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Harvard Forest Data Archive

HF031

Hemlock Mapped Tree Plot at Harvard Forest since 1990

Related Publications

Data

Overview

  • Lead: David Foster, Audrey Barker Plotkin
  • Investigators: Ann Lezberg, David Orwig
  • Contact: Audrey Barker Plotkin
  • Start date: 1989
  • End date: 2016
  • Status: ongoing
  • Location: Prospect Hill Tract (Harvard Forest)
  • Latitude: +42.54
  • Longitude: -72.18
  • Elevation: 355 meter
  • Taxa: Tsuga canadensis (eastern hemlock)
  • Release date: 2016
  • Revisions:
  • EML file: knb-lter-hfr.31.22
  • DOI: digital object identifier
  • Related links:
  • Study type: long-term measurement
  • Research topic: ;
  • LTER core area: populations, disturbance
  • Keywords: hemlock, land use, permanent plots, tree maps, vegetation dynamics
  • Abstract:

    Most of the central New England landscape was cleared for agriculture in the mid-19th century and then naturally reforested into "secondary forests" with the abandonment of agricultural land. Some sites, often poorly drained, remained forested, but were usually subjected to intensive fuelwood cutting or logging and are termed "primary forests." The Hemlock Woodlot was never cleared for agriculture, but has a history of cutting and natural disturbance. The hemlock woodlot is located in the center of Harvard Forest's Prospect Hill Tract, adjacent to a spruce-blackgum swamp. Soils are moist and rocky, with a thick organic layer. Hemlock dominates tree species composition (62% by basal area), with hardwoods and scattered large white pine comprising the remainder. Most of the trees are 100-150 years old, with a few hemlock trees up to 230 years old. While the site was never cleared for agriculture, it was logged several times and chestnut blight removed a chestnut-dominated overstory in the 1910s. The 0.72 ha stem-mapped plot is at the center of a 4-ha hemlock-dominated forest. This plot serves as a major reference site and is part of a network of hemlock forests that are being intensively sampled as the hemlock woolly adelgid arrives.

  • Methods:

    In 1990, the 120m x 60m plot was established with a 10m x 10m grid. The long axis of the plot runs approximately East-West and the 0,0 point is the northwest corner. All trees greater than or equal to 5 cm dbh were mapped using a technique in which inter-tree distances were measured to the nearest centimeter (Boose, E.R., E.F. Boose and A.L. Lezberg. 1998. A practical method for mapping trees using distance measurements. Ecology 79:819-827). For each tree, species, canopy position, health, and diameter were recorded. Trees with multiple stems originating from a single base were measured as separate individuals if the stems forked at less than 1.3m high. Tree diameter and condition was re-measured in 1999, 2009 and 2014; hemlock vigor was also recorded.

    In 2002, sapling density and understory cover was sampled in three 20x20m subplots in or adjacent to the stem-mapped plot. In 2002 a nitrogen cycling study was initiated in the same three 20m x 20m plots.

    Hemlock woolly adelgid was detected on 20% of the hemlock trees examined in 2009. In 2014, adelgid infested 98% of hemlock trees examined, and the forest canopy was noticeably thinning.

  • 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:

    Foster D, Barker Plotkin A. 2016. Hemlock Mapped Tree Plot at Harvard Forest since 1990. Harvard Forest Data Archive: HF031.

