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Demography of Sarracenia Purpurea in Massachusetts and Vermont 1997-2021

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  • Lead: Aaron Ellison, Nicholas Gotelli
  • Investigators:
  • Contact: Information Manager
  • Start date: 1997
  • End date: 2021
  • Status: complete
  • Location: Hawley Bog (Hawley MA), Molly Bog (Morristown VT)
  • Latitude: +42.57528 to +44.49917 degrees
  • Longitude: -72.88972 to -72.63944 degrees
  • Elevation: 236 to 543 meter
  • Datum: WGS84
  • Taxa: Endothenia daeckeana (pitcher plant moth), Exyra fax (pitcher plant moth), Papaipema appassionata (pitcher plant borer), Sarracenia purpurea (northern pitcher plant)
  • Release date: 2023
  • Language: English
  • EML file: knb-lter-hfr.202.13
  • DOI: digital object identifier
  • EDI: data package
  • DataONE: data package
  • Related links:
  • Study type: long-term measurement, modeling
  • Research topic: biodiversity studies; conservation and management; physiological ecology, population dynamics and species interactions
  • LTER core area: population studies
  • Keywords: carnivorous plants, demography, extinction, population dynamics
  • Abstract:

    The northern pitcher plant Sarracenia purpurea is a model system for forecasting extinction risk in the face of environmental change. We have monitored demographic variables of two mapped cohorts of S. purpurea in ombrotrophic bogs of northern New England from 1997-2005 (Hawley Bog, Massachusetts) and 1997-present (Molly Bog, Vermont). Growth, survivorship, and reproduction are in close balance, and matrix-models with four life stages (seeds, seedlings/juvenile plants, non-flowering adult plants, flowering adults) predicted population growth rates close to zero, with long doubling times. To further assess seed-to-seedling transitions, we measured and weighed Sarracenia seeds, and conducted a greenhouse experiment on density-dependent dynamics of newly germinated seedlings of S. purpurea.

  • Methods:

    Field sampling

    In fall 1997, we located and tagged 400 S. purpurea plants at Hawley Bog and 444 plants at Molly Bog (400 in one area, 44 in another area of the bog); one-half of each marked cohort were "adult" plants (rosette diameters greater than 100 mm), the other half were "juvenile" plants (rosette diameters less than 100 mm). Each year since then (through 2005 at Hawley Bog, when the population was trampled by moose), plants are relocated and measured (as described in A. M. Ellison and N. J. Gotelli, 2001, Proc. Nat. Acad. Sci. 99: 4409-4412), and flowering status, and whether or not the plant has been damaged by herbivores noted. Plants were mapped with transit and stadia rods in 1999.

    Seed size

    Mature seeds of S. purpurea and other recognized species of Sarracenia were collected in the field. Maximum length and width of 100-200 seeds of each species were measured with an ocular micrometer at 100x magnification under a dissecting microscope. A random subset of 20 seeds of each species were individually weighed to the nearest 10 ug.

    Density dependence

    In September 1998, 1000 S. purpurea seeds were randomly scattered in a planting bed (3 x 1 x 0.25 m) filled with milled Sphagnum. Germinated seedlings were individually flagged with toothpicks, and their location was mapped (+- 1 mm). The number of seedling leaves, plant diameter, length of longest leaf, and rosette diameter of each plant were measured in May 1999, June 1999, August 1999, May 2000, June 2000, August 2000, September 2001, and August 2002. Surviving plants in August 2002 were harvested, dried, and weighed after separating roots and shoots. The flowers from the three flowering plants were also dried and weighed.

  • Organization: Harvard Forest. 324 North Main Street, Petersham, MA 01366, USA. Phone (978) 724-3302. Fax (978) 724-3595.

  • Project: The Harvard Forest Long-Term Ecological Research (LTER) program examines ecological dynamics in the New England region resulting from natural disturbances, environmental change, and human impacts. (ROR).

  • Funding: National Science Foundation LTER grants: DEB-8811764, DEB-9411975, DEB-0080592, DEB-0620443, DEB-1237491, DEB-1832210.

  • Use: This dataset is released to the public under Creative Commons CC0 1.0 (No Rights Reserved). Please keep the dataset creators informed of any plans to use the dataset. Consultation with the original investigators is strongly encouraged. Publications and data products that make use of the dataset should include proper acknowledgement.

