Alpine fir( Abies lasiocarpa ( Hook ) Nutt. ) needles and cones were studied in natural stands to determine the variability of several traits such as needle length, width, stomatal distance in a row line on the abaxial surface, difference between cone scale and bract lengths, seed-wing areas, etc. Additional histological characteristics of needle, cone scale and bract are presented. Sixty-five stands, located on the West Coast of North America, were sampled. Continuous distribution of variable characteristics has not been found in the 65 stands. Correlation analysis shows that stomatal distance is directly associated with precipitation. Therefore, stomatal frequency increases with higher precipitation. Analysis of variance shows that the difference between cone scale and bract lengths is highly significant between the different stands. These differences indicate actual variations in the cone collection. Varieties and clines are suggested to exist in the natural range of alpine fir. / Science, Faculty of / Botany, Department of / Graduate

Thesis (Ph. D.)--Oregon State University, 1999. / Typescript (photocopy). Includes bibliographical references. Also available on the World Wide Web.

Thesis (Ph.D.)--University of Washington, 1995. / Vita. Includes bibliographical references (leaves [110]-144).

Enzyme electrophoresis, chromosome counts and self-incompatibility trials were used to compare genetic and clonal diversity in Carex lasiocarpa and C. lanuginosa, two closely-related wetland sedge species of north-temperate distribution. Genetic variation was similar in the two species, but C. lanuginosa was somewhat less diverse and had a higher coefficient of genetic differentiation among populations than C. lasiocarpa. Wright's fixation index indicated that both species are primarily outcrossing, although crossing experiments suggested that C. lanuginosa may be self-fertile. The haploid chromosome numbers were n = 38 for C. lasiocarpa and n = 40 or 41 for C. lanuginosa. Cluster analysis using genetic identities and principal components analysis of allele frequencies clearly grouped the two species, but the separation was less clear for morphological data. Clonal diversity was higher and clone size smaller in C. lasiocarpa than in C. lanuginosa, but C. lasiocarpa showed less clonal and genetic diversity at dry than at wet sites.

No description available.

Thesis (M.S.)--Wake Forest University. Dept. of Biology, 2003. / Vita. Includes bibliographical references (leaves 51-57).

Human activities are changing wildfire regimes globally through ignition, spread of invasive species, fire suppression, and climate change. Because of this, ecosystems are experiencing novel fire regimes that may alter plant growth and patterns of succession. Annual growth rings are one metric that can track changes in tree and shrub growth patterns over time in response to changing fire frequency. In Chapter 1 we explored the effects of fire on resprouting native shrubs in the Mojave Desert. Fires are becoming increasingly frequent due to the spread of highly flammable invasive grasses in the region. We monitored growth and fruit production of Larrea tridentata D.C. (creosote bush) on burned and unburned transects from three independent 2005 wildfires. Even though creosote has a high fire mortality rate, we found that resprouting creosote produced 4.7 times the amount of fruit and had stems that grew nearly twice as fast compared to creosote in unburned areas. Our data suggest that creosote can resprout after fire and thrives in its growth rates and reproduction in post-fire environments. In Chapter 2 we used annual Basal Area Increment to investigate how fire suppression has altered facilitation and competition interactions through stages of succession in mixed aspen-conifer forests. We found that aspen had lower growth rates in mixed aspen-conifer stands compared to aspen dominant stands. We also found that aspen growing with an associated fir tree due to facilitation had increasingly lower growth rates over time than those growing independently. Fir trees in mixed stands were facilitated over time by associated aspen trees while fir trees growing in association and independently in aspen stands showed no statistical difference from each other but grew better than independent fir trees in mixed stands. Our data suggest that restoring a more frequent fire regime will balance competitive interactions between aspen and conifer in subalpine forests.

Old-growth stands are important for management, conservation, wildlife, recreation, and maintaining biological diversity in forested landscapes. However, we are lacking the information needed to adequately identify and characterize old-growth stands. This is especially true for high elevation, interior forests. The characterization of stand structure and regeneration pattern will help in the development of site-specific guidelines for identifying old growth stands and restoring some of the old-growth characteristics in managed stands. This pamphlet presents a synopsis of a study investigating stand structure and regeneration of old-growth stands in the Moist Cold Engelmann Spruce - Subalpine Fir (ESSFmc) Subzone near Smithers, B.C. The three stands selected for the study were located on zonal sites, each in different watersheds, and the stands were established after fire. The criteria used for selection were: i) absence of lodgepole pine, ii) presence of advanced regeneration, and iii) abundant snags and coarse woody debris. These stands were presumed to represent the old-growth stage of stand development or the final (climax) stage of secondary succession.