The Climatic Response in the Partitioning of the Stable Isotopes of Carbon in Juniper Trees from Arizona
AuthorArnold, Larry David
C-13 / C-12
Junipers -- Climatic factors -- Arizona
Carbon -- Isotopes
Climatic changes -- Research
Climatic changes -- Research -- Arizona
Committee ChairLong, Austin
MetadataShow full item record
PublisherThe University of Arizona.
RightsCopyright © is held by the author. Digital access to this material is made possible by the Antevs Library, Department of Geosciences, and the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author or the department.
Collection InformationThis item is part of the Geosciences Dissertations collection. It was digitized from a physical copy provided by the Antevs Library, Department of Geosciences, University of Arizona. For more information about items in this collection, please email the Antevs Library, firstname.lastname@example.org.
AbstractJuniper trees (Juniperus osteosperma, J. monosperma, J. deppeana and J. scopulorum) grow under widely varying climatic and edaphic conditions throughout the American southwest. This study is chiefly concerned with a test of the climatic response in the partitioning of the stable isotopes of carbon in such trees. The relationships developed here, for example, might be used to extract paleoclimatic information from ancient juniper samples preserved in cave middens. In order to test for a climatic response in the leaf cellulose δ¹³C values, leaves from a total of 29 trees were sampled in the immediate vicinity of 9 meteorological stations across the state of Arizona. Care was taken to insure that 22 of the trees experienced only the temperature and precipitation values reflected by their site meteorological stations. As a cross-check, 7 trees exposed to temperature and/or precipitation levels clearly deviant from their site averages were also sampled. In general, each tree was sampled at four places, approximately 2 m above the ground. All leaf samples were reduced to cellulose (holocellulose) before combustion and analysis for their δ¹³C value. The δ¹³C value for each site was derived from an average of 2 to 4 trees per site, the value of each tree being the average of its individual samples. The one sigma 13C variation found between trees at any given site is ±0.38‰; within a single tree, ±0.36‰; and for repeat combustions, ±0.20‰. The δ¹³C values of the juniper sites were regressed against the temperature and precipitation of the individual months and running averages of months across the year using polynomial, multiple regression analysis. Temperature and precipitation were entered as separate variables in a general multiple regression model and also as a combined, single variable (T /P) in a more specific approach. The pattern formed by the multiple correlation coefficients, when plotted by months across the year, closely follows the seasonal variations in photosynthetic activity. Cellulose δ¹³C values have minimum correlation with temperature and precipitation (considered jointly) during summer months and maximum correlation during spring months. For an individual month, the temperature and precipitation (jointly) of April correlated at the highest level with a multiple adj. R = 0.994 and an F = 166; for a maximum seasonal response, March-May reached a multiple adj. R = 0.985, F = 66. The results using the combined, single variable (T /P) were nearly equivalent for the same months: April's adj. R = 0.957, F = 45; March-May's adj. R = 0.985 with an F = 132. The ability of T and P as independent predictors is considerably less than their ability in combination; e.g., 13C g(T) for March-May has an adj. R = 0.80 and 6 13C = h(P) has an adj. R = -0.67 compared to their in- concert adj. R value of 0.985. The results of this study, therefore, strongly support a high degree of climatic sensitivity in the partitioning of the stable isotopes of carbon in juniper leaf cellulose: the correlation coefficients and their F statistics are sufficiently high to consider temperature and precipitation (acting jointly) as accurate predictors of cellulose δ¹³C values in the system studied.
Degree ProgramGraduate College
Degree GrantorUniversity of Arizona
Showing items related by title, author, creator and subject.
Informing Climate Adaptation: Climate Impacts on Glacial Systems and the Role of Information Brokering in Climate ServicesPapuga, Shirley A.; Guido, Zack Scott; Papuga, Shirley A.; Garfin, Gregg; Russell, Joellen; Buizer, James; McIntosh, Jennifer (The University of Arizona., 2015)Recent climate changes show that the historical record is not an appropriate analog for future climate conditions. This understanding calls into question management decisions that assume climate stationarity and consequently the demand for climate information has increased in order to help frame climate risk more accurately. However, deficits in knowledge about climate impacts and weak connections between existing information and resource managers are two barriers to effective incorporation of climate information in resource management, development, risk management, and other climate-sensitive decisions. In research presented here, I showcase results that address knowledge gaps in the impact of climate on glacial resources in Bolivia, South America. I present a mixing model analysis using isotopic and anion tracers to estimate that glacial meltwater contributed about 50% of the water to streams and reservoirs in La Paz region of Bolivia during the 2011 wet and 2012 dry seasons. To assess how future warming may impact water supplies, I develop a temperature-driven empirical model to estimated changes in a future glacial area. Surface temperature changes were extracted from a multi-model ensemble of global climate models produced for the latest Intergovernmental Panel on Climate Change (IPCC) fifth assessment report and for two greenhouse gas emission scenarios. In both scenarios, declines in glacial area are substantial. For many small glaciers, temperatures at the toe of each glacier rise above the glacier's maximum elevation by 2050 suggesting that water resources will be substantially impacted with continued warming. While these results address a knowledge gap, the extent to which they inform resource management is unknown because the research was conducted without an explicit connection to resource management. Information produced in this fashion is generally acknowledged as being less immediately useful for decision-making because of access and comprehension barriers. These challenges may be mollified, however, with information management strategies. Therefore, I present results from an experiment to see if translating and contextualizing existing climate-related information - information produced similarly to the glacier results highlighted above - help facilitate its use. During a drought afflicted period in Arizona and New Mexico, a monthly synthesis of climate impacts information was disseminated to more than 1400 people. Survey responses from 117 people who consulted the information indicated that the majority of them made at least one drought-related decision and the information in the synthesis at least moderately influenced the majority of those decisions. In addition, more than 90% of the survey respondents indicated that the synthesis improved their understanding of climate and drought; it also helped the majority of them better prepare for drought. The results demonstrate that routine interpretation and synthesis of existing climate information can help enhance access to and understanding of climate information.
