Harvard Forest

Data Archive

HF126

Overstory Vegetation in Hemlock Removal Experiment at Harvard Forest since 2003

Related Publications

Data

• hf126-01: plot coordinates (preview)
• hf126-02: trees (preview)
• hf126-03: tree height and crown (preview)
• hf126-04: Hemlock vigor (preview)

Overview

• Lead: Aaron Ellison, Audrey Barker Plotkin
• Investigators: Marco Albani, David Foster, David Orwig
• Contact: Information Manager
• Start date: 2003
• End date: 2024
• Status: ongoing
• Location: Simes Tract (Harvard Forest)
• Latitude: +42.47 to +42.48 degrees
• Longitude: -72.22 to -72.21 degrees
• Elevation: 200 to 240 meter
• Datum: WGS84
• Taxa: Tsuga canadensis (eastern hemlock)
• Release date: 2024
• Language: English
• EML file: knb-lter-hfr.126.19
• DOI: digital object identifier
• EDI: data package
• DataONE: data package
• Related links:
• Understory Vegetation in Hemlock Removal Experiment at Harvard Forest since 2003
• Study type: long-term measurement
• Research topic: large experiments and permanent plot studies; physiological ecology, population dynamics and species interactions
• LTER core area: disturbance patterns, human-environment interactions
• Keywords: hemlock, hemlock woolly adelgid, timber harvest, tree maps, vegetation dynamics
• Abstract:

  Hemlock decline in New England is caused by direct and indirect effects of invasion of the hemlock woolly adelgid. Direct damage from the insect is causing gradual mortality of hemlock. Widespread harvesting of hemlock in advance of mortality, in contrast, causes immediate mortality and removal of biomass from the site. Although both processes affect thousands of acres of forest annually we have only a limited understanding of their effects on forest ecosystem function and productivity and the nature of the subsequent forest community. We anticipate that harvesting will yield different consequences than gradual mortality from the insect. Therefore, we designed an experiment to simulate these contrasting impacts, by logging or girdling hemlock stands. Results from the experimental treatments will be compared to the changes observed in forests that are being infested by adelgid and can also be included in integrated analyses of a suite of large experiments that form a core component of the Harvard Forest LTER program.

• Methods:

  Study Design

  The study uses large plots and a Before After Control Impact (BACI) design. Plots were established and most response parameters were monitored for 1-2 growing seasons prior to the manipulations. There are two replicates of four treatments: control, hardwood control, commercial logging and girdling. In 2009 the control became infested by hemlock woolly adelgid; the effects of HWA now overlay all treatments. Intensive study plots are 30 x 30 m within 90 x 90 m treatment units - that is, the center (or "core area") is surrounded by approximately one tree height of treatment area (overstory tree heights range from ~25-35m). Intensive measurements focus on the central plots, but the buffers and outlying areas provide additional area for other studies and manipulations. Treatments include:

  1. Control plots are hemlock dominated and received no manipulation other than sampling.

  2. Hardwood Control plots simulate a likely future forest condition after hemlock woolly adelgid kills all hemlock in a stand and deciduous trees grow into the site. They received no manipulation other than sampling.

  3. Commercial Logging plots simulate an intensive commercial logging operation. Hemlock and other commercially valuable trees were removed, including larger hardwoods and pine for saw logs as well as smaller stems that a logger might take in order to improve future stand quality, facilitate skidding and general operation, or initiate a new cohort of sprouts. Two-thirds to three-fourths of the stand basal area was cut in these two plots, using hand-felling by chainsaw and skidding with a rubber-tired skidder. The intent was to generate an extreme response that is within the range of those seen on real commercial cuts. This treatment took place in Winter 2004-05.

  4. Girdling plots simulate some of the characteristics of hemlock woolly adelgid. All sizes of hemlock were girdled, resulting in gradual mortality and standing dead hemlock. No other species were girdled, and there is no further site disturbance. Important characteristics of hemlock woolly adelgid infestation missing include the very lengthy period of decline during which the plant is undergoing physiological stress and metabolic imbalance that may induce biogeochemical and microbial changes on the site. This treatment took place in late May 2005

  Plot size Plots 1 and 3 are 7650m2 (90m by 85m) Plot 2 is 7225m2 (85m by 85m) Plots 4, 5, 6 and 8 are 8100m2 (90m by 90m) Plot 7 is 8100m2 for data collected through 2009. Starting in 2010, Plot 7 is ca. 6000m2.

