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Hemlock Removal Experiment - Understory Vegetation

HF106 EML Publications Archive

Data

Overview

  • Lead: Aaron Ellison, Audrey Barker Plotkin
  • Investigators: David Foster, David Orwig
  • Contact: Audrey Barker Plotkin
  • Start date: 2003-06-01
  • End date: ongoing
  • Location: Simes Tract (Harvard Forest)
  • Latitude: +42.47 to +42.48
  • Longitude: -72.22 to -72.21
  • Elevation: 200 to 240 meters
  • Taxa: Tsuga canadensis (eastern hemlock)
  • Research topic: plot, community
  • Study type: long-term measurement
  • LTER core area: disturbance
  • Keywords: forest dynamics, girdling, hemlock, hemlock woolly adelgid, logging, tree maps
  • Release date: 2005
  • EML version: knb-lter-hfr.106.11
  • Revisions: data updated 2006-02-21
  • Related links:
  • 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

    Understory Vegetation Sampling

    In 2003, we established two transects running north-south through the center 30m x 30m of each plot at the Simes Tract of Harvard Forest for understory vegetation sampling. Five 1 m2 subplots were spaced evenly along each transect. We labeled the NW corner, unless otherwise marked. Transects are marked with string and yellow tent stakes, and plots are marked with orange flags.

    We annually estimate percent cover for herbs, shrubs, and seedlings to the nearest one percent. We counted the number of seedlings by species. A seedling is a tree less than 1.3m tall. If rocks, stumps, slash, standing tree bases or coarse woody debris covered more than 5% of the plot, their percent cover was recorded to the nearest 5%. In addition, the depth of the organic soil layer was measured to the nearest 0.5 cm at the NW corner of each subplot (2003 and 2006 only). We searched each plot and compiled a species list for the entire 30m x 30m area.

  • Use:

    This dataset is released to the public and may be freely downloaded. 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. For more information on LTER Network data access and use policies, please see: http://www.lternet.edu/data/netpolicy.html.

  • Citation:

    Ellison A, Barker Plotkin A. 2005. Hemlock Removal Experiment - Understory Vegetation. Harvard Forest Data Archive: HF106.

Detailed Metadata

hf106-01: species codes

  1. type: type
    • Tree: tree
    • Shrub: shrub
    • Herb: herb
    • Fern / Lycopod: fern/lycopod
    • Graminoid: graminoid
  2. code: species code
  3. name: species name

hf106-02: o-layer and substrate

  1. Plot: plot number
  2. Subplot: subplot number
  3. Year: year of survey (YYYY)
  4. O-layer: depth of o-layer (centimeter )
  5. Down Wood: percent cover (number )
  6. Slash: percent cover (number )
  7. Rock: percent cover (number )
  8. Standing Tree: percent cover (number )
  9. Stump: percent cover (number )
  10. Root: percent cover (number )

