Mapping avian habitat characteristics using cloud-cleared satellite image mosaics
Forest age, vertical structure, disturbance history, and tree species composition affect bird habitat. For studies of wintering habitat for the endangered Kirtland's Warbler, scientists from the Forest Service, Colorado State University, and other collaborators showed for the first time that forest vertical structure can be mapped with a time series of satellite imagery. They mapped forest height, height variance, and foliage height profiles on the island of Eleuthera, The Bahamas. They also provided the first example of simultaneously mapping forest age and disturbance type with an image time series in which the each time step in the image sequence is a mosaic of the cloud-free parts of many scenes. The types of imagery that this study used are widely and freely available, including Landsat imagery dated from 1984 to 2002 and Advanced Land Imagery (ALI) data from around 2005. The entire time series of images was critical to accurately mapping forest vertical structure. After forest disturbance the spectral responses of developing forests change as they grow taller and denser. Consequently, the scientists determined that the pattern of spectral responses over time was related to forest height. The information proved invaluable for characterizing this species' wintering habitat and for providing the first estimates of forest disturbance rates by disturbance type.
Forest Service Partners