DOI: 10.5061/dryad.m0cfxppcf
title: Repeated tree inventories of pine forests in South Florida's Big Cypress National Preserve

description: The natural forest ecosystems of South Florida, USA, support a high
 biodiversity of plant and animal species and provide valuable ecosystem
 services. However, these ecosystems remain poorly represented in global
 studies, primarily due to a paucity of standardized data. Here, we present
 previously unpublished data from 332 censuses of 54 permanent 1-hectare
 tree inventory plots in the Racoon Point area of Big Cypress National
 Preserve, Florida, USA, including a total of nearly 100,000 measurements
 (diameter or height) of &gt;17,000 individual living trees and palms
 (with additional measurements of nearly 6,000 dead pine snags) collected
 sporadically over a 19-year period (1993 – 2012). These data, which were
 originally collected as part of a project to investigate tree responses to
 different experimental burning regimes, provide unique insight into the
 diversity, composition, structure, and dynamics of South Florida’s unique
 and endangered pine forest ecosystems.  Data files include the
 species identity, size (dbh = diameter at breast height), and location of
 all trees ≥5 cm dbh in 54 individual tree plots. Additional data are
 provided about heights of palm trees, and the location and burn history of
 each plot. Users are encouraged to cite this dataset.
description: The Raccoon Point area in eastern Big Cypress National Preserve
 is the largest remaining area of mature south Florida slash pine
 (<em>P. elliottii var. densa</em>) forest, having escaped the
 logging activities of 1900-1960 (Patterson & Robertson, 1981). The
 pinelands consist of a mosaic of small, slightly elevated and dryer
 "islands" isolated among wetland swamp areas of dwarf cypress
 prairies and cypress domes. The isolation and inaccessibility of the
 Raccoon Point pine islands provided <em>de facto</em>
 protection against logging. However, the federal government did not
 acquire the mineral rights in Big Cypress when the preserve was created in
 1974 and in 1977 Exxon Company, USA, constructed an all-weather private
 access road running north from U.S. Highway 41 to multiple active oil well
 pads in the Raccoon Point oil field in BCNP. The study
 area surrounds the Raccoon Point oil field. It is divided into 18
 experimental burn units. Each burn unit includes at least 50 ha of pine
 forest. Within each unit, three permanent 1-ha tree plots were established
 and repeatedly censused (Snyder & Belles, 2000) starting in the
 early- to mid-1990s. The experimental burn treatments
 consisted of burning at three seasons (spring, or early wet season
 [May-June], when the largest human-caused or lightning-caused wildfires
 occur; summer, or mid wet season [July-August], when there are frequent,
 but generally smaller, lightning-ignited fires; and winter, or mid dry
 season [December 15- February 15], when conditions are frequently
 favorable for prescribed burning) and two burn frequencies (every 3 years
 and every 6 years) for a total of six treatment combinations. Each
 treatment was replicated three times, with one replicate originally
 scheduled to burn per year for three years. Actual burn treatments did not
 always follow the prescribed schedule due to abnormally wet conditions,
 state-wide burning bans brought on by drought conditions, or the
 occurrence of natural unplanned fires. All pinelands in the Raccoon Point
 study area were burned twice by the National Park Service as initializing
 burns before the start of this study (January 3 - February 9, 1990, and
 February 27 - April 4, 1994). A table of burn dates is included in the
 data files. The permanent 1-hectare tree plots were all
 established between 1993 and 1995 (Snyder & Belles, 2000). Within
 each burn unit, the tree plot locations were chosen by overlaying a grid
 on enlarged aerial photographs and randomly choosing points that fell
 within areas that appeared to be pineland. If it was subsequently
 determined during visits to the field that the area was not large enough
 to contain the 1-ha plot, or if more than 10% of the area was dominated by
 cypress trees, another point was chosen. The final geographic coordinates
 of all 54 tree plots are included in the data files (coordinates indicate
 approximate plot centers). Plots were oriented in a
 north-south direction so that the permanent markers would be easier to
 locate in the future. To set up each 1.0 ha tree plot, an east-west 100 m
 line was first established by driving 60 or 90 cm pieces of 1.3 cm
 diameter steel reinforcement bar (i.e., rebar) into the ground at 0, 25,
 75, and 100 m. Two north-south 100 m lines were then established from the
 25 and 75 m rebars using a double right-angle prism to place 2 additional
 rebar stakes 50 m apart. The two remaining plot corners were put into
 place last. A total of 10 rebar stakes were placed in each plot. In most
 cases a rotary hammer demolition drill was needed to secure the rebar in
 the very hard Tamiami limestone that is close to the surface throughout
 BCNP. Round aluminum tags with unit and plot numbers were wired to the
 four corner stakes of each tree plot. Each tree plot was then divided into
 quarters to make tree mapping more efficient. The quarters were identified
 by compass orientation: NW, NE, SW, and SE. Each quarter was further
 subdivided into halves. A 50 m tape was laid out along the center line
 that separated these two halves. A right-angle prism was used to locate
 the position of each tree along the center line and a second tape was used
 to measure the distance from the center line to the tree. The field
 distances were subsequently adjusted to a single plot-level XY cartesian
 coordinate system (Snyder & Belles, 2000).
