Study sites:
Eight of the 11 transect sites were established in January 1977, two additional transect sites were added in January 1978, and one additional transect site in January 1980, all within Archbold's West Section. The eight 1977 transects were placed adjacent to existing mammal trapping transects previously established by James N. Layne. The original intent was to observe and record plant species and plant community responses to fires over time and to correlate vegetation changes with mammal population patterns.
WS20 and WS21 are classified as wet prairies. Wet prairie is an open association with dense grass and sedge cover. At our transects, most cover is by the Florida-endangered cutthroat grass (Coleataenia abscissa). In slightly elevated locations, shrubs such as gallberry (Ilex glabra), fetterbush (Lyonia lucida), shiny blueberry (Vaccinium myrsinites), dwarf huckleberry (Gaylussacia dumosa), and wax myrtle (Morella cerifera) provide considerable coverage. Shrub height is dependent on time-since fire. WS20 is underlain by very poorly drained, Placid fine sand (an Inceptisol). The substrate of the WS21, which includes both wet prairie and flatwoods, varies along the transect lines. Placid fine sand underlies about 22% of the transect’s length and poorly drained Basinger fine sand (an Entisol) accounts for the remaining 78% of substrate.
Flatwoods vary from open savanna-like associations to sites with dense to scattered slash pine (Pinus elliottii) canopies. Groundcover can be dominated by wiregrass (Aristida stricta) on drier sites or by cutthroat grass on more mesic sites with scattered to dense saw palmetto (Serenoa repens), gallberry, and fetterbush. Dwarf live oak (Quercus minima) and sand live oak (Q. geminata) are often present. The density and height of vegetation are dependent on edaphic conditions and time-since fire. About 70% of the WS42 wiregrass flatwoods transect is underlain by Basinger fine sand and 30% by somewhat poorly drained, droughty Satellite fine sand (an Entisol).
Oak scrub is a low shrubby association of predominantly evergreen, xeromorphic plants including scrub oak (Q. inopina), Chapman’s oak (Q. chapmanii), sand live oak, saw palmetto, and scrub palmetto (Sabal etonia). The presence of pine is variable, typically consisting of scattered slash pine and/or sand pine (P. clausa). The height of shrubs varies with edaphic conditions and time-since fire but is often 1-2 m. Oak scrub WS26 is underlain by moderately well-drained, very droughty Duette (Spodosol) sand. WS24 and WS25 are primarily oak scrub but both have embedded areas of rosemary scrub. Basinger fine sand underlies roughly 27% of WS24 and Satellite fine sand accounts for the remaining 73%. Satellite fine sand is the substrate for the entire WS25 transect.
Rosemary scrub is an open community with a shrub layer dominated by Florida rosemary (Ceratiola ericoides), clumps of oaks (especially scrub oak), and scrub palmetto. There is typically little tree canopy except for small silk bay (Persea borbonia var. humilis) and sand pine. The size of bare-ground gaps among shrubs is dependent on time-since fire. Gaps are crucial for forbs including several federally and Florida-endangered endemics: FL jointweed (Polygonum basiramia), Florida gayfeather (Liatris ohlingerae), highlands scrub St. John’s-wort (Hypericum cumulicola), and scrub eryngium (Eryngium cuneifolium). The WS27 rosemary scrub transect is on an ancient dune composed of Satellite fine sand.
Hickory scrub has a dense understory dominated by myrtle oak (Q. myrtifolia), sand live oak, and Chapman’s oak, along with scrub and saw palmettos, and Florida-endemic scrub hickory (Carya floridana). The overstory contains scattered sand pine and/or slash pine. Understory plants include wiregrass, Florida-threatened garberia (Garberia heterophylla), Feay’s palafox (Palafoxia feayi), coastalplain staggerbush (Lyonia fruticosa), and tough bully (Sideroxylon tenax). Understory height is typically less than 3-4 m, but it increases with time-since fire. Hickory scrub transect WS29 is underlain by Duette fine sand.
During January 1977, we determined pre-burn, initial dominance for each species at the above eight transects prior to prescription burning on 21 January 1977.
Two additional transects were added in January 1978. WSP1 transect is classified as wiregrass flatwoods and WSP2 as oak scrub. WSP1 and WSP2 are underlain by moderately well-drained Archbold fine sand (an Entisol). Both transect sites were unburned for an estimated 35 yr. when initially sampled in 1978. These two “unburned controls” were intended to provide measures of vegetation change during prolonged periods without fire. Following the 5th sampling of these stands, both were burned on 26 September 1984 by a railroad-ignited fire.
The final transect, cutthroat grass flatwoods WS30, was sampled initially in January 1980 prior to prescription burning on 25 January 1980. About 93% of this transect is underlain by poorly drained Basinger fine sand and poorly drained Immokalee fine sand (a Spodosol) supports the remaining 7% of the WS30 transect.
Data collection:
We determined the percentage cover (i.e., dominance) of each encountered species at the 11 transect sites by measuring the transect intercepts for each species (to the nearest cm) along the 200-m transect.
Rarefaction analysis indicated that 200 m was adequate to sample stands. The most species-poor wet prairie (WS20) required only 77 m of sampling to reach 90% and 82 m to reach 95% of encountered species. We sampled 90% of encountered species at 116 m and 95% at 122 m at the most species-rich oak/rosemary scrub (WS25) while the most species-rich flatwoods (WSP1) required 111m to reach 90% and 117 m to encounter 95% of sampled species.
Each transect site was sampled at selected times, ranging from five to 12 repeated samplings, during the 38-yr period beginning in 1977 and continuing to 2015. Transects were sampled during January (mid-way during the winter dry season) except for sampling four stands sampled in May 1977 and eight stands in July 1977 to document short-term 4-mo. and 6-mo. vegetation recovery following the initial January 1977 prescription burn.
Each permanent transect used two parallel 100-m transects except at WS27 rosemary scrub transect where three 60-m and one 20-m parallel transects were used to restrict sampling to rosemary scrub vegetation. In total, we sampled 21,600 m of vegetation during the study. The GPS locations for each transect and each angle aluminum pin that marks the transect are available from the Archbold data manager. Parallel transect lines are marked with angle-aluminum pins at their origins and at 20-m intervals. Each pin is embossed to identify its position within the array of pins (e.g., AS24S-40-m means Abrahamson (A) transect WS24, south transect, 40-m from the origin pin). GPS coordinates of each pin were recorded with a Trimble GPS unit.
