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Harvard Forest Data Archive

HF121

Stream Macroinvertebrates in Hemlock and Deciduous Watersheds at Harvard Forest 2005-2007

Related Publications

Data

Overview

  • Lead: James Willacker, William Sobczak, Elizabeth Colburn
  • Investigators:
  • Contact: William Sobczak
  • Start date: 2005
  • End date: 2007
  • Status: completed
  • Location: Prospect Hill Tract (Harvard Forest)
  • Latitude: +42.53 to +42.55
  • Longitude: -72.20 to -72.17
  • Elevation: 280 to 420 meter
  • Taxa: Tsuga canadensis (eastern hemlock), Adelges tsugae (hemlock woolly adelgid)
  • Release date: 2009
  • Revisions:
  • EML file: knb-lter-hfr.121.11
  • DOI: digital object identifier
  • Related links:
  • Study type: short-term measurement
  • Research topic: watershed ecology
  • LTER core area: disturbance
  • Keywords: hemlock, hemlock woolly adelgid, macroinvertebrates, stream ecology
  • Abstract:

    Tsuga canadensis (Eastern Hemlock) is a common forest species that is declining throughout its range in the eastern United States because of the invasion of an exotic forest pest, Adelges tsugae (Hemlock Woolly Adelgid). This pest kills infected trees, and over time, infected stands are replaced by deciduous forests. The conversion of forests from Hemlock to deciduous species is predicted to impact the hydrology, chemistry, and biology of associated headwater streams. In this study, we examined the macroinvertebrate communities of two adjacent headwater streams with differing Hemlock influence in central Massachusetts. Abundance, taxa richness, diversity, and unique taxa were generally greater in the deciduous stream. Differences in the distribution of functional feeding groups were observed: the Hemlock stream had a greater percentage of collector-gatherers while the deciduous stream had a greater percentage of shredders and predators. These findings suggest that macroinvertebrate communities in streams draining Hemlock and deciduous watersheds may differ in structure and function, and that anticipated Hemlock mortality may impact the region’s stream ecology.

  • Methods:

    Field collection

    Invertebrate samples were taken from four randomly chosen locations in each stream during a two-week period in late July and early August of 2005. At each location, one sample was taken from the nearest riffle area and one from the nearest depositional area; thus, eight samples were taken from each stream. Moss was sampled when present on the substratum. Peak emergence of insects usually occurs in early to late spring; hence, it is likely that our sampling regime underestimated the abundance, richness, and diversity of the streams’ macroinvertebrate communities. Samples were taken by thoroughly disturbing the substrate within a 0.25-m2 quadrat for a 30-second period and collecting all dislodged material in standard D-frame kick nets (250-μm mesh) placed downstream. Samples were live-picked, with care being taken to collect all sizes of specimens.

    Laboratory methods and analysis

    In the laboratory, invertebrates were sorted and identifi ed to the genus level (with the exception of Chironomidae, which were identifi ed to the subfamily/tribe level) using dissecting and compound microscopes. Taxa were then segregated among the grazer, shredder, collector-gatherer, collector-fi lterer, and predator functional feeding groups based on the ecological information known for each taxon (Merritt and Cummins 1996, Stewart et al. 1993, Wiggins 2000). In addition, taxa unique to each stream were identifi ed. We calculated mean abundance (number of specimens/m2), richness (number of taxa/sample), and Shannon’s diversity index of macroinvertebrates in each stream and compared them using a Student’s t-test. In addition, the composition of the two streams was compared at the order level and among functional feeding groups.

  • 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:

    Willacker J, Sobczak W, Colburn E. 2009. Stream Macroinvertebrates in Hemlock and Deciduous Watersheds at Harvard Forest 2005-2007. Harvard Forest Data Archive: HF121.

Detailed Metadata

hf121-01: macroinvertebrate abundance

  1. species: species name
  2. order: order name
  3. group: functional feeding group
  4. hemlock: mean abundance for hemlock stream (unit: number / missing value: NA)
  5. deciduous: mean abundance for deciduous stream (unit: number / missing value: NA)