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Harvard Forest Data Archive

HF120

Tree Seed Dispersal in Hemlock Removal Experiment at Harvard Forest 2005

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Data

Overview

  • Lead: Sydne Record, Aaron Ellison
  • Investigators:
  • Contact: Aaron Ellison
  • Start date: 2005
  • End date: 2005
  • Status: completed
  • Location: Prospect Hill Tract (Harvard Forest), Simes Tract (Harvard Forest)
  • Latitude: +42.47 to +42.55
  • Longitude: -72.22 to -72.17
  • Elevation: 200 to 420 meter
  • Taxa: Acer platanoides, Betula lenta, Quercus rubra, Tsuga canadensis
  • Release date: 2009
  • Revisions:
  • EML file: knb-lter-hfr.120.15
  • DOI: digital object identifier
  • Related links:
  • Study type: short-term measurement
  • Research topic: large experiments and permanent plot studies; physiological ecology, population dynamics and species interactions
  • LTER core area: disturbance
  • Keywords: hemlock, hemlock woolly adelgid, seed dispersal, wind
  • Abstract:

    Throughout the northeast, the hemlock woolly adelgid (Adelges tsugae) threatens eastern hemlock (Tsuga canadensis) through direct mortality resulting from infestation followed by defoliation and indirect mortality in the form of pre-emptive logging. The efficacy of regeneration of vegetation following hemlock decline depends upon advance regeneration of seedlings and saplings, seed dispersal, and recruitment. In this study, we investigated (1) whether the basic parameters of height of release and wind velocity affected seed dispersal distance and (2) tested the fit of a basic ballistic model of seed dispersal to empirical data in areas both with and without canopies. We collected empirical data from seed dropping and seed rain experiments at Harvard Forest. Height and wind velocity only affected seed dispersal distance in open areas. Predicted values of dispersal distance generated by the basic ballistic model did not provide a good fit to observed dispersal data. Poor fits of the ballistic model to the data were due to the model’s inability to account for rare, long distance dispersal events. More complex models with additional parameters are necessary to model non-localized seed dispersal.

  • Methods:

    Seed Dropping Experiment

    The open area data were collected in the parking lot of Shaler Hall on 28 of October 2005. The closed canopy data were collected in the forest at the Prospect Hill Tract on 18 November 2005. The study species for the seed dropping experiment were Acer platanoides L. (Norway maple) and Quercus rubra L. (red oak). Seeds were dropped at a range of heights between 0.5 m and 17.0 m. We recorded wind velocity simultaneously as seeds were released and the distance seeds traveled from the point of release.

    Seed Rain Experiment

    The study site was comprised of two 90 x 90 m adjacent plots that are part of the hemlock woolly adelgid, large-scale hemlock removal experiment at the Simes Tract of Harvard Forest. One plot consisted of a control stand (Plot 3) that is dominated by Tsuga canadensis L. (eastern hemlock) and the other plot (Plot 2) consisted of a commercially logged treatment in which all T. canadensis over 20 cm in DBH and all economically profitable hardwoods were logged and removed in the winter and spring of 2005. A total of 57 seed traps were placed every ten meters along three 180 m long transects that traversed the plots from east to west on 17 September 2005. Seeds were collected from traps every two weeks from 14 October to 13 November 2005. The design of the seed traps was biased towards collecting the light, wind dispersed seeds of B. lenta, which began dehiscing from trees in mid-October. Observed dispersal distances of seeds were calculated by mapping the location of trapped seeds in relation to the nearest B. lenta individual. Predicted values of dispersal distances were calculated using a basic ballistic model of seed dispersal.

  • Use:

    This dataset is released to the public under Creative Commons license CC BY (Attribution). Please keep the designated contact person informed of any plans to use the dataset. Consultation or collaboration with the original investigators is strongly encouraged. Publications and data products that make use of the dataset must include proper acknowledgement.

  • Citation:

    Record S, Ellison A. 2009. Tree Seed Dispersal in Hemlock Removal Experiment at Harvard Forest 2005. Harvard Forest Data Archive: HF120.

Detailed Metadata

hf120-01: maple

  1. canopy.type: canopy condition (open versus closed) at the location where we dropped seeds
    • Closed: closed canopy refers to a forested area in the Prospect Hill Tract
    • Open: open canopy refers to the parking lot behind Shaler Hall
  2. height: height in meters at which we dropped each seed (unit: meter / missing value: NA)
  3. wind.velocity: wind velocity in meters/second taken with a digital anemometer as we dropped each seed (unit: metersPerSecond / missing value: NA)
  4. distance: distance in meters that each seed travelled from the point at which we dropped it (unit: meter / missing value: NA)

hf120-02: oak

  1. canopy.type: canopy condition (open versus closed) at the location where we dropped seeds
    • Closed: closed canopy refers to a forested area in the Prospect Hill Tract
    • Open: open canopy refers to the parking lot behind Shaler Hall
  2. height: height in meters at which we dropped each seed (unit: meter / missing value: NA)
  3. wind.velocity: wind velocity in meters/second taken with a digital anemometer as we dropped each seed (unit: metersPerSecond / missing value: NA)
  4. distance: distance in meters that each seed travelled from the point at which we dropped it (unit: meter / missing value: NA)

hf120-03: birch

  1. date: date when we collected seeds off of seed traps
  2. transect: transect that seed trap was placed along
    • A: Transect A
    • B: Transect B
    • C: Transect C
  3. distance: distance in meters of placement of seed trap along transect. Zero meters was at the western edge of the Hemlock Removal Experiment plot 3. The transect extended east through plot 3 til the eastern edge of the Hemlock Removal Experiment plot 2. (unit: meter / missing value: NA)
  4. seeds: number of seeds collected from a trap on a particular date (unit: number / missing value: NA)