Hyperspectral discrimination of sea barley grass and the implications for mapping salinised land

Abstract

Sea barley grass (Hordeum marinum) is considered an important early indicator of emerging soil salinity. Saline areas that have good cover of salt tolerant plants are difficult to map with broadband satellite imagery. Hyperspectral imagery may provide a more reliable salinity mapping method because of its potential to discriminate halophytic plant cover from non-halophytes. In this paper we statistically compare the reflectance spectra of sea barley grass to other annual plant species, to determine whether the sea barley grass has the potential to be discriminated and mapped with hyperspectral imagery. Plant spectra were collected during spring senescence in an attempt to capture the spectral differences between the late senescing sea barley grass and other annual grasses. Multiple reflectance spectra of each species were collected with an ASD Fieldspec Pro spectrometer. The plant spectra were collected at plot scale in the field, and at plant and foliage scale in the laboratory under controlled conditions. Two-group t-tests comparing reflectance of pairs of species at each wavelength showed broad spectral regions where sea barley grass differed significantly from other species for both field and laboratory spectra. The existence of these broad regions of spectral difference suggests that it should be possible to discriminate and map sea barley grass during spring senescence with hyperspectral imagery.