Ontario's forest growth and yield modelling program: Advances resulting from the Forestry Research Partnership
The province of Ontario holds approximately 70.2 million hectares of forests: about 17% of Canada's and 2% of the world's forests. Approximately 21 million hectares are managed as commercial forests, with an annual harvest in the early part of the decade approaching 200 000 ha. Yield tables developed by Walter Plonski in the 1950s provide the basis for most wood supply calculations and growth projections in Ontario. However, due to changes in legislation, policy, and the plan ning process, they no longer fully meet the needs of resource managers. Furthermore, Plonskis tables are not appropri ate for the range of silvicultural options now practised in Ontario. In October 1999, the Canadian Ecology Centre Forestry Research Partnership (CEC FRP) was formed and initiated a series of projects that collectively aimed at characterizing, quantifying and ultimately increasing the economically available wood supply. Comprehensive, defensi ble, and reliable forecasts of forest growth and yield were identified as key knowledge gaps. The CEC FRP, with support from the broader science community and forest industry, initiated several new research activities to address these needs, the results of which are outlined briefly in this paper. We describe new stand level models (e.g. benchmark yield curves, FVS Ontario stand density management diagrams) that were developed using data collected from permanent sample plots and permanent growth plots established and remeasured during the past 5 decades. Similarly, we discuss new height diameter equations developed for 8 major commercial tree species that specifically account for stand density. As well, we introduce a CEC FRP supported project aimed at developing new taper equations for plantation grown jack pine and black spruce trees established at varying densities. Furthermore, we provide an overview of various projects under taken to explore measures of site productivity. Available growth intercept and site index equations are being evaluated and new equations are being developed for major commercial tree species as needed. We illustrate how these efforts are advancing Ontario's growth and yield program and supporting the CEC FRP in achieving its objective of increasing the supply of fibre by 10% in 10 years while maintaining forest sustainability.