Detailed Metadata

HF031-01: tree data

  1. tree: tag number (#1-744 present in 1989; 800 and up recruited in 1999, 2009 or 2014)
  2. x: x-coordinate within grid (meter; 0,0 is northwest corner; X is the 60m axis of the plot) (unit: meter / missing value: NA)
  3. y: y- coordinate within grid (meter; 0,0 is northwest corner; Y is the long axis of the plot) (unit: meter / missing value: NA)
  4. cc: canopy class
    • CD: codominant
    • D: dominant
    • I: intermediate
    • S: suppressed
  5. spec: species code
    • ACRU: Acer rubrum
    • BEAL: Betula alleghaniensis
    • BELE: Betula lenta
    • BEPA: Betual papyrifera
    • CADE: Castanea dentata
    • FAGR: Fagus grandifolia
    • HAVI: Hamamelis virginiana
    • PIRU: Picea rubens
    • PIST: Pinus strobus
    • QURU: Quercus rubra
    • TSCA: Tsuga canadensis
    • UNK: unknown
  6. dbh90: diameter at breast height in 1990 (unit: centimeter / missing value: NA)
  7. cond89: tree condition in 1989
    • D: dead
    • L: living
    • M: moribund
  8. cond93: tree condition in 1993
    • D: dead
    • L: living
    • M: moribund
  9. dbh99: diameter at breast height in 1999 (unit: centimeter / missing value: NA)
  10. cond99: tree condition in 1999
    • D: dead
    • G: tree could not be located
    • L: living
    • M: moribund
  11. vigor99: tree vigor in 1999
    • 1: 0-25% foliar loss
    • 2: 25-50% foliar loss
    • 3: 50-75% foliar loss
    • 4: 75-99% foliar loss
    • 5: dead
  12. dbh09: diameter at breast height in 2009 (unit: centimeter / missing value: NA)
  13. cond09: tree condition in 2009
    • D: dead
    • L: living
  14. vigor09: tree vigor in 2009
    • 1: 0-25% foliar loss
    • 2: 25-50% foliar loss
    • 3: 50-75% foliar loss
    • 4: 75-99% foliar loss
    • 5: dead
  15. hwa09: presence/absence of hemlock woolly adelgid in 2009, assessed on two branches. Only trees with branches within reach were assessed (49 of the 309 live hemlocks in the plot in 2009)
    • 1: present
    • 0: absent
  16. dbh14: diameter at breast height in 2014 (unit: centimeter / missing value: NA)
  17. cond14: tree condition in 2014
    • D: dead
    • L: living
  18. vigor14: tree vigor in 2014
    • 1: 0-25% foliar loss
    • 2: 25-50% foliar loss
    • 3: 50-75% foliar loss
    • 4: 75-99% foliar loss
    • 5: dead
  19. hwa14b1: presence/absence of hemlock woolly adelgid in 2014, first branch. Only trees with branches within reach were assessed (41 of the 284 live hemlocks in the plot in 2014)
    • 1: present
    • 0: absent
  20. hwa14b2: presence/absence of hemlock woolly adelgid in 2014, second branch. Only trees with branches within reach were assessed (41 of the 284 live hemlocks in the plot in 2014)
    • 1: present
    • 0: absent
  21. ehs14: presence/absence of elongate hemlock scale. Only trees with branches within reach were assessed (41 of the 284 live hemlocks in 2014)
    • 1: present
    • 0: absent
  22. cond16: tree condition in 2016
    • D: dead
    • L: living
  23. vigor16: tree vigor in 2016
    • 1: 0-25% foliar loss
    • 2: 25-50% foliar loss
    • 3: 50-75% foliar loss
    • 4: 75-99% foliar loss
    • 5: dead
  24. hwa16b1: presence/absence of hemlock woolly adelgid in 2016, first branch. Only trees with branches within reach were assessed (41 of the 271 live hemlocks in the plot in 2016)
    • 1: present
    • 0: absent
  25. hwa16b2: presence/absence of hemlock woolly adelgid in 2016, second branch. Only trees with branches within reach were assessed (41 of the 271 live hemlocks in the plot in 2016)
    • 1: present
    • 0: absent
  26. ehs16: presence/absence of elongate hemlock scale. In 2016 Only trees with branches within reach were assessed (41 of the 271 live hemlocks in 2016)
    • 1: present
    • 0: absent
  27. megatag: tree tag number for those trees that fall within the 35-ha Forest Dynamics Plot
  28. note: notes from 1989, 1993 and 1999
  29. note2009: notes from 2009
  30. note2014: notes from 2014