Automatic segmentation of forest stands using a canopy height model and aerial photography

Forest management planning is based on stand-level information. The stands are typically visually delineated based on aerial photographs. Because of visual interpretation, the estimation of stand boundaries is always subjective. Moreover, there are no definite criteria for the delineation. For one forest area, several different solutions could be obtained. Automated segmentation of digital imagery offers a possible solution to these problems, by producing more objective delineation, reducing time and costs, and increasing consistency of stand delineation. The aim of this study was to evaluate the applicability of a canopy height model (CHM) in automatic segmentation of forest stands. In addition, the mosaic produced with CHM was compared with one that was produced automatically using an aerial photograph (RGB). The usefulness of combining CHM and an aerial photograph in the automatic segmentation process was also examined. The results showed that delineation based on CHM is a good option compared with aerial photographs, when aiming for homogeneity of the delineated stands. The explained proportion of the whole variability of mean diameter was 74% and of mean height 83% in the CHM mosaic, compared with 65% and 73% in the RGB mosaic, and 60% and 73% in the reference. However, a visual interpreter was able to produce delineation almost as homogeneous as the reference with respect to volume, and better with respect to mean diameter and height.