Potential of Sentinel-2 spectral configuration to assess rangeland quality
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Society of Photo-optical Instrumentation Engineers (SPIE)
Abstract
Sentinel-2 is intended to improve vegetation assessment at local to global scales.
Today, estimation of leaf nitrogen (N) as an indicator of rangeland quality is possible using
hyperspectral systems. However, few studies based on commercial imageries have shown a
potential of the red-edge band to accurately predict leaf N at the broad landscape scale. We
intend to investigate the utility of Sentinel-2 for estimating leaf N concentration in the African
savanna. Grass canopy reflectance was measured using the analytical spectral device (ASD) in
concert with leaf sample collections for leaf N chemical analysis. ASD reflectance data were
resampled to the spectral bands of Sentinel-2 using published spectral response functions.
Random forest (RF), partial least square regression (PLSR), and stepwise multiple linear regression
(SMLR) were used to predict leaf N using all 13 bands. Using leave-one-out cross validation,
the RF model explained 90% of leaf N variation, with a root mean square error of 0.04
(6% of the mean), which is higher than that of PLSR and SMLR. Using RF, spectral bands
centered at 705 nm (red edge) and two shortwave infrared bands centered at 2190 and 1610 nm
were found to be the most important bands in predicting leaf N.
Description
Keywords
Sentinel-2, Leaf nitrogen, WorldView-2, RapidEye, Red-edge band, Random forest
Sustainable Development Goals
Citation
Ramoelo, A, Cho, M, Mathieu, R & Skidmoree, AK 2015, 'Potential of Sentinel-2 spectral configuration to assess rangeland quality', Journal of Applied Remote Sensing, vol. 9, pp. 094096-1-11.