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Harvard Forest Data Archive

HF160

Ants and Ecosystem Function in Hemlock Removal Experiment at Harvard Forest since 2006

Related Publications

Data

Overview

  • Lead: Aaron Ellison
  • Investigators: Aimee Classen, Israel Del Toro, Nicholas Gotelli, Shannon Pelini, Nathan Sanders
  • Contact: Aaron Ellison
  • Start date: 2006
  • End date: 2014
  • Status: complete
  • Location: Simes Tract (Harvard Forest)
  • Latitude: +42.47
  • Longitude: -72.22
  • Elevation: 200 to 240 meter
  • Taxa: Formicidae, Aphaenogaster rudis, Camponotus pennsylvanicus, Tsuga canadensis
  • Release date: 2016
  • Revisions:
  • EML file: knb-lter-hfr.160.20
  • DOI: digital object identifier
  • Related links:
  • Study type: long-term measurement
  • Research topic: physiological ecology, population dynamics and species interactions; large experiments and permanent plot studies
  • LTER core area: disturbance
  • Keywords: ants, hemlock, hemlock woolly adelgid, nitrogen, soil respiration, soil temperature, species diversity, species richness
  • Abstract:

    Eastern hemlock (Tsuga canadensis) is a foundation species in eastern North American forests. Hemlock stands host unique assemblages of flora and fauna, and the structure of these assemblages is expected to change as hemlock declines due to infestation by the hemlock woolly adelgid (Adelges tsugae) and is removed by pre-emptive salvage logging. A 2003 survey of hemlock stands in central Connecticut and Massachusetts showed that ant species richness and abundance is substantially greater in logged and adelgid-infested hemlock stands than it is in intact hemlock stands (see HF065) and we hypothesized that we would see similar changes in ant species diversity following application of treatments in the Hemlock Removal Experiment at the Simes Tract (see HF118). We further hypothesized that because ants are known to modulate ecosystem function in other habitats that observed changes in ant species diversity would be accompanied by changes in ecosystem processes including soil respiration rate and nitrogen availability. In April 2006, we established a set of sub-plots in all eight canopy manipulation plots of the Hemlock Removal Experiment. In each canopy manipulation plot, we installed two ant exclosure plots, two disturbance control plots, and two control plots. Ant species richness and abundance, as well as effectiveness of the exclosures, is monitored with pitfall traps monthly during the summer. Soil nitrogen availability is measured using resins that are collected every three months, and soil respiration is measured bi-weekly during the growing season.

  • Methods:

    Exclosure construction: These sub-plots are located in the buffer-area of Simes plots 1-8. Exclosures are 3 x 3 m squares built from fiberglass roofing (3-m long x 30 cm high). The roofing is embedded 10-cm in the ground, leaving a 20-cm high wall. Corners are screwed to wooden posts and sealed with silicon caulk. Within this 3 x 3-m enclosure, a 2nd enclosure, 2 x 2 m in size, is constructed of 8” (~20-cm) diameter PVC sewer pipe cut in half lengthwise. The pipe is buried 5-cm deep, leaving 15-cm exposed, with the cut-edge (C-profile) pointing outwards. Corners are bolted into right-angle (90-degree) PVC elbows, also cut in half lengthwise, and sealed with silicon caulk. The result is a double-walled barrier separated by a 50-cm space. All monitoring and measurements are taken in the inner 2 x 2 m portion of the sub-plot. Exposed portions of both the fiberglass roofing and the PVC pipe barriers are sprayed with Tanglefoot insect barrier in May and July each year.

    Disturbance controls: These sub-plots are 2 x 2 m squares to match the working area of the exclosures, and they are located in the buffer area and within 5-15 m of the exclosures. Corners are marked with red plastic pipe (Pex) and the edges were dug and cleared of rocks in the same way we dug the exclosures to embed the PVC pipes.

    Controls: These sub-plots are also 2 x 2 m squares. In Simes plots 1-6, we co-located these sub-plots with two of the sub-plots used by Kathleen Savage and Eric Davidson to measure soil respiration in the center 30 x 30-m core area (see HF-130). In Simes plots 7 and 8 (the hardwood controls), control sub-plots are located in the buffer area within 5-m of the disturbance controls and the exclosures.

