Harvard Forest

Data Archive

HF424

Oak Forest Response to Lymantria dispar Defoliation in Central Massachusetts since 2019

Related Publications

Data

• hf424-01: plot data (preview)
• hf424-02: tree data (preview)
• hf424-03: defoliation data (preview)
• hf424-04: understory cover (preview)
• hf424-05: saplings (preview)

Overview

• Lead: Audrey Barker Plotkin
• Investigators: Savanna Brown, Emerson Conrad-Rooney, Joseph Elkinton, Sofia Kruszka, Danelle Laflower, Richard MacLean, Jaclyn Matthes, Valerie Pasquarella, Greta VanScoy
• Contact: Information Manager
• Start date: 2019
• End date: 2019
• Status: ongoing
• Location: Quabbin Reservoir, Simes Tract (Harvard Forest), Slab City Tract (Harvard Forest)
• Latitude: +42.46 to +42.53 degrees
• Longitude: -72.32 to -72.17 degrees
• Elevation: 160 to 300 meter
• Datum: WGS84
• Taxa: Quercus spp., Lymantria dispar
• Release date: 2024
• Language: English
• EML file: knb-lter-hfr.424.3
• 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
• Lymantria dispar Defoliation Survey at the Quabbin Watershed in Central Massachusetts 2017
• Nonstructural Carbohydrates in Defoliated Oaks in Central Massachusetts 2019-2020
• Study type: long-term measurement
• Research topic: invasive plants, pests and pathogens; large experiments and permanent plot studies; physiological ecology, population dynamics and species interactions
• LTER core area: primary production, population studies, disturbance patterns,
• Keywords: defoliation, insects, invasive species, mortality, oak, trees
• Abstract:

  Invasive forest insects are a major global change driver, and the Northeastern U.S. is an invasion hotspot. Lymantria dispar is one of the region’s most destructive defoliators. After thirty years of quiescence, a surprisingly severe outbreak began in 2015 in southern New England, and by 2018 had caused dramatic oak mortality across thousands of forested acres.

  Lymantria dispar is considered a generalist, but in New England, oaks (Quercus sp.) are its preferred host trees. Oaks are key overstory trees in eastern North America. In New England, they have been a dominant component of the forest for thousands of years, and play a leading role in providing habitat, timber, and carbon sequestration. However, oak prominence is declining throughout New England.

  The reasons for oak’s decreasing abundance are the subject of lively debate but the role of L. dispar is likely underappreciated. Therefore, we need to understand the causes and consequences of oak dieback and mortality to this disturbance event, so that we can better predict responses to future outbreaks. To address this need, we established a set of permanent plots in central Massachusetts, chosen to capture a range of defoliation severity.

• Methods:

  Ten plots each consisting of three 0.04 ha (20m x 20m) sub-plots were established in oak forests in north-central Massachusetts: eight are on the Quabbin Watershed Forest (Commonwealth of MA), and two are on Harvard Forest property. The plots vary in severity of defoliation during the L. dispar outbreak of 2016-2018. We collected preliminary data on some of the sites in 2018 and established the permanent plots in Spring 2019. The corners of each sub-plot are marked with PVC pipe. Sub-plot 1 is to the north, sub-plot 2 to the southeast, and sub-plot 3 is to the south-west of the overall plot center.

  We estimated defoliation severity based on change-in-condition scores from Pasquarella, Valerie J. (2018). Landsat-based Gypsy Moth Defoliation Assessment (Southern New England) (Version 3.0) [Data set]. Zenodo. https://doi.org/10.5281/zenodo.1493407. For each plot, we used the mean change-in-condition score for the 3x3 set of Landsat pixels (each 30m x 30m) surrounding each plot. For 2016, 2017, and 2018, we calculated the mean change-in-condition score using the actual score (e.g., -2.34499) rather than the binned score (e.g., -2 to -3), using the ‘Focal Statistics’ tool in ArcGIS Spatial Analyst extension. We then extracted that mean score for each year for each plot, using the ‘Extract Multi Values to Points’ tool in ArcGIS Spatial Analyst extension. Finally, we summed the values for 2016, 2017, and 2018 to get a cumulative defoliation severity score for each plot.

