Date of Award

1994

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Plant, Enviromental and Soil Sciences

First Advisor

Wayne H. Hudnall

Abstract

Much of the traditionally used remotely sensed data is surface-oriented, which places some limits on its utility in wetland soil studies. In wetland environments the sediment surface is often obscured by vegetation and/or by water making the soil difficult to view. This study examines the possible utility of remotely sensed data from selected regions of the EM spectrum for wetland soil and gas flux studies. The visible, near-infrared, mid-infrared, thermal, and microwave regions (all mostly surface-oriented); and the ground penetrating radar (VLF) and inductive EM (ULF) regions (mostly subsurface-oriented) were investigated and example wetland soil applications demonstrated. Study sites ranged from a subarctic peatland to temperate coastal wetlands to the subtropical Florida Everglades. All the spectral regions studied helped characterize the water component. The surface-oriented regions aided in determining water inundation extent, and the inductive EM region determined water depth and conductivity (useful in salinity calculations). The reflective and thermal data provided good information for generalized vegetation maps, while the microwave region helped characterize canopy structure, both useful in gas flux extrapolation. The ground penetrating radar characterized peat depth and internal peat stratification in a resistive environment over a conductive clay. This investigation identified remote sensing utility for paleoecological evaluations and for the potential of mapping peat volumes when merged with landcover classification. The airborne inductive EM investigation calculated sediment conductivity, which could be used to differentiate organic from mineral sediments and fine-textured from coarse-textured sediments. Anomalies in sediment porosity, implicative of gas evolution, were also noted. Regional scale contour maps of water depth, water conductivity and sediment conductivity were generated from the EM data transects. While wetland soils cannot be characterized directly by the reflective, thermal and microwave regions of the spectrum, these regions can provide much information about vegetative and wetness conditions of the soil which can be used indirectly to infer certain soil properties. The lower spectral frequencies provide penetration capabilities for more direct characterization of subsurface properties and conditions. Incorporating ancillary data in a GIS will aid in wetland soil and gas flux research and applications.

Pages

234

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