    Ant species composition and treatment effectiveness: To track changes in ant species richness and abundance, and to simultaneously determine effectiveness of the treatments, two pitfall traps are set in each sub-plot. Pitfall traps are 180-ml, 8-cm diameter urinalysis cups buried in the soil so that the rim of the cup is flush with the soil surface. Three times each summer, during the first weeks of June, July, and August, the cups are opened, filled with 10-ml of water to which dish detergent has been added (1 drop / gallon = 3.89 L) and left to collect ants for 48 hours. After 48 hours, trap contents are collected and cups are re-capped to await the next sample. Ants collected are identified and stored in 95% Ethanol in the Harvard Forest Sample Archive. Capped cups remain in place year-round to avoid repeated disturbance and further perforation of these small experimental units.

    Soil respiration: Soil respiration is measured in each sub-plot using Kathleen Savage and Eric Davidson’s Li-Cor 6000/6200 back-pack system. Permanent 25-cm diameter PVC collars are embedded in each sub-plot and repeated respiration measurements are made every two weeks during the growing season (May through October). Measurements were made in 2006-2008 (see HF-130).

    Nitrogen availability: Nitrogen availability is measured as extractable NO3 and NH4 on commercial resin-capsules (Unibest; WECSA, Inc.). Resin capsules are placed at the end of permanently embedded Wecsa-style samplers and are collected and replaced quarterly (January, April, July, October). Nitrogen is extracted and measured using a Lachat Autoanalyzer (see HF-054).

    Soil temperature: Soil temperature was initially measured using I-buttons, but failure rates more than 25% led to their abandonment in early 2008. We consider as reliable only plot-level soil temperature data from HF-108 and spot-measurements taken during soil respiration measurements.

    Decomposition rates of standard substrates: Whatman filter paper disks (10-cm) and tongue depressors (20-cm) were placed on the soil suface in flat mesh litter bags. Replicates were collected in 2008, 2009, and 2010, dried, and weighed.

    Ant samples and vouchers are stored in the Harvard Forest Sample Archive.

  • 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. 2016. Ants and Ecosystem Function in Hemlock Removal Experiment at Harvard Forest since 2006. Harvard Forest Data Archive: HF160.

Detailed Metadata

hf160-01: soil temperatures from ibuttons

  1. datetime: date and time
  2. date: date
  3. time.24hr: time of day
  4. soilt: soil temperature at 10cm depth (unit: celsius / missing value: NA)
  5. block: one of two treatment blocks
    • 1: valley block, including canopy manipulation plots 1-3 and 8
    • 2: ridge block, including canopy manipulation plots 4-7
  6. treatment: canopy-level treatment
    • hemlock control: hemlock control
    • hardwood control: hardwood control
    • girdled: all hemlock trees girdled
    • log: all hemlocks > 20 cm dbh and all merchantable hardwoods and white pine cut and removed from plot
  7. plot: plot number. Range 1-8.
  8. subplot: ant manipulation sub-plot group. Levels are A and B (two groups per canopy manipulation plot)
  9. subplot.t: sub-plot-level treatment. Levels are control, disturbance (disturbance control) and exclosure.
    • control: control
    • disturbance: disturbance control
    • exclosure: exclosure

hf160-02: locations of individual subplots

  1. treatment: canopy-level treatment
    • hemlock control: hemlock control
    • hardwood control: hardwood control
    • girdled: all hemlock trees girdled
    • log: all hemlocks greater than 20 cm dbh and all merchantable hardwoods and white pine cut and removed from plot
  2. block: one of two treatment blocks
    • 1: valley block, including canopy manipulation plots 1-3 and 8
    • 2: ridge block, including canopy manipulation plots 4-7
  3. plot: plot number. Range 1-8.
  4. subplot: ant manipulation sub-plot group. Levels are A and B (two groups per canopy manipulation plot)
  5. subplot.t: sub-plot-level treatment
    • control: control
    • disturbed: disturbance control
    • exclosure: exclosure
  6. x.m: longitude in Massachusetts State Plane Meters, NAD-83 (unit: meter / missing value: NA)
  7. y.m: latitude in Massachusetts State Plane Meters, NAD-83 (unit: meter / missing value: NA)
  8. elevation: elevation in meters above sea level (unit: meter / missing value: NA)

