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Harvard Forest Data Archive

HF270

Monitoring Amphibians in the Declined Hemlocks at Harvard Forest 2013-2014

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Data

Overview

  • Lead: Aaron Ellison, Ahmed Siddig
  • Investigators:
  • Contact: Aaron Ellison
  • Start date: 2013
  • End date: 2014
  • Status: completed
  • Location: Simes Tract (Harvard Forest)
  • Latitude: +42.47 to +42.48
  • Longitude: -72.22 to -72.21
  • Elevation: 215 to 300 meter
  • Taxa: Plethodon cinereus (red back salamander), Notophthalmus viridescens (eastern red-spotted newt), Tsuga canadensis (eastern hemlock)
  • Release date: 2016
  • Revisions:
  • EML file: knb-lter-hfr.270.2
  • DOI: digital object identifier
  • Related links:
  • Study type: short-term measurement
  • Research topic: biodiversity studies; conservation and management; physiological ecology, population dynamics and species interactions
  • LTER core area: populations, disturbance
  • Keywords: abundance, amphibians, hemlock, monitoring, salamanders
  • Abstract:

    Disturbances such as outbreaks of nonnative insects and pathogens can devastate unique habitats and directly reduce biodiversity. The foundation tree species Tsuga canadensis (eastern hemlock) is declining due to infestation by the nonnative insect Adelges tsugae (hemlock woolly adelgid). The decline and expected elimination of hemlock from northeastern US forests is changing forest structure, function, and assemblages of associated species. We assessed changes in occupancy, detection probability, and relative abundance of two species of terrestrial salamanders, Plethodon cinereus (eastern red-back salamander) and Notopthalmus viridescens viridescens (eastern red-spotted newt), in the experimental removal of T. canadensis at Harvard Forest. Four treatments (logging, girdling, hemlock control and hardwood control) have been applied and replicated in eight 0.81-ha plots. Salamanders were sampled under cover boards and using visual encounter surveys in June-July of 2013 and 2014.

    Removal of the hemlock canopy increased occupancy of P. cinereus but significantly reduced its estimated detection probability and abundance. Estimated abundance of N. v. viridescens also declined dramatically after canopy manipulations. Our results suggest that ten years after hemlock loss due to either the adelgid or pre-emptive salvage logging, and 50-70 years later when these forests have become mid-successional mixed deciduous stands, that the abundance of these salamanders likely will be less than 50% of their abundance in current, intact hemlock stands.

  • Methods:

    We counted red-backs under artificial cover objects (ACOs) on two (in 2013), and five (in 2014) sampling dates from June and July of 2013 and 2014. During the second and third weeks of May 2013, five 1 × 0.25 × 0.02-m rough-sawn T. canadensis boards (ACOs) were placed at 15-m interval along two 75-m transects in each of the eight HF-HeRE plots. All ACOs were placed at least 15 m from the edge of the plots. In both years, we sampled all of the ACOs in all of the plots on the same day. The 1–2-week interval between sampling individual ACOs was sufficient to ensure that repeated sampling did not impact detection probability (Marsh and Goicocchea 2003).

    Red efts were sampled using visual encounter surveys only in 2014, both concurrently with sampling ACOs for red-backs. The 2014 survey was done along two 60 × 1-m parallel transects separated by 30 m from one another.

    All amphibian sampling methods were approved by Harvard University’s Institutional Animal Care and Use Committee (File 13-02-144; last updated June 02, 2014).

  • 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, Siddig A. 2016. Monitoring Amphibians in the Declined Hemlocks at Harvard Forest 2013-2014. Harvard Forest Data Archive: HF270.

Detailed Metadata

hf270-01: red backs count

  1. species: species
    • PLCI: red-back salamander
  2. date: date of data collection
  3. block: topography of the study site
    • valley: valley
    • ridge: ridge
  4. treatment: type of experimental treatments applied in the hemlock removal experiment
    • Girdled: girdled
    • Logged: logged
    • Hardwood Control: hardwood control
    • Hemlock Control: hemlock control
  5. plot: plot number [1-8]. Each plot is 90×90m (0.81 ha).
  6. transect: transect number in which data was collected [ 1- 2]. In each plot there are two 90-m transects.
  7. aco: location of Artificial Cover Object (ACO) in each transect
  8. sample.n: sampling occasion [1-7]
  9. count: number of salamanders observed under each ACO in specific date (unit: number / missing value: NA)
  10. rh: relative humidity at sampling date (unit: dimensionless / missing value: NA)

hf270-02: red efts count

  1. species: species
    • NOVI: red spotted newt (Notopthalmus viridescens viridescens)
  2. date: date of data collection
  3. block: topography of the study site
    • valley: valley
    • ridge: ridge
  4. treatment: type of experimental treatment applied in the hemlock removal experiment
    • Girdled: girdled
    • Logged: logged
    • Hardwood Control: hardwood control
    • Hemlock Control: hemlock control
  5. plot: plot number [1-8]. Each plot is 90m×90m (0.81 ha).
  6. transect: transect number in which data was collected [ 1- 2]. In each plot there are two 60m×1m transects.
  7. location: area within each transect 15m×1m in which red efts were searched for. There are 4 areas/transect.
  8. sample.n: sampling occasion [1-5]
  9. count: number of efts observed at each 15m×1m box in each transect on specific date
  10. rh: relative humidity at sampling date