The growth of Abies amabilis (Dougl. ex Forbes) in relation to climate and soils in southwestern British Columbia.

摘要

To provide comprehensive and coherent information on productivity and on the factors that constrain growth of mature trees, I studied the growth of amabilis fir (Abies amabilis) across the native range of the species in southern coastal British Columbia in five relatively independent studies.; I developed conventional polymorphic and climate-specific height growth and site index models for amabilis fir from stem analysis data obtained from 67 study plots, which were deliberately chosen to represent the largest variation in climate and soil conditions across the study area.; To quantify the gradient of plant available nutrients on high-elevation sites, samples were collected of forest floor and mineral soil (0 to 30 cm) from montane and subalpine sites across a continentality gradient. Using discriminant analysis 70% agreement was found between field-identified SNRs and the classification based on measured (chemical) soil properties. Nitrogen-related variables (total N, mineralizable-N, and C:N ratio) and the sum of extractable Ca, Mg, and K were the properties most strongly related to the field-identified SNRs.; A dendroecological approach was used to identify climatic factors that limit radial growth of amabilis fir at high-elevation sites in the study area. I developed 11 residual ring-width chronologies and 3 residual maximum density chronologies from stands on intermediate sites located along a continentality gradient. According to principal components, correlation, and pointer-year analyses, three types of growth responses to year-to-year variations in climate were associated with a strong regional ring-width pattern: (i) a negative response to April 1st snow depth, (ii) a positive response to July temperature of the current year, and (iii) a negative response to summer temperature of the previous year.; To determine the influence of elevation, continentality of climate, soil, and seasonal weather patterns on 9 tree-ring properties, I utilized dbh-discs from three dominant trees sampled at 62 stem analysis plots (Studies 1 and 5). The widths of earlywood and latewood as well as total ring width decreased significantly with increasing elevation.; To provide quantitative information about the influence of the environment on amabilis fir growth, I examined relationships between continentality strata, orographic strata, elevation, soil moisture regime, and soil nutrient regime with site index and the diameter at breast height (1.3 m) at 30 years (D30). On zonal sites, site index decreased by 1.9 m every 100m increase in elevation in the maritime windward stratum, by 2.7 m in the maritime leeward stratum, and by 0.8 m in the submaritime/subcontinental stratum. (Abstract shortened by UMI.)