Comparison of Changes in Oak-Saw Palmetto Scrub Openings
By comparing data, including area and species composition, before and after a prescribed burn, management of the scrub is possible. Results showed that Galactia elliottia was one of the first species to respond in terms of growth. The area of recently burned openings was much greater than that of the previously burned openings. This knowledge can help with the management of scrub.
Above: Measuring vegetation cover along the major axis of the elliptical opening.
Background
Management of the oak – saw palmetto scrub is critical for the survival of several endangered species, like the Florida Scrub – Jay (Aphelocoma coerulescens), and the gopher tortoise (Gopherus polyphemus). Scrub vegetation varies depending on the region, yet it also varies locally within regions (Myers 1990, Schmalzer 1999). Evergreen oaks, palmettos, and vines dominate the vegetation of scrub in Florida (Myers 1990, Schmalzer 2003). This environment is naturally controlled by fires caused by frequent lightning strikes. At Kennedy Space Center (KSC), these fires are simulated by conducting prescribed burns. Piles of oak stems help to burn the scrub during this restoration process. These piles cause openings to appear within the scrub. Prescribed burning of scrub vegetation at the study site on Kennedy Space Center (KSC)/ Merritt Island National Wildlife Refuge (MINWR) began in 1993.
Methods
The location of this study was two areas between State Route 3 and WSEG Rd. There was a total of eleven openings, seven of which burned this past May. The lengths of the major and minor axes of these openings were measured to determine the area. The current area was measured by subtracting the encroachment length of surrounding vegetation. The species occurring on the major axis were also measured. Cover data were summarized as the percent cover of each species. The linear association between area and time since burning was analyzed by performing a Pearson Correlation. A paired sample t – test was calculated to test for a significant difference (p = 0.05) in areas remaining open before and after the last burn.
Results and Figures
• In 2003, after ten years of growth, Quercus geminata was the most abundant vegetation cover in openings (Figure 1).
• Galactia elliottii was the most abundant vegetation cover in openings after the 2004 burn (Figure 1).
• Opening area declined significantly from 1993-2003 (Figure 2): Pearson Correlation coefficient r = -0.626 with p value of 0.01.
• Openings that burned in 1993 but not 2004 (Figure 3) did not differ significantly in open area between 2003 and 2004 (paired t- test, t = 2.28, p > 0.05, df = 3).
• Openings that burned in 2004 (Figure 4) differed significantly in area remaining open between 2003 and 2004 (paired t- test, t = 3.77, p = 0.05, df = 6).
Author: Antonnine R. Cooper, Oakwood College
Principal Investigators: Paul Schmalzer, Dynamac Corporation
Click here to download a printable Microsoft PowerPoint version of this research.
|
