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Harvard Forest Data Archive


Dendrochronological Record in Hemlock Removal Experiment at Harvard Forest 2004-2006

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  • Lead: Peter Bettmann-Kerson, Aaron Ellison
  • Investigators:
  • Contact: Information Manager
  • Start date: 2004
  • End date: 2006
  • Status: completed
  • Location: Simes Tract (Harvard Forest)
  • Latitude: +42.47
  • Longitude: -72.22
  • Elevation: 200 to 240 meter
  • Taxa: Acer spp. (maple), Betula spp. (birch), Ostrya virginiana (ironwood), Pinus strobus (white pine), Quercus spp. (oak), Tsuga canadensis (eastern hemlock)
  • Release date: 2014
  • Revisions:
  • EML file: knb-lter-hfr.86.19
  • DOI: digital object identifier
  • EDI: data package
  • DataONE: data package
  • Related links:
  • Study type: short-term measurement
  • Research topic: large experiments and permanent plot studies
  • LTER core area: primary production, disturbance
  • Keywords: dendrochronology, forest disturbance, hemlock, land use
  • Abstract:

    As part of the long-term goal of reconstructing the stand and land-use history of the Simes Tract at Harvard Forest, trees were cored from the 8 hemlock and hardwood plots in the Hemlock Removal Experiment. Cores were sanded and growth was measured. The data were used for the 2006 senior thesis (Division III paper) of Peter Bettman-Kerson at Hampshire College ("Dendrochronological reconstruction of historical disturbances in a hemlock forest at the Harvard Forest, Petersham, MA"). This dataset is the raw growth data for 230 trees sampled across the 8 plots.

  • Methods:

    Stratified random sampling was used to select which trees to core. Trees were divided into five size classes of 11-20, 21-30, 31-40, 41-50 and 51 cm DBH or larger. At least one tree was sampled at random from each size class where available, and the number of trees selected from each size class was decided based on the relative frequency of that size class out of the total number of stems in the plot. Dead trees and trees less then 10cm DBH were not sampled while trees showing enough decay to make the sample unreadable were replaced with an alternate of the same species and size class where available. In plots 2 and 4, which were logged for the HWA experiment, stump-level transverse segments ("cookies") were used when they were available and stumps were cored where necessary to complete the sampling from these plots. In all of the plots, one core was collected from between one-third and one-half of the stems on the site.

    Cores were collected in July 2004 and October - December 2005, using an increment borer from as close to the ground as possible to maximize the number of years in the sample. Samples were rough-sanded using a random orbit palm sander, after which hard-to-read cores were hand sanded with sand paper up to 380, 660 or 1,200 grains/inch as needed to reveal the rings.

    In the lab, rings on the tree cores were counted from the bark to the center using a binocular microscope to determine the approximate age of each tree. Decades were marked on the core in pencil. Next the annual radial growth was measured using a Velmex tree-ring measuring system (Velmex 2003) and Measure J2X software (VoorTech 2005) which provided measurements accurate to 0.01mm.

    Data were converted from Velmex format to tabular spreadsheet format using program FMT from the dendrochronology program library (University of Arizona Laboratory of Tree Ring Research,

  • 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.

  • Citation:

    Bettmann-Kerson P, Ellison A. 2014. Dendrochronological Record in Hemlock Removal Experiment at Harvard Forest 2004-2006. Harvard Forest Data Archive: HF086 (v.19). Environmental Data Initiative:

Detailed Metadata

hf086-01: dendochronology data

  1. plot: plot of the Hemlock Removal Experiment (1-8)
  2. genus: genus of tree
  3. species: species of tree
  4. code: four-letter abbreviation (genus + species)
  5. tree.num: unique tree identification number (3-769)
  6. year: growth year (1862-2004)
  7. mmperyear: growth increment of tree in millimeters per year (0-15.155) (unit: millimeter / missing value: NA)

hf086-02: R code and csv file to accompany Ellison et al. 2014 paper

  • Compression: zip
  • Format: R Markdown, csv
  • Type: script, document