Evaluation of field-measured vertical obscuration and full waveform lidar to assess salt marsh vegetation biophysical parameters

Local, high-resolution, accurate data sets are needed to support restoration and other management initiatives in coastal salt marshes, yet field collections of site-specific vegetation data is often impractical. In this study, a novel combination of full-waveform light detection and ranging (lidar) and field techniques for assessing the distribution of aboveground biomass throughout its height and its light blocking properties were investigated. Using new field methods, strong correlations were observed (r > 0.9) between subsamples' vertical biomass (VB), the distribution of vegetation biomass by height, and vertical obscuration (VO), the measure of the vertical distribution of the ratio of vegetation to airspace, for Spartina alterniflora. Also, it was found that simple metrics derived from the lidar waveforms, such as waveform width, can provide new information to estimate salt marsh vegetation parameters. The strong correlations between field-collected biophysical parameters and metrics derived from lidar data suggest that remote sensing methods can be used to estimate some vegetation biophysical parameters such as plant height and proportion of vegetation area (PVA) using smaller, more targeted field surveys. Future work will be needed to verify the extensibility of the methods to other sites and vegetation types.