  Overstory Vegetation Sampling

  Throughout each plot, trees (minimum size: 5cm dbh) were labeled with numbered aluminum tags. Prior to treatment, species, diameter at breast height, condition (live or dead; dead included if solid and taller than about 5m) and X, Y, Z coordinates were recorded for each tree. We used a manual autolevel to map the trees within each plot and determine their elevation relative to an arbitrary point in each plot. New trees growing above 5cm dbh in 2009, 2014, and 2019 (recruits) were mapped based on distance and angle from a known starting point (plot post or previously mapped tree), or used the coordinates of the parent tree if the recruit was a sprout from a previously mapped tree. Tree heights and crown dimensions were recorded for a subset of trees in each core area prior to manipulations by Marco Albani and Mary Anderson.

  Response of trees to treatments and stand change over time is assessed with a variety of methods. From July 2005 through June 2008, crown vigor of hemlocks in the center 30m x 30m area was assessed twice per year. We used a visual rating system (1 = 0-25% loss; 2 = 25-50% loss; 3 = 50-75% loss; 4 = 75-99% loss; 5 = dead). Across the entire suite of plots, we assessed survival, growth, damage and sprouting. Survival, damage and sprouting were surveyed in 2006 (the second growing season after manipulations) and these factors plus diameter growth of surviving trees and recruitment of new stems were surveyed in summers 2009, 2014, 2019, and 2024. In 2009, 2014, 2019, and 2024, all hemlock trees with live branches within reach were visually inspected for presence of hemlock woolly adelgid (2009, 2014, 2019, and 2024) and hemlock elongate scale (2014, 2019). Starting in 2014, crown vigor of all hemlocks was assessed, using the visual rating system noted above.

• 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: Ellison A, Barker Plotkin A. 2024. Overstory Vegetation in Hemlock Removal Experiment at Harvard Forest since 2003. Harvard Forest Data Archive: HF126 (v.19). Environmental Data Initiative: https://doi.org/10.6073/pasta/f8d2a159d226aa4c6a3ab0922c8de971.

Detailed Metadata

hf126-01: plot coordinates

1. plot: plot number (1-8). Note: Plots 1, 2 & 3 are 5m short on the E-W and/or N-S axis so that we could squeeze the plots into the hemlock-dominated area of forest.
   • 1: Plot 1 (X range 0-90; Y range 5-90)
   • 2: Plot 2 (X range 0-85; Y range 5-90)
   • 3: Plot 3 (X range 0-85; Y range 0-90)
   • 4: Plot 4
   • 5: Plot 5
   • 6: Plot 6
   • 7: Plot 7
   • 8: Plot 8
2. plot.x: local coordinates within each plot (0-90m) (unit: meter / missing value: NA)
3. plot.y: local coordinates within each plot (0-90m) (unit: meter / missing value: NA)
4. easting.spm: Easting spm. Massachusetts State Plane Meters; Datum = NAD1983 (unit: meter / missing value: NA)
5. northing.spm: Northing spm. Massachusetts State Plane Meters; Datum = NAD1983 (unit: meter / missing value: NA)
6. longitude.wgs1984: Longitude wgs1984, Datum = WGS 1984 (unit: degree / missing value: NA)
7. latitude.wgs1984: Latitude wgs1984, Datum = WGS 1984 (unit: degree / missing value: NA)
8. height.wgs1984: Elevation in meter, Datum = WGS 1984 (unit: meter / missing value: NA)