  Within each plot, live trees with a diameter greater than 5.0 centimeters were tagged and assessed for crown dieback, species, DBH, canopy exposure, and percent defoliation. Dead trees with a diameter greater than 15.0 centimeters were tagged and assessed for species and canopy exposure. In 2019, a follow-up assessment of percent defoliation was conducted each week until mid-July, and crown dieback was re-assessed in August-September 2019. In 2020 and 2021, we recorded oak crown dieback each summer.

  In August-September 2019, we collected increment cores from all trees greater than 20 cm dbh. In addition, we cored every third tree in the 10-20cm range, to facilitate calculation of plot-level biomass increment. If possible, we collected 2 cores per tree: one 20cm long, and a second 10cm long core collected 90 degrees from the first. We cored at or below breast height (1.3m). Finally, we cored additional dead oak trees outside the plots (but within 50m of the plot center) to get a total of 10 dead oaks at each site. Tree cores are being processed in the R. Fahey lab at University of Connecticut and those data will comprise another data set when completed.

  In November 2019 and November 2020, we counted the number of L. dispar egg masses present on all trees in sub-plot 1 of each plot.

  In Summer 2020, we surveyed the understory vegetation in each sub-plot. For each vascular plant species observed, we estimated cover class (1: less than 1%; 2: 1-5%; 3: 6-25%; 4:26-50%; 5: 51-75%; 6: 76-100%). We also counted the number of tree saplings by species (stems greater than 1.3m tall but less than 5cm dbh) in each plot.

• 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. 2024. Oak Forest Response to Lymantria dispar Defoliation in Central Massachusetts since 2019. Harvard Forest Data Archive: HF424 (v.3). Environmental Data Initiative: https://doi.org/10.6073/pasta/489204eb8d33365688adcb43eda413e7.

Detailed Metadata

hf424-01: plot data

1. plot: unique plot name for the 10 plots in Quabbin reservoir, Simes Tract, Slab City tract
2. notes: comments at time of plot selection
3. 161718cond: defoliation in 2016, 2017, and 2018 as determined by Landsat change-in-condition (e.g. NYY indicates defoliation in 2017 and 2018, but not 2016)
4. n.defol: number of years plot was defoliated from 2016-2018, based on Landsat change-in-condition scores (unit: dimensionless / missing value: NA)
5. forest.type: forest type based on Quabbin forest records (Quabbin plots) or observations (SC and S8)
   • DEC: hardwood-dominated
   • MIX: mix of hardwood and softwood trees
6. WGS84.lat: latitude using WGS 1984 (unit: degree / missing value: NA)
7. WGS84.lon: longitude using WGS 1984 (unit: degree / missing value: NA)
8. plot2019: inclusion in 2019 permanent plot set
   • Y: plot included in 2019 permanent plot set
   • N: plot not part of permanent plot set
9. plot2018: inclusion in 2018 preliminary field survey
   • Y: plot included in 2018 preliminary field survey
   • N: plot not part of 2018 preliminary field survey
10. NSCplot: part of non-structural carbohydrate study
    • Y: oaks sampled for non-structural carbohydrates in 2019-2020
    • N: not part of non-structural carbohydrate study
11. 2018mean3by3: mean change-in-condition score for the 3x3 set of Landsat pixels (each 30m x 30m) surrounding the plot in 2018 (unit: dimensionless / missing value: NA)
12. 2017mean3by3: mean change-in-condition score for the 3x3 set of Landsat pixels (each 30m x 30m) surrounding the plot in 2017 (unit: dimensionless / missing value: NA)
13. 2016mean3by3: mean change-in-condition score for the 3x3 set of Landsat pixels (each 30m x 30m) surrounding the plot in 2016 (unit: dimensionless / missing value: NA)
14. defol.sum: sum of mean change-in-condition scores from 2016, 2017, and 2018 (unit: dimensionless / missing value: NA)
15. prop.oak: proportion of total biomass in plot that is oak (unit: dimensionless / missing value: NA)
16. note2020: notes from the 2020 field season

