Where timber production is the primary management objective, knowledge of the relationship between the potential productivity of candidate tree species and levels of light, heat, nutrient, moisture and aeration is necessary for species- and site-specific decision making. For example, foresters need to decide which tree species to regenerate on a particular harvested area to obtain maximum sustainable productivity. Similarily, when considering the application of silvicultural treatments such as spacing or fertilizing, foresters need to determine whether the potential productivity of a particular site warrants the cost of the treatment. We used the site index (height of dominant trees at breast height age) of western redcedar (Thuja plicata Donn. ex D. Don.) as a measure of productivity, and described the pattern of mean site index in relation to field identified soil moisure and soil nutrient regimes.

One of the key factors in the site classification of the biogeoclimatic ecosystem classification is soil nutrient regime. Soil nutrient regime (SNR) represents the amount of essential soil nutrients available to plants over a period of several years. SNRs classes are assessed based on field identifiable (qualitative) criteria, not using quantitative measures. There have been several studies that attempted to quantitatively characterize regional soil nutrient gradients in the Coastal Western Hemlock (CWH) zone. In the study summarized here, the soils are influenced by a perhumid cool mesothermal climate. The objective of the study was to examine relationships between soil chemical properties and field-estimated SNRs.