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Harvard Forest Data Archive

HF289

Hemlock Woolly Adelgid and Elongate Hemlock Scale Surveys in Connecticut and Massachusetts 1997-2011

Related Publications

Data

Overview

  • Lead: David Orwig, Nina Lany, Evan Preisser
  • Investigators:
  • Contact: David Orwig
  • Start date: 1997
  • End date: 2011
  • Status: completed
  • Location: Eastern Connecticut, Eastern Massachusetts
  • Latitude: +41.27 to +42.71
  • Longitude: -72.75 to -72.13
  • Elevation: 0 to 378 meter
  • Taxa: Adelges tsugae (hemlock woolly adelgid), Fiorinia externa (elongate hemlock scale)
  • Release date: 2017
  • Revisions:
  • EML file: knb-lter-hfr.289.2
  • DOI: digital object identifier
  • Related links:
  • Study type: long-term measurement
  • Research topic: conservation and management; invasive plants, pests and pathogens; large experiments and permanent plot studies; physiological ecology, population dynamics and species interactions; regional studies
  • LTER core area: populations, disturbance
  • Keywords: abundance, climate, hemlock, hemlock woolly adelgid, invasive species
  • Abstract:

    In the eastern USA, eastern hemlock (Tsuga canadensis) is the host plant for two invasive insect species - hemlock woolly adelgid (Adelges tsugae) and elongate hemlock scale (Fiorinia externa). We observed the density of adult hemlock woolly adelgid and elongate hemlock scale on eastern hemlock branches on five occasions over 14 years at 142 stands across a latitudinal transect encompassing 7,500 km2 in Connecticut and Massachusetts to assess whether there is a difference in the response to abiotic conditions (winter temperature, summer temperature, summer precipitation) between the two species, and whether the distribution and abundance of each insect species is dependent on biotic interactions with the co-occurring insect species.

  • Methods:

    Insect Sampling

    Forest stands containing at least 10% eastern hemlock (Tsuga canadensis) cover in eastern Connecticut and Massachusetts were located via black-and-white aerial photographs, and 142 eastern hemlock stands within the study area were intensively sampled. In the initial year of sampling (1997 in Connecticut and 2002-2003 in Massachusetts), each stand was given an ordinal score for each insect species (hemlock woolly adelgid and elongate hemlock scale) representing the average infestation level of the stand based on thorough examination of trees as follows: 0 = 0 insects per meter of branch; 1 = 1-10 insects per meter; 2 = 11 – 100 insects per meter; 3 = more than 100 insects per meter. In subsequent years (2005, 2007, 2009, 2011), 50 trees were haphazardly selected in each stand for observation, and the density of each insect species on each tree was assigned to one of the above categories. Individual trees could not be marked. Fewer than 50 trees were sampled per stand in some highly-damaged stands, and stands impacted by logging or development during the study period were not sampled post-disturbance.

    Climate Data

    Daily temperature (maximum/minimum) and precipitation data were obtained for each stand from 1996 to 2011 from the online PRISM Gridded Climate database (PRISM Climate Group, Oregon State University, http://prism.oregonstate.edu, created 26 Mar 2015) by interpolating 4km2 resolution climate data at the centroid of each eastern hemlock stand using values from surrounding grid cell centers and inverse-distance squared weighting.

  • 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:

    Orwig D, Lany N, Preisser E. 2017. Hemlock Woolly Adelgid and Elongate Hemlock Scale Surveys in Connecticut and Massachusetts 1997-2011. Harvard Forest Data Archive: HF289.

Detailed Metadata

hf289-01: stand characteristics

  1. plot: character identifying each eastern hemlock stand
  2. year: year the plot was first sampled
  3. long: longitude (unit: degree / missing value: NA)
  4. lat: latitude (unit: degree / missing value: NA)
  5. elevation: elevation in meters above sea level (unit: meter / missing value: NA)
  6. area: area of stand (unit: hectare / missing value: NA)

hf289-02: data specific to each stand-year

  1. plot: character identifying each eastern hemlock stand
  2. year: year of sampling
  3. sample.size: number of trees in the stand for which abundance was recorded in the year of sampling (unit: number / missing value: NA)
  4. temp.min: minimum winter temperature in the preceding winter (unit: celsius / missing value: NA)
  5. tmean.winter: mean winter temperature (Dec 1 through Mar 31) in the winter preceding sampling (unit: celsius / missing value: NA)
  6. precip: precipitation sum April 1 – Sept 30 of the sampling year (unit: millimeter / missing value: NA)
  7. temp.max: maximum temperature April 1 through Sept 31 of the sampling year (unit: celsius / missing value: NA)

hf289-03: tree-level ordinal abundance data

  1. plot: character identifying each eastern hemlock stand
  2. year: year of sampling
  3. tree: tree number (individual trees were not marked, so e.g. tree #3 is the third tree observed in a stand in a year, but tree #3 is not the same individual year after year)
  4. hwa: hemlock woolly adelgid density per meter of branch
    • 0: 0 insects per meter of branch
    • 1: 1-10 insects per meter
    • 2: 11 – 100 insects per meter
    • 3: more than 100 insects per meter
  5. ehs: elongate hemlock scale density per meter of branch
    • 0: 0 insects per meter of branch
    • 1: 1-10 insects per meter
    • 2: 11 – 100 insects per meter
    • 3: more than 100 insects per meter