Harvard Forest

Data Archive

HF352

Lymantria dispar Defoliation and Mortality Survey at the Quabbin Watershed in Central Massachusetts 2017-2022

Related Publications

Data

• hf352-01: plots (preview)
• hf352-02: trees (preview)
• hf352-03: understory vegetation (preview)
• hf352-04: oak regeneration (preview)
• hf352-05: hotspot species codes (preview)

Overview

• Lead: Audrey Barker Plotkin, Richard MacLean, Charlotte Malmborg, Valerie Pasquarella, Dominick Sullivan
• Investigators: Derek Beard, Ken Canfield, Virginia Dautreuil, Herm Eck, Helen Johnson, Brian Keevan, Matthew Pena, Grace Shiffrin, Steven Wood
• Contact: Information Manager
• Start date: 2017
• End date: 2022
• 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: 2025
• Language: English
• EML file: knb-lter-hfr.352.5
• DOI: digital object identifier
• EDI: data package
• DataONE: data package
• Related links:
• Leaf and Soil Nitrogen Following Lymantria dispar Defoliation in Central Massachusetts 2018-2019
• Oak Forest Response to Lymantria dispar Defoliation in Central Massachusetts since 2019
• Nonstructural Carbohydrates in Defoliated Oaks in Central Massachusetts 2019-2020
• 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. In 2022, we returned to 204 of these plots to assess oak mortality, understory vegetation, and oak regeneration.

• 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.

  In 2022, we returned to a stratified random sample of 204 of these plots, selected to represent a range of defoliation intensity in 2017 and be distributed among the six hotspots. We navigated to each selected plot, and recorded latitude and longitude from a hand-held Garmin GPS. For each plot, we recorded slope, aspect, evidence of recent timber harvest (e.g. fresh stumps), and presence/absence of invasive plant species. As in 2017, we used a 10BAF prism to select trees to measure. For each tree, we recorded species; condition (live or dead); canopy dieback class (1 = 0-25% canopy dieback, 2 = 25-50% canopy dieback, 3 = 50-75% canopy dieback, 4 = 75-100% canopy dieback); diameter at breast height (to nearest 0.1 cm); canopy exposure (1 = full sun, 2 = partially shaded, 3 = mostly shaded). For oaks only, we recorded presence or absence of epicormic sprouts, which can be a sign of tree stress. We assessed the cover class (1: 0-25% cover; 2: 25-50% cover; 3:50-75% cover; 4: 75-100% cover) and life-forms (conifer, hardwood tree, shrub, herb, fern/fern allies, graminoids) for ground-layer (less than 1 m tall) and understory (1 m tall) plants, and noted major species. Finally, we recorded presence/absence of oak regeneration in 8 subplots each 1.8 m (6 ft.) radius at 5m and 10m in each cardinal direction from plot center by species (we observed 4 Quercus species across all of these plots) and 3 height classes (less than 0.5 m tall; 0.5 – 1.3 m tall; greater than 1.3 m tall).

• 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: Barker Plotkin A, MacLean R, Malmborg C, Pasquarella V, Sullivan D. 2025. Lymantria dispar Defoliation and Mortality Survey at the Quabbin Watershed in Central Massachusetts 2017-2022. Harvard Forest Data Archive: HF352 (v.5). Environmental Data Initiative: https://doi.org/10.6073/pasta/5d0b9ef91ed85c0aed5778d2e14cd596.

