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Harvard Forest Data Archive

HF176

Nonstructural Carbohydrates in Forest Trees at Harvard Forest 2007-2010

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Data

Overview

  • Lead: Andrew Richardson
  • Investigators:
  • Contact: Andrew Richardson
  • Start date: 2007
  • End date: 2010
  • Status: completed
  • Location: Prospect Hill Tract (Harvard Forest)
  • Latitude: +42.54
  • Longitude: -72.17
  • Elevation: 340 meter
  • Taxa: Acer rubrum (red maple), Quercus rubra (red oak), Tsuga canadensis (eastern hemlock)
  • Release date: 2012
  • Revisions:
  • EML file: knb-lter-hfr.176.8
  • DOI: digital object identifier
  • Related links:
  • Study type: short-term measurement
  • Research topic: forest-atmosphere exchange; physiological ecology, population dynamics and species interactions; regional studies
  • LTER core area: primary production
  • Keywords: carbohydrates, carbon, tree physiology
  • Abstract:

    Forest trees accumulate and store surplus nonstructural carbohydrates (NSC) as resources to be used to support future growth. This can be viewed as a conservative investment strategy, providing reserves that the tree can utilize in times of stress. NSC reserves are thus important in the context of forest responses to climate change, and forest ecosystem carbon cycling. At quarterly intervals over a three year period, we have monitored stemwood nonstructural carbohydrate (NSC) reserves of the dominant tree species of New England at three sites along a forest composition gradient: an oak-dominated transition hardwood forest (Harvard Forest), a maple-beech-birch northern hardwood forest (Bartlett Experimental Forest), and a spruce-fir boreal transition forest (Howland Forest). Adding to recent evidence indicating that in mature forest trees the nonstructural carbohydrate pool is surprisingly large, our results suggest that this pool is also highly dynamic, and unexpectedly old. In most species, seasonal dynamics in starch (2-4x higher in the growing season, lower in the dormant season) mirrored those of sugars.

    This data set contains 3 y of quarterly NSC concentration measurements (stemwood starch and sugars - sucrose, glucose, fructose, raffinose, stachyose - in mg per g OD wood tissue) for red maple, eastern hemlock, and red oak at the Harvard Forest.

  • Methods:

    In May 2007, transects were established in the AmeriFlux tower footprint at each site, and 60 trees (20 trees for each of three species) were tagged, measured, and mapped. We focused on three key species at each site: red maple (Acer rubrum), red spruce (Picea rubens), and eastern hemlock (Tsuga canadensis) at Howland; red maple, paper birch (Betula papyrifera), and American beech (Fagus grandifolia) at Bartlett; and red maple, eastern hemlock, and red oak (Quercus rubra) at Harvard. We sought out healthy, dominant or codominant individuals of at least 25 cm DBH (diameter at breast height), although in a small fraction of cases (17 of 180 trees, or 9%), it was necessary to relax the minimum diameter requirement to 20 cm DBH.

    Every three months (June, August, November and March), one-half of the trees of each species at each site were cored at breast height to a depth of 3 cm with a standard increment borer.

    Samples were shipped frozen, on dry ice, to the USDA Forest Service laboratory in Burlington, VT, for NSC determination. Analytical procedures followed the methods of Wong et al. (2003). Analysis was conducted only on the outer 2 cm of each increment core. Cores were vacuum-infiltrated with 80% ethanol at 52KPa for 15 minutes and then boiled. Samples were then finely diced with a razor blade and macerated in existing ethanol solutions using a Brinkman Instruments (Westbury, MA) Polytron. Macerated samples were extracted twice with 5 ml fresh 80% ethanol at 80 deg C for 15 minutes and centrifuged at 3000 rpm. Supernatants for each sample were combined, filtered through a 0.45 um syringe filter and used for soluble sugar analysis. The ethanol-insoluble pellets were used to determine starch content.

    Ethanol-soluble fractions were analyzed for sucrose, glucose, fructose, raffinose, and stachyose using a Waters (Milford, MA) Alliance HPLC system with a Waters Sugar-pak column and solvent (0.1 mmol-1 Ca EDTA) at 90 deg C (Wong et al. 2003). Sugars were detected with a Waters 2414 refractive index detector and Waters PC-based Empower software. The separated soluble sugars were identified and quantified with known standards and converted to milligrams of sugar per gram dry weight.

    The branched form of starch was determined after gelatinization with 0.1M KOH and neutralization with acetic acid by hydrolysis with amyloglucosidase for 30 min at 55 deg C (Wargo et al. 2002). Enzymatic digestions were terminated by placing the digests in a boiling water bath for 4 min. Glucose formed by hydrolysis was determined with a glucose hexokinase kit (Pointe Scientific, Canton, MI) at 340nm with a Bio-Tek Instruments ELx800 UV microplate reader (Winooski, VT). Concentrations of starches were calculated from glucose standard curves and are expressed here as milligrams per gram dry weight.

    The standard deviation (across trees of the same species on a given sampling date) on the total (starch + sugars) stemwood NSC was 1 standard deviation = plus or minus 25% of the measured value. With n = 10 replicate trees per species at each sample date, the standard error on the species-level mean is thus approximately plus or minus 9%.

  • 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:

    Richardson A. 2012. Nonstructural Carbohydrates in Forest Trees at Harvard Forest 2007-2010. Harvard Forest Data Archive: HF176.

Detailed Metadata

hf176-01: TNC

  1. month: month
  2. year: year
  3. site: site name
    • Harvard: Harvard Forest, an oak-dominated transition hardwood forest
    • Bartlett: Bartlett Experimental Forest, a northern hardwood forest
    • Howland: Howland Foret, a spruce-fir boreal transition forest
  4. species: species
    • acru: Acer rubrum
    • quru: Quercus rubrum
    • tsca: Tsuga canadensis
    • bepa: Betula papyrifera
    • fagr: Fagus grandifolia
    • piru: Picea rubens
  5. tree: tree number
  6. starch: starch concentration (unit: milligramPerGram / missing value: NA)
  7. stachyose: stachyose concentration (unit: milligramPerGram / missing value: NA)
  8. raffinose: raffinose concentration (unit: milligramPerGram / missing value: NA)
  9. sucrose: sucrose concentration (unit: milligramPerGram / missing value: NA)
  10. glucose: glucose concentration (unit: milligramPerGram / missing value: NA)
  11. fructose: fructose concentration (unit: milligramPerGram / missing value: NA)