@mastersthesis {511, title = {Unraveling environmental factors that affect Pinus longaeva growth in the White Mountains, California}, volume = {PhD}, year = {2010}, school = {University of Arizona}, abstract = {

Two of the most pressing questions involving ancient bristlecone pines are how microsite factors lead to differences in tree responses to climate at high-elevation sites, and how global change has impacted growing season events. Disparities in climate response at treeline and subalpine locations have been associated with local environmental characteristics while the increasing growth trend found at treeline has been linked to warming. In this study, environmental conditions were considered in order to identify microsite differences between trees growing at two different elevations on four aspects of a conical-shaped mountain in the White Mountains, California. Dendrochronological, environmental, correlational, and spectral methods were employed to explore differences in ring-width chronologies. Albedo, soil thickness, and percent slope led to ring-width variability. Northwestern upper site was most highly correlated with precipitation, while the Southeastern lower site showed a strong negative correlation with temperature. This work indicates that selection of climate-sensitive trees a priori necessitates the consideration of local environmental factors, and these microsite differences resulted in different climate responses between nearby trees. By monitoring growing season events at the historic phenology site from the 1962-64 (Fritts 1969), natural variations and responses to climate change can be identified. Morphological and physiological phenophases, dendrometer traces, and environmental data were collected throughout the summers of 2007 and 2008. Duration and timing of cambial activity (tracheid lifespan) in the present study were similar to those recorded in the Fritts (1969) investigation, while pollination onset and bud opening occurred earlier in this study. No change was found in duration and timing of cambial activity suggesting that changes in cambial phenology are not an explanation for the increasing growth trend found at upper forest borders. On the other hand, changes in bud opening and pollination onset may be related to recent warming. To monitor diurnal and seasonal stem variability as part of phenologic studies on several trees, a point potentiometer dendrometer was designed. The newly designed point potentiometer dendrometer was tested in multiple environments and found to be versatile, cost-effective, and portable, working well in semi-arid and arid environments.

}, keywords = {Physical geography}, url = {http://ezproxy.library.arizona.edu/login?url=http://proquest.umi.com/pqdweb?did=2108905281\&sid=32\&Fmt=2\&clientId=43922\&RQT=309\&VName=PQD}, author = {Hallman, Christine Lee} } @mastersthesis {664, title = {Reflected-light image analysis of conifer tree rings for dendrochronological research}, volume = {Phd}, year = {1995}, school = {University of Arizona}, abstract = {

The primary objective of this dissertation research is to use reflected-light image analysis to measure brightness of standard samples of conifer rings and then use brightness in dendrochronological research as a substitute for density. I developed an imaging system that ensures identical configuration of all components and measuring steps for all rings of a sample so that subsequent comparison of brightness between rings would be valid. From a mesic New England tree-ring site, I measured ring brightness of cores that had been previously measured using X-ray densitometry. Latewood brightness and density both correlate with April-May temperature such that they reconstruct that climate variable equally well. From a semiarid Southwest tree-ring site, I measured ring brightness of cores with severe extraneous color--mostly due to heartwood-sapwood color differences. Bleaching and organic extraction of cores did not overcome the problem of extraneous color, but autoregressively modeling brightness index series did. Various brightness and width variables combined to model July-October precipitation, a climate variable not usually reconstructed by Southwest tree-ring sites. From a stand of trees affected by a past earthquake, I measured ring brightness of one tree that responded to surface deformation with an apparent change in latewood density. Absolute latewood brightness did not change per se after the earthquake, but the amount of latewood relative to the total ring increased dramatically. Although technical and paleoenvironmental issues remain for future research, this study indicates that reflected-light image analysis is an excellent tool in dendrochronological research for increasing our understanding paleoenvironmental processes of the latest Holocene. The secondary objective of this dissertation research is to demonstrate a method for identifying low-frequency variation of tree-ring chronologies and/or past climate as reconstructed using tree-rings. This method provides confidence intervals with which to judge the significance or importance of low-frequency departures in tree-ring data as well as a visual basis for determining whether or not low-frequency variation is robustly estimated. This method is a re-ordering of the individual steps commonly used in constructing tree-ring chronologies or reconstructions.

}, url = {http://ezproxy.library.arizona.edu/login?url=http://proquest.umi.com/pqdweb?did=742087251\&sid=3\&Fmt=2\&clientId=43922\&RQT=309\&VName=PQD}, author = {Paul Sheppard} } @mastersthesis {904, title = {Fire Regime of the Lodgepole Pine (Pinus contorta var. murrayana) Forests of the Mt. San Jacinto State Park Wilderness, California}, volume = {Master of Science}, year = {1984}, note = {

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

}, month = {08/1984}, pages = {93}, school = {Cornell University}, address = {Ithaca}, abstract = {

For the purpose of providing recommendations for the fire management plan of the Mt. San Jacinto State Park Wilderness, California, the natural fire regime of the lodgepole pine forests within the wilderness was determined. Fire-scarred lodgepole pine trees were cored, and their growth rings crossdated against a composite ring series, to obtain fire date estimates of fires that have burned within the forests during the last 300 years. U.S. Forest Service fire records and personal accounts were also used to determine recent fire history.

Results indicate that the fires within the lodgepole pine forests of Mt. San Jacinto probably were quite small (\< 0.4 ha). Because of this, the fire regime is probably one of low-intensity fires. Fires started principally by lightning and they generally did not spread far because of low woody fuel loading on the ground. These small fires, however, occurred quite frequently throughout the lodgepole pine forests. Fires probably burned every one to two years, and in many years, more than one fire burned. The average fire return interval for separate locations within the lodgepole pine forests was not determined exactly because most of the burned trees had only one fire-scar.

The effects of this fire-regime on the forest vegetation composition was determined. This was accomplished with multiple regression analyses of vegetative and physiographic data collected from the area of each verified fire.

In the 2500 to 2900 m elevation range, white fir generally increased in importance (relative basal area) over lodgepole pine as years since the fire increased. However, the relationships of lodgepole pine and white fir importances to the time since the fire were not statistically significant. Above 2800 m elevation, neither lodgepole pine nor limber pine importance was affected by the fire regime. Throughout the lodgepole pine forests of this wilderness area, the fire regime has not greatly affected the forest vegetation composition.

To compare two methods of obtaining fire year estimates from living, fire-scarred trees, both wedging and coring was done on ten fire-scarred lodgepole pine trees. The rings of the wedges and cores were then crossdated against a composite ring series, and the respective fire year estimates of each method were compared for each tree. Seven pairs of wedges and cores were crossdated, and each pair gave the same fire year estimate for the respective tree. In the situation of single-scarred trees, the coring method, along with dendrochronology dating, should be attempted instead of wedging, which is more destructive to the tree than coring.

Based on this study, I recommend that the fire management plan for the lodgepole pine forests of the Mt. San Jacinto State Park Wilderness contain two options for fire control. First, in areas that have heavy use by recreationists and cultural or historical benefits, fire suppression should begin immediately after a fire has been detected. Second, in all other areas, a \“let burn\” policy should be attempted, whereby the fire would be allowed to die out on its own. This would save the expense of fire suppression, which can be very costly in remote wilderness areas. These fires should be monitored in case they do burn near valuable areas. Prescribed burning is not recommended because of the weak relationship of the fire regime to the forest vegetation composition.

}, keywords = {california, coring, dendrochronology, fire, fire management, fire scar, Limber pine, lodgepole, mt san jacinto, mt san jacinto state park wilderness, pine, pinus contortata, regime, suppression, tree ring, var murrayana, wedging, white fir}, author = {Paul Sheppard} }