The Study on Fresh Biomass Estimation of Zizania latifolia Based on Different Spectral Transformations of Spectral Reflectance

The reflectance spectrum were collected and fresh biomass were measured for Zizania latifolia in situ of Jianhu Wetland, and the analysis of reflectance spectral for Z. latifolia based on 24 spectral transformations. Then establishment of the fresh biomass estimation models based on the characteristic bands selection were sensitive to biomass on analysis of the full bands (350−2 350 nm) of 16 spectral transformations. The results showed that spectral characteristics can be more easily analyzed by the different spectral transformation. The visible band characteristics was enhanced by logarithmic reciprocal and reciprocal transformation. The near infrared band characteristics was enhanced by first-order derivative of logarithmic reciprocal transformation. The short-wave infrared band characteristics was enhanced by second-order derivatives of reciprocal and second-order derivative of logarithmic reciprocal. And 4−5 scale continuous wavelet transformation were suitable for the original spectral characteristics analyzing. The highest correlation coefficient of 0.734 after continuous wavelet transformation, and followed second-order derivative transformation with the highest correlation coefficient of −0.730 in all spectral transformations. The best effective model on estimating fresh biomass of Z. latifolia was multivariate regression model based on second-order derivative of cubic root transformation, R², RMSE, P and RPD were 0.88, 1 044.90 g/m², 83.95% and 2.64, respectively.