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Harvard Forest Data Archive

HF126

Overstory Vegetation in Hemlock Removal Experiment at Harvard Forest since 2003

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Data

Overview

  • Lead: Aaron Ellison, Audrey Barker Plotkin
  • Investigators: Marco Albani, David Foster, David Orwig
  • Contact: Audrey Barker Plotkin
  • Start date: 2003
  • End date: 2014
  • Status: ongoing
  • Location: Simes Tract (Harvard Forest)
  • Latitude: +42.47 to +42.48
  • Longitude: -72.22 to -72.21
  • Elevation: 200 to 240 meter
  • Taxa: Tsuga canadensis (eastern hemlock)
  • Release date: 2015
  • Revisions:
  • EML file: knb-lter-hfr.126.14
  • DOI: digital object identifier
  • Related links:
  • Study type: long-term measurement
  • Research topic: large experiments and permanent plot studies; physiological ecology, population dynamics and species interactions
  • LTER core area: disturbance
  • 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, and 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 the 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. Eventually the control will become infested by hemlock woolly adelgid; the effects of HWA will 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. Commerical 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 and 2014 (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 Summer 2009 and 2014. In 2009 and 2014, all hemlock trees with live branches within reach were visually inspected for presence of hemlock woolly adelgid (2009 and 2014) and hemlock elongate scale (2014). In 2014, crown vigor of all hemlocks was assessed, using the visual rating system noted above.

  • Use:

    This dataset is released to the public under Creative Commons license CC BY (Attribution). Please keep the designated contact person informed of any plans to use the dataset. Consultation or collaboration with the original investigators is strongly encouraged. Publications and data products that make use of the dataset must include proper acknowledgement.

  • Citation:

    Ellison A, Barker Plotkin A. 2015. Overstory Vegetation in Hemlock Removal Experiment at Harvard Forest since 2003. Harvard Forest Data Archive: HF126.

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: tree number. Each tree is labeled with a numbered tag. As of 2014, there are records for 7241 trees. 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). 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
    • 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. 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
  7. condt0: condition of tree at time of first measurement
    • L: live
    • D: dead
  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
  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
    • D: dead
  22. dam09: damage to tree noted in 2009
    • 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
  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. hwa1b09: presence of hemlock woolly adelgid on first branch examined in 2009
    • 0: absent
    • 1: present
  26. hwa2b09: 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
    • D: dead
  29. dam14: damage to tree noted in 2014
    • 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
  30. sprt14: sprouts noted in 2009
    • 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. vigor2014: 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
  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
    • NA: branch(es) not examined
  35. notes14: notes recorded in 2014 survey. “Off HF” refers to trees discontinued after 2009.

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