hf424-02: tree data

1. plot: unique plot name for the 10 plots in Quabbin reservoir, Simes Tract, Slab City tract
2. subplot: the 0.04 subplot of the plot, assigned by location
   • 1: North subplot
   • 2: Southwest subplot
   • 3: Southeast subplot
3. tree: unique tag number on the tree
4. nsc.tag: for the trees sampled for nonstructural carbohydrates, the tree number in that study
5. core: how many increment cores collected in August-September 2019 from that tree (unit: dimensionless / missing value: NA)
6. core.note: notes about the tree core collection
7. species: species
   • ACRU: Acer rubrum
   • ACSA: Acer saccharum
   • BEAL: Betula alleghaniensis
   • BELE: Betula lenta
   • BEPA: Betula papyrifera
   • CADE: Castanea dentata
   • CAGL: Carya glabra
   • CAOV: Carya ovata
   • CASP: Carya species unknown
   •  FAGR: Fagus grandifolia
   • FRAM: Fraxinus americana
   • FRNI: Fraxinus nigra
   • PIST: Pinus strobus
   • QUAL: Quercus alba
8. dbh.19: diameter at breast height in 2019 (unit: centimeter / missing value: NA)
9. cond.jun.19: condition in June 2019
   • L: alive
   • D: dead
10. can.exp.19: canopy exposure in June 2019
    • 1: dominant
    • 2: intermediate
    • 3: subdominant
11. defol.final.19: percent defoliation when L. dispar pupated (early July 2019)
    • 1: less than 25%
    • 2: 25-50%
    • 3: 50-75%
    • 4: 75-95%
    • 5: dead
12. dieback.jun19: percent dieback in June 2019
    • 1: minimal
    • 2: less than 25%
    • 3: 25-50%
    • 4: 50-75%
    • 5: 75-95%
    • 6: dead
13. dieback.augsept19: percent dieback in August-September 2019
    • 1: minimal
    • 2: less than 25%
    • 3: 25-50%
    • 4: 50-75%
    • 5: 75-95%
    • 6: dead
14. notes.19: notes, 2019
15. n.egg.below2m.Nov2019: number of L. dispar egg masses observed on the tree below 2m in November 2019 (subplot 1 only) (unit: dimensionless / missing value: NA)
16. n.egg.above2m.Nov2019: number of L. dispar egg masses observed on the tree above 2m in November 2019 (subplot 1 only) (unit: dimensionless / missing value: NA)
17. cond.jul20: condition in July 2020
    • L: alive
    • D: dead
18. dieback.jul20: percent dieback in July 2020
    • 1: less than 25%
    • 2: 25-50%
    • 3: 50-75%
    • 4: 75-95%
    • 5: dead
19. n.egg.below2m.Nov2020: number of L. dispar egg masses observed on the tree below 2m in November 2020 (subplot 1 only) (unit: dimensionless / missing value: NA)
20. n.egg.above2m.Nov2020: number of L. dispar egg masses observed on the tree above 2m in November 2020 (subplot 1 only) (unit: dimensionless / missing value: NA)
21. cond.aug21: condition in August 2021
    • L: alive
    • D: dead
22. dieback.aug21: percent dieback in August 2021
    • 1: less than 25%
    • 2: 25-50%
    • 3: 50-75%
    • 4: 75-95%
    • 5: dead
23. notes.21: notes, 2021