Detailed Metadata

hf352-01: plots

1. hotspot: one of six clusters of sample points
2. point: sample point within each cluster
3. latitude_2017: latitude (decimal degrees) of sample point in 2017 (unit: dimensionless / missing value: NA)
4. longitude_2017: longitude (decimal degrees) of sample point in 2017 (unit: dimensionless / missing value: NA)
5. acres: size of forest stand within which the plot is located (unit: acre / missing value: NA)
6. forest_type: stand type
   • Wp: white pine
   • WpHd: white pine/hardwood
   • WpOk: white pine/oak
   • Ro: red oak
   • OkHd: oak/hardwood
   • OkMx: oak mixed on a dry site
   • BbRm: black birch/red maple/cherry
   • NrHd: northern hardwoods (ash sugar maple yellow birch)
   • Rm: red maple
7. meas_2017: was the plot sampled in 2017
   • 1: yes
   • 0: no
8. date_2017: date plot was measured in 2017
9. observ_2017: initials of the person measuring the plot
10. latitude_2022: we navigated to the lat/long collected in 2017 but we recorded lat/long of the center of the sample plot in 2022 as well because GPS precision has some error (decimal degrees) (unit: dimensionless / missing value: NA)
11. longitude_2022: we navigated to the lat/long collected in 2017 but we recorded lat/long of the center of the sample plot in 2022 as well because GPS precision has some error (decimal degrees) (unit: dimensionless / missing value: NA)
12. meas_2022: was the plot sampled in 2022
    • 1: yes
    • 0: no
13. date.2022: date plot was measured in 2022
14. observ_2022: initials of the person measuring the plot
15. slope_degrees_2022: estimated slope in degrees (a few plots listed as <91>gentle<92> were converted to 2 degrees) (unit: dimensionless / missing value: NA)
16. aspect_2022: aspect (N, E, S, W, NW, NE, SE, SW, flat)
17. invasives_2022: invasive plants present in plot
    • yes: invasive plants present in plot
    • no: no invasive plants present in plot
18. recent_harv_plot: did we see evidence of recent timber harvest when we measured the plot in 2022
    • yes: evidence of recent timber harvest
    • no: no evidence of recent timber harvest
19. harv_since_2017_GIS: plot within polygon indicated as harvest with completed date between 2017 and July 2022 (harvest polygon shapefile provided by Quabbin forester)
    • yes: plot within polygon indicated as harvest completed between 2017 and 2022
    • no: plot not within polygon indicated as harvest completed between 2017 and 2023
20. notes_2022: observations about the plot

hf352-02: trees

1. hotspot: one of six clusters of sample points
2. point: sample point within each cluster
3. year: year of measurement
4. genusp: first four letters of the genus and first two letters of the species of tree
   • ACERRU: Acer rubrum
   • ACERSA: Acer saccharum
   • AMELLA: Amelanchier sp.
   • BETUAL: Betula alleghaniensis
   • BETULE: Betula lenta
   • BETUPA: Betula papyrifera
   • CARYSP: Carya sp.
   • FAGUGR: Fagus grandifolia
   • FRAXAM: Fraxinus americana
   • FRAXNI: Fraxinus nigra
   • HARD: Hardwood, species unknown
   • LARILA: Larix laricina
   • NYSSSY: Nyssa sylvatica
   • OSTRVI: Ostrya virginiana
   • PICEAB: Picea abies
   • PICERU: Picea rubens
   • PINURE: Pinus resinosa
   • PINUST: Pinus strobus
   • POPUSP: Populus sp.
   • PRUNSE: Prunus serotina
   • QUERAL: Quercus alba
   • QUERBI: Quercus bicolor
   • QUERCO: Quercus coccinea
   • QUERPR: Quercus prinus
   • QUERRU: Quercus rubra
   • QUERVE: Quercus velutina
   • TSUGCA: Tsuga canadensis
   • ULMUAM: Ulmus americana
   • UNKNWN: unknown
5. dbh_cm: diameter at breast height (1.37 m) in centimeters (note: 2017 data originally recorded to the nearest inch) (unit: centimeter / missing value: NA)
6. 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
7. ref_clss_2017: refoliation class (i.e. how much foliage the tree has at the end of the growing season after Lymantria dispar defoliation in 2017)
   • 1: 75-100% foliage
   • 2: 50-75% foliage
   • 3: 25-50% foliage
   • 4: 0-25% foliage
8. conf_2017: how confident is the observer in their 2017 refoliation classification
   • 1: high confidence
   • 2: medium confidence
   • 3: low confidence
9. cond_2022: tree condition in 2022 (not recorded in 2017; most trees were alive but check individual tree notes in 2017 for some likely dead trees)
   • L: live
   • D: dead
10. dieback_2022: visual estimate of how much of the tree crown is recently dead
    • 1: 0-25% crown dieback
    • 2: 25-50% crown dieback
    • 3: 50-75% crown dieback
    • 4: 75-100% crown dieback
11. epi_sprt_2022: for oaks (Quercus) only, whether epicormic sprouts are present (yes) or absent (no)
    • yes: present
    • no: absent
12. notes: notes about the tree

