Author Description

Site index is the measure of a given tree species' productivity. Relationships between site index & ecological site quality have been the focus of recent research efforts in British Columbia that have used categorical measures of ecological site quality to explain the variation in site index of major tree species. This report describes a study that expands these efforts to lodgepole pine & interior spruce. To establish a link between ecological site quality & forest productivity in the sub-boreal spruce zone of the Prince Rupert Forest Region, site index & site data were obtained from 93 lodgepole pine stands and 77 interior spruce stands distributed across two climatic regimes, eight soil moisture regimes, and five soil nutrient regimes. These regimes were used as categorical variables to stratify the stands and in the subsequent regression analysis of the data. Six types of regression models were developed and one model, which showed strong relationships between site index & some ecological parameters, was used to draft site index isolines which were then superimposed onto edatopic grids. The results test the capability of estimates of soil moisture & soil nutrient regimes as predictors of pine & spruce site index.