Hemlock Removal Experiment - Overstory Vegetation

Data

• hf126-01: plot coordinates
• hf126-02: trees
• hf126-03: saplings
• hf126-04: Hemlock vigor

Overview

• Lead: Aaron Ellison, Audrey Barker Plotkin
• Investigators: Marco Albani, 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.126.3
• Revisions: data updated 2009-04-22
• Related links:
• Hemlock Removal Experiment - Understory Vegetation
• 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

  Overstory Vegetation Sampling

  Throughout each 90m x 90m 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. 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 is assessed at two levels. For hemlocks only, we rate crown vigor in the center 30m x 30m area. We use 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 assess 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 will be surveyed in Summer 2009.

  Saplings: Trees greater than 1.3m tall but less than 5cm dbh are tallied by species in the core 30m x 30m area of each plot (prior to treatments in Winter 2004-2005 and once since treatments in Winter 2007-2008).

• 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 - Overstory Vegetation. 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) (meter )
3. plot Y: local coordinates within each plot (0-90m) (meter )
4. Easting spm: Easting spm. Massachusetts State Plane Meters; Datum = NAD1983 (meter )
5. Northing spm: Northing spm. Massachusetts State Plane Meters; Datum = NAD1983 (meter )
6. Longitude wgs1984: Longitude wgs1984, Datum = WGS 1984 (degree )
7. Latitude wgs1984: Latitude wgs1984, Datum = WGS 1984 (degree )
8. Height m wgs1984: Elevation in meter, Datum = WGS 1984 (meter )

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. There are 6953 trees. 1-7009, excluding 744, 1604, 2004, 2263, 4374, 4734 and 3752-3825. There are 24 trees with a 0.1 place.
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
   • 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. (centimeter )
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) (YYYY)
9. xcoord: tree location within plot along X (west-east) axis. Ranges from 0-90 with a few outside these bounds. (meter )
10. ycoord: tree location within plot along Y (south-north) axis. Ranges from 0-90 with a few outside these bounds. (meter )
11. zelev: elevation of tree relative to arbitrary point within plot that is designated as 0 elevation (meter )
12. elev0: X,Y coordinates of the arbitrary 0 elevation point within plot (meter )
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

hf126-03: saplings

1. Plot: plot number (1-8), Sapling count for central 30x30m plots only. Plots 2 and 4 were surveyed in January and February 2005. Plots 1, 3, and 5-8 were surveyed in May 2005.
2. TSCA live: numbe of live TSCA individuals (number )
3. TSCA dead: numbe of dead TSCA individuals (number )
4. ACRU live: numbe of live ACRU individuals (number )
5. ACRU dead: numbe of dead ACRU individuals (number )
6. ACSA live: numbe of live ASCA individuals (number )
7. ACSA dead: numbe of dead ASCA individuals (number )
8. PRSE live: numbe of live PRSE individuals (number )
9. PRSE dead: numbe of dead PRSE individuals (number )
10. BELE live: numbe of live BELE individuals (number )
11. PIST live: numbe of live PIST individuals (number )
12. BEAL dead: numbe of dead BEAL individuals (number )
13. QURU dead: numbe of dead QURU individuals (number )
14. Other dead: numbe of dead "other" individuals (number )

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. (centimeter )
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