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Harvard Forest Data Archive

HF106

Understory Vegetation in Hemlock Removal Experiment at Harvard Forest since 2003

Related Publications

Data

Overview

  • Lead: Aaron Ellison, Audrey Barker Plotkin
  • Investigators: David Foster, David Orwig
  • Contact: Information Manager
  • Start date: 2003
  • End date: 2021
  • 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: 2022
  • Revisions:
  • EML file: knb-lter-hfr.106.30
  • DOI: digital object identifier
  • EDI: data package
  • DataONE: data package
  • 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, understory vegetation, 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 are 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. In 2009, HWA was observed on trees in the experimental plots; 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. 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.

    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, with an orange flag.

    For each quadrat, we annually estimate percent cover for herbs, shrubs, and seedlings to the nearest one percent. We count 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 cover more than 5% of the plot, their percent cover is recorded to the nearest 5%. In addition, the depth of the organic soil layer is measured to the nearest 0.5 cm at the NW corner of each subplot (2003, 2006 and 2016). Finally, we search each plot and compile a species list for the entire 30m x 30m area.

    Saplings were censused by species within the central 30m x 30m area of each plot prior to the treatments, and every two years thereafter. A sapling is a tree greater than 1.3m tall but less than 5cm dbh (diameter at breast height, 1.3m). In 2015, we measured sapling heights with a telescoping height pole. We measured all stems for uncommon species, and a random subsample (e.g. every 10th stem encountered) for frequent species. Stems that recruited into the greater than 5cm dbh class were tagged, measured and mapped in the 2009, 2014, and 2019 tree censuses (see HF126).

    In 2021, we reviewed and revised species names to make them consistent with Arthur Haines’ “Flora Novae Angliae: A Manual for the Identification of Native and Naturalized Vascular Plants of New England” (2011). In addition, we attempted to resolve taxa that were typically identified to species but sometimes were only identified to genus (e.g. we typically distinguished Vaccinium corymbosum and V. angustifolium, but for very small plants, we sometimes listed them simply as Vaccinium spp.). This poses a problem when analyzing data for species richness and turnover. We examined the ambiguous cases relative to the species occurring in a quadrat in later years; when a species identity became clear over time, we corrected the prior data to reflect that species identity (e.g. if V. spp was in a quadrat in 2005 and 2006 and then V. corymbosum from 2007 on, we changed the 2005 and 2006 data to V. corymbosum). Cases that remained ambiguous were left at the genus level; we note that these need to be dealt with in analyses of community change. Some taxa were only identified to genus throughout the survey (e.g. Amelanchier), so they may represent an underestimate of true species richness. Finally, some taxa that were incorrectly identified were corrected (e.g. both Goodyera pubescens and G. tesselata were in the species records, but these are all G. tesselata so we re-coded all as G. tesselata).

  • 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.

  • Citation:

    Ellison A, Barker Plotkin A. 2022. Understory Vegetation in Hemlock Removal Experiment at Harvard Forest since 2003. Harvard Forest Data Archive: HF106 (v.30). Environmental Data Initiative: https://doi.org/10.6073/pasta/e39bf309223f5caabf91439ce4659e74.

Detailed Metadata

hf106-01: species codes

  1. type: life-form
    • Tree: tree
    • Shrub: shrub
    • Herb: herb
    • Fern / Lycopod: fern/lycopod
    • Graminoid: graminoid
  2. code: species code (first 2 letters of genus and species for trees; first 3 letters of genus and species for other life-forms)
  3. name.Haines.2011: species name, based on Arthur Haines’ “Flora Novae Angliae: A Manual for the Identification of Native and Naturalized Vascular Plants of New England” (2011)
  4. old.name: species name before updating to Haines (2011)
  5. note: notes on whether a taxon is identified to genus only, or other notes
  6. invasive: whether species is invasive or native
    • N: native
    • Y: non-native invasive

hf106-02: o-layer and substrate

  1. plot: plot number
  2. subplot: subplot number
  3. year: year of survey
  4. o.layer: depth of o-layer (unit: centimeter / missing value: NA)
  5. down.wood: percent cover (unit: number / missing value: NA)
  6. slash: percent cover (unit: number / missing value: NA)
  7. rock: percent cover (unit: number / missing value: NA)
  8. tree: standing tree percent cover (unit: number / missing value: NA)
  9. stump: percent cover (unit: number / missing value: NA)
  10. root: percent cover (unit: number / missing value: NA)

