The Use of Aerial Color Infrared Photography in Mapping the Vegetation of a Freshwater Marsh

Abstract

Spring and fall vegetation maps were prepared from a freshwater marsh on the Patuxent River, Marlyland. Low altitude, color infrared (IR) aerial photos were correlated with data obtained from field surveys. The vegetation units mapped refer to areas of homogeneous color on the photos. These areas of homogeneous color represent species associations or monospecific stands which produce a distinctive tonal signature. Color fluctuations within an area having a distinctive tonal signature are primarily caused by a quantitative variation of plant species but are also related to the growth habit, vigor of the plant species, and environmental conditions which affect the vegetation and in turn the color of the recorded image. Changes in the color over the growing season reflect plant succession, and vegetative decline. Tonal signatures of several plant association were due to their unique colors, saturations, and textures, Comparison of photographs made in nearby marshes demonstrated that three of the twelve spring and five of the fourteen fall vegetation units that were mapped can be reliably identified.