You are here

Harvard Forest Data Archive

HF128

Impacts of Hemlock Harvesting in Central Massachusetts 2003-2009

Related Publications

Data

Overview

  • Lead: David Orwig, David Foster
  • Investigators: Laura Barbash, Brian Hall, Heidi Lux
  • Contact: David Orwig
  • Start date: 2003
  • End date: 2009
  • Status: completed
  • Location: Central Massachusetts
  • Latitude: +42.0 to +42.7
  • Longitude: -72.9 to -71.7
  • Elevation:
  • Taxa: Acer rubrum (red maple), Adelges tsugae (hemlock woolly adelgid), Betula lenta (black birch), Carex spp. (sedges), Dennstaedtia punctilobula (hayscented fern), Pinus strobus (white pine), Rubus spp. (brambles), Tsuga canadensis (eastern hemlock)
  • Release date: 2009
  • Revisions:
  • EML file: knb-lter-hfr.128.11
  • DOI: digital object identifier
  • Related links:
  • Study type: short-term measurement
  • Research topic: conservation and management; invasive plants, pests and pathogens; regional studies
  • LTER core area: inorganic nutrients, disturbance
  • Keywords: hemlock, hemlock woolly adelgid, nitrogen mineralization, soil chemistry, soil moisture, soil temperature, timber harvest, vegetation dynamics
  • Abstract:

    The recent unimpeded infestation of the hemlock woolly adelgid (HWA; Adelges tsugae) across the northeastern U.S. is driving large-scale hemlock decline and mortality. HWA has already infested over 40% of the towns in Massachusetts and, as a result, many landowners are considering pre-emptively harvesting their eastern hemlock (Tsuga canadensis) stands. To examine the local impacts of this cutting activity, we examined stand and ecosystem dynamics in 10 hemlock-dominated sites on public and private lands where hemlocks were harvested between 1 to12 years ago with nearby uncut forests. Forty-two to ninety-seven percent of hemlock stems and basal area were removed from the harvested sites. Sapling densities of 10,500 to 24,000 stems ha-1 dominated the vegetation at older cuts and consisted primarily of black birch (Betula lenta), red maple (Acer rubrum), and white pine (Pinus strobus). Seedling densities averaged 5 m-2 across sites, peaked at 20 m-2 at 6 to 9 year old sites, and consisted of hemlock, white pine, black birch, and red maple. Additional understory species that were common in cuts sites included various raspberry (Rubus) species, often averaging 30% cover, hay-scented fern (Dennstaedtia punctilobula), and various sedge (Carex) species. Harvesting resulted in soils that were 3 to 5 (deg C) warmer and tended to be drier in recent vs. older cuts. Net nitrogen mineralization rates in organic soils averaged just over 10 kg N ha-1yr-1 in recent cuts and approx. 5 kg N ha-1yr-1 in older cuts. Mineral soil net mineralization rates were lower among all cuts, ranging from 2.1 to 3.5 kg N ha-1yr-1. Nitrification rates were low in both soil horizons at all harvest ages. Recent cuts had much higher nitrogen capture (NH4- + NO3+) on resin bags averaging around 1200 μg N g resin-1 vs. 300 to 600 μg N g resin-1 captured in older cuts. Nitrification rates and nitrate capture on resin bags were lower in Massachusetts sites than those reported on sites with a long history of HWA that were then subsequently logged.

    Findings from this study corroborate past work, as more recent cuts also exhibited increased birch and maple establishment and higher N availability than older cuts. In contrast to prior studies, cutting in Massachusetts sites also led to abundant conifer regeneration of white pine and hemlock, suggesting that seed tree availability, seedbed characteristics, and lack of HWA at several of the MA sites contributed to the higher conifer seedling densities found in this study.

  • Methods:

    Ten hemlock-dominated stands in central Massachusetts that experienced logging during the previous 12 years were selected to examine the compositional, structural, and microenvironmental changes associated with logging, and their impact on ecosystem processes including N- mineralization, nitrification, and N-availability. Results were compared with ongoing measurements in nearby uninfested hemlock forests. Vegetation was sampled in two 400 m2 plots systematically located in the central portion of each harvest area. All remaining trees (stems greater than 8 cm dbh) were tallied by species and dbh and assigned a canopy position based on the amount of intercepted light received by the tree crown. Pre-harvest basal area was reconstructed allometrically using the following regression equation relating stump diameter to dbh: hemlock (y = 0.884x + 0.0003; r2=0.995) from a sample of 215 stems (Kizlinski et al. 2002). For all other species, equations from Wharton (1984) were used. All saplings (less than 8 cm dbh and greater than 1.4 m tall) were tallied by species in each plot while herb and shrub cover and seedling (less than 1.5 cm dbh) densities were determined in ten, 1-m2 subplots located randomly within the plot grid.

