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Harvard Forest Data Archive

HF150

Leaf Area Index at Harvard Forest HEM and LPH Towers since 1998

Related Publications

Data

Overview

  • Lead: David Orwig, Julian Hadley
  • Investigators: Mark VanScoy, Liza Nicoll
  • Contact: Mark VanScoy
  • Start date: 1998
  • End date: 2017
  • Status: ongoing
  • Location: Prospect Hill Tract (Harvard Forest)
  • Latitude: +42.539 to +42.542
  • Longitude: -72.185 to -72.180
  • Elevation: 355 to 380 meter
  • Taxa:
  • Release date: 2017
  • Revisions:
  • EML file: knb-lter-hfr.150.18
  • DOI: digital object identifier
  • Related links:
  • Study type: long-term measurement
  • Research topic: large experiments and permanent plot studies
  • LTER core area: primary production
  • Keywords: canopy cover, leaf area index, leaves
  • Abstract:

    Leaf area index (LAI) measurements are made to detect changes in forest leaf area that are important in understanding forests’ carbon dioxide (CO2) uptake and water use. Measurements of LAI in different forest types are useful understanding differences between forests in CO2 uptake and water use, while variation in LAI in the same forest type over time helps to explain interannual variation and long-term trends in carbon storage and water use. Within a single year, especially for deciduous forests, seasonal changes in LAI are very important in determining the forest’s cycle of CO2 uptake and water use. LAI measurements at Harvard Forest were begun in the old-growth hemlock stand in 1998 in order to understand and develop a predictive model for its carbon exchange, and were begun at the Little Prospect Hill site in 2002 to better understand CO2 uptake and carbon storage at this site, which were measured by the eddy-covariance method beginning in 2002. Due to a lack of personnel, multiple annual measurements of LAI to examine seasonal change in leaf area did not begin until 2007.

  • Methods:

    Leaf area index is measured with the LAI-2000 canopy analyzer (Licor, Inc., Lincoln, NE, USA). Data are collected under diffuse-light conditions, either around the time of sunrise or in cloudy weather, with one LAI sensor continuously logging data above the canopy on an eddy flux tower, and measurements with the other sensor made at multiple plots within each forest type - usually 12 plots within the old-growth hemlock forest, and 36 plots on Little Prospect Hill. For details on the positions of plots, see HF148. Data collected in Hemlock stand in November 1998, August 2009, and November 2009 (planned). Data collected annually at LPH stand during September 2002, 2003, 2004, 2005 and 2007, and multiple times in 2008 and 2009.

  • 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, Hadley J. 2017. Leaf Area Index at Harvard Forest HEM and LPH Towers since 1998. Harvard Forest Data Archive: HF150.

Detailed Metadata

hf150-01: Hemlock leaf area index

  1. datetime: date and time
  2. date: date
  3. doy: day of year (unit: nominalDay )
  4. time: time
  5. distance: distance