TEXTURE IN AIRBORNE SAR IMAGERY OF TROPICAL FOREST AND ITS RELATIONSHIP TO FOREST REGENERATION STAGE

At C-band, SAR imagery often exhibits little variation in mean amplitu de between different types of natural land cover. However, there is fr equently a large amount of information to be found in the textural pro perties of such imagery, especially when it is acquired at high spatia l resolution. This textural information may be useful in observing pro cesses that affect the homogeneity of land surface vegetation such as the staged succession of regenerating tropical forest following human disturbance which is characterized by the gradual decrease in canopy h omogeneity as regrowth species are succeeded by hardwood species. In t his study, three techniques of measuring the texture in C-band airborn e SAR imagery from a tropical forest region in central Brazil are comp ared. The dependence of these measures on the stage of forest regenera tion is assessed by using a temporal sequence of Landsat;TM imagery to independently estimate the age of regrowth. Each texture measure is a ble to discriminate well between mature forest and other classes of ve getation where the image amplitude alone cannot be used to make the sa me distinction. Further discrimination between different ages of regro wth appears possible but is difficult to demonstrate quantitatively be cause a satisfactory validation of regeneration age is difficult to ac hieve.