Date of Award

8-2006

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Geography

Major Professor

Henri D. Grissino-Mayer

Committee Members

Carol Harden, Ken Orvis, David Buckley

Abstract

The purpose of this research was to use longleaf pine trees at three major sites in the Southeastern Coastal Plain to: (1) determine how longleaf pine trees respond to climate, (2) reconstruct past climate conditions using long tree-ring chronologies, (3) determine the effects of atmospheric teleconnections on longleaf pine growth, and ( 4) reconstruct fire history from fire-scar data. The native range of longleaf pine and its associated communities extends from southeastern Virginia south and westward to the Trinity River in eastern Texas. I collected samples from living and remnant longleaf pine wood in coastal South Carolina, Eglin Air Force Base in the Florida panhandle, and the Big Thicket National Preserve of Texas.

In the climate response analysis, the Palmer Drought Severity Index (PDSI) and Palmer Hydrological Drought Index (PHDI) had the highest correlation with longleaf pine growth. The strongest relationships between longleaf pine growth and the Palmer indices occur between the months of July and November. Precipitation in the spring and summer was also positively related to growth at all sites. The relationship between temperature and growth was the weakest among all climate variables, but warm summer temperatures had a consistent, negative relationship with longleaf pine growth. The climate signal in the latewood was generally more robust than those in total ring width and earlywood width.

developed chronologies for total ring width at all sites and for earlywood and latewood widths in Texas and South Carolina. The master chronologies for each site spanned the years from 1629-2003 in Texas, 1503-2003 in Florida, and 1455-2003 in South Carolina. I reconstructed September PHDI at all sites using a transfer function with tree-ring indices as the independent variable. For all reconstructions, the most widespread and intense year of drought since 1700 was 1925. The driest five-year period common to all reconstructions was 1951-1955. At decadal scales, extremely wet periods were often followed immediately by extremely dry periods. My reconstructions showed evidence for several historic disturbances, including the Charleston earthquake of 1886 and the arctic outbreak of 1835. Spectral analysis showed no significant spectral signatures in any of the reconstructions.

Atmospheric teleconnnections such as El Nino-Southern Oscillation (ENSO), the Pacific Decadal Oscillation (PDO), the North Atlantic Oscillation (NAO) and the Atlantic Multidecadal Oscillation (AMO) significantly affected longleaf pine growth at all sites, but the strength of the teleconnections varied through time. ENSO in the summer and fall correlated significantly with tree growth in Texas and South Carolina. The PDO in the year prior to growth was generally directly related to longleaf pine growth, while PDO in the current year usually showed an inverse association. The NAO from August of the previous year and May of the current year were generally negatively related to longleaf pine growth. The AMO was generally positively associated with longleaf pine growth in all months of the year.

The reconstruction of fire history revealed that fire was frequent at all sites prior to the advent of fire suppression in the 20th century. The nature of the fire regime varied according to site conditions, such as the size of fire compartments and soil types. Fire frequency and seasonality of fires were also variable over time, reflecting the combined influence of climatic conditions and anthropogenic ignitions. Fire-scarred samples were not particularly abundant at any of the sites, and most scars were embedded deep inside the tree rather than on obvious, fire-scarred surfaces. Trauma rings that are abundant at the root-stem interface may be useful indicators of injury from fire, but more samples will be required to verify this hypothesis.

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