Project Definition

Description of AVIRIS Data

Feature Extraction of Hyperspectral Data

Classification Methodology

Classification Results

Conclusion



Project Definition

The research performed for this project consists of the classification of wetland vegetation at the Kennedy Space Center, Florida using hyperspectral imagery. Hyperspectral data were acquired over KSC on March 23, 1996 using JPL's Airborne Visible/Infrared Imaging Spectrometer.


Landsat TM false color composite (Bands 4,3,2) of the Kennedy Space Center

The use of impoundments and other structural marsh management methods within wetlands for mosquito control and other wetland uses at KSC has led to considerable discussion regarding the potential effects on the natural marsh sustaining processes and the emergent marsh vegetation [1]. As a result, many impounded marshes are currently being reconnected with the adjacent estuaries so that they may return to a more natural hydrology. Thus, there is a need to develop a protocol which can quickly and accurately classify and map the distribution of vegetation types within the impoundments using remotely sensed data acquired over a multi-year time horizon.

The increased spectral resolution of hyperspectral imagery shows increased potential for accurately mapping marsh vegetation versus broad-band sensors.

Description of Test Site

The test site for this project consists of a series of impounded estuarine wetlands of the northern Indian River Lagoon (IRL) which reside on the western shore of the Kennedy Space Center. The impoundments, shown in the adjacent figure, were created during the 1950's and 1960's for the purpose of mosquito control.


Map of impounded marshes along the western shore of KSC

The marshes along the IRL contain both high and low marsh communities. The three dominant marsh groups which comprise the high marsh communities are cabbage palm savanna, sand cordgrass, and black rush. The cabbage palm savanna consists of isolated canopies of Cabbage Palm (Sabal palmetto) and a graminoid layer of sand cordgrass (Spartina bakerii ), whereas sand cordgrass marsh is dominated by Spartina bakerii and black rush marsh (Juncus roemerianus) is dominated by Juncus. The low marsh communities are dominated by salt tolerant grasses and halophytes. The primary salt tolerant grass is (Distichilis spicata). Halophytes typically include saltwort(Batis maritima) and glasswort (Salicornia virginica) [2].


Spartina bakerii marsh

The wetland environments also contain other communities. Sea Oxeye (Borrichia frutescens ) can occur as homogeneous patches within both the low and high marsh. Mangroves, Black (Avicennia germinans) and White (Languncularia racemosa), grow in small dense stands typically along the edges of embankments. Mangroves can grow quite tall, but their population is reduced by freezing temperatures. Mud flats, which are also common to the landscape, occur when either excessive flooding or salinity have prevented the growth of vegetation. Saltmarsh cordgrass (Spartina alterniflora) can typically be found along the shoreline of some marshes.

This study also includes investigation of upland vegetation as it is adjacent to the impounded wetlands, so the two units are related hydrologically. In addition, accurate classification and mapping of upland vegetation is important for monitoring habitat of endangered birds. The majority of the upland vegetation at KSC is oak scrub and saw palmetto scrub. Other upland communities include slash pine (Pinus elliottii) and hardwood swamps which are dominated by deciduous trees such as Red Maple (Acer rubrum). Dense hammocks of Cabbage Palm (Sabal palmetto) and Live Oaks (Quercus virginiana) are also common.


Upland Vegetation of Slash Pine with Saw Palmetto understory



Vegetation map of project site

Use of Marsh Management Structures

The creation of mosquito control impoundments during the 1950's has blocked the natural tidal flow between the Indian River Lagoon estuarine system and the wetlands. By flooding the impounded marshes during the breeding season (May through October), the mosquito population can be controlled as they lay their eggs on moist soil rather than standing water. However, research has shown that impounding can cause severe environmental impacts including the degradation of water quality, the elimination of productive marsh vegetation, and the interruption of the free flow of nutrients between the wetlands and the lagoon [3].


Depiction of impounded marsh

The establishment of the impoundments at the Kennedy Space Center has left much of the wetland environment disturbed, as evidenced by the invasion of upland shrubs such as Willow (Salix caroliniana) and Brazilian Pepper (Schinus terebinthifolius). Much of the low salt marsh was replaced by open water or by extensive cattail marshes (Typha domingensis ) where freshwater was used to flood the impoundment [2]. The reduction of productive marsh vegetation has limited the species of fauna which occupy and visit the marshes. For example, many cattail marshes are dominated solely by Typha and have a low value as a feeding habitat for wading birds [2].