D8ING AM AIRBORNE LASER TO MEASURE VEGETATION PROPERTIES

A laser altimeter mounted in a twin-engine airplane: was used to measure surface patterns on the landscape of! Walnut Gulch Watershed near Tombstone, Arizona. The j airborne laser altimeter is a pulsed gallium-arsenide diode laser, transmitting and receiving 4,000 pulses per second at a wavelength of 0.904 Jim. The laser has a 1 mrad field-of-view and is designed to have a vertical recording accuracy of 0.05 m on a single measurement. Aircraft altitude was between 100 and 300 m for the flights. Digital data from the laser are collected with a portable computer and analyzed to provide information,on surface features of the landscape. Changes in landscape topography and vegetation patterns were measured with the laser data. Vegetation height, spatial patterns, and patchiness of vegetation cover were measured. Laser measured vegetation properties were significantly related with field measurement made using line-transect methods. These studies demonstrate the potential of airborne laser data to measure landscape patterns of large areas quickly and quantitatively. Rapid methods of determining canopy height and cover are valuable for understanding vegetation patterns and characteristics, improving estimates of infiltration, erosion, and evapotranspiration, and making decisions for managing our natural resources