Thesis (Ph. D.)--University of Washington, 2003. / Includes bibliographical references (leaves 145-160).

Thesis (M.S.)--Humboldt State University, 2009. / Includes bibliographical references (leaves 71-82). Also available via Humboldt Digital Scholar.

published_or_final_version / Botany / Master / Master of Philosophy

published_or_final_version / Zoology / Master / Master of Philosophy

No description available.

Sugar maple foliage litters from fertilized and unfertilized plots on a base-poor site and from a naturally base-rich site were incubated in litterbags of 1 and 3 mm mesh on fertilized and unfertilized plots at the base-poor site. Mass loss of unfertilized litter was slower in fertilized than unfertilized plots, suggesting a negative effect of fertilization on decomposers. Mass loss of fertilized litter was faster than unfertilized litter in the same plots, indicating that changes in litter quality due to fertilization enhanced microbial decomposition. Mass loss was higher in large mesh than in small mesh size bags, suggesting that larger soil fauna played a significant role in litter decomposition. / Potassium appeared to be rapidly leached, whereas Ca and Mg were released at rates more closely related to litter mass loss. Nitrogen was mineralized from N-rich Arboretum litter only; all other litters immobilized N. Release of Ca and Mg was reduced significantly on fertilized plots. Large soil fauna enhanced Ca release, while they delayed N-mineralization in Arboretum litter.

Significant species differences in foliar litter quality have been well-documented but differences within species, as a function of variation in genotype or environment, have not been directly addressed and, thus, remain poorly understood. We studied the significance of genetics, the environment, and their interaction in regulating forest nutrient dynamics and productivity using trees from four full-sib black spruce (Picea mariana (Mill.) B.S.P.) families of a complete 7 x 7 diallel cross experiment at the Petawawa National Forestry Institute (Chalk River, Ontario). Foliar litter composites from each family-plot on two sites of contrasting water availability were collected in October, 1993, and sub-samples were analyzed for initial N, P, K, Ca, Mg, cellulose and lignin concentrations. Inherent decomposition rates and nutrient dynamics of the litter composites were followed for one year. Samples of forest floor and mineral soil collected from within each plot were used to determine organic matter accumulation, pH, total nutrient contents in the forest floor and extractable nutrient concentrations in the mineral soil. Height, dbh, and total tree cubic volume, were used to characterize tree productivity. (Abstract shortened by UMI.)

The objective of this study was to assess tree species influence on forest floor fertility in a mixed forest stand using Redundancy Analysis (RDA). Eighty microsites were located in a beech-hemlock-red maple forest. Forest floor was analyzed for thirteen variables; total N, P, K, Ca and Mg, extractable Ca, Mg and K, mineralizable N (NH$ sb{4+}$), basal microbial respiration (CO$ sb2$), pH, thickness and bulk density. The influence of seven tree species was calculated as a function of tree diameter and distance from each microsite. Spatial patterns were detected by using correlograms and incorporated in a variation-partitioning model with trend surface analysis. Tree species, microtopography, and spatial structure explained 53% of the total variation in forest floor data. The fraction explained by tree species alone (16%) was studied with a RDA ordination biplot. The main source of variation in the soil data was related mainly to the opposite effects of American beech and eastern hemlock on calcium while most of the other species had a beneficial effect on soil fertility. This study showed the potential of RDA as a tool for studying the role of tree species in mixed forests.

Thesis (M.Ag.Sc.)--University of Adelaide, Dept. of Entomology, 1967. / Includes bibliographical references.

Thesis (MS)--University of Montana, 2010. / Contents viewed on May 28, 2010. Title from author supplied metadata. Includes bibliographical references.