hf126-02: trees

1. plot: plot number (1-8)
   • 1: Plot 1 (girdled)
   • 2: Plot 2 (logged)
   • 3: Plot 3 (hemlock control)
   • 4: Plot 4 (logged)
   • 5: Plot 5 (girdled)
   • 6: Plot 6 (hemlock control)
   • 7: Plot 7 (hardwood control)
   • 8: Plot 8 (hardwood control)
2. sec: section. Each plot is divided into nine, 30m x 30m sections.
   • C: center
   • SW: southwest
   • S: south
   • SE: southeast
   • E: east
   • NE: northeast
   • N: north
   • NW: northwest
   • W: west
3. tree: Each tree is labeled with a numbered tag. Trees surveyed in 2003-2004 use tag numbers 1-7009, excluding 744, 1604, 2004, 2263, 4374, 4734 and 3752-3825. There are 24 trees with a 0.1 place. In 2009, new trees start with #8000 (8000-8069, excluding 8005). In 2014, new trees start with #8100 (8100-8330, excluding 8112, 8200, 8301-8305, 8312-8314, 8318-8320). In 2019, new trees begin with tag #8400. In 2024, new trees begin with tag # 9453. There are 172 trees in plot 7 with no data after 2009 (discontinued section of this plot).
4. species: species code
   • ACRU: Acer rubrum
   • ASCA: Acer saccharum
   • BEAL: Betula alleghaniensis
   • BELE: Betula lenta
   • BEPA: Betula papyrifera
   • BEPO: Betula populifolia
   • CACA: Carpinus caroliniana
   • CADE: Castanea dentata
   • CAGL: Carya glabra
   • CAOV: Carya ovata
   • CASP: Carya sp.
   • FAGR: Fagus grandifolia
   • FRAM: Fraxinus americana
   • FRNI: Fraxinus nigra
   • HAVI: Hamamelis virginiana
   • OSVI: Ostrya virginiana
   • PIST: Pinus strobus
   • PRPE: Prunus pensylvanica
   • PRSE: Prunus serotina
   • QUAL: Quercus alba
   • QUBI: Quercus bicolor
   • QURU: Quercus rubra
   • QUVE: Quercus velutina
   • SAAL: Sassafras albidum
   • SOAM: Sorbus americana
   • TSCA: Tsuga canadensis
   • UNK: Unknown (one, dead at initial measurement)
5. dbht0: Diameter at breast height (1.3m) at time of first measurement (not including trees that recruited since 2009). Minimum diameter is 5.0 cm, but there are a few undersize trees included. (unit: centimeter / missing value: NA)
6. cc: crown class, recorded for live trees at time of first measurement
   • D: dominant
   • C: codominant
   • I: intermediate
   • S: suppressed
   • NA: not recorded
7. condt0: condition of tree at time of first measurement
   • L: live
   • D: dead
   • NA: trees that recruited since 2009
8. yeart0: year of first measurement (mostly 2003 and 2004, but a few in 2005 or 2006)
9. xcoord: tree location within plot along X (west-east) axis. Ranges from 0-90 with a few outside these bounds. (unit: meter / missing value: NA)
10. ycoord: tree location within plot along Y (south-north) axis. Ranges from 0-90 with a few outside these bounds. (unit: meter / missing value: NA)
11. zelev: elevation of tree relative to arbitrary point within plot that is designated as 0 elevation (unit: meter / missing value: NA)
12. elev0: X,Y coordinates of the arbitrary 0 elevation point within plot, in meters
13. markmanip: designated manipulation for trees in girdled and logged plots
    • cut: marked to be cut in winter 2004-2005
    • girdle05: marked to be girdled in May 2005
    • none: no manipulation to tree
14. actualmanip: actual manipulation differs from the marked manipulation in several cases: (1) hemlock trees less than 20cm were not marked to be cut, but were allowed to be cut by logger if logger chose to do so; (2) a few trees marked to be cut were inaccessible to logger so were left standing; (3) a few mix-ups
    • cut: marked to be cut in winter 2004-2005
    • girdle05: marked to be girdled in May 2005