hf106-03: shrub and herb cover

  1. plot: plot number (1-8)
  2. subplot: subplot number (1-10)
  3. trt: experimental treatment
    • girdled: girdled
    • hardwood: hardwood reference
    • hemlock: hemlock reference
    • logged: logged
  4. block: block
    • valley: valley
    • ridge: ridge
  5. year: year of survey, completed June – August
  6. species: species code, see HF106-01 for species codes. In addition, for each quadrat, the sum of the total cover of all species is listed as ‘ztot.cover’
  7. cover: percent cover; values represent percent cover to the nearest 1%. Values less than 1% are listed as 0.5% (unit: dimensionless / missing value: NA)

hf106-04: seedling count and cover

  1. plot: plot number
  2. subplot: subplot number
  3. trt: experimental treatment
    • girdled: girdled
    • hardwood: hardwood reference
    • hemlock: hemlock reference
    • logged: logged
  4. block: block
    • valley: valley
    • ridge: ridge
  5. year: year of survey, completed June – August
  6. species: species code, see HF106-01 for species codes. In addition, the total cover and number of seedlings are listed as ‘total’
  7. cover: percent cover; values represent percent cover to the nearest 1%. Values less than 1% are listed as 0.1% (unit: dimensionless / missing value: NA)
  8. number: the number of seedlings in the quadrat (unit: number / missing value: NA)

hf106-05: saplings

  1. plot: plot number (1-8)
  2. year: year (2004=Winter 2004/2005; 2007=Winter 2007/2008; 2009=Winter 2009/2010; 2017=Winter 2017/2018; 2019=Winter 2019/2020)
  3. species: species code (see hf106-01 for species codes)
  4. count: number of live stems in the core 30m x 30m portion of the plot (unit: number / missing value: NA)
  5. numperha: stems per hectare (unit: number / missing value: NA)
  6. note: note

hf106-06: species list

  1. year: year (2003, then annually since 2005, sampled July)
  2. plot: plot number (1-8)
  3. acpe: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  4. acru: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  5. acsa: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  6. beal: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  7. bele: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  8. bepa: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  9. bepo: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  10. besp: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  11. casp: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  12. fagr: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  13. fram: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  14. osvi: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  15. pisp: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  16. pist: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  17. potr: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  18. prpe: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  19. prse: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  20. qual: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  21. quru: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  22. quve: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  23. tsca: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  24. amesp: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  25. berthu: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  26. celorb: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  27. coralt: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  28. corcor: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  29. crasp: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  30. dielon: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  31. gaupro: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  32. hamvir: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  33. ilemuc: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  34. ilever: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  35. loncan: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  36. lonsp2: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  37. mitrep: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  38. comper: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  39. parqui: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  40. ruonud: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  41. rhafra: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  42. rhucop: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  43. rhurad: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  44. ruball: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  45. rubhis: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  46. rubida: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  47. rubsp: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  48. sampub: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  49. sasalb: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  50. sorame: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  51. spispe: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  52. vacang: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  53. vaccor: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  54. vacsp: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  55. vibace: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  56. vibcas: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  57. vitsp: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  58. aqucan: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  59. arahis: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  60. aranud: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  61. araspi: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  62. ariatr: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  63. astacu: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  64. astdiv: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  65. chimac: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  66. clibor: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  67. copgro: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  68. cypacu: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  69. epirep: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  70. erehie: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  71. goopub: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  72. gootes: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  73. lacspe: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  74. lysqua: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  75. maican: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  76. medvir: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  77. monhyp: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  78. monuni: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  79. phyame: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  80. prespei: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  81. pyrmin: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  82. pyrrot: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  83. smirac: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  84. solsp: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  85. tribor: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  86. trilsp: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  87. uvuses: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  88. denpun: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  89. dryspi: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  90. lyccom: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  91. lycluc: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  92. lycobs: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  93. osmcin: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  94. osmcla: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  95. polvul: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  96. polacr: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  97. pteaqu: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  98. thenov: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  99. braera: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  100. carpen: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  101. carsp: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  102. pansp: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent
  103. gram: see HF106-01 for species codes
    • 1: present in the 30x30m interior of the plot
    • 0: absent

hf106-07: sapling heights

  1. year (2015=Winter 2015/2016): year of survey
  2. plot: plot number
  3. species: species code (see hf106-01 for species codes)
  4. height.m: sapling height in meters (unit: meter / missing value: NA)
  5. note: note