Abstract: The canopy reflectance and Chl-a concentration of Calamagrostis angustifolia grown under the conditions of different vegetation coverage and water depth were measured with ASD spectroradiometer. Hyperspectral visible light-near infrared bands and their derivative spectral bands (350-1 050 mm) were adopted to construct the vegetation indices FNDVI, FRVI, FDVI, FDNDVI, FDRVI and FDDVI one by one, search after the best band for each vegetation index which had the best correlation with Chl-a, and establish the optimum estimation models for the Chl-a concentration of C. angustifolia. The comparison of the prediction precision between optimum estimation models and linear models showed that the prediction precision of the best forecasting models (FDNDVI, FDRVI and FDDVI) for derivative spectral vegetation indices and Chl-a was respectively 6.86%, 4.82% and 10.10% higher than that of the optimum reflectance vegetation index models (FNDVI, FRVI and FDVI). Vegetation indices (FNDVI, FDVI, FDNDVI, FDRVI) had a great linear relationship with Chl-a, and the prediction precision of the optimum estimation models were only increased by 0.60%, 1.40%, 1.02% and 0.93%, respectively than the linear models, suggesting that the simple linear models could be used to retrieve the Chl-a concentration of C. angustifolia in wetland.

Key words: Chongqing, Ecological footprint, Available ecological capacity