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Harvard Forest Symposium Abstract 2008

  • Title: How are ground-dwelling micro-arthropod communities and nutrient flow affected by the loss of hemlock?
  • Primary Author: Tara Sackett (University of Toronto)
  • Additional Authors: Aimee Classen (University of Tennessee at Knoxville); Aaron Ellison (Independent); Nicholas Gotelli (University of Vermont (UVM)); Nick Reynolds (University of Tennessee at Knoxville); Nathan Sanders (University of Tennessee at Knoxville)
  • Abstract:

    Litter-dwelling arthropod communities in hemlock stands infested by the Hemlock Woolly Adelgid (Adelges tsugae) may shift in composition as deciduous species become more predominant in the canopy and litter. These changes may also affect associated ecosystem functions. In this experiment we are testing for changes in microarthropod communities (mites and collembolans) and nutrient flow as a result of a shift in litter composition from hemlock to deciduous.

    Our experiment uses 0.5 x 0.5 m blocks of litter (“litter loaves”) as sample units; these loaves are removed from the ground just above the mineral horizon, so that the litter strata of the loaf remain intact. At Harvard Forest in October 2007 we switched litter loaves between hemlock and deciduous stands, as well as maintaining control plots (within stand switches) and undisturbed controls in each stand type (6 treatments).

    There were 6 sample units per treatment, and we replicated the experiment in two pairs of stands. One ion-exchange resin bag (15 mL resin) was placed under each litter loaf and control plot in November 2007. Six initial samples of litter were taken from each of the four stands.

    We will leave the litter plots for two years. The resin bags will be replaced every six months and analyzed for changes in nutrient flow. In the spring of 2008 we will destructively sample half of the replicates by sifting and extracting arthropods from the litter using Winkler sacs. In 2009 we will sample the remaining replicates.

  • Research Category: Biodiversity Studies, Invasive Plants, Pests & Pathogens