hf160-03: monthly ant diversity

  1. date: date on which pitfall trap was retrieved
  2. treatment: canopy-level treatment; levels are hemlock control, hardwood control, girdled (all hemlock trees girdled), and log (all hemlocks > 20 cm dbh and all merchantable hardwoods and white pine cut and removed from plot.
    • hemlock control: hemlock control
    • hardwood control: hardwood control
    • girdle: all hemlock trees girdled
    • log: all hemlocks greater than 20 cm dbh and all merchantable hardwoods and white pine cut and removed from plot
  3. block: one of two treatment blocks
    • 1: valley block, including canopy manipulation plots 1-3 and 8
    • 2: ridge block, including canopy manipulation plots 4-7
  4. plot: plot number. Range 1-8.
  5. subplot: ant manipulation sub-plot group. Levels are A and B (two groups per canopy manipulation plot)
  6. subplot.t: sub-plot-level treatment
    • control: control
    • disturbance: disturbance control
    • exclosure: exclosure
  7. vial.num: vial number, refers to vial in Harvard Forest Sample Archive
  8. subfamily: Subfamily of ant species. Valid levels are: Myrmicinae, Formicinae, Ponerinae, Dolichoderinae
  9. genus: Genus of ant species
  10. species: Species of ant species
  11. spec.code: six- or seven-character species code for ant species. See HF147 for additional details.
  12. count: number of individuals recovered in the pitfall trap (unit: number / missing value: NA)

hf160-04: quarterly nitrogen availability

  1. year: year of measurement; range 2006 - present
  2. quarter: indicates end date of three-month period of nitrogen accumulation
    • 1: January – March
    • 2: April – June
    • 3: July – September
    • 4: October – December
  3. treatment: canopy-level treatment; levels are hemlock control, hardwood control, girdled (all hemlock trees girdled), and log (all hemlocks > 20 cm dbh and all merchantable hardwoods and white pine cut and removed from plot.
    • hemlock control: hemlock control
    • hardwood control: hardwood control
    • girdle: all hemlock trees girdled
    • log: all hemlocks greater than 20 cm dbh and all merchantable hardwoods and white pine cut and removed from plo
  4. block: one of two treatment blocks
    • 1: valley block, including canopy manipulation plots 1-3 and 8
    • 2: ridge block, including canopy manipulation plots 4-7
  5. plot: plot number. Range 1-8.
  6. subplot: ant manipulation sub-plot group. Levels are A and B (two groups per canopy manipulation plot)
  7. subplot.t: sub-plot-level treatment. Levels are control, disturbance (disturbance control) and exclosure.
    • control: control
    • disturbance: disturbance control
    • exclosure: exclosure
  8. res.mass: mass of the rinsed, air-dried resin following collection (unit: gram / missing value: NA)
  9. tot.nh4: total extractable ammonium (unit: microgram / missing value: NA)
  10. tot.no3: total extractable nitrate (unit: microgram / missing value: NA)
  11. res.nh4: extractable ammonium per resin (unit: microgramsPerGram / missing value: NA)
  12. res.no3: extractable nitrate per resin (unit: microgramsPerGram / missing value: NA)
  13. tot.n: total extractable nitrogen = TotNH4 + TotNO3 (unit: microgram / missing value: NA)
  14. res.n: total extractable nitrogen per resin = ResNH4 + ResNO3 (unit: microgramsPerGram / missing value: NA)
  15. daily.nh4: total extractable ammonium per day (unit: microgramsPerGram / missing value: NA)
  16. daily.no3: total extractable nitrate per day (unit: microgramsPerGram / missing value: NA)
  17. daily.n: total extractable nitrate per day = DailyNH4 + DailyNO3 (unit: microgramsPerGram / missing value: NA)

