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Harvard Forest Data Archive

HF187

Lake Sediment Pollen from Knob Hill Pond in Marshfield VT from 14000 BP to Present

Related Publications

Data

Overview

  • Lead: Wyatt Oswald, David Foster
  • Investigators:
  • Contact: Wyatt Oswald
  • Start date: -12000
  • End date: 2010
  • Status: completed
  • Location: Knob Hill Pond (Marshfield VT)
  • Latitude: +44.3605
  • Longitude: -72.3737
  • Elevation: 370 meter
  • Taxa: Betula spp. (birch), Fagus spp. (beech), Picea spp. (spruce), Pinus spp. (pine), Quercus spp. (oak), Tsuga spp. (hemlock)
  • Release date: 2011
  • Revisions:
  • EML file: knb-lter-hfr.187.6
  • DOI: digital object identifier
  • Related links:
  • Study type: paleological
  • Research topic: historical and retrospective studies
  • LTER core area: disturbance, populations
  • Keywords: climate, hemlock, lakes, paleoecology, pollen, sediments, vegetation dynamics
  • Abstract:

    The abrupt, range-wide decline of Tsuga canadensis ~5500 calibrated years before present (cal. yr BP) is one of the most-studied events in North American paleoecology. Little attention, however, has been given to an earlier Tsuga decline, dated to ~6000 cal. yr BP in southern Ontario, Canada. To investigate whether this event occurred elsewhere in eastern North America, we analyzed the middle-Holocene interval of a lake-sediment record from Knob Hill Pond, located in northern Vermont, USA, an area of historically high Tsuga abundance. A dramatic, short-lived drop in Tsuga pollen abundance does occur at ~6000 cal. yr BP in the Knob Hill Pond record, indicating that Tsuga populations declined in various parts of its range. We hypothesize that both middle-Holocene declines of Tsuga were caused by the deleterious effects of pronounced droughts on this moisture-sensitive tree. Close examination of pollen data from a transect of sites across New England reveals that the earlier decline of Tsuga is present in other records, although some aspects of the event appear to have varied geographically. While northern and higher-elevation sites exhibit a nearly full recovery of Tsuga populations between the two declines, records further to the south are characterized by a stair-step pattern of progressive decline. At sites near its southern range limit, relatively warm conditions between ~6000 and 5500 cal. yr BP were apparently not conducive to the reestablishment and survival of Tsuga, and thus it was unable to recover between the drought events.

  • Methods:

    For detailed methods, please see: Day, L. T., Oswald, W. W., Doughty, E. D., Foster, D. R. 2013. Analysis of hemlock pollen size in Holocene lake sediments from New England. Quaternary Research 76: 362-365.

  • 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:

    Oswald W, Foster D. 2011. Lake Sediment Pollen from Knob Hill Pond in Marshfield VT from 14000 BP to Present. Harvard Forest Data Archive: HF187.

Detailed Metadata

hf187-01: pollen

  1. cal.age.bp: calibrated age before present in years (unit: number / missing value: NA)
  2. depth: depth in sediment column (unit: centimeter / missing value: NA)
  3. taxa: name of taxa
  4. count: number of pollen grains or spores of individual taxa (unit: number / missing value: NA)

hf187-02: age

  1. depth: depth in sediment column (unit: centimeter / missing value: NA)
  2. cal.age.bp: calibrated age before present (years; present=1950 AD) (unit: number / missing value: NA)
  3. notes: notes and methods of age determination; 210Pb=lead-210 dating; 14C=radiocarbon dating; Euro settlement=determined by rise in abundance of weedy and agricultural taxa
  4. c14: un-calibrated radiocarbon years (unit: number / missing value: NA)
  5. error: analytical error for 14C dates in years (unit: number / missing value: NA)

hf187-03: microchar

  1. depth: depth in sediment column (unit: centimeter / missing value: NA)
  2. char.area: area of charcoal pieces greater than 10 and less than 180 microns in length (unit: millimeter / missing value: NA)
  3. exotic.char: number of exotic marker grains encountered during charcoal analysis (unit: number / missing value: NA)
  4. pollen.sum: number of pollen grains and spores of upland taxa encountered during pollen analysis (unit: number / missing value: NA)
  5. exotic.pollen: number of exotic maker grains encountered during pollen analysis (unit: number / missing value: NA)
  6. exotic.added: total number of exotic marker grains added to sample (unit: numberPerCentimeterCubed / missing value: NA)
  7. sed.vol: volume of the sediment samples (unit: centimeterCubed / missing value: NA)