hf352-03: understory vegetation

1. hotspot: one of six clusters of sample points
2. point: sample point within each cluster
3. type: type of understory
   • all: any understory vegetation (used in 2017)
   • g: vegetation less than 1 m tall (used in 2022)
   • u: understory vegetation greater than 1 m tall (used in 2022)
4. year: year (2017 or 2022)
5. conifer: conifer
   • 1: conifer trees present
   • 0: conifer trees absent or uncommon
6. hardwood: hardwood
   • 1: hardwood trees present
   • 0: hardwood trees absent or uncommon
7. shrub: shrub
   • 1: shrubs present
   • 0: shrubs absent or uncommon
8. herb: herb (not recorded in 2017)
   • 1: herbs present
   • 0: herbs absent or uncommon
9. fern_allies: ferns or fern allies
   • 1: ferns and/or fern allies present
   • 0: ferns and/or fern allies absent or uncommon
10. gram: graminoids (not recorded in 2017)
    • 1: graminoids present
    • 0: graminoids absent or uncommon
11. cover_cl: cover class (2017 metadata had these categories listed in reverse order but we think were used in this way in the field)
    • 1: 0-25% cover
    • 2: 25-50% cover
    • 3: 50-75% cover
    • 4: 75-100% cover
12. major_species1: (2022 only) prominent species in plot, recorded as first 4 letters of genus and first 2 letters of species (see hotspot species codes for other ways of coding)
13. major_species2: (2022 only) prominent species in plot, recorded as first 4 letters of genus and first 2 letters of species (see hotspot species codes for other ways of coding)
14. major_species3: (2022 only) prominent species in plot, recorded as first 4 letters of genus and first 2 letters of species (see hotspot species codes for other ways of coding)
15. major_species4: (2022 only) prominent species in plot, recorded as first 4 letters of genus and first 2 letters of species (see hotspot species codes for other ways of coding)
16. notes: (2022 only) notes about understory vegetation in the plot

hf352-04: oak regeneration

1. hotspot: one of six clusters of sample points
2. point: sample point within each cluster
3. loc: cardinal direction (N, E, S, W) and distance (5 or 10 m) of the subplot from the plot center
4. size: height class of tree
   • 1: less than 0.5 m tall
   • 2: 0.5 - 1.3 m tall
   • 3: greater than 1.3 m tall
5. RO: presence or absence of red oak, Quercus rubra
   • 1: presence of red oak
   • 0: absence of red oak
6. BO: presence or absence of black oak, Quercus velutina
   • 1: presence of black oak
   • 0: absence of black oak
7. WO: presence or absence of white oak, Quercus alba
   • 1: presence of white oak
   • 0: absence of white oak
8. CO: presence or absence of chestnut oak, Quercus prinus
   • 1: presence of chestnut oak
   • 0: absence of chestnut oak

hf352-05: hotspot species codes

1. USFSCode: US Forest Service numerical code (not all species have one)
2. Common_Name: common name
3. Hotspot2017_code: code used on 2017 hotspot data sheets
4. Hotspot2022_code: code used on 2022 hotspot data sheets
5. Scientific_Name: Genus species
6. gesp: abbreviation, typically first two letters of genus and first two letters of species for trees or first three letters of genus and first three letters of species for understory plants
7. host_class: susceptibility to spongy moth defoliation based on Liebhold, A. M., Gottschalk, K. W., Muzikam, R.-M., Montgomery, M. E., Young, R., O'Day, K., & Kelley, B. (1995). Suitability of North American Tree Species to the Gypsy Moth
   • 1: susceptible
   • 2: resistant
   • 3: immune
8. genusp: first four letters of genus and first two letters of species
9. allometry_source: if available, source of allometry to estimate aboveground biomass