Nonparametric estimation of stand volume using spectral and spatial features of aerial photographs and old inventory data

Abstract

The forest management planning inventories for private forests in Finland are currently carried out in stand-level field inventories. To decrease the amount of fieldwork, aerial photographs and old inventory data could be utilized. The main objectives were to test the accuracy of a method based on these data sources and the effect of stand shape on the accuracy. Median pixel values, semivariances, and old inventory data were extracted for each of the 577 stands in the study. These data were applied as indicator attributes in k-nearest-neighbor estimation of stand volume. Stand-level estimates were computed as weighted means of k most similar neighbors. When all the stands were used, a root mean square error of 29.9% was obtained. Old inventory data proved to be valuable auxiliary information. It was also found that exclusion of stands with tortuous boundaries and small area decreased the error. The accuracy of mean volume estimation just met the requirements for stand-level inventory, but the method still needs further research before the final conclusion of the applicability for management planning.