Dissertation/Thesis Abstract

The effects of climate on Picea engelmannii (Parry ex Engelmann) seedlings at the subalpine zone of the Wasatch Plateau, Utah, U.S.A.
by Hamblin-Hart, Kimberly, Ph.D., Washington State University, 2013, 197; 3598069
Abstract (Summary)

In this dissertation I have looked at treeline development from several different spatial and temporal levels. The first chapter, Drivers and mechanisms of temperate treeline migration, investigates the development and history of treeline studies at the physiological/individual level, the local/landscape scale, and the regional/global level. The subsequent 3 chapters look at specific original research performed at some of these different spatial and temporal levels and are organized from the smallest level to the larger ones. Physiological and growth responses to low temperature in Engelmann Spruce (Picea engelmannii) seedlings, is a study of the ecophysiological responses of Engelmann spruce seedlings at the individual scale during one growing season. I measured biomass and both phenological and physiological responses to decreased daily thermal amplitude. Overall stem elongation and root:shoot ratios decreased, as did starch concentrations, with an increase in temperature. The results showed little variation of gas exchange between the different treatments. Engelmann Spruce (Picea engelmannii) seedling survival at subalpine meadows: water sources, warming, and cover, was a field study of 300 seedlings that used open-topped warming cones. It included the use of stable isotopes to determine variations in depth of water used by different plant forms (grasses, forbs, shrubs and trees). Overall, seedlings grown in warming cones had greener needles than the control, although there was no effect on total seedling survival. Grasses were getting water with a signature similar to that of rain water. Survival of seedlings was connected to the percent of forbs versus grasses at each site. Forty-five years of change (1964-2009) on the Wasatch Plateau, UT: Using aerial images to determine forest invasion into subalpine meadows is the final chapter and looks at the Wasatch Plateau's recent history. In this study I compared three aerial images over a 45 year period and determined there has been an increase of cover and treeline invasion into subalpine meadows. In summary, overall design of research for this dissertation recognized the complexity of the spatial/temporal scales involved in treeline studies and thus integrated laboratory, field, and remote sensing procedures.

Indexing (document details)
Advisor: Felsot, Allan
Commitee: Pratt, James R., Swanson, Mark
School: Washington State University
Department: Environmental and Natural Resource Sciences
School Location: United States -- Washington
Source: DAI-B 75/02(E), Dissertation Abstracts International
Subjects: Plant biology, Ecology, Environmental science
Keywords: Climate change, Picea engelmannii, Remote sensing, Spruce seedlings, Treeline, Warming
Publication Number: 3598069
ISBN: 9781303465406
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