  • License: Creative Commons Zero v1.0 Universal (CC0-1.0)

  • Citation: Ellison A, Gotelli N. 2023. Demography of Sarracenia Purpurea in Massachusetts and Vermont 1997-2021. Harvard Forest Data Archive: HF202 (v.13). Environmental Data Initiative:

Detailed Metadata

hf202-01: Sarracenica demography data (1997-2021)

  1. site: site name
    • Molly: Molly Bog, Vermont
    • Hawley: Hawley Bog, Massachusetts
  2. plant.num: plant number
  3. init.stage: initial stage
    • A: Adult (rosette > 10cm)
    • J: Juvenile (rosette < 10cm)
  4. group: group, R, G (Molly) – two spatially separate populations; H (dummy variable for Hawley)
    • R: Molly
    • G: Molly
    • H: dummy variable for Hawley
  5. year: sample year
  6. pitchers: number of pitchers (unit: number / missing value: NA)
  7. phyllodes: number of phyllodes (unit: number / missing value: NA)
  8. buds: number of buds (since 2000) (unit: number / missing value: NA)
  9. flowers: number of flowers (unit: number / missing value: NA)
  10. fruits: number of fruits (unit: number / missing value: NA)
  11. damage: damage to flower/fruit (not taken in 2000)
    • 0: none
    • A: abort
    • H: herbivory
    • P: moth damage by Papaipema
    • PE: moth damage by Papaipema + Endothenia
    • E: moth damage by Endothenia
  12. rosette: rosette diamter (since 1998) (unit: millimeter / missing value: NA)
  13. leaf.len: length of leaf (since 1998) (unit: millimeter / missing value: NA)
  14. diam1: mouth diameter (since 1998) (unit: millimeter / missing value: NA)
  15. diam2: mouth diameter (since 1998) (unit: millimeter / missing value: NA)
  16. tube: tube width at widest point (since 2001) (unit: millimeter / missing value: NA)
  17. keel: keel width at widest point (since 2001) (unit: millimeter / missing value: NA)
  18. censor: censoring status for survivorship analysis (Hawley since 2005, Molly since 2008)
    • 1: alive
    • 0: known dead
    • -1: plant missing (cannot assume dead)

hf202-02: Hawley and Molly plant coordinates

  1. site: site name
    • Hawley: Hawley Bog, Massachusetts
    • Molly: Molly Bog, Vermont
  2. plant.num: plant number
  3. group: group, R, G (Molly) – two spatially separate populations; H (dummy variable for Hawley)
    • H: dummy variable for Hawley
    • R: Molly
    • G: Molly
  4. x: location in meters (from survey origin) (unit: meter / missing value: NA)
  5. y: location in meters (from survey origin) (unit: meter / missing value: NA)

hf202-03: Sarracenia seed size data (1997-1998)

  1. species: species of Sarracenia; one of alata, flava, leucophylla, minor, psittacina, purpurea_purpurea, purpurea_venosa, rubra
  2. length: seed length (unit: millimeter / missing value: NA)
  3. width: seed width (unit: millimeter / missing value: NA)
  4. mass: seed mass (for subset of each species) (unit: gram / missing value: NA)

hf202-04: Sarracenia density-dependence coordinates

  1. plant number (matches value in hf202-05-sarr-dd-meas.csv)
  2. x coordinate of location of plant (unit: millimeter / missing value: NA)
  3. y coordinate of location of plant (unit: millimeter / missing value: NA)

hf202-05: Sarracenia density-dependence measurements

  1. plant number (matches value in hf202-04-sarr-dd-coords.csv)
  2. date: date
  3. measure: measurement
    • nleaves: number of leaves
    • leaflen: length of longest leaf
    • rosette: rosette diameter
    • leafdiam1: diameter of pitcher opening; measured in 2001 only);
    • leafdiam2: diameter of pitcher opening, perpendicular to leafdiam1, measured in 2001 only
    • shootmass: oven-dried mass of shoot at harvest in 2002
    • rootmass: oven-dried mass of roots at harvest in 2002
    • flowermass: oven-dried mass of flower at harvest in 2002
  4. units: units of measurement
    • count: count
    • mm: millimeters
    • g: grams
  5. value: value of measurement