hf424-03: defoliation data

1. plot: unique plot name for the 10 plots in Quabbin reservoir, Simes Tract, Slab City tract
2. subplot: the 0.04 subplot of the plot, assigned by location
   • 1: North subplot
   • 2: Southwest subplot
   • 3: Southeast subplot
3. tree: unique tag number on the tree
4. species: species
   • ACRU: Acer rubrum
   • ACSA: Acer saccharum
   • BEAL: Betula alleghaniensis
   • BELE: Betula lenta
   • BEPA: Betula papyrifera
   • CADE: Castanea dentata
   • CAGL: Carya glabra
   • CAOV: Carya ovata
   • CASP: Carya species unknown
   •  FAGR: Fagus grandifolia
   • FRAM: Fraxinus americana
   • FRNI: Fraxinus nigra
   • PIST: Pinus strobus
   • QUAL: Quercus alba
5. dbh: diameter at breast height (unit: centimeter / missing value: NA)
6. cond.jun.19: condition in June 2019
   • L: alive
   • D: dead
7. defol.first: percent defoliation in late May/early June
   • 1: less than 25%
   • 2: 25-50%
   • 3: 50-75%
   • 4: 75-95%
   • 5: dead
8. defol.6.11: percent defoliation update for June 11
   • 1: less than 25%
   • 2: 25-50%
   • 3: 50-75%
   • 4: 75-95%
   • 5: dead
9. defol.6.18: percent defoliation update for June 18
   • 1: less than 25%
   • 2: 25-50%
   • 3: 50-75%
   • 4: 75-95%
   • 5: dead
10. defol.6.19: percent defoliation update for June 19
    • 1: less than 25%
    • 2: 25-50%
    • 3: 50-75%
    • 4: 75-95%
    • 5: dead
11. defol.6.21: percent defoliation update for June 21
    • 1: less than 25%
    • 2: 25-50%
    • 3: 50-75%
    • 4: 75-95%
    • 5: dead
12. defol.6.27: percent defoliation update for June 27
    • 1: less than 25%
    • 2: 25-50%
    • 3: 50-75%
    • 4: 75-95%
    • 5: dead
13. defol.6.28: percent defoliation update for June 28
    • 1: less than 25%
    • 2: 25-50%
    • 3: 50-75%
    • 4: 75-95%
    • 5: dead
14. defol.7.8: percent defoliation update for July 8
    • 1: less than 25%
    • 2: 25-50%
    • 3: 50-75%
    • 4: 75-95%
    • 5: dead
15. defol.7.9: percent defoliation update for July 9
    • 1: less than 25%
    • 2: 25-50%
    • 3: 50-75%
    • 4: 75-95%
    • 5: dead
16. defol.final.19: percent defoliation as of July 8-9. 2019
    • 1: less than 25%
    • 2: 25-50%
    • 3: 50-75%
    • 4: 75-95%
    • 5: dead

hf424-04: understory cover

1. plot: unique plot name for the 10 plots in Quabbin reservoir, Simes Tract, Slab City tract
2. subplot: the 0.04 subplot of the plot, assigned by location
   • 1: North subplot
   • 2: Southwest subplot
   • 3: Southeast subplot
3. lifeform: type of understory cover
   • fern/lycopod: fern/lycopod
   • grass/sedge/rush: grass/sedge/rush
   • herb: herb
   • shrub: shrub
   • tree: tree
4. genspe: 6-letter acronym for the taxon (first 3 letters of genus; first three letters of species. For taxa identified only to genus, SPP is the species abbreviation)
5. cover.cl.2020: cover class, 2020
   • 1: less than 1%
   • 2: 1-5%
   • 3: 6-25%
   • 4: 26-50%
   • 5: 51-75%
   • 6: 76-100%
6. note: note
7. genus: genus
8. species: species
9. other.name: common name

hf424-05: saplings

1. plot: unique plot name for the 10 plots in Quabbin reservoir, Simes Tract, Slab City tract
2. subplot: the 0.04 subplot of the plot, assigned by location
   • 1: North subplot
   • 2: Southwest subplot
   • 3: Southeast subplot
3. gesp: 4-letter acronym for each tree species (first two letters of genus; first two letters of species)
4. genus: genus
5. species: species
6. count: number of stems in the 20m x 20m plot (therefore, divide by 0.04 to get stems per hectare) (unit: dimensionless / missing value: NA)