    Nitrogen mineralization was measured at 6-week intervals during the growing season with one set of cores left over winter from May 2004 to May 2005, using a modified core method. Soil inorganic N concentrations were determined colorimetrically with a Lachat 8500 flow-injection autoanalyzer (Lachat Instruments, Inc., Milwaukee, Wisconsin, USA) An assessment of forest floor N availability and mobility was determined at each soil subplot from mixed-bed cation + anion resin bags (IONAC NM-60, Sybron Chemicals Inc., Birmingham, NJ). Soil temperature at 1 and 5 cm depths were measured every hour using small, buried data loggers (iButton, Dallas Semiconductor Corp.) at each soil-sampling plot. Soils collected during our initial sampling at each site were also analyzed for pH in a soil and CaCl2 slurry (1:10 organic soil:solution; 1:4 mineral soil:solution), and total C and N content by dry combustion with a Fisons CHN autoanalyzer. Texture was determined on mineral soils using the hydrometer method.

  • 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, Foster D. 2009. Impacts of Hemlock Harvesting in Central Massachusetts 2003-2009. Harvard Forest Data Archive: HF128.

Detailed Metadata

hf128-01: site descriptions

  1. site.name: name of site
  2. owner: name of owner
  3. site.code: site code
  4. site.description: description of when site logged

hf128-02: soil temperature

  1. datetime: date and time
  2. date: date
  3. year: year
  4. month: month
  5. day: day of year
  6. hour: hour (24 hour time)
  7. llsf.o: average hourly organic soil temperature, PLOT 1 and 2 (LLSF) (unit: celsius / missing value: NA)
  8. llsf.m: average hourly mineral soil temperature, PLOT 2(LLSF) (unit: celsius / missing value: NA)
  9. mgsf.m: average hourly mineral soil temperature, PLOT 2(MGSF) (unit: celsius / missing value: NA)
  10. mgsf.o: average hourly organic soil temperature, PLOT 3(MGSF) (unit: celsius / missing value: NA)
  11. nssf.o: average hourly organic soil temperature, PLOT 3(NSSF) (unit: celsius / missing value: NA)
  12. nssf.m: average hourly mineral soil temperature, PLOT 4(NSSF) (unit: celsius / missing value: NA)
  13. lero.o: average hourly organic soil temperature, PLOT 4(LERO) (unit: celsius / missing value: NA)
  14. lero.m: average hourly mineral soil temperature, PLOT 5(LERO) (unit: celsius / missing value: NA)
  15. heca.o: average hourly organic soil temperature, PLOT 5(HECA) (unit: celsius / missing value: NA)
  16. heca.m: average hourly mineral soil temperature, PLOT 6(HECA) (unit: celsius / missing value: NA)
  17. egbr.o: average hourly organic soil temperature, PLOT 6(EGBR) (unit: celsius / missing value: NA)
  18. egbr.m: average hourly mineral soil temperature, PLOT 7(EGBR) (unit: celsius / missing value: NA)
  19. swri.o: average hourly organic soil temperature, PLOT 7(SWRI) (unit: celsius / missing value: NA)
  20. swri.m: average hourly mineral soil temperature, PLOT 8(SWRI) (unit: celsius / missing value: NA)
  21. hahi.o: average hourly organic soil temperature, PLOT 8(HAHI) (unit: celsius / missing value: NA)
  22. hahi.m: average hourly mineral soil temperature, PLOT 8(HAHI) (unit: celsius / missing value: NA)
  23. atho.o: average hourly organic soil temperature, PLOT 8(ATHO) (unit: celsius / missing value: NA)
  24. atho.m: average hourly mineral soil temperature, PLOT 8(ATHO) (unit: celsius / missing value: NA)
  25. grla.o: average hourly organic soil temperature, PLOT 8(GRLA) (unit: celsius / missing value: NA)
  26. grla.m: average hourly mineral soil temperature, PLOT 8(GRLA) (unit: celsius / missing value: NA)

