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Harvard Forest Data Archive

HF230

Litterfall in the Clearcut Site at Harvard Forest 2012

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Data

Overview

  • Lead: Christopher Williams
  • Investigators: Myroslava Khomik, Richard MacLean
  • Contact: Christopher Williams
  • Start date: 2012
  • End date: 2012
  • Status: completed
  • Location: Prospect Hill Tract (Harvard Forest)
  • Latitude: +42.546
  • Longitude: -72.174
  • Elevation: 403 meter
  • Taxa: Acer rubrum (red maple), Aralia nudicaulis (wild sarsaparilla), Betula spp. (birch), Dennstaedtia punctilobula (hayscented fern), Fagus spp. (beech), Polygonum sp. (knotweed), Prunus pensylvanica (pin cherry), Prunus serotina (black cherry), Quercus rubra (red oak), Rubus allegheniensis (Allegheny blackberry), Rubus idaeus (American red raspberry)
  • Release date: 2015
  • Revisions:
  • EML file: knb-lter-hfr.230.2
  • DOI: digital object identifier
  • Related links:
  • Study type: short-term measurement, modeling
  • Research topic: ecological informatics and modelling; forest-atmosphere exchange; physiological ecology, population dynamics and species interactions
  • LTER core area: primary production, disturbance
  • Keywords: leaves, litterfall, maple, oak, plant biomass, understory vegetation
  • Abstract:

    Clearcutting a forest ecosystem can result in a drastic reduction of the stand’s productivity. Despite the severity of this disturbance type, past studies have found that the productivity of young regenerating stands can quickly rebound, approaching that of mature undisturbed stands within a few years. One of the obvious reasons is increased leaf area with each year of recovery. However, a less obvious reason may be the variability in species composition and distribution during the natural regeneration process. The purpose of this study was to investigate to what extent the increase in GEP, observed during the first four years of recovery, in a naturally regenerating clearcut stand was due to 1) an overall expansion of leaf area, and 2) an increase in the canopy’s photosynthetic capacity stemming from either species compositional shifts or drift in physiological traits within species. We found that the multi-year rise in GEP following harvest was clearly attributed to the expansion of leaf area rather than a change in vegetation composition. Sizeable changes in relative abundance of species were masked by remarkably similar leaf physiological attributes for a range of vegetation types present in this early successional environment. Comparison of upscaled leaf-chamber to eddy-covariance-based light-response curves revealed broad consistency in both maximum photosynthetic capacity and quantum yield efficiency. The approaches presented here illustrate how chamber- and ecosystem-scale measurements of gas exchange can be blended with species-level leaf area data to draw conclusive inferences about changes in ecosystem processes over time in a highly dynamic environment.

  • Methods:

    In August 2012, we deployed 25 litter traps across the site along the five transects used for the line-intercept survey. The traps were square frames, constructed out of wood planks: either 70 cm x 70 cm (0.490 m2 in area) or 30.48 cm x 30.48 cm (0.372 m2) in dimension, with fine-mesh window-screening stapled over the bottom of each frame. Traps were placed close to the ground to maximize capture of falling shrub foliage, while still elevated to avoid ground contact and associated stimulation of decomposition. Litter in the traps was collected on a biweekly basis, starting from September 20, 2012, until November 17, 2012 and air dried in the lab. Each bag’s litter was sorted by species, separating-out intact foliage. Unidentifiable leaf samples, fruits, twigs, dead insects and seeds were placed into an aggregate “other” sub-sample. Each identified foliar species subsample was weighed and this weight was used to calculate the site LAI for 2012, with the corresponding specific leaf area. Given the deciduous nature of the foliage at our site, species-specific LAI was estimated by collecting fallen leaves with traps of fixed area, weighing the resulting foliage by species, and multiplying this by the species-specific leaf areas:

    LAI.j = (weight.j * SLA.j)/(10.12 m2)

    where weight.j is the total dry weight of the foliage of species j (in grams, g) collected at the end of the growing season within all traps (i.e. 22 traps in total, equating to 10.12 m2); and SLA.j is the mean specific leaf area of species j (m2/g). Each species-specific LAI value was grouped into the three corresponding vegetation groups (x) and weighted to account for missing vegetation. The final site-level LAI value was the sum of LAI values from each group: herb, shrub and trees.

    NOTES: The first data file contains data from our litter-trap litter collection in the fall of 2012. Weights of litter are reported, sorted by individual species (as best as possible by us), that were found in each of the litter bag collected from the various traps at our clear-cut site. Litter traps were emptied on about biweekly basis from late September to mid November, untill all foliage was off (see tables below for sampling summary). On some occasions, several bags were collected from each trap, and sorted individually (was most convenient and prevented loss of sample from handling dry, crumbly leaves) - therefore for some traps and dates, you may find several entries of the same species (it is not a mistake). The second data file contains additional details on litter traps and sampling methods.

  • 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:

    Williams C. 2015. Litterfall in the Clearcut Site at Harvard Forest 2012. Harvard Forest Data Archive: HF230.

Detailed Metadata

hf230-01: litterfall data

  1. sampling.date: sampling date
  2. transect: transect number (litter traps were spread out along the five line-intercept transects at the site)
  3. trap: trap number
  4. species: species code
    • bb: blackberry
    • bc: black cherry
    • bi: birch
    • fern: ferns except woodfern
    • other: other
    • pc: pin cherry
    • rb: raspberry
    • rm: red maple
    • be: beech
    • red pine: red pine
    • ro: red oak
    • unknown: unknown
    • white pine: white pine
    • wood fern: wood fern
    • grasses: grasses
    • kw: knotweed
    • hemlock: hemlock
    • maple 2: maple (striped?)
    • NA: missing value
  5. weight: sample weight (unit: gram / missing value: NA)
  6. notes: notes
  7. data.entry: when data was digitized
  8. combined.date: sampling dates that were combined for later analysis – treated as one
  9. species.final: final species identification used in later analysis
    • bb: black berry
    • bc: black cherry
    • bi: birch
    • fern: ferns except woodfern
    • other: other
    • pc: pin cherry
    • rb: raspberry
    • rm: red maple
    • be: beech
    • ro: red oak
    • kw: knotweed
    • NA: missing value
  10. omit: whether or not the sample point was omitted from later analysis
    • 1: omitted from later analysis
    • 0: not omitted from later analysis
  11. trap.code: trap code used in data processing
  12. trap.area: area of the trap (unit: squareMeter / missing value: NA)

hf230-02: additional details

  • Compression: none
  • Format: pdf
  • Type: pdf file