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Harvard Forest Data Archive


Lymantria dispar Defoliation Survey at the Quabbin Watershed in Central Massachusetts 2017

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  • Lead: Richard MacLean, Valerie Pasquarella, Audrey Barker Plotkin
  • Investigators: Derek Beard, Ken Canfield, Virginia Dautreuil, Herm Eck, Helen Johnson, Brian Keevan, Steven Wood
  • Contact: Information Manager
  • Start date: 2017
  • End date: 2017
  • Status: complete
  • Location: Central Massachusetts
  • Latitude: +42.31 to +42.44 degrees
  • Longitude: -72.3955 to -72.2314 degrees
  • Elevation: 160 to 375 meter
  • Datum: WGS84
  • Taxa: Quercus rubra (red oak), Quercus alba (white oak), Lymantria dispar
  • Release date: 2023
  • Language: English
  • EML file: knb-lter-hfr.352.4
  • DOI: digital object identifier
  • EDI: data package
  • DataONE: data package
  • Related links:
  • Study type: short-term measurement
  • Research topic: invasive plants, pests and pathogens; physiological ecology, population dynamics and species interactions
  • LTER core area: population studies, disturbance patterns
  • Keywords: defoliation, disturbance, invasive species, mortality, oak
  • Abstract:

    For most of the 20th century, the invasive Lymantria dispar was the most serious insect threat to forests and shade trees in the northeastern United States, but outbreaks have been sporadic and light since 1989, after the successful establishment of a fungal pathogen, Entomophaga maimaiga. However, in 2016 a surprising new outbreak of Lymantria dispar began in southern New England, resulting in dramatic oak (Quercus spp.) mortality across thousands of forested hectares by 2018. In 2017, during the height of the outbreak, a rapid assessment of defoliation across 486 plots in six clusters (aka ‘hotspots’) across the Quabbin Watershed Forest in central Massachusetts was conducted. These sample points can be related to satellite-based defoliation estimates, and the tree and site data analyzed for predictors of defoliation severity.

  • Methods:

    We examined late-season Lymantria dispar damage in 2017 by selecting six ~350 hectare “hotspots” representing a range of forest types and defoliation severity (based on Landsat change-in-condition scores; Pasquarella, V.J., Bradley, B.A. and Woodcock, C.E., 2017. Forests, 8(8), p.275) across the Quabbin Reservoir Watershed. Within each hotspot, we identified and sampled 100 random points on the ground using horizontal point sampling between 21 September and 6 October 2017, before canopy senescence. For each tree at a point, we recorded species,; defoliation class (1 = 75-100% foliage remaining, 2 = 50-75% foliage, 3 = 25-50% foliage, 4 = 0-25% foliage); diameter at breast height (by 5 cm size classes); and canopy exposure (1 = full sun, 2 = partially shaded, 3 = mostly shaded). The defoliation estimate for each tree represented net canopy damage after defoliation, including any recovery of new foliage after cessation of Lymantria dispar larval feeding ended in early July. Because of time constraints, we completed sampling was completed for only 486 of the 600 points. Of these, three points had no trees because of recent timber harvest.

  • 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: MacLean R, Pasquarella V, Barker Plotkin A. 2023. Lymantria dispar Defoliation Survey at the Quabbin Watershed in Central Massachusetts 2017. Harvard Forest Data Archive: HF352 (v.4). Environmental Data Initiative:

Detailed Metadata

hf352-01: measured points

  1. hotspot: one of six clusters of sample points
  2. point: sample point within each cluster
  3. undstry: most common understory vegetation type
    • 1: conifer trees
    • 2: hardwood trees
    • 3: mixed conifer and hardwood trees
    • 4: shrubs
    • 5: ferns
  4. undstry2: second most common understory vegetation type (if any)
    • 1: conifer trees
    • 2: hardwood trees
    • 3: mixed conifer and hardwood trees
    • 4: shrubs
    • 5: ferns
  5. und.per: understory vegetation coverage
    • 1: 75-100% cover
    • 2: 50-75% cover
    • 3: 25-50% cover
    • 4: 0-25% cover
  6. date: date
  7. observ: initials of the person who collected the data at this point
  8. baf: basal area factor used (e.g. 10 means that each tree measured represents 10 square feet per acre of basal area)

hf352-02: point location

  1. hotspot: one of six clusters of sample points
  2. point: sample point within each cluster
  3. latitude: latitude of the point (unit: degree / missing value: NA)
  4. longitude: longitude of the point (unit: degree / missing value: NA)
  5. acres: size in acres of stand that the point is located in (unit: acre / missing value: NA)
  6. code: forest type number
  7. forest type abbreviated
  8. type: forest type full name

hf352-03: trees

  1. hotspot: one of six clusters of sample points
  2. page: refers to the page of the paper data sheets
  3. line: refers to the line on the page of the paper data sheets
  4. point: sample point within each cluster
  5. spp: species
  6. dbh: diameter at breast height of the tree in inches (unit: inch / missing value: NA)
  7. cnp.exp: canopy exposure of the tree
    • 1: full sky exposure
    • 2: canopy partially obscured by taller trees
    • 3: canopy mostly obscured by taller trees
  8. refoliation class (i.e. how much foliage the tree has at the end of the growing season after Lymantria dispar defoliation)
    • 1: 75-100% foliage
    • 2: 50-75% foliage
    • 3: 25-50% foliage
    • 4: 0-25% foliage
  9. conf: how confident is the observer in their refoliation classification
    • 1: high confidence
    • 2: medium confidence
    • 3: low confidence
  10. notes: notes about the tree

hf352-04: tree and plot data wrangling

  • Compression: none
  • Format: R Markdown
  • Type: script