A programmed computer system estimates the age of trees from a number of remotely sensed images of an area of interest. Vegetation Index (V.I.) values are determined for pixel locations in the number of images. The V.I. values are analyzed to find a V.I. value that correlates with a known age of a tree. Once the date of the image that produced the V.I. value is known, the current age of the trees that correspond to the pixel location is determined.