higher than that of first-order differentiation,the nitrogen content estimation models based on the"three-edge"of the spectral para-meters had the highest accuracy and the least error;the estimation results for nitrogen content based on"three-edge"parameters of 4 wetland plants are good using a multiple stepwise regression estimation model.The estima-tion models techniques of wetland plants of nutrient contents based on hyperspectral technology can rapidly mon-itor the spatio-temporal dynamic changes of nutrient contents of large-scale wetland plants in a long time series,providing basic data and technical support for remote management of wetland plants.
Dianchihyperspectrawetland plantnitrogen contentestimation model
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