hf128-03: soil moisture

  1. site: site code (see site descriptions)
  2. age: number of years since harvest at the time of the study (1-12)
  3. series: series
  4. month: month soil sample was collected
  5. subplot: number of 1 x 1 m subplot within each plot ( n = 10)
  6. o.m: soil horizon
    • O: organic
    • M: mineral
  7. moisture: total evaporable moisture content of sample (unit: gram / missing value: NA)

hf128-04: soil chemistry

  1. site: site code (see site descriptions)
  2. plot: number of 20 x 20 m plot in each site (n=2)
  3. subplot: number of 1 x 1 m subplot within each plot ( n = 10)
  4. o.m: soil horizon
    • O: organic
    • M: mineral
  5. ph: soil pH (unit: dimensionless / missing value: NA)
  6. n: sample content percent nitrogen (unit: dimensionless / missing value: NA)
  7. c: sample content percent carbon (unit: dimensionless / missing value: NA)
  8. c.n: sample carbon:nitrogen ratio (C/N) (unit: dimensionless / missing value: NA)

hf128-05: resin bags

  1. gs.ow: resin bags are deployed in the soil for the growing season (May-Oct) or over winter (Oct-May).
    • GS: growing season
    • ow: over winter
  2. site: site code (see site descriptions)
  3. subplot: number of 1 x 1 m subplot within each plot ( n = 10)
  4. nh4.n: nitrogen in the form of ammonium in solution (unit: milligramsPerLiter / missing value: NA)
  5. no3.n: nitrogen in the form of nitrate in solution extract (unit: milligramsPerLiter / missing value: NA)
  6. nh4.n.r: nitrogen in the form of ammonium captured in resin (ug/g resin) (unit: microgramsPerGram / missing value: NA)
  7. no3.n.r: nitrogen in the form of nitrate captured in resin (ug/g resin) (unit: microgramsPerGram / missing value: NA)

hf128-06: nitrogen mineralization

  1. site: site code (see site descriptions)
  2. core.in: date the core was placed in the study site
  3. core.out: date the core was extracted from the study site
  4. subplot: subplot where the core was located
  5. horizon: soil horizon
    • O: organic
    • M: mineral
  6. net.nh4.n: net ammonia (unit: kilogramsPerHectare / missing value: NA)
  7. net.ho3.n: net nitrate (unit: kilogramsPerHectare / missing value: NA)

hf128-07: herbs and ferns

  1. site: site code (see site descriptions)
  2. plot: number for 20 x 20 m plot within each site (n = 2)
  3. subplot: number of 1 x 1 m subplot within each plot ( n = 10)
  4. species: species code, listed by 4 letter abbreviation (see species codes)
  5. cover: percent herb cover to the nearest 0.5% within 1 x 1 m subplot for each species (unit: dimensionless / missing value: NA)

hf128-08: shrubs

  1. site: site code (see site descriptions)
  2. plot: number for 20 x 20 m plot within each site (n = 2)
  3. subplot: number of 1 x 1 m subplot within each plot ( n = 10)
  4. species: species code, listed by 4 letter abbreviation (see species codes)
  5. cover: percent shrub cover to the nearest 0.5 % within 1 x 1 m subplot for each species (unit: dimensionless / missing value: NA)

hf128-09: seedling cover

  1. site: site code (see site descriptions)
  2. plot: number for 20 x 20 m plot within each site (n = 2)
  3. subplot: number of 1 x 1 m subplot within each plot ( n = 10)
  4. species: species code, listed by 4 letter abbreviation (see species codes)
  5. cover: percent seedling cover to the nearest 0.5 % within 1 x 1 m subplot for each species (unit: dimensionless / missing value: NA)

hf128-10: seedling density

  1. site: site code (see site descriptions)
  2. plot: number for 20 x 20 m plot within each site (n = 2)
  3. subplot: number of 1 x 1 m subplot within each plot ( n = 10)
  4. species: species code, listed by 4 letter abbreviation (see species codes)
  5. density: seedling densities within 1 x 1 m subplot for each species (unit: numberPerMeterSquared / missing value: NA)

hf128-11: stumps

  1. site: site code (see site descriptions)
  2. plot: number of 20 x 20 m plot in each site (n=2)
  3. species: 4 letter species code of tree cut
  4. diameter: diameter of cut stump (unit: centimeter / missing value: NA)

hf128-12: species codes

  1. code: species codes consist of first two letters of Latin genus and species
  2. name: full Latin names according to Gleason and Cronquist