Variable stocking version of Plonski's yield tables formulated

Plonski's yield tables have been used extensively in forest management, economic evaluation, and as a basis for management planning in Ontario. However, because these tables are based on site classes, they are not directly applicable to uneven-aged mixed-wood cover types. A four-parameter nonlinear model was employed to express various stand attributes as a function of stand age and recently developed basal area indices for the major species in Ontario. The resulting variable stocking yield functions will be applicable to even-aged stands as well as the boreal mixedwood. Basal area index proved superior to site index for estimating both merchantable basal area and volume for the James River/Marathon data set representing boreal mixed from Northcentral Ontario. In addition, stand basal area index may be determined easily and inexpensively via horizontal point sampling or prism cruising. Key word: Basal area index, sigmoidal growth curve, variable stocking