USING GEOGRAPHICAL INFORMATION-SYSTEMS (GIS) AND LARGE-AREA DATABASESTO PREDICT YIELD CLASS - A STUDY OF SITKA SPRUCE IN WALES

A geographic information system (GIS) is used to combine and analyse d ata from a variety of existing large area databases concerning tree gr owth, plantation management and the environmental characteristics of p lanted sites. Principal component analysis and regression techniques a re employed to estimate a number of Yield Class models for Sitka spruc e (Picea sitchensis (Bong). Carr.). The GIS is used to extrapolate res ults and generate maps of predicted yield for a large study area (the entirety of Wales). The resulting methodology produces well fitting mo dels of timber yield which compare favourably with those reported in t he literature while the GIS generated maps are readily compatible with those currently under construction by various UK forestry authorities in order to plan for a proposed increase in afforested land.