@mastersthesis {539, title = {Using False Rings to Reconstruct Local Drought Severity Patterns on a Semiarid River}, volume = {PhD}, year = {2008}, school = {University of Arizona}, abstract = {In this research, I describe the use of false rings to reconstruct local histories of seasonal drought in riparian ecosystems in semiarid regions. In tree-ring analysis, false rings are boundary-like features often formed as a response to drought within the growing season. Drought can be a common feature in hydrologic regimes of dryland rivers but in recent decades drought has been intensifying due to climate change and increasing water use by cities, agriculture and industry. Identifying when and where water availability has decreased along the river course is critical for understanding, and therefore managing, these generally endangered ecosystems. The higher density of trees compared to instrumental data make them ideal candidates for reconstructing site-specific drought patterns. The first part of this dissertation is an observational study conducted on the San Pedro River in southeastern Arizona during 2002. I used dendrometer data and local hydrological data to show that a period of negligible radial growth in cottonwood during the middle of the growing season coincided with a channel drying event. Tree-ring core samples confirmed that false-rings had formed in each of the instrumented trees. The second part of this dissertation is an experimental study designed to evaluate the effect of different levels of water stress on false-ring formation in cottonwood and willow. I showed that experimental decreases in water availability for periods as short as ten days were enough to induce false-ring formation in willow. Longer periods of reduced water availability were generally required to induce false-ring formation in cottonwood. In the final part of this dissertation, I reconstructed false-ring occurrence in Fremont cottonwoods at three sites along the San Pedro River. I infer from false-ring frequencies that the severity of summer drought has been increasing over the last four to six decades but that the drought severity varies along a hydrological gradient. Overall, the findings in this body of research confirm that false rings in riparian tree species can be used as indicators of seasonal drought and underscore the importance of identifying site-specific responses to reduced water availability along the riparian corridor.}, keywords = {Geography}, url = {http://ezproxy.library.arizona.edu/login?url=http://proquest.umi.com/pqdweb?did=1500068401\&sid=3\&Fmt=2\&clientId=43922\&RQT=309\&VName=PQD}, author = {Morino, Kiyomi Ann} } @mastersthesis {521, title = {Fire-Climate-Vegetation Interactions in Subalpine Forests of the Selway-Bitterroot Wilderness Area, Idaho and Montana, USA}, volume = {PhD}, year = {2003}, school = {University of Arizona}, abstract = {The long term patterns of fire-climate interactions and forest recovery processes in subalpine forests are poorly understood. This study used a suite of dendrochronological techniques to identify tree growth-climate relationships, assess the interactions of fire with interannual climate variability, and reconstruct summer temperature in subalpine forests of the Selway-Bitterroot Wilderness Area on the border of Idaho and Montana, USA. Comparison of ring-width chronologies from whitebark pine ( Pinus albicaulis Engelm.) and subalpine larch ( Larix lyallii Parl.) with modern climate data indicated that summer temperatures were most limiting to growth in these conifers. Warm summers were generally conducive to radial growth. However, the temporal stability of the climate-tree growth relationship weakens from the early to later periods of the record. Alterations to growing season length, possibly modified by snow pack, may be related to the reduction in climate-growth relationships. A 748-year reconstruction of average summer temperature was developed that explains [approximate]36\% of the variance of the instrumental record. Positive values of the coefficient of efficiency and reduction of error verification statistics indicated that the reconstruction was of good quality. Warm and cool periods in the reconstruction include a warm decade around the 1650s and prolonged cooling around 1700. Peaks in variance in reconstructed average summer temperature occurred at 87, 15, and 2 years. More than 2000 fire scar and age structure samples were used to evaluate fire-climate relationships. Comparison of widespread fire events to climate variables indicated dry conditions both during the fire year and one year before a fire. Multiple spatial patterns of drought and El Ni{\~n}o were related to widespread fire occurrence. Forest recovery following fires generally proceeds from lodgepole pine ( Pinus contorta var. latifolia Dougl.) toward spruce-fir forests ( Picea engelmannii Parry- Abies lasiocarpa (Hook) Nutt.). Two successional pathways occur, one beginning with an initial lodgepole pine stage, the other a spruce-fir stage. Initial composition was related to the presence of overstory lodgepole pine at the time of fire occurrence as well as the intervals between successive fires. Collectively, these results suggest a strong multi-year drought linkage between climate and fire, and dependence on fire intervals for structuring forest communities.}, keywords = {Geography}, url = {http://ezproxy.library.arizona.edu/login?url=http://proquest.umi.com/pqdweb?did=765957031\&sid=4\&Fmt=2\&clientId=43922\&RQT=309\&VName=PQD}, author = {Kipfmueller, Kurt Foster} } @mastersthesis {653, title = {Aspen: Ecological processes and management eras in northwestern Wyoming, 1807--1998}, volume = {PhD}, year = {2000}, school = {University of Arizona}, abstract = {Quaking aspen stands in many areas of the intermountain west are currently dominated by older (>100 year) age classes and may be in decline. The goals of my research are to: (1) place current observations of aspen decline into context by using historical and ecological data to investigate the interaction of fire, ungulate browsing, climate and human institutions in the regeneration of aspen stands over the last two centuries; (2) evaluate the challenges and limitations associated with using ecological history for management of aspen and other systems; and (3) compare current and historical aspen regeneration across three elk winter range areas in the intermountain West. Based on results from stand age structures, aspen regeneration in the Jackson Valley has occurred episodically since 1830, with three major periods of regeneration: 1860-1885; 1915-1940; and 1955-1990. These multi-decadal episodes of aspen regeneration are related to similar variability in precipitation, where above average periods of annual precipitation are associated with aspen regeneration. However, significant levels of aspen regeneration have only coincided with low or moderate elk population estimates and fewer aspen have regenerated than expected when elk populations are high ( X 2 = 59.92, p < 0.0001). Current aspen reproduction, though minimal, is strongly affected by elk browse with percent browse significantly higher in elk winter range than outside of elk winter range (p = 0.051). Though extensive or frequent fires may have maintained aspen communities during the pre-settlement era, current management controlled fires have not affected aspen sucker density. The influence of multiple interacting processes and drivers in the Jackson Valley suggests that reconstructing past ecosystems as benchmarks for ecological management should be considered carefully. Given future environmental variability, reconstructions of past systems should focus on ecological relationships rather than on single states or processes. Comparison of aspen in the three elk winter range areas indicates that heavy browsing by elk populations has had a strong influence on episodes of aspen regeneration for the last 150 years in all three elk winter ranges. However, elk are not having strong impacts on aspen outside of elk winter range. }, keywords = {Ecology, Geography, Paleoecology}, url = {http://ezproxy.library.arizona.edu/login?url=http://proquest.umi.com/pqdweb?did=731957311\&sid=11\&Fmt=2\&clientId=43922\&RQT=309\&VName=PQD}, author = {Amy Hessl} } @mastersthesis {538, title = {Reconstruction and Interpretation of Historical Patterns of Fire Occurrence in the Organ Mountains, New Mexico}, volume = {Master of Science}, year = {1996}, pages = {144}, school = {University of Arizona}, address = {Tucson}, abstract = {