    • none: no manipulation to tree
15. cond06: condition of tree in 2006. Cut trees are designated as dead.
    • L: live
    • D: dead
    • G: gone
    • NA: trees that recruited since 2009 or missed in 2006
16. dam06: damage to tree noted in 2006
    • BENT: stem bent
    • FALL: stem fallen over
    • LEAN: stem leaning from vertical
    • SNAP: trunk snapped below crown
    • UPRT: tree uprooted, leaving a pit and mound structure
17. sprt06: sprouts noted in 2006
    • BASP: tree sprouting from base (basal sprout)
    • TRSP: tree sprouting from trunk (trunk sprout)
    • BASP/TRSP: tree has both basal and trunk sprouts
18. notes1: notes recorded in first years of study
19. notes06: notes recorded in 2006 survey of tree condition, damage and sprouting
20. dbh09: diameter at breast height (1.3m) in 2009 (unit: centimeter / missing value: NA)
21. cond09: condition of tree in 2009
    • L: live (live in 2003/2004 and live in 2009)
    • D: dead (died since 2003/2004; that is, live in 2003/2004 but dead in 2009)
    • R: recruited since 2003/2004 (all recruits are live trees)
    • NA: not yet recruited OR dead in prior census
22. dam09: damage to tree noted in 2009
    • BENT: stem bent
    • LEAN: stem leaning from vertical
    • SNAP: trunk snapped below crown
    • UPRT: tree uprooted, leaving a pit and mound structure
23. sprt09: sprouts noted in 2009
    • BASP: tree sprouting from base (basal sprout) in 2009
    • TRSP: tree sprouting from trunk (trunk sprout) in 2009
    • BASP/TRSP: tree has both basal and trunk sprouts in 2009
24. notes09: notes recorded in 2009 survey
25. hwab109: presence of hemlock woolly adelgid on first branch examined in 2009
    • 0: absent
    • 1: present
26. hwab209: presence of hemlock woolly adelgid on second branch examined in 2009
    • 0: absent
    • 1: present
27. dbh14: diameter at breast height (1.3m) in 2014 (unit: centimeter / missing value: NA)
28. cond14: condition of tree in 2014
    • L: live (live in 2009 and live in 2014)
    • D: dead (died since 2009; that is, live in 2009 but dead in 2014)
    • R: recruited since 2009 (all recruits are live trees)
    • NA: not yet recruited OR dead in prior census
29. dam14: damage to tree noted in 2014
    • BENT: stem bent
    • LEAN: stem leaning from vertical
    • SNAP: trunk snapped below crown
    • UPRT: tree uprooted, leaving a pit and mound structure
30. sprt14: sprouts noted in 2014
    • BASP: tree sprouting from base (basal sprout) in 2014
    • TRSP: tree sprouting from trunk (trunk sprout) in 2014
    • BASP/TRSP: tree has both basal and trunk sprouts in 2014
31. vigor14: for hemlock trees only. Vigor rating is based on visual estimate of foliage loss.
    • 1: 0-25% foliar loss
    • 2: 25-50% foliar loss
    • 3: 50-75% foliar loss
    • 4: 75-99% foliar loss
    • 5: dead (only for trees that died between 2009-2014)
    • NA: non-hemlock or a hemlock that was dead in prior census
32. hwab114: for Hemlock tree only. Presence of hemlock woolly adelgid on first branch examined in 2014
    • 0: HWA absent in 2014
    • 1: HWA present in 2014
    • NA: branch not examined
33. hwab214: for Hemlock tree only. Presence of hemlock woolly adelgid on second branch examined in 2014
    • 0: HWA absent in 2014
    • 1: HWA present in 2014
    • NA: branch not examined
34. scale14: for Hemlock tree only. Presence of hemlock elongate scale on branches examined in 2014
    • 0: hemlock elongate scale absent in 2014
    • 1: hemlock elongate scale present in 2014
    • NA: branch(es) not examined