hf106-03: shrub and herb

  1. Plot: plot number
  2. Subplot: subplot number
  3. Year: year of survey (YYYY)
  4. AMSP: percent cover. Values less than 1% represented by 0.5%. (number )
  5. COCO: percent cover. Values less than 1% represented by 0.5%. (number )
  6. CRSP: percent cover. Values less than 1% represented by 0.5%. (number )
  7. GAPR: percent cover. Values less than 1% represented by 0.5%. (number )
  8. HAVI: percent cover. Values less than 1% represented by 0.5%. (number )
  9. MIRE: percent cover. Values less than 1% represented by 0.5%. (number )
  10. PAQU: percent cover. Values less than 1% represented by 0.5%. (number )
  11. RHNU: percent cover. Values less than 1% represented by 0.5%. (number )
  12. VAAN: percent cover. Values less than 1% represented by 0.5%. (number )
  13. VACO: percent cover. Values less than 1% represented by 0.5%. (number )
  14. VASP: percent cover. Values less than 1% represented by 0.5%. (number )
  15. VIAC: percent cover. Values less than 1% represented by 0.5%. (number )
  16. VICA: percent cover. Values less than 1% represented by 0.5%. (number )
  17. VITSP: percent cover. Values less than 1% represented by 0.5%. (number )
  18. ANQU: percent cover. Values less than 1% represented by 0.5%. (number )
  19. ARNU: percent cover. Values less than 1% represented by 0.5%. (number )
  20. ASAC: percent cover. Values less than 1% represented by 0.5%. (number )
  21. ASDI: percent cover. Values less than 1% represented by 0.5%. (number )
  22. CHMA: percent cover. Values less than 1% represented by 0.5%. (number )
  23. CLBO: percent cover. Values less than 1% represented by 0.5%. (number )
  24. COGR: percent cover. Values less than 1% represented by 0.5%. (number )
  25. GOTE: percent cover. Values less than 1% represented by 0.5%. (number )
  26. MACA: percent cover. Values less than 1% represented by 0.5%. (number )
  27. MEVI: percent cover. Values less than 1% represented by 0.5%. (number )
  28. MOHY: percent cover. Values less than 1% represented by 0.5%. (number )
  29. MOUN: percent cover. Values less than 1% represented by 0.5%. (number )
  30. PYMI: percent cover. Values less than 1% represented by 0.5%. (number )
  31. PYRO: percent cover. Values less than 1% represented by 0.5%. (number )
  32. TRBO: percent cover. Values less than 1% represented by 0.5%. (number )
  33. UVSE: percent cover. Values less than 1% represented by 0.5%. (number )
  34. DEPU: percent cover. Values less than 1% represented by 0.5%. (number )
  35. DRSP: percent cover. Values less than 1% represented by 0.5%. (number )
  36. LYLU: percent cover. Values less than 1% represented by 0.5%. (number )
  37. LYOB: percent cover. Values less than 1% represented by 0.5%. (number )
  38. OSCI: percent cover. Values less than 1% represented by 0.5%. (number )
  39. OSCL: percent cover. Values less than 1% represented by 0.5%. (number )
  40. POAR: percent cover. Values less than 1% represented by 0.5%. (number )
  41. THNO: percent cover. Values less than 1% represented by 0.5%. (number )
  42. CAPE: percent cover. Values less than 1% represented by 0.5%. (number )
  43. CASP2: percent cover. Values less than 1% represented by 0.5%. (number )

hf106-04: seedling density

  1. Plot: plot number
  2. Subplot: subplot number
  3. Year: year of survey (YYYY)
  4. TSCA: individual count per 1 m2 subplot (number )
  5. ACRU: individual count per 1 m2 subplot (number )
  6. QURU: individual count per 1 m2 subplot (number )
  7. PRSE: individual count per 1 m2 subplot (number )
  8. PIST: individual count per 1 m2 subplot (number )
  9. BEAL: individual count per 1 m2 subplot (number )
  10. BELE: individual count per 1 m2 subplot (number )
  11. BESP: individual count per 1 m2 subplot (number )
  12. ACSA: individual count per 1 m2 subplot (number )
  13. QUAL: individual count per 1 m2 subplot (number )
  14. UNK: individual count per 1 m2 subplot (number )

hf106-05: seedling cover

  1. Plot: plot number
  2. Subplot: subplot number
  3. Year: year of survey (YYYY)
  4. TSCA: percent cover. 0.1% used for '+' cover. (number )
  5. ACRU: percent cover. 0.1% used for '+' cover. (number )
  6. QURU: percent cover. 0.1% used for '+' cover. (number )
  7. PRSE: percent cover. 0.1% used for '+' cover. (number )
  8. PIST: percent cover. 0.1% used for '+' cover. (number )
  9. BEAL: percent cover. 0.1% used for '+' cover. (number )
  10. BELE: percent cover. 0.1% used for '+' cover. (number )
  11. BESP: percent cover. 0.1% used for '+' cover. (number )
  12. ACSA: percent cover. 0.1% used for '+' cover. (number )
  13. QUAL: percent cover. 0.1% used for '+' cover. (number )
  14. UNK: percent cover. 0.1% used for '+' cover. (number )

