Document Type

Dissertation

Degree

Doctor of Philosophy (PhD)

Department

Geosciences

First Advisor's Name

William Anderson

First Advisor's Committee Title

Committee chair

Second Advisor's Name

René M. Price

Second Advisor's Committee Title

Committee member

Third Advisor's Name

Michael Ross

Third Advisor's Committee Title

Committee member

Fourth Advisor's Name

Evelyn Gaiser

Fourth Advisor's Committee Title

Committee member

Keywords

stable isotope-dendrochronology, carbon isotopes, oxygen isotopes, Big Pine Key, Pinus elliottii, slash pine, tree-ring, paleotempestology

Date of Defense

10-28-2016

Abstract

The global paleoclimate archive is lacking in tropical dendrochronology studies as a result of limitations from inconsistent tree-ring production imposed by precipitation-driven seasonality. The slash pine, Pinus elliottii Engelm. var. densa, is the dominant canopy species of Big Pine Key (BPK) rocklands and has been shown to produce complicated, but distinct, ring structures; however, traditional dendrochronology studies have not established correlations between ring width measurements and major climate drivers controlling South Florida precipitation. My study utilized the carbon (δ13C) and oxygen (δ18O) isotope records in the α-cellulose component of tree-rings to extract information about the physiological responses of trees to climate and tropical cyclone activity. The δ13C measurements in the earlywood and latewood of four P. elliottii var. densa trees were used to build a chronology (1922-2005) and to distinguish annual growth from intra-annual density fluctuations (IADFs). Empirical orthogonal functions were used to determine individual response to precipitation, El Niño-Southern Oscillation (ENSO), and the Atlantic Multidecadal Oscillation (AMO). There is a distinct relationship between the δ13C values of cellulose and ENSO; however the nature (direct vs. inversely correlated) is temporally controlled by the prevailing phase of the AMO. The appearance of some IADFs coincide with the timing of El Niño winters occurring during the cool AMO phase, resulting in enriched δ13C values. The additional precipitation may encourage tree growth, but subsequent dry periods may slow growth and cause the tree to employ water-conservation strategies. Tree growth is influenced by the major climate drivers and the control they exert over the timing of precipitation; however, growth is ultimately controlled by the microenvironment surrounding individual trees. The δ18O and δ13C values of the latewood cellulose were compared to tropical cyclone activity occurring within a 100km radius of BPK. Tropical storms and depressions appeared as anomalously depleted values in the δ18O residual record, reflecting large amounts of tropical rain. The effects of hurricanes varied by storm; however, many of the major hurricanes (category 3-5) were preserved as an enrichments in the δ13C value of the following earlywood season. The application of stable isotope analyses greatly increases the breadth of paleoclimate information available from the trees.

Identifier

FIDC001213

ORCID

orcid.org/0000-0001-5684-2846

Available for download on Monday, December 04, 2017

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