Southwest Climate Research and Education: Investigating the North American Monsoon in Arizona and Teaching Climate Science on the Tohono O'odham NationComrie, Andrew C.; Kahn-Thornbrugh, Casey Curtiss; Marsh, Stuart E.; Yool, Steve R.; Hiller, Joseph G.; Parezo, Nancy J.; Comrie, Andrew C. (The University of Arizona., 2013)Western science and Indigenous knowledge understand Southwest climate and the North American monsoon from different cultural perspectives. However, scant literature exists relating to climate and Indigenous communities in the Southwest. On the contrary, substantial climate research has occurred with Arctic Indigenous communities; however, a general aspiration among communities is Indigenous-led climate research and education. This requires more Native scientists and culturally responsive climate science curricula. Southwest Indigenous communities are primed to do this. This dissertation examines 1) the current scientific understanding of the North American monsoon, 2) the state of climate research in Indigenous communities, and 3) the development of culturally responsive climate science curricula. The first paper synthesizes the current scientific understanding of the monsoon and its interannual variability. Pacific Ocean-based teleconnections, such as ENSO-PDO combined indices do add skill in early-season monsoon forecasting. However, general circulation models continue to deal with computational-spatial resolution limitations challenging their application in future climate change projections of the monsoon. The second paper focuses on climate-related research in Indigenous communities in the Arctic and the Southwest to highlight lessons-learned. Climate researchers working with Native communities must exercise cultural considerations for Indigenous relationships with the climate and Indigenous protocols for acquiring and disseminating knowledge. Furthermore, increasing the number of Native students in science and Native scientists are ways to improve climate-related research in Indigenous communities. The third paper is a participatory action research approach to develop a culturally responsive climate science curriculum for Tohono O'odham high school and college students. This project worked with a community advisory board as well as Tohono O'odham Community College instructors and student interns. Pre-assessment surveys were given to community members learn of the most relevant weather and climate topics. The curriculum was developed incorporating local, culturally relevant topics. Climate workshops were offered in the communities using activities developed for the curriculum. Workshop evaluations were positive; however, they also addressed the need for more culturally relevant examples. The overlapping theme for these dissertation papers is cultural understanding for climate research and education in Indigenous communities toward a means for Indigenous-led climate research/education within their own communities.
Making Carbon Count: Global Climate Change and Local Climate Governance in the United StatesRobbins, Paul F.; Rice, Jennifer Lea; Robbins, Paul F.; Marston, Sallie A.; Jones, III, John Paul; Woodhouse, Connie A.; Comrie, Andrew; Overpeck, Jonathan (The University of Arizona., 2009)In the absence of federally-mandated climate change regulations in the United States, many municipalities have begun to design and implement their own climate mitigation and adaptation programs during the past decade. These include programs such as the US Mayors Climate Protection Agreement, where more than 1,000 cities have pledged to meet Kyoto Protocol greenhouse gas (GHG) reductions targets within their own jurisdictions, as well as efforts to integrate climate information (e.g. tree-ring reconstructions of streamflow) into resource planning efforts to better assess the effects of climate change on water supplies. Using three related case studies in these areas, this dissertation examines the emergence and spread of local climate change programs in the US, with an emphasis on how government institutions work to make climate governable, and the potential effects these practices have on social life and the production and circulation of scientific knowledge. Central findings of the dissertation include: 1) Cities, through the use of everyday and routine political mechanisms that they have available to them, have become key sites of government action on climate change. In the process, local governments have been able to reaffirm, and in some cases expand, their influence within the public sector of environmental policy; 2) Carbon is the political currency of local climate change programs. Through the creation of GHG inventories (i.e. "carbon territories") and the production of carbon-relevant citizens, climate has become the object of urban environmental governance; and 3) Climate science is utilized in complex and contradictory ways in climate mitigation and adaptation programs. Several framings of climate science have been constructed by local governments as a means to justify action on climate change, while resource managers have begun to incorporate paleoclimate data into water resources planning. In both cases, the use of science has advanced political action on climate change, but the reliance and privilege of scientific discourses may preclude other "non-expert" communities from participating in the debate. This also demonstrates the "science effect," where the practices of science and the state are constructed as separate and distinct, when they are, in fact, coproduced through the practices of climate governance.