The purpose of this research was to reconstruct and interpret the history of fire in the Organ Mountains, New Mexico. I used dendrochronological techniques to date fire scars on 90 trees comprising ten sites within the Fillmore Canyon watershed. Two fire regimes were identified during the pre-settlement period. Fire Regime I, 1650-1805, was characterized by a high fire frequency (ca. once every two years) and a predominance of patchy fires. Fire Regime II, 1805-1874, was characterized by a lower fire frequency (ca. once every 3.5 years) and a predominance of widespread fires. During the post-settlement period fire was virtually non-existent. I hypothesize that Apache use-of-fire influenced patterns during the pre-settlement period, while Euro-American land use activities influenced patterns during the post-settlement period. Fire-precipitation associations suggest that low fuel moisture levels were a pre-condition for widespread fires.

}, keywords = {dendrochronology, fillmore canyon, fire, Geography, historical, new mexico, organ mountains, reconstruction}, author = {Morino, Kiyomi Ann} } @book {876, title = {A Directory of Tree-Ring Dated Native American Sites in the American Southwest}, year = {1993}, month = {09/1993}, publisher = {Laboratory of Tree-Ring Research}, organization = {Laboratory of Tree-Ring Research}, address = {Tucson}, keywords = {apache, Archaeology, dating, dendrochronology, directory, Geography, native american, navajo, Pueblo, quandrangle, site, southwest, tree ring, ute}, author = {Robinson, William J. and Ronald H. Towner} } @mastersthesis {905, title = {A Dendrochronological Study of the Great Salt Lake Basin}, volume = {Master of Science}, year = {1989}, note = {

Please contact the Laboratory of Tree Ring Research to view this thesis.

}, month = {03/1989}, pages = {77}, school = {University of Utah}, address = {Salt Lake City}, abstract = {

To date, no tree-ring chronologies have been generated for the Great Salt Lake basin. There is evidence of a winter air mass boundary across this area. Since the region receives a precipitation maximum in the winter and spring, information about boundary location variability would be useful. Tree-ring widths may be related to climatic variables and provide a record of past climate.

Four tree-ring chronologies in the four corners of the Great Salt Lake basin were generated using standard dendrochronological techniques. Precipitation and temperature data for the area were regionalized and tree-ring indices were correlated with regional temperature seasons and with precipitation regions and seasons. The chronologies were factor analyzed for the period of common growth, 1593-1985, and broken down into seven overlapping one hundred-year periods.

During the period for which there are weather records, tree growth in the northwest site was correlated with temperature variables, while in the other three sites, tree growth was mostly correlated with precipitation. The results of the factor analysis of the chronologies for the seven time periods were consistent with the correlation results. The results also indicate a similar pattern of variation of growth for the time periods of 1593-1650 and 1825-1940.

The four Great Basin chronology sites are located in a unique region and may be used to learn about climatic variability in this area.

}, keywords = {climatic variability, dendrochronology, dendroclimatology, Geography, great salt lake basin, indices, precipitation, salt lake, temperature, tree ring}, author = {Connie Woodhouse} } @mastersthesis {522, title = {Comparative Analysis of Climatic Reconstructions Derived from Tree-Ring and Ice Core Indicators in Southern Greenland}, volume = {MA}, year = {1980}, school = {University of Nebraska}, keywords = {Geography}, author = {Kuivinen, Karl C.} } @mastersthesis {525, title = {The Climate of the Great American Desert}, volume = {PhD}, year = {1972}, school = {Clark University}, keywords = {Geography}, author = {Lawson, Merlin P.} } @article {799, title = {Physical Geography}, volume = {I}, year = {1906}, note = {Copies of this are available in the Tree Ring Laboratory; please contact the lab for more information. }, keywords = {address, Douglass, Geography, historic, newspaper, school, tempe}, author = {Douglass, A.E.} }