 Within each plot, all tree stems with a diameter at breast height
 (dbh) ≥ 5.0 cm and palms with a height to the apical bud ≥ 1.4 m were
 tagged with a round, 3.2 cm diameter, pre-numbered aluminum tag using a
 5.4 cm aluminum nail. The tags were placed on live trees at breast height
 (approximately 1.4 m) and the diameter was measured just above the nail.
 Tags were placed in the most secure location on palm trees (i.e., a smooth
 area of the stem without remnant leaf bases). In addition to live trees,
 dead pine snags were also tagged and measured (Snyder & Belles,
 2000). Data collected on individuals included tag
 number, XY cartesian coordinates within the plot, dbh, and species
 identity. For palms, the height to the apical bud was recorded rather than
 dbh since palm diameters do not increase with age. The heights of palms
 and some trees were measured using a telescoping pole up to a maximum of
 ~6 meters; taller trees were not measured (with the exception of some
 uprooted, but still living, trees that could be measured with measuring
 tapes). Tree plots were recensused between 3 and 10
 times each, with the last censuses completed in 2012 (the last censuses
 for most plots were prior to 2003). During the plot recensuses, it was
 determined whether trees were living or had died since the previous
 census, and the dbhs of all living individuals were remeasured (along with
 dead pine snags). Additional notes were taken on features such as basal
 fire scars on pine trees. Tags were replaced as necessary. In addition,
 all new recruits with dbh ≥ 5.0 cm were measured and tagged. Attempts were
 made to census plots immediately before and after prescribed
 burns. In 2024, the original tree census datasets were
 cleaned and reformatted to facilitate data sharing and statistical
 analyses. Data cleaning consisted primarily of correcting typographic and
 data entry errors (e.g., remove leading and trialing blank spaces, etc.).
 In addition, we screened the dbh data for outlier values; if any value
 appeared to be erroneous based on the other measurements of the same
 individual tree, we adjusted it accordingly (in the vast majority of these
 cases the incorrect values had been recorded in the wrong unit - i.e., 10×
 too small or too large - so the required corrections were obvious).
 Notable to the reformatting, since the dbhs of palms were not measured or
 recorded in the censuses, they were set to 35 cm and 10 cm for
 <em>Sabal palmetto </em>and <em>Serenoa
 repens</em>, which are the approximate mean dbh’s for these species,
 respectively (Jones 1995). Also, all cypress trees were reassigned to
 <em>Taxodium ascendens</em> in accord with updated
 nomenclature. While the censuses did measure dead pine snags, the dbhs for
 all dead trees were set to “NA” in the reformatted data files to minimize
 the risk of including dead trees in aboveground biomass or growth
 estimates. The original dbh values for all stems are included.
 <strong>REFERENCES</strong> Black,
 D. W., & Black, S. (1980). <em>Plants of Big Cypress
 National Preserve: a preliminary checklist of vascular plants</em>:
 US National Park Service, South Florida Research Center, Everglades
 National Park. Duever, M. J. (2005). Big Cypress
 regional ecosystem conceptual ecological model. <em>Wetlands,
 25</em>(4), 843-853. Gunderson, L. H., &
 Loope, L. L. (1982). <em>An Inventory of the Plant Communities in
 the Levee-28 Tieback Area, Big Cypress National Preserve</em>:
 National Park Service, South Florida Research Center, Everglades National
 Park. Jones, D.L. (1995). <em>Palms throughout
 the World</em>. Smithsonian Institution Press, Washington
 DC. Muss, J. D., Austin, D. F., & Snyder, J. R.
 (2003). Plants of the Big Cypress National Preserve, Florida.
 <em>Journal of the Torrey Botanical Society</em>,
 119-142. Patterson, G. A., & Robertson, W. B.
 (1981). <em>Distribution and habitat of the red-cockaded woodpecker
 in Big Cypress National Preserve</em>: National Park Service, South
 Florida Research Center, Everglades National Park.
 Snyder, J. R., & Belles, H. (2000). Long-term study of
 fire season and frequency in pine forest and associated cypress wetlands,
 Big Cypress National Preserve: project description and preliminary data.
 <em>US Geological Survey, Big Cypress National Preserve Field
 Station, Ochopee, Florida</em>. Snyder, J. R.
