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 amplitude between different types of natural land cover. However, there is frequently a large amount of information to be found in the textural properties of such imagery, especially when it is acquired at high spatial resolution. This textural information may be useful in observing processes 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 homogeneity as regrowth species are succeeded by hardwood species. In this study, three techniques of measuring the texture in C-band airborne SAR imagery from a tropical forest region in central Brazil are compared. The dependence of these measures on the stage of forest regeneration is assessed by using a temporal sequence of Landsat;TM imagery to independently estimate the age of regrowth. Each texture measure is able to discriminate well between mature forest and other classes of vegetation where the image amplitude alone cannot be used to make the same distinction. Further discrimination between different ages of regrowth appears possible but is difficult to demonstrate quantitatively because a satisfactory validation of regeneration age is difficult to achieve.