The potential for using data collected in the first four bands of the proposed thematic mapper for monitoring intertidal salt marsh vegetation is assessed, using ground spectral data collected with a portable multiband radiometer. Results from a field study in Chichester Harbour, Southern England, show that certain species can be separated using transformations of these data. The estimation of above ground biomass from ground spectral data was not possible forSpartina × townsendii agg., due to the combined effects of mixtures of different substrate types and mixtures of live and dead vegetation within the field of view of the radiometer. However, biomass estimation was possible for bothZostera marina L. andFucus vesiculosus L. The relationships between biomass and bidirectional reflectance for these species followed a similar pattern, despiteFucus vesiculosushaving carotenoids rather than chlorophylls as the dominant leaf pigments.