 (1991). Fire regimes in subtropical south Florida. <em>Proceedings
 of the Tall Timbers Fire Ecology Conference 17</em>,
 303-319.
description: # Data from "Repeated tree inventories of pine forests in south
 Florida USA’s Big Cypress National Preserve"
 [https://doi.org/10.5061/dryad.m0cfxppcf](https://doi.org/10.5061/dryad.m0cfxppcf) Big Cypress National Preserve (BCNP) protects nearly 300,000 hectares of pine forests, hardwood hammock forests, cypress swamps, swamp prairies, and mangroves/estuaries in southwest Florida, USA (Gunderson & Loope, 1982). Combined, these natural habitats support more than 800 native plant species (&gt;140 plant families), including nearly 100 rare and endangered species (Black & Black, 1980; Muss, Austin, & Snyder, 2003). The distribution of habitats and species remain poorly studied but is commonly associated with differences in elevation, and flooding and fire regimes (Duever, 2005; J. R. Snyder, 1991). The forest habitats of BCNP are dominated by Slash Pine (*Pinus elliottii* var. *densa*) and Cypress trees (Bald Cypress [*Taxodium distichum*] and Pond or Dwarf Cypress [*T. ascendens;* formerly *T. distichum var.* imbricarium]. Other notable tree species include Pond Apple (*Annona glabra*), Pop Ash (*Fraxinus caroliniana*), Red Maple (*Acer rubrum*), and Cabbage Palm (*Sabal palmetto*) (Black & Black, 1980; Muss et al., 2003). Prior to the establishment of the preserve, many of the cypress and pine forests of BCNP were logged (primarily for construction and ship building). Today, the forests of BCNP are protected from direct exploitation but remain exposed to large-scale environmental pressures such as climate change and alterations in regional hydrological and fire patterns. As part of a long-term study to document the ecological effects of possible fire management strategies on South Florida’s pinelands, the National Park Service (NPS) and United States Geological Survey (USGS) established a network of 54 permanent 1-hectare tree inventory plots in the Raccoon Point area of BCNP (J. Snyder & Belles, 2000). The main objective of the plot censuses was to provide detailed data on vegetation response to different burning regimes which could be used to refine prescribed burning programs on Department of Interior lands in South Florida. ## Description of the data and file structure The following data files are provided in comma separated values (*.csv) format: RP.Plot_data.csv: ·         TREEKEY: a unique identifier for each tree stem combining the unit, unitplot, and tree tag numbers. ·         UNIT: The burn unit 1-18 containing the plot. ·         UNITPLOT: The plot number 1-3 within each burn unit. ·         PLOT: A unique plot number between 1 and 54. ·         TREETAG: Number recorded on the tree tag; tag numbers are repeated between plots. ·         SP: Species binomial. ·         XCOORD: East-West cartesian coordinate of tree within the plot (in m). ·         YCOORD: North-South cartesian coordinate of tree within the plot (in m). ·         DEAD: Code indicating if tree was alive (=0) or dead (=1) at the time of census. ·         DBH: Diameter at breast height in cm. ·         OBDAT: Observation date; date of measurement (yyyy-mm-dd). ·         CENSUS: Number 1-12 indicating the census number. Since plots had different numbers of censuses and were not censused at the same times, CENSUS should not be used in place of OBDAT for temporal analyses. ·         ORIGDBH: The dbh as recorded in the original census datafiles. ·         TOTHT: Height (m) of the tree or height of the palm’s apical bud tip. RP.Plot_locations.csv: ·         UNIT: The burn unit 1-18 containing the plot. ·         PLOT: A unique plot number between 1 and 54. ·         LONGITUDE: Longitude (in decimal degrees; WGS84 Datum) of the approximate plot center. ·         LATITUDE: Latitude (in decimal degrees; WGS84 Datum) of the approximate plot center. RP.Plot_burndates.csv: ·         UNIT: The burn unit 1-18 containing the plot. ·         PLOT: A unique plot number between 1 and 54. ·         BURNDATE: Recorded date of fire affecting the plot (yyyy-mm-dd). ## Sharing/Access information Users are encouraged to cite this dataset. ## Code/Software No custom code has been used in this study. ## References Black, D. W., & Black, S. (1980). *Plants of Big Cypress National Preserve: a preliminary checklist of vascular plants*: US National Park Service, South Florida Research Center, Everglades National Park. Duever, M. J. (2005). Big Cypress regional ecosystem conceptual ecological model. *Wetlands, 25*(4), 843-853. Gunderson, L. H., & Loope, L. L. (1982). *An Inventory of the Plant Communities in the Levee-28 Tieback Area, Big Cypress National Preserve*: National Park Service, South Florida Research Center, Everglades National Park. Jones, D.L. (1995). *Palms throughout the World*. Smithsonian Institution Press, Washington DC. Muss, J. D., Austin, D. F., & Snyder, J. R. (2003). Plants of the Big Cypress National Preserve, Florida. *Journal of the Torrey Botanical Society*, 119-142. Patterson, G. A., & Robertson, W. B. (1981). *Distribution and habitat of the red-cockaded woodpecker in Big Cypress National Preserve*: National Park Service, South Florida Research Center, Everglades National Park. Snyder, J. R., & Belles, H. (2000). Long-term study of fire season and frequency in pine forest and associated cypress wetlands, Big Cypress National Preserve: project description and preliminary data. *US Geological Survey, Big Cypress National Preserve Field Station, Ochopee, Florida*. Snyder, J. R. (1991). Fire regimes in subtropical south Florida. *Proceedings of the Tall Timbers Fire Ecology Conference 17*, 303-319.