LIGHT REFLECTANCE CHARACTERISTICS AND FILM IMAGE RELATIONS AMONG THREE AQUATIC PLANT SPECIES

摘要

Radiometric canopy light reflectance measurements were made on three aquatic plant species in Lake Texana near Edna in southeast Texas. Plant species studied included waterhyacinth (Eichhornia crassipes), American lotus (Nelumbo lutea) and hydrilla (Hydrilla verticillata). Reflectance measurements were made at the visible green (0.52-0.60 μm), visible red (0.63-0.69μm), and near-infrared (NIR) (0.76-0.90μm) wavelengths. Reflectance values differed significantly (P=0.05) among the three species at all three Wavelengths. Differences in reflectance were primarily attributed to variable foliage Coloration and vegetative density; however, the NIR reflectance of hydrilla was also Contributed to by a large percentage of the plant being below the water surface. Color-infrared (CIR) aerial photographs of the three species showed that they could be Readily differentiated. Reflectance measurements were related to the image tonal responses Of the plant species on CIR film.