Abstract
The campus of the University of West Florida (UWF) was constructed among second-growth longleaf pine (Pinus palustris) stands that survived extensive logging in the Florida Panhandle. Previous studies on longleaf pine on the main UWF campus have estimated, based on a model from old-growth longleaf in southern Georgia, that oldest stems were just under 200 yr old and that > 80% of stems on the main UWF are between 50 and 125 years old. More accurate age data can be obtained from disks collected locally from recently fallen trees. On 16 September 2020, Hurricane Sally impacted UWF as a Category 2 storm, with winds reaching 49 m/sec. Our study took advantage of longleaf pine blowdowns by Sally to obtain cross-sections for age determinations. Two natural areas of the UWF campus were chosen for sampling: the Edward Ball Nature Trail and the Baars-Firestone Wildlife Sanctuary. For each sampled section, diameter at breast height (DBH) and number and width of annual rings were recorded. Based on a total of 50 sampled trees, linear regression revealed a statistically significant (P < 0.00001; R2 = 0.82) relationship between DBH and age. Applying this to DBH measurements of 2,165 stems on the main campus indicates that the oldest longleaf pines are ~ 130 years old (mean age = 63.9 ± 0.4 yr), consistent with cessation of historically widespread harvesting in the region. Mean age for the Trails site (55.7 ± 1.6 yr) was significantly lower than that of the Sanctuary (66.7 ± 2.0 yr), suggesting that they represent sites of contrasting land-use history. Annual growth rates of older pines were mostly negatively correlated with temperature. Directions of stem windthrows did not vary between natural areas and were consistent with characteristics of the eyewall of Hurricane Sally with strongest wind gusts moving from a southeast to northwest direction. This study confirms that college/university campuses can be used as a units of ecological study in a way that takes advantage of stochastic events such as tropical cyclones.
Highlights
Previous work on the campus of the University of West Florida—the UWF CampusEcosystem Study (CES)—has focused on (1) population structure of longleaf pine (Pinus palustris Mill.) on the main campus and effects of burrowing by gopher tortoises (Gopherus polyphemus Daudin) (Gilliam et al 2020) and (2) composition, structure, and soil fertility of chronically-unburned remnant longleaf stands in campus natural areas (Gilliam et al 2021)
Applying this to diameter at breast height (DBH) measures of 2,165 stems on the main campus indicates that the oldest longleaf pines are ~130 years old, consistent with cessation of historically wide-spread harvesting in the region
Direction of stem windthrows did not vary between natural areas and was consistent with characteristics of the eyewall of Hurricane Sally with strongest wind gusts moving from a southeast to northwest direction
Summary
Ecosystem Study (CES)—has focused on (1) population structure of longleaf pine (Pinus palustris Mill.) on the main campus and effects of burrowing by gopher tortoises (Gopherus polyphemus Daudin) (Gilliam et al 2020) and (2) composition, structure, and soil fertility of chronically-unburned remnant longleaf stands in campus natural areas (Gilliam et al 2021). A major impetus for the initial phase of the CES was to assess the size and age structure of longleaf pines on the main campus, comprising the areas of various permanent structures (e.g., classroom and academic department buildings), parking lots, and green spaces. In addition to findings regarding the profound effects that gopher tortoises have on soil fertility and herbaceous plant communities, conclusions of that study suggested that oldest longleaf pines were just under 200 yr old and that >80% of stems on the main UWF are between 50 and 125 years old
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