Agricultural and Forestry Experiment Station (AFES) Theses
SITE INDEX OF PAPER BIRCH IN ALASKAHeight growth patterns and site index were developed using stem analysis of four dominant or codominant trees from 64 plots located in 50 year-old plus, natural, fully stocked, even-aged stands of paper birch (Betula papyrifera Marsh.) in Interior and Southcentral Alaska. Observed height-over-age data were modeled using the Chapman-Richards nonlinear growth model. Plots were grouped into five site quality classes based on tree height at breast-height age of 50 years. Polymorphic site index curves were developed from the data. The families of curves indicate different height growth patterns (polymorphism). Comparison of existing Alaskan anamorphic site index curves with the polymorphic site index curves developed in this study demonstrates differences in predicted heights at different levels of site quality. The polymorphic site index curves developed in this study should replace existing anamorphic curves since they represent a more accurate pattern of height growth for the range of paper birch in Alaska.
A PATH TOWARD IMPROVED MANAGEMENT OF THE NORTHERN FORESTS OF ALASKA: FOREST INVENTORY, BARK THICKNESS, AND STEM VOLUMEThis thesis provides three essential forest management tools that resource managers and researchers can use to improve management the northern forests of Alaska. The Cooperative Alaska Forest Inventory (CAFI) is a comprehensive database of northern forest conditions and dynamics. The basis for the CAFI database is a system of permanent sample plots located throughout interior and south-central Alaska. This information can be used to develop forest growth models and track long-term forest changes. The bark thickness model was developed because there was no published white spruce bark thickness model for Alaska. The data used to develop this and volume models were taken from stands located throughout interior and south-central Alaska. Analysis shows that this Alaska statewide bark thickness model accuracy estimates white spruce bark thickness when compared to other bark thickness models. Cubic-foot volume models were developed to estimate total stem and merchantable volume of white spruce in Alaska. These multiple-entry (diameter and height) models estimate volume both outside and inside bark. Analysis shows that these volume models were more accurate for Alaska when compared to published and unpublished white spruce models. These models can be used to estimate individual stem volume, volume per unit area, and to develop biomass models.
A CHARACTERIZATION OF MIXED FOREST STANDS IN THE TANANA VALLEY, ALASKAThe objective of this thesis is to define the composition, age structure, volume ranges, and community types present in the Tanana Valley mixed stands. Sixty-six permanent sample plots were established in 22 forest stands located throughout the Valley. Plots were at least 100 feet from a road. Total height, crown height, diameter breast height were measured and health and vigor were assessed for 5,415 trees. Five tree species and 57 herb and shrub species were found. White spruce, birch, and aspen numbers are generally less in mixed stands than predicted for pure stands. Stand density index values, a method of assessing species' use of growing space, ranged from 61 to 422 stems per acre with a mean of 269. Existing individual tree volume tables need revision to avoid negative values for small trees. Existing site index curves for pure stands of lnterior species are inadequate for comparing to mixed stands.