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South Florida Pollen Data

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Frequently-anticipated questions:

What does this data set describe?

Title: South Florida Pollen Data
Analysis of 209 pollen assemblages from surface samples in ten vegetation types in the Florida Everglades form the basis to identify wetland sub-environments from the pollen record. This calibration dataset makes it possible to infer past trends in hydrology and disturbance regime based on pollen assemblages preserved in sediment cores. Pollen assemblages from sediment cores collected in different vegetation types throughout the Everglades provide evidence on wetland response to natural fluctuations in climate as well as impacts of human alteration of Everglades hydrology. Sediment cores were located primarily in sawgrass marshes, cattail marshes, tree islands, sawgrass ridges, sloughs, marl prairies, and mangroves. The datasets contain raw data on pollen abundance as well as pollen concentration (pollen grains per gram dry sediment).
  1. How should this data set be cited?

    Willard, Debra, 2007, South Florida Pollen Data.

    Online Links:

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -81.25
    East_Bounding_Coordinate: -80.25
    North_Bounding_Coordinate: 26.5
    South_Bounding_Coordinate: 25

  3. What does it look like?

    <https://sofia.usgs.gov/exchange/willard/pollendata-map.gif> (GIF)
    map showing surface sample sites for 1960's, 1995, and 1998
    <https://sofia.usgs.gov/exchange/willard/Willardetal2001sitemapx.gif> (GIF)
    map showing 2001 sampling sites
    <https://sofia.usgs.gov/exchange/willard/Willardetal2002sitemapx.gif> (GIF)
    map showing 2002 sampling sites
    <https://sofia.usgs.gov/exchange/willard/EvergladesCoreMap5-07x.jpg> (JPEG)
    map showing all cores collected through 2007

  4. Does the data set describe conditions during a particular time period?

    Beginning_Date: 1962
    Ending_Date: 2007
    Currentness_Reference: ground condition

  5. What is the general form of this data set?

    Geospatial_Data_Presentation_Form: spreadsheet

  6. How does the data set represent geographic features?

    1. How are geographic features stored in the data set?

      Indirect_Spatial_Reference: South Florida
      This is a Point data set. It contains the following vector data types (SDTS terminology):
      • Point (209)

    2. What coordinate system is used to represent geographic features?

      Horizontal positions are specified in geographic coordinates, that is, latitude and longitude. Latitudes are given to the nearest 0.001. Longitudes are given to the nearest 0.001. Latitude and longitude values are specified in Degrees and decimal minutes.

      The horizontal datum used is North American Datum of 1983.
      The ellipsoid used is Geodetic Reference System 80.
      The semi-major axis of the ellipsoid used is 6378137.
      The flattening of the ellipsoid used is 1/298.257.

  7. How does the data set describe geographic features?

    The data for each collection site include the sample id and raw abundance data for each species identified. In the 1960s dataset, raw abundance was back-calculated from percentage data because original raw data was unavailable. The data for the 1990s dataset include the sample number and map ID and percent abundance for each species. See the individual datasets for the species found at the sites.
    Entity_and_Attribute_Detail_Citation: USGS personnel

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)

    • Debra Willard

  2. Who also contributed to the data set?

    Project personnel included Anne Bates, Christopher Bernhardt, Patrick Buchanan, Margo Corum, Julie Damon, Charles Holmes, David Korejwo, Bryan Landacre, Harry Lerch, Marci Marot, James Murray, William Orem, Tom Sheehan, Neil Waibel, Lisa Weimer (deceased) , and Debra Willard.

  3. To whom should users address questions about the data?

    Debra A Willard
    U.S. Geological Survey
    926A National Center
    Reston, VA 20192

    703 648 5320 (voice)
    703 648 6953 (FAX)

Why was the data set created?

Terrestrial ecosystems of south Florida have undergone numerous human disturbances, ranging from alteration of hydroperiod, fire history, and drainage patterns from the introduction of the canal system to expansion of agricultural activity to the introduction of exotic species, Over historical time, dramatic changes in the ecosystem have been documented and these changes have been attributed to various human activities. However, the natural variability of the ecosystem was unknown and needed to be determined to assess the true impact of human activity on the modern ecosystem. The project was designed to document historical changes in the terrestrial ecosystem quantitatively, to date any changes and determine whether they resulted form documented human activities, and to establish the baseline level of variability on the south Florida ecosystem to estimate whether the observed changes are greater than would occur naturally.