hf106-06: 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) (meter )
  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) (meter )
  7. dbh: diameter breast height (1.3 meters), measured in centimeters using a dbh tape (centimeter )
  8. distance: distance in meters from the tree at which the height and crown depth measurements were taken (meter )
  9. heightpercenttop: the height percent to the top of the tree, measured using a clinometer (number )
  10. heightpercentbase: the height percent to the base of the tree, measured using a clinometer (number )
  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 (number )
  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 (number )
  13. majoraxis: the length, in meters, of the crown diameter at its largest point (determined by visual inspection), measured with a 50 meter tape (meter )
  14. minoraxis: the length, in meters, of the crown diameter at its smallest point (determined by visual inspection), measured with a 50 meter tape (meter )
  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) (meter )
  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) (meter )
  17. meancrowndiameter: the average of the major and minor axes of the crown diameter = (major axis + minor axis)/2 (meter )
  18. notes: field notes taken on variables in situation and structure that might impact the measurements being taken

hf106-07: species list

  1. Type: vegetation type
    • F: ferns/lycopods
    • G: graminoids
    • H: herbs
    • S: shrubs
    • T: trees
  2. Species: species name. An asterisk indicates species first observed in 2005.
  3. Code: species code
    • ACPE: Acer pensylvanicum
    • ACRU: Acer rubrum
    • ACSA: Acer saccharum
    • BEAL: Betula alleghaniensis
    • BELE: Betula lenta
    • BESP: Betula sp.
    • CASP: Carya sp.
    • FAGR: Fagus grandifolia
    • FRAM: Fraxinus americana
    • PIST: Pinus strobus
    • PRSE: Prunus serotina
    • QUAL: Quercus alba
    • QURU: Quercus rubra
    • TSCA: Tsuga canadensis
    • AMSP: Amelanchier sp.
    • COCO: Corylus cornuta
    • CRSP: Crataegus sp.
    • GAPR: Gaultheria procumbens
    • HAVI: Hamamelis virginiana
    • LOSP: Lonicera (native)
    • MIRE: Mitchella repens
    • PAQU: Parthenocissus quinquefolia
    • RHNU: Rhododendron nudiflorum
    • RUAL: Rubus allegheniensis
    • RUHI: Rubus hispidis
    • RUSP: Rubus sp.
    • VAAN: Vaccinium angustifolium
    • VACO: Vaccinium corymbosum
    • VASP: Vaccinium sp.
    • VIAC: Viburnum acerifolium
    • VICA: Viburnum cassinoides
    • VITSP: Vitis sp.
    • ANQU: Anemone quinquefolia
    • ARNU: Aralia nudicalis
    • ASAC: Aster acuminatus
    • ASDI: Aster divaricatus
    • CHMA: Chimaphila maculata
    • CLBO: Clintonia borealis
    • COGR: Coptis groenlandica
    • ERHY: Erichtites hyracifolia
    • GOPU: Goodyera pubescens
    • GOTE: Goodyera tesselata
    • LYQU: Lysimachia quadrifolia
    • MACA: Maianthemum canadense
    • MEVI: Medeola virginiana
    • MOHY: Monotropa hypopithys
    • MOUN: Monotropa uniflora
    • PYMI: Pyrola minor
    • PYRO: Pyrola rotundifolia
    • SOSP: Solidago sp.
    • TRBO: Trientalis borealis
    • UVSE: Uvularia sessifolia
    • DEPU: Dennstaedtia punctilobula
    • DRSP: Dryopteris spinulosa
    • LYCO: Lycopodium complanatum
    • LYLU: Lycopodium lucidulum
    • LYOB: Lycopodium obscurum
    • OSCI: Osmunda cinnamomea
    • OSCL: Osmunda claytoniana
    • POVU: Polypoduium vulgare
    • POAR: Polystichum arostichoides
    • PTAQ: Pteridium aquilinum
    • THNO: Thelypteris novaboracensis
    • CAPE: Carex cf. pennsylvanicum
    • GRAM: Graminoid sp.
  4. Year: year of observation (YYYY)
  5. Plot1: presence or absence of each species
    • 0: absent
    • 1: present
  6. Plot2: presence or absence of each species
    • 0: absent
    • 1: present
  7. Plot3: presence or absence of each species
    • 0: absent
    • 1: present
  8. Plot4: presence or absence of each species
    • 0: absent
    • 1: present
  9. Plot5: presence or absence of each species
    • 0: absent
    • 1: present
  10. Plot6: presence or absence of each species
    • 0: absent
    • 1: present
  11. Plot7: presence or absence of each species
    • 0: absent
    • 1: present
  12. Plot8: presence or absence of each species
    • 0: absent
    • 1: present
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