Different methods based on optimal hyperspectral bands for estimation of
aboveground plant biomass in alpine grassland ecosystems in the
Qinghai-Tibetan Plateau
Abstract
Hyperspectral technology has received great attention for estimating
aboveground plant biomass. Corrections using ground spectrometer data
have been proposed for more accurate integrated assessments of
aboveground plant biomass. In this study, we sampled the aboveground
plant biomass and the corresponding hyperspectral data from three types
of alpine grassland ecosystems (alpine desert, alpine steppe, and alpine
meadow) from the Qinghai-Tibetan Plateau to improve the biomass
estimation accuracy. We used partial least squares regression and the
vegetation indices (VIs) (using all two-band combinations
(601*601combinations in all) involving 601 narrow bands between 400nm
and 1000nm), and the optimal band combinations were used to calculate
four most commonly used VIs. We found that the VIs are better than the
least square method for alpine meadow, and that the most effective
combinations were shown in the combinations of reflectance at the red
edge (rather than red) and near-infrared bands(728nm,764nm). For alpine
steppe and alpine desert, however, partial least squares regression is
better than VIs. While the most important band for alpine steppe is
between 600nm and 700nm in the red spectrum, the most important band for
alpine desert is around 400nm. Our results can provide a theoretical
basis for accurately estimating the aboveground plant biomass of
different grassland types in the Qinghai Tibet Plateau.