Date of Award

8-2016

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Geography

Major Professor

Henri D. Grissino-Mayer

Committee Members

Sally P. Horn, Nicholas N. Nagle, Yingkui Li, Wayne K. Clatterbuck

Abstract

Pine rocklands are fire-prone ecosystems with limited spatial extent, and have experienced reduced area in the previous decades through habitat conversion and urbanization. The purpose of this dissertation research was to evaluate the historical range of variability of fire activity and spatial patterns of fires in a pine rockland ecosystem in the National Key Deer Refuge (NKDR) on Big Pine Key in the Lower Florida Keys. To investigate the temporal and spatial patterns in fire activity, I (1) evaluated the temporal patterns for fires in my study area in the NKDR, (2) analyzed differences in standard fire history metrics since the advent of land management in the 1950s, (3) mapped the spatial extents of fires that scarred > 25% of the recording trees, (4) investigated how regression relationships fire activity and microtopographic parameters changed with aggregated scale, and (5) calculated global and local indications of spatial autocorrelation in the geographic fire-scar data.

The 2011 fire was no more severe than other historic fires in the dataset, and was within a range of expectations for severe fires in the area. The relationships between fire activity and microtopography peaked at approximately 50 m (residual topography p < 0.05; curvature p < 0.10). Finally, spatial autocorrelation analyses found statistically significant (p < 0.01) clustering in the fire-scar data network across the study area, and significant low-clustering (p < 0.05) at the at smaller scales. Recent lack of fire return intervals consistent with pre-management periods confirms the influence that people have had on fire in this ecosystem, and the presence of the neighborhood adjacent to the study area in the south may have dampened fire activity in that area.

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