How was the data set created?

  1. From what previous works were the data drawn?

  2. How were the data generated, processed, and modified?

    Date: 1997 (process 1 of 3)
    Coring Procedure

    Sediment cores were collected using a piston corer with a 10 cm diameter core barrel. The core barrel was pushed through the sediments until it contacted the underlying limestone at all sites except in Loxahatchee NWR, where peat thicknesses in excess of 2 meters would require alternative coring strategies. After core collection, sediment was extruded from the core barrel and sampled it at 1 cm increments for the upper 20 cm and at 2 cm increments at greater depths. Sediment lithology was described as samples were extruded. Samples were dried in a 50 deg C oven and subsampled sediments at the base of each core and at 20 cm increments above the base for radiocarbon dating. Bulk peats were dated using conventional radiocarbon dating

    Date: 1997 (process 2 of 3)

    Age models for the last century of deposition are based on 210Pb (lead-210) and, where applicable, first occurrences of pollen of the exotic plant Casuarina which was introduced to south Florida in the late 19th century (Langeland, 1990). Lead-210 (210Pb) activity was measured by alpha spectroscopy using the method outlined in Flynn (1968) in which 210Pb and its progeny, polonium-210 (210Po), are assumed to be in secular equilibrium. Supported 210Pb activity was determined by continuing measurements until activity became constant with depth. Excess 210Pb activity was calculated by subtracting the supported 210Pb activity from the total 210Pb activity. Accumulation rates were calculated by fitting an exponential decay curve to the measured data using least squares optimization and making the assumptions of a constant initial excess lead-210 concentration (the CIC [constant initial concentration] model).

    In pre-20th century sediments, models are derived from linear interpolation between radiocarbon data points obtained on bulk sediment samples, which were calibrated to calendar years using the Pretoria Calibration Procedure (Stuiver et al., 1993; Talma and Vogel, 1993; Vogel et al., 1993). The shorter hydroperiods and shallower water depths on tree-island heads result in seasonal drying and oxidation of sediments. Radiocarbon dates from tree-island head sediments appear to be artificially old relative to those in the tail and adjacent marsh. Cores collected in the near tail, directly downstream from the head, have radiocarbon dates and vegetational trends that are consistent both internally and with adjacent wetlands. Therefore, cores were used from the near tail as our representative sites to detect vegetation changes on teardrop-shaped tree islands and for comparison with patterns documented in the adjacent marsh.

    Date: 2007 (process 3 of 3)
    Analysis of Pollen assemblages

    Approximately 0.5-1.0 gram of dry sediment was used for palynological analysis. Pollen and spores were isolated from these samples using standard palynological techniques (Traverse, 1988; Willard et al, 2001a,b). After drying and weighing samples, Lycopodium marker tablets with known concentrations of Lycopodium spores were added to approximately 0.5 g of sediment for calculation of absolute pollen concentrations (Stockmarr, 1971). The samples were first acetolyzed (9 parts acetic anhydride : 1 part sulfuric acid) in a hot-water bath (100 deg C) for 10 minutes, then neutralized, and treated with 10% KOH in a hot-water bath for 15 minutes. Neutralized samples were sieved with 10 µm and 200 µm sieves, and the 10-200 µm fraction was stained with Bismarck Brown, mixed with warm glycerin jelly, and mounted on microscope slides. Raw data for pollen samples are reposited in the North American Pollen Database (NAPD) at the World Data Center for Paleoclimatology in Boulder, CO (<http://www.ngdc.noaa.gov/paleo/pollen.html>) and at the US Geological Survey South Florida Information Access (SOFIA) site (<https://sofia.usgs.gov>).

