Describing prairie C4 plant species area coverage using hyperspectral reflectance

Abstract

ABSTRACTC3 and C4 photosynthesis pathways represent fundamental differences in vegetation characteristics and physiology. Spectral reflectance collected on the ground and from satellite successfully described the fraction of C4 species coverage in the Konza Prairie Long-Term Ecological Reserve (LTER) which supports a grassland made up of mixtures of C3 and C4 plants. Plant species area coverage was measured within the LTER and also at study sites of the First International Land Surface Climatology Project Field Experiment (FIFE) in 1987. Ground-measured visible-near infrared (VNIR) spectral reflectances were collected in FIFE and from a 2015 Hyperion spectrometer image from the Earth Observing 1 (EO-1) satellite.Partial least squares regression (PLSR) successfully described C4 cover fraction from the FIFE ground VNIR reflectances (R2 = 0.75). Convolving the bands to 10-nm Hyperion spectral bands decreased the accuracy of the retrievals (R2 = 0.43). PLSR applied to Hyperion reflectances extracted for the LTER watersheds was also successful describing C4 cover fraction for the VNIR Hyperion bands (R2 = 0.89), but showed little improvement when the shortwave infrared bands were included (R2 = 0.92). The coefficients from the FIFE data convolved to VNIR Hyperion bands are similar to the coefficients derived from the Hyperion data, suggesting this approach works over a range of conditions and spatial scales.