@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 {839, title = {Spatial Relationships in Frost-Damaged High-Elevation Pines and Links to Major Volcanic Eruptions}, volume = {MS}, year = {2001}, pages = {67}, school = {University of Arizona}, address = {Tucson}, abstract = {

Frost injury in the annual growth rings of pines growing at upper treeline is a consequence of sudden freezing temperatures during the growing season (LaMarche \& Hirschboeck 1984). This updated and spatially extensive frost-ring study involves the systematic identification of frost rings in high-elevation pines located in 16 western USA tree-ring sites whose chronologies range from 1692 BC to AD 2000. Several \"notable frost events\" were identified, based on the criteria of frost damage occurring in greater than 25\% of trees at a given site and in two or more sites. The spatial variations between frost events indicate regional variations based on differences in elevation, latitude, and the location of polar outbreaks and their associated upper-level atmosphere circulation patterns. The 17 notable frost events correspond to previous frost ring and light ring evidence, and 13 of them are associated with climatically effective volcanic eruptions.

}, keywords = {atmosphere circulation, damage, dendrochronology, dendroclimatology, frost, high elevation, pine, polar outbreak, relationship, spacial, tree ring, tree-ring, volcanic eruption}, author = {Hallman, Christine Lee} }