Mapping Sawgrass Densities in the Florida Everglades Using Spectral Data and Digital Multispectral Video.
Abstract
Changes in vegetation distribution patterns within the Florida Everglades have been documented by many researchers. Competition between native and invasive species are mainly due to altered hydrologic regimes and nutrient fluxes fostered by agriculture and urbanization. The eutrophication of many areas in the Everglades is blamed for the success of Typha spp. (L.) where it Outcompetes the native C. jamaicense (C.). Plant composition and density have been shown to affect surface flow, prolonging retention times for nutrients. Hydrologically, the sheet flow in the Everglades is interrupted by plant material occupying a shallow water column. Presently, efforts are being made to develop vegetation resistance-to-flow models that will predict flow rates based upon vegetation density. This paper describes the derivation of plant density from digital multispectral videography (DMSV) for the purpose of large-scale vegetation modeling. Seasonal sampling is being conducted at quadrats established in the Everglades representing different densities of sawgrass. Non-imaging spectral measurements are also being collected to characterize plant communities as well as calibrate imagery data sets. Early results show biomass correlates with near IR imagery reflectance (r = 0.72). However, stronger correlations (r = 0.77) between biomass and reflectance occurred for sampling periods when the water level was at its lowest. Furthermore, change analysis between wet and dry season images showed a >20 percent difference in vegetation available to the DMSV field-of-view. These results indicate that characterization of vegetation density is more effective at lower water levels.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 1997
- Accession Number
- ADA355124
Entities
People
- D. R. Morgan
- Greg Desmond
- J. E. Anderson