    Pollen and spore identification (minimally 300 grains per sample) was based on reference collections of the United States Geological Survey (Reston, VA) and Willard et al. (2004). Absolute pollen concentrations were calculated using the marker-grain method described by Benninghoff (1962). Marker tablets of Lycopodium spores were the source of the exotic grains, and the quantity of Lycopodium spores in the marker tablets was determined by the manufacturer with a Coulter Counter following the procedures of Stockmarr (1973). Absolute pollen concentration was calculated using the formula (Maher, 1981):

    Pconc=RM/V, Where: Pconc = pollen per gram dry sediment; R=pollen grains counted/marker grains counted; M=marker grains added; V=dry weight of sediment

    The interpretations of past plant communities are based on the quantitative method of modern analogs (Overpeck et al., 1985). We calculated squared chord distance (SCD) between down-core pollen assemblages and a suite of 197 surface samples collected throughout southern Florida in the early 1960s and 1995-2002 (Willard et al., 2001b and this research) to define the similarity between each fossil and modern pollen assemblage. Internal comparison among surface samples from ten vegetation types indicates that samples with SCD values < 0.15 may be considered close analogs (Willard et al., 2001b). If analogs were present for a fossil assemblage, the source vegetation for the fossil assemblage was identified as one of the twelve types represented in the modern database. Cores were divided into pollen zones based on a combination of visual inspection, objective zonation using CONISS (Grimm, 1992), and modern analogs.

    Person who carried out this activity:

    Debra A Willard
    U.S. Geological Survey
    926A National Center
    Reston, VA 20192

    703 648 5320 (voice)
    703 648 6953 (FAX)

  3. What similar or related data should the user be aware of?

    Willard, Debra A. Weimer, Lisa M., 1997, Palynological Census Data from Surface Samples in South Florida: USGS Open-File Report 97-0867, U.S. Geological Survey, Reston, VA.

    Online Links:

    Willard, Debra A., 1997, Pollen Census Data from Southern Florida: Sites Along an Nutrient Gradient in Water Conservation Area 2A: USGS Open-File Report 97-0497, U.S. Geological Survey, Reston, VA.

    Online Links:

    Willard, Debra A. Bernhardt, Christopher E.; , 2004, Atlas of Pollen and Spores of the Florida Everglades: Palynology 28, American Association of Stratigraphic Palynologists, Arlington, TX.

    Online Links:

    Posted with permission from Palynology and the American Association of Stratigraphic Palynologists
    Marshall, Curtis H. Pielke, Roger A., Sr.; Stey, 200401, The Impact of Anthropogenic Land-Cover Change on the Florida Peninsula Sea Breezes and Warm Season Sensible Weather: Monthly Weather Review v. 132, n. 1, American Meterological Society, Boston, MA.

    Online Links:

    Permission to post a copy of this work on the SOFIA server has been provided by the American Meterological Society
    Willard, Debra A. Weimer, Lisa M.; Riegel, W., 2001, Pollen assemblages as paleoenvironmental proxies in the Florida Everglades: Review of Palaeobotany and Palynology v. 113, n. 4, Elsevier Science B.V., Amsterdam, The Netherlands.

    Online Links:

    The full article is available via journal subscription or single article purchase. The abstract may be viewed on the Science Direct website by selecting the volume and issue number.
    Willard, D. A. Holmes, C. W.; Korvela, M. , 200302, Paleoecological Insights on Fixed Tree Island Development in the Florida Everglades: I. Environmental Controls: Kluwer Academic Publishers, Dordrecht, Netherlands.

    Online Links:

    in Tree Islands of the Everglades

    Sklar, F. H. and van der Valk A. (editors)

    Bernhardt, C. E. Willard, D. A.; Marot, M.; , 2004, Anthropogenic and natural variation in Ridge and Slough pollen assemblages: USGS Open-File Report 2004-1448, U.S. Geological Survey, Reston, VA.

    Online Links:

    Willard, D. A. Holmes, C. W.; Weimer, L. M, 2001, The Florida Everglades Ecosystem: Climatic and Anthropogenic Impacts over the Last Two Millenia: Bulletins of American Paleontology v. 361, Paleontological Research Institute, Ithica, NY.

    Other_Citation_Details: in Paleoecology of South Florida, B. R. Wardlaw, ed.
    Grimm, E. C., 1992, CONISS: a Fortran 77 program for stratigraphically constrained cluster analysis by the mothod of incremental sum of squares: Computers & Geosciences v. 13, issue 1, Elsevier Science, Ltd., Amsterdam, The Netherlands.

    Online Links:

    The abstract may be viewed online at the Science Direct website. The full article is available for purchase from the Science Direct website.
    Traverse, A., 1988, Paleopalynology: Unwin Hyman, Boston, MA.

