Yield prediction for mixed species stands in boreal Ontario

Abstract

Wood supply of the major industrial species groups (spruce–pine–fir [Picea–Pinus–Abies spp.] and poplar [Populus spp.]) in the boreal forest of Ontario is forecast to fall below demand in the relatively near future. This has lead to more interest in the growth and yield of mixedwood forests. Mixedwood stands are defined for forest management planning as stands in which 26% to 75% of the canopy is softwood. With an average growth rate one-third higher than the average for all forest types combined, mixed species stands have potential to mitigate some of the shortfalls. This paper reviews the history of yield curve development in Ontario and some of the current initiatives in mixedwood modeling. The Forestry Research Partnership, a partnership between Tembec, the Ontario Ministry of Natural Resources, the Canadian Forest Service, and the Canadian Ecology Centre, was formed in 1999. One of the first projects of the Partnership was to update the provincial yield curves. These updated curves provide good estimates of yield for mixedwoods on upland, drier sites but mixedwoods on moister sites need to be further stratified by leading species. Mid-rotation activities such as density regulation and partial harvesting in the selection or shelterwood silvicultural systems are generally tree-level activities. These are more compatible with tree-level models. Ontario is calibrating the Forest Vegetation Simulator (FVS) for use in Ontario and this shows particular promise in mixedwood modeling. Key words: mixedwood growth, yield tables, FVS