35. note14: notes recorded in 2014 survey. “Off HF” refers to trees discontinued after 2009.
36. dbh19: diameter at breast height (1.3m) in 2019 (unit: centimeter / missing value: NA)
37. cond19: condition of tree in 2019
    • L: live (live in 2014 and live in 2019)
    • D: dead (died since 2014; that is, live in 2014 but dead in 2019)
    • R: recruited since 2014 (all recruits are live trees)
    • NA: not yet recruited OR dead in prior census
38. dam19: damage to tree noted in 2019
    • BENT: stem bent
    • LEAN: stem leaning from vertical
    • SNAP: trunk snapped below crown
    • UPRT: tree uprooted, leaving a pit and mound structure
39. sprt19: sprouts noted in 2019
    • BASP: tree sprouting from base (basal sprout) in 2019
    • TRSP: tree sprouting from trunk (trunk sprout) in 2019
    • BASP/TRSP: tree has both basal and trunk sprouts in 2019
40. vigor19: for hemlock trees only. Vigor rating is based on visual estimate of foliage loss.
    • 1: 0-25% foliar loss
    • 2: 25-50% foliar loss
    • 3: 50-75% foliar loss
    • 4: 75-99% foliar loss
    • 5: dead (only for trees that died between 2009-2014)
    • NA: non-hemlock or a hemlock that was dead in prior census
41. hwab119: for Hemlock tree only. Presence of hemlock woolly adelgid on first branch examined in 2019
    • 0: HWA absent in 2019
    • 1: HWA present in 2019
    • NA: branch not examined
42. hwab219: for Hemlock tree only. Presence of hemlock woolly adelgid on second branch examined in 2019
    • 0: HWA absent in 2019
    • 1: HWA present in 2019
    • NA: branch not examined
43. scale19: for Hemlock tree only. Presence of hemlock elongate scale on branches examined in 2019
    • 0: hemlock elongate scale absent in 2019
    • 1: hemlock elongate scale present in 2019
    • NA: branch(es) not examined
44. note19: notes recorded in 2019 survey
45. dbh24: diameter at breast height (1.3m) in 2024 (unit: centimeter / missing value: NA)
46. cond24: condition of tree in 2024
    • L: live (live in 2019 and live in 2024)
    • D: dead (died since 2019; that is, live in 2019 but dead in 2024)
    • R: recruited since 2019 (all recruits are live trees)
    • NA: not yet recruited OR dead in prior census
47. dam24: damage to tree noted in 2024
    • BENT: stem bent
    • LEAN: stem leaning from vertical
    • SNAP: trunk snapped below crown
    • UPRT: tree uprooted, leaving a pit and mound structure
48. sprt24: sprouts noted in 2024
    • BASP: tree sprouting from base (basal sprout) in 2024
    • TRSP: tree sprouting from trunk (trunk sprout) in 2024
    • BASP/TRSP: tree has both basal and trunk sprouts in 2024
49. vigor24: for hemlock trees only. Vigor rating is based on visual estimate of foliage loss.
    • 1: 0-25% foliar loss
    • 2: 25-50% foliar loss
    • 3: 50-75% foliar loss
    • 4: 75-99% foliar loss
    • 5: dead (only for trees that died between 2009-2019)
    • NA: non-hemlock or a hemlock that was dead in prior census
50. hwab124: for Hemlock tree only. Presence of hemlock woolly adelgid on first branch examined in 2024
    • 0: HWA absent
    • 1: HWA present
    • NA: branch not examined
51. hwab224: for Hemlock tree only. Presence of hemlock woolly adelgid on second branch examined in 2024
    • 0: HWA absent
    • 1: HWA present
    • NA: branch not examined
52. scale24: for Hemlock tree only. Presence of hemlock elongate scale on branches examined in 2024
    • 0: hemlock elongate scale absent
    • 1: hemlock elongate scale present
    • NA: branch(es) not examined
53. note24: notes recorded in 2024 survey