hf160-05: soil respiration

  1. date: date on which soil respiration measurement was made
  2. doy: Julian day in which soil respiration measurement was made (range: 137 – 264) (unit: nominalDay / missing value: NA)
  3. treatment: canopy-level treatment
    • hemlock control: hemlock control
    • hardwood control: hardwood control
    • girdled: all hemlock trees girdled
    • log: all hemlocks greater than 20 cm dbh and all merchantable hardwoods and white pine cut and removed from plot
  4. block: one of two treatment blocks
    • 1: valley block, including canopy manipulation plots 1-3 and 8
    • 2: ridge block, including canopy manipulation plots 4-7
  5. plot: plot number. range 1-8.
  6. subplot: ant manipulation sub-plot group. Levels are A and B (two groups per canopy manipulation plot)
  7. subplot.t: sub-plot-level treatment
    • control: control
    • disturbed: disturbance control
    • exclosure: exclosure
  8. soilt.10cm: soil temperature measured at 10 cm (unit: celsius / missing value: NA)
  9. co2.flux: flux of carbon dioxide (soil respiration), in units of mg C m-2 hr-1 (unit: milligramPerMeterSquaredPerHour / missing value: NA)

hf160-06: decomposition of lignin and cellulose, 2008-2010

  1. date.out: date litter bag collected
  2. months.f: number of months in field (unit: number / missing value: NA)
  3. block: one of two treatment blocks
    • valley: valley block, including canopy manipulation plots 1-3 and 8
    • ridge: ridge block, including canopy manipulation plots 4-7
  4. plot: plot number. Range 1-8.
  5. treatment: canopy-level treatment; levels are hemlock control, hardwood control, girdled (all hemlock trees girdled), and log (all hemlocks > 20 cm dbh and all merchantable hardwoods and white pine cut and removed from plot.
    • hemlock control: hemlock control
    • hardwood control: hardwood control
    • girdled: all hemlock trees girdled
    • logged: all hemlocks greater than 20 cm dbh and all merchantable hardwoods and white pine cut and removed from plo
  6. subplot: ant manipulation sub-plot group. Levels are A and B (two groups per canopy manipulation plot)
  7. subplot.t: sub-plot-level treatment. Levels are control, disturbance (disturbance control) and exclosure.
    • control: control
    • disturbance: disturbance control
    • exclosure: exclosure
  8. litter.type: litter type
    • cellulose: cellulose
    • lignin: lignin
  9. bag.num: unique number identifying each litter decomposition bag
  10. i.adm: initial air-dried mass of material in the litter decomposition bag (unit: gram / missing value: NA)
  11. i.odm: initial oven-dried mass of material in the litter decomposition bag (unit: gram / missing value: NA)
  12. i.afodm: initial ash-free oven-dried mass of material in the litter decomposition bag (unit: gram / missing value: NA)
  13. f.odm: final oven-dried mass of material remaining in the litter decomposition bag after collection from the field after MonthsInF months (unit: gram / missing value: NA)
  14. crb.no: crucible number
  15. crb.mass: mass of the crucible (unit: gram / missing value: NA)
  16. sam.crb.mass: sample mass + crucible mass (unit: gram / missing value: NA)
  17. ash.crb.mass: ash mass + crucible mass (unit: gram / missing value: NA)
  18. ash.mass: ash mass. AshMass = AshCrbMass - CrbMass (unit: gram / missing value: NA)
  19. p.ash.free: proportion of fODM attributable to material other than ash (range 0 – 1) = (fODM – AshMass)/fODM (unit: dimensionless / missing value: NA)
  20. f.afodm: final oven-dried mass of material, minus mass of the ash fAFODM = fODM × pAshFree (unit: gram / missing value: NA)
  21. f.loss: mass of sample lost to decomposition fLoss = iAFODM - fAFODM (unit: gram / missing value: NA)
  22. m.loss.frac: proportion of the original mass of the sample lost to decomposition (range 0 – 1) mLossFrac = fLoss / iAFODM (unit: dimensionless / missing value: NA)
  23. remain.per: percentage of original mass remaining in the decomposition bag at the time of collection (range 0 – 100) pctRemain = (1 – mLossFrac) × 100 (unit: dimensionless / missing value: NA)

hf160-07: R code and associated csv files to accompany Kendrick et al. 2015 paper

  • Compression: zip
  • Format: csv, Rmd, html
  • Type: R code and csv files