Digital image measurement of the area and anatomical structure of tree rings

A microcomputer coupled to a video digitizer was used to develop methods for measuring areas of tree rings and for delineating and measuring microscopic anatomical features. Digitally imaged areas of individual rings of a loblolly pine cross section were within 2.6% of areas measured with a planimeter and were more accurate than areas calculated from radius widths. Various anatomical features were "mapped" within digitized images of consecutive rings, individual rings, and highly magnified parts of the rings of green ash. Fibers within various ring zones, including those known to have formed when trees were flooded, were readily differentiated on the basis of image brightness. The image-determined ratio of lumen to wall material within different groups of fibers was considered a measure of structural comparability. These techniques thus provide a rapid, accurate method to study relationships between tree rings and factors affecting their development. Methods could be improved by increasing both spatial and brightness resolution.