Thesis (M.S.)--Oregon State University, 2009. / Printout. Includes bibliographical references (leaves 20-23). Also available on the World Wide Web.

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Thesis (M.S.- Fishery Management)--University of Arizona. / Includes bibliographical references (leaves 70-74).

Thesis (M.S.)--University of Wisconsin, 1973. / eContent provider-neutral record in process. Description based on print version record.

Few dendrochronological studies have been carried out in Spain or Portugal. Mountain pine (Pinus uncinata Ram.) may be especially suitable for investigation because of its broad altitudinal range and great age. Samples from a site in the Sierra de Cebollera were prepared and dated using several cross-dating techniques. The dated series were used to develop a ring-width index chronology that was compared with local climate data. Ring-width variability is related to precipitation, but temperature can also be important, indicating a complex climate response. Future studies of this species will be important for dendroclimatology and for study of ecophysiology of subalpine plants in the Mediterranean area.

X-ray densitometry has proven useful in dendroclimatic research on relatively fast growing, complacent trees in mesic climates. The best dendrochronological materials, however, come from semiarid-site conifers that grow very slowly, have missing rings, are extremely sensitive to climate, and attain advanced ages. This study presents the first evaluation of X-ray densitometry of Douglas-fir, ponderosa pine, and pinyon from four semiarid sites in the eastern San Juan River Basin (northwestern New Mexico and southwestern Colorado). The relationship of climate with intra-annual tree-ring anatomy is anlyzed. Moving slit X-ray densitometry definest earlywood and latewood zones, yielding eight data types for each annual ring: total ring width, earlywood and latewood width, mean ring density, mean earlywood and latewood density, and minimum earlywood and maximum latewood density. response functions using regional averages of monthly mean temperature and total precipitation indicate that climate may strongly influence all eight types of data, depending on species and site conditions. Low moisture stress (cooler, wetter climate) increases total ring width, earlywood and latewood width, and ring, latewood, and maximum latewood density. High moisture stress increases earlywood and minimum earlywood density. The climate response of the density parameters differs from that reported for conifers in more mesic environments, although selected density parameters from a relatively mesic southwestern site are strongly related to climate. Site selection has nevertheless proven to be an important factor in getting the most climatically sensitive densitometric data. This study demonstrates that densitometry is feasible with conifers from semiarid sites. The intra-annual width and density data derived can increase the climate information available from these dry-site trees and should lead to improved seasonal and annual reconstructions of paleoclimate. Practical constraints imposed by current X-ray densitometric techniques may be removed with promising new procedures such as surface image analysis of cell anatomy.

Pines’ and Gottlieb’s Formulations for the gravitational potential provides expressions for the gravitational potential, U, and its derivatives in a co-ordinate system that produces non-singular values. This report summarizes the origin of the singularities due to the spherical co-ordinate system and a discussion of the methods by which the singularity produced by the conventional representation of the gravitational potential is removed by the implementations described in this report. / text

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Thesis (Ph.D. - Geosciences)--University of Arizona. / Includes bibliographical references (leaves 248-263).

The assumption that each latewood ring in trees represents one year of growth was tested for Utah juniper (Juniperus osteosperma) and pinyon pine (Pinus edulis). Ring characteristics and growth rates were evaluated for 72 years of growth following scars of consistent date on all trees sampled. Errors in age and growth rate estimates based on ring counts were evaluated. Potential variation among observers was accounted for. Average error in ring counts was lowest when rings were counted on the fastest-growing portions of each cross-section. Errors for more than 40% of the junipers exceeded 10 percent with about half of the trees with more rings and half with less rings than actual years. Pinyons rarely had more rings than years and only 5% of the trees were missing more than 10% of the 72 annual rings. Percentage errors in growth rate estimates based on ring counts were similar to ring count errors for both species. Assigning junipers to age classes based on ring counts also can lead to error in assumed ages of trees. Assuming that ring count error for each tree for the 72 year period studied approximates potential error over the life of each tree, more than half of junipers older than 250 years would be assigned to the wrong age class when using 50 year age classes. Number of rings in junipers was highly correlated with growth rate. Competition from surrounding trees explained as much as 53% and 40% of the variation in growth rates of junipers and pinyons respectively. Relating growth rates and ring counts to ordinations of stand, site and soil characteristics indicated that trees with relatively fast growth rates or trees with the most rings tended to occur on gentle, north to northeast aspects with relatively better- developed soils. However, stand competition often had an overriding influence on growth. Presence of Koelaria pyramidata in the understory was generally an indicator of relatively favorable growing conditions for junipers. Results suggest the need for more caution in the use of ring counts for estimating ages or growth rates of Utah junipers and pinyons than has generally been used in the past, especially when drawing conclusions about specific individuals.