hf126-03: tree height and crown

1. tract: the tract of the Harvard Forest in which the tree is located
2. plot: the mapped plot within the specified tract in which the tree is located (Simes)
3. tree: all trees within these plots are tagged in the field with their identifying number
4. species: species of the tree
   • ACRU: Acer rubrum
   • ACSA: Acer saccharum
   • BEAL: Betula alleghaniensis
   • BELE: Betula lenta
   • BEPA: Betula papyrifera
   • CADE: Castanea dentata
   • FRAM: Fraxinus americana
   • PIST: Pinus strobus
   • QURU: Quercus rubra
   • TSCA: Tsuga canadensis
5. xcoord: the Cartesian coordinate identifying the location of the tree along the north-south axis of the plot (in meters; range is 30-60) (unit: meter / missing value: NA)
6. ycoord: the Cartesian coordinate identifying the location of the tree along the east-west axis of the plot (in meters; range is 30-60) (unit: meter / missing value: NA)
7. dbh: diameter breast height (1.3 meters), measured in centimeters using a dbh tape (unit: centimeter / missing value: NA)
8. distance: distance in meters from the tree at which the height and crown depth measurements were taken (unit: meter / missing value: NA)
9. heightpercenttop: the height percent to the top of the tree, measured using a clinometer (unit: number / missing value: NA)
10. heightpercentbase: the height percent to the base of the tree, measured using a clinometer (unit: number / missing value: NA)
11. crowndepthpercenttop: the height percent to the top of the live crown, measured from the same position as the height percent, also using the clinometer (unit: number / missing value: NA)
12. crowndepthpercentbottom: the height percent to the bottom of the live crown, measured from the same position as the height percent, also using the clinometer (unit: number / missing value: NA)
13. majoraxis: the length, in meters, of the crown diameter at its largest point (determined by visual inspection), measured with a 50 meter tape (unit: meter / missing value: NA)
14. minoraxis: the length, in meters, of the crown diameter at its smallest point (determined by visual inspection), measured with a 50 meter tape (unit: meter / missing value: NA)
15. height: the height (in meters) of the tree, calculated from the height percent and the distance at which that was measured = (distance*height percent top)/100)-((distance*height percent base)/100) (unit: meter / missing value: NA)
16. crowndepth: length of live crown in meters, using crown depth percentages, and the distance at which those were measured =((distance*crown depth percent top)/100)-((distance*crown depth percent bottom)/100) (unit: meter / missing value: NA)
17. meancrowndiameter: the average of the major and minor axes of the crown diameter = (major axis + minor axis)/2 (unit: meter / missing value: NA)
18. notes: field notes taken on variables in situation and structure that might impact the measurements being taken

hf126-04: Hemlock vigor

1. plot: plot number (1-8). Sampling is limited to center 30m x 30m only of each plot, Hemlock only, live as of Fall 2003 only, uncut trees in logged plots only, live hemlock saplings (stems >1.3m but <5cm diameter) also included; these are tagged with strip tags (S1. . . SXX), and plot 8 is not included because there are no hemlock within the center section of this plot.
2. tree: tree number corresponds to tag. Sapling numbers begin with an S and start at 1 in each plot
3. spec: species code
4. dbh03: diameterat breast height, measured in 2003. NA for saplings. (unit: centimeter / missing value: NA)
5. v.jul05: vigor rating from 1-5 in July 2005
   • 1: 0-25% foliar loss
   • 2: 25-50% foliar loss
   • 3: 50-75% foliar loss
   • 4: 75-99% foliar loss
   • 5: dead
6. v.oct05: vigor rating from 1-5 in October 2005
   • 1: 0-25% foliar loss
   • 2: 25-50% foliar loss
   • 3: 50-75% foliar loss
   • 4: 75-99% foliar loss
   • 5: dead
7. v.jun06: vigor rating from 1-5 in June 2006
   • 1: 0-25% foliar loss
   • 2: 25-50% foliar loss
   • 3: 50-75% foliar loss
   • 4: 75-99% foliar loss
   • 5: dead
8. v.oct06: vigor rating from 1-5 in October 2006
   • 1: 0-25% foliar loss
   • 2: 25-50% foliar loss
   • 3: 50-75% foliar loss
   • 4: 75-99% foliar loss
   • 5: dead
9. v.jun07: vigor rating from 1-5 in June 2007
   • 1: 0-25% foliar loss
   • 2: 25-50% foliar loss
   • 3: 50-75% foliar loss
   • 4: 75-99% foliar loss
   • 5: dead
10. v.oct07: vigor rating from 1-5 in October 2007
    • 1: 0-25% foliar loss
    • 2: 25-50% foliar loss
    • 3: 50-75% foliar loss
    • 4: 75-99% foliar loss
    • 5: dead
11. v.jun08: vigor rating from 1-5 in June 2008
    • 1: 0-25% foliar loss
    • 2: 25-50% foliar loss
    • 3: 50-75% foliar loss
    • 4: 75-99% foliar loss
    • 5: dead