Spectral and spatial variation at leaf and patch scale of invasive wetland weeds

The establishment of invasive weeds in wetland environments is a prominent threat in Australia with adverse impacts on native flora. Current management is hindered by the lack of information available on which to base and justify management interventions, in particular, mapping of weed distributions. Remote sensing is a possible solution to difficulties of this type as illustrated by its successful application to wetland mapping in general. This paper explores the potential of multiscale spectral reflectance to discriminate between two particularly offensive, invasive woody weeds, bitou bush (Chrysanthemoides monilifera ssp rotundata), and lantana (Lantana camara). Spectral reflectance at the leaf and patch-level scales was measured at multiple sites using a field spectrometer. Derivative analyses of spectra as well as t-tests were used to evaluate spectral separability between species across scales. Results suggest further analysis is warranted at the patch level where species are intermixed and structural factors more complex.