Eastern hemlocks (Tsuga canadensis (L.) Carr) in the Great Smoky Mountain National Park: community and ecosystem dynamics as hemlock forests transition.

Field Methods: My work will test three predictions: (1) Hemlock decline alters nutrient cycling and decomposition rates. (2) Hemlock decline alters plant and soil communities, including microbial (bacteria and fungi) and soil arthropods (ants). (3) Hemlock decline and ant interactions with ecosystem processes will vary across elevation. To test my predictions, I will establish a series of 10- 20 m2 plots throughout the GSMNP to inventory and monitor hemlock stands. I will choose sites across a gradient of elevation throughout the park. Additionally I will classify each site based on its hemlock mortality (calculated using the percent of the hemlock crown remaining). Vegetation sampling: All overstory trees within plots will be identified to species and the diameter at breast height measured. All shrubs and tree saplings will be identified to species and the density of individual stems will be calculated. All hemlock seedlings within the plots will be counted. Within each of these 20 m2 plots, 10 randomly stratified 1 m2 subplots will be established for understory woody vegetation, herbs, and ferns, which will be identified to species, and percent groundcover will be estimated to determine density. I will compare community composition, richness, and structure (for the overstory trees) across each of the 20 m2 plots. Soil community sampling: To assess the soil community I will remove soil cores, sample ants, and take measurements of soils in situ at three locations within each 20 m2 plot. To monitor the ant community, I will lay out 10 pitfall traps within each plot, which will be left open for 48 hours. After this time, pitfall traps will be collected and taken to my lab to have the contents sorted and ants identified to species. I will collect 3 soil core samples per plot, to determine the abundance of soil microbial communities using qPCR, and to determine enzyme activity and microbial biomass in the soil. Soil samples will be taken back to the lab for detailed nutrient analysis including total nutrient content, nitrogen mineralization, and carbon evolution. Hemlock leaf litter will be collected and used to measure decomposition rates, using decomposition bags. Nine decomposition bags will be placed within each of the 20 m2 plots, and three bags will be removed after 3, 9, and 15 months. I will also collect in situ soil measurements including soil moisture, temperature, and respiration using a Li-Cor, and measurements will be compared across plots.

                                            [
  "010:24"
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    "@type": "dcat:Distribution",
    "title": "GRSM01096_PostedToDataStore20181017.zip",
    "format": "ZIP",
    "mediaType": "application/zip",
    "description": "ant, plant and summary data",
    "downloadURL": "https://irma.nps.gov/DataStore/DownloadFile/608807?Reference=2256904"
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                                            [
  "APHN",
  "Appalachian Highlands Network",
  "Ecological Framework: Biological Integrity | Focal Species or Communities | Terrestrial Invertebrates",
  "GRSM",
  "Great Smoky Mountains National Park",
  "Origin:External",
  "SER",
  "Southeast Region",
  "StudyID:GRSM-01096"
]
                                        

                                            [
  "010:118",
  "010:119"
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                                            {
  "name": "National Park Service",
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  "Generic Dataset"
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