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Harvard Forest Data Archive


Sap Flow of Northern Red Oak Trees Under Ecosystem Warming at Harvard Forest 2011

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  • Lead: Pamela Templer, Nathan Phillips, Stephanie Juice, Aaron Ellison
  • Investigators: Shannon Pelini
  • Contact: Information Manager
  • Start date: 2011
  • End date: 2011
  • Status: completed
  • Location: Prospect Hill Tract (Harvard Forest)
  • Latitude: +42.53
  • Longitude: -72.19
  • Elevation: 340 meter
  • Taxa: Quercus rubra (northern red oak)
  • Release date: 2015
  • Revisions:
  • EML file: knb-lter-hfr.247.6
  • DOI: digital object identifier
  • EDI: data package
  • DataONE: data package
  • Related links:
  • Study type: short-term measurement
  • Research topic: large experiments and permanent plot studies; physiological ecology, population dynamics and species interactions
  • LTER core area: disturbance
  • Keywords: air temperature, climate change, relative humidity, tree physiology, water balance
  • Abstract:

    Over the next century, air temperature increases up to 5 °C are projected for the northeastern USA. Because evapotranspiration dominates water loss from terrestrial ecosystems, tree ecophysiological response to warming will have important consequences for forest water budgets. We measured growing season sap flow rates in mature northern red oak (Quercus rubra L.) trees in a combined air (up to 5.5 °C above ambient) and soil (up to 1.85 °C above ambient at 6-cm depth) warming experiment at Harvard Forest, MA, USA. Principal components analysis found air and soil temperatures had the largest effects on sap flow. On average, each 1 °C increase in temperature increased sap flow rates by approximately 1100 kg H2O m-2 sapwood area day-1 throughout the growing season and by 1200 kg H2O m-2 sapwood area day-1 during the early growing season. Reductions in the number of cold winter days correlated positively with increased sap flow at night during the early growing season (a decrease of 100 heating-degree-days was associated with a sapflow increase of approximately 5 kg H2O m-2 sapwood area day-1). Soil moisture declined with increased treatment temperatures, and each soil moisture percentage increase resulted in an increase in sap flow of approximately 360 kg H2O m-2 sapwood area day-1. At night, soil moisture correlated positively with sap flow rate. These results demonstrate that warmer air and soil temperatures in winter and throughout the growing season lead to increased sap flow rates, which could affect forest water budgets throughout the year.

  • Methods:

    This research was conducted in the Prospect Hill Tract of Harvard Forest. Our study was conducted within an ongoing warming experiment. The design of the experiment is described thoroughly by Pelini and others (2011); only salient details are presented here. Twelve open-top octagonal chambers (5-m diameter, 1.2-m tall; internal volume = 21.7 m3) were installed in 2009 in a forest tract dominated by ca.70-year-old northern red oak and red maple trees. Each chamber is centered around an overstory northern red oak tree; the diameters (measured at 1.3 m aboveground) of the twelve trees used in this study ranged from 20−50 cm.

    Sap flux density measurements were made using thermal dissipation probes consisting of a pair of 1-mm diameter, 11-mm-long stainless-steel hollow needles with copper constantan (type T) thermocouples inserted at the midpoint (Granier 1987). Probes were installed in April 2011 in freshly drilled holes at 1.3-m height on both the north and south side of the trunk of each of the 12 trees.

    All statistical analyses were done using various functions within the R statistical software system, version 3.0.3 (R Core Team 2013).

  • Use:

    This dataset is released to the public under Creative Commons CC0 1.0 (No Rights Reserved). Please keep the dataset creators informed of any plans to use the dataset. Consultation with the original investigators is strongly encouraged. Publications and data products that make use of the dataset should include proper acknowledgement.

  • Citation:

    Templer P, Phillips N, Juice S, Ellison A. 2015. Sap Flow of Northern Red Oak Trees Under Ecosystem Warming at Harvard Forest 2011. Harvard Forest Data Archive: HF247 (v.6). Environmental Data Initiative:

Detailed Metadata

hf247-01: sap flow

  1. datetime: date and time
  2. year: year
  3. doy: day of year (unit: nominalDay / missing value: NA)
  4. time: time of day
  5. hour: hour of day (unit: nominalHour / missing value: NA)
  6. air.temp: air temperature (unit: celsius / missing value: NA)
  7. rh: relative humidity (%) (unit: dimensionless / missing value: NA)
  8. vpd: vapor pressure deficit (unit: kilopascal / missing value: NA)
  9. tree: tree identification number
  10. sensor: sensor identification code
  11. dbh: diameter at breast height (unit: centimeter / missing value: NA)
  12. deltat: temperature above ambient (unit: celsius / missing value: NA)
  13. sap.flux.den: rate of sap flow (unit: gramsPerCentimeterSquaredPerHour / missing value: NA)

hf247-02: R code

  • Compression: none
  • Format: R Markdown
  • Type: script