    Stockmarr, J., 1971, Tablets with spores used in absolute pollen analysis: Pollen et Spores v. 13, Museum national d'histoire naturelle, Paris, France.

    Overpeck, J. T. Webb, III, T.; Prentice, I., 1985, Quantitative interpretation of fossil pollen spectra: Dissimilarity coefficients and the method of modern analogs: Quaternary Research v 23, issue 1, Elsevier Science, Ltd., Amsterdam, Netherlands.

    Online Links:

    The abstract may be viewed online at the Science Direct website. The full article is available for purchase from the Science Direct website.
    Riegel, W. L., 1965, Palynology of environments of peat formation in southwestern Florida: The Pennsylvania State University, University Park, PA.

    Willard, D. A., 2004, Tree Islands of the Florida Everglades - Long-term stability and response to hydrologic change: USGS Fact Sheet 2004-3095, U.S. Geological Survey, Reston, VA.

    Online Links:

    Bernhardt, C.E Willard, D. A., 2007, Marl prairie vegetation response to 20th century hydrologic change: USGS Open-File Report 2006-1355, U.S. Geological Survey, Reston, VA.

    Online Links:

    Willard, D. A. Cronin, T. M., 2007, Paleoecology and ecosystem restoration: case studies from Chesapeake Bay and the Florida Everglades: Frontiers in Ecology and the Environment vol. 5, issue 9, Ecological Society of America, ithica, NY.

    Online Links:

    The full article is available via journal subscription or single article purchase. The abstract may be viewed at the URL below by selecting the article.
    Willard, D. A. Bernhardt, C. E.; Holmes, C, 2006, Response of Everglades tree islands to environmental change: Ecological Monographs v. 76, n. 4, Ecological Society of America, Ithica, NY.

    Online Links:

    The full article is available via journal subscription or single article purchase. The abstract may be viewed at the URL below by selecting the article.
    Langeland, K., 1990, Exotic Woody Plant Control Florida: Circular 868, Florida Coooperative Extension Service, Florida.

    Flynn, W. W., 1968, The determination of low levels of polonium-210 in environmental materials: Analytica Chimica Acta v. 43, Elsevier B. V., Amsterdam, The Netherlands.

    The abstract may be viewed online at the Science Direct website. The full article is available for purchase from the Science Direct website.
    Stuiver, M. Reimer, P. J., 1993, Extended 14C database and revised CALIB 3.0 14C age calibration program: Radiocarbon v. 35, n. 1.

    Talma, A. S. Vogel, J. C., 1993, A simplified approach to calibrating C14 dates: Radiocarbon v. 35, n. 2, University of Arizona, Tucson, AZ.

How reliable are the data; what problems remain in the data set?

  1. How well have the observations been checked?

  2. How accurate are the geographic locations?

  3. How accurate are the heights or depths?

  4. Where are the gaps in the data? What is missing?

    Data from all cores were used in absolute pollen concentration calculations

  5. How consistent are the relationships among the observations, including topology?

    For 12 of the sites from the 1960's, original raw data on total pollen grains was unavailable so back-calculations from percentages in Riegel, 1965 (Doctoral thesis, The Pennsylvania State University) to original counts were unavailable.

How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?

Access_Constraints: none
Use_Constraints: none

  1. Who distributes the data set? (Distributor 1 of 1)

    Heather S.Henkel
    U.S. Geological Survey
    600 Fourth St. South
    St. Petersburg, FL 33701

    727 803-8747 ext 3028 (voice)
    727 803-2030 (FAX)

  2. What's the catalog number I need to order this data set?

    South Florida Pollen Data

  3. What legal disclaimers am I supposed to read?

    The data have no implied or explicit guarantees

  4. How can I download or order the data?

Who wrote the metadata?

Last modified: 28-Apr-2008
Metadata author:
Heather Henkel
U.S. Geological Survey
600 Fourth Street South
St. Petersburg, FL 33701

727 803-8747 ext 3028 (voice)
727 803-2030 (FAX)

Metadata standard:
Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)

This page is <https://sofia.usgs.gov/metadata/sflwww/sfl_pollen_data.faq.html>

U.S. Department of the Interior, U.S. Geological Survey
Comments and suggestions? Contact: Heather Henkel - Webmaster
Generated by mp version 2.8.18 on Mon Apr 28 09:29:08 2008