Monitoring plant response to phenanthrene using the red edge of canopy hyperspectral reflectance

- Potential and mechanism for remote sensing of polluted vegetation was demonstrated.
- A flattened red edge was observed under phenanthrene pollution.
- Spectral changes were not related to leaf photosynthetic pigment concentrations.
- Spectral changes were related to aboveground biomass and canopy pigments density.
- Field validation was vital to correctly interpret the data of remote sensing.

To investigate the mechanisms and potential for the remote sensing of phenanthrene-induced vegetation stress, we measured field canopy spectra, and associated plant and soil parameters in the field controlled experiment in the Yellow River Delta of China. Two widely distributed plant communities, separately dominated by reed (Phragmites australis) and glaucous seepweed (Suaeda salsa), were treated with different doses of phenanthrene. The canopy spectral changes of plant community resulted from the decreases of biomass and foliar projective coverage, while leaf photosynthetic pigment concentrations showed no significance difference among treatments. The spectral response to phenanthrene included a flattened red edge, with decreased first derivative of reflectance. The red edge slope and area consistently responded to phenanthrene, showing a strong relationship with aboveground biomass, coverage and canopy pigments density. These results suggest the potential of remote sensing and the importance of field validation to correctly interpret the causes of the spectral changes.

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