Adapting Finnish multi-source forest inventory techniques to the New Zealand preharvest inventory

To measure many small areas in a forest, each to the required detail and pr ecision, and sufficiently frequently, is too expensive using ground-based i nventories alone. The Finnish satellite image-aided National Forest Invento ry (NFI) method was modified and tested with a View to developing a new pre harvesting forest inventory method for assessing the volumes of potential t imber assortments (log products) in New Zealand radiata pine (Pinus radiata D. Don) plantations. Data from 188 ground plots were supplied by a forest company for a 1000 ha block of radiata pine. This material was combined wit h known stand boundaries from maps and data from a Landsat TM image in orde r to predict for each pixel and each stand the pruned and unpruned sawlog, pulp and total standing volumes. A k-nearest neighbour algorithm was applie d for the estimation. Some stand characteristics, obtained from stand histo ries, were used as co-variates. in addition to spectral features. Cross-val idation tests indicated that estimates of plot variables were unbiased, tho ugh with high RMSEs. Stand level estimates were also unbiased on average, b ut showed high RMSEs. Research into the effects of stratification and metho ds by which to segment stands into sub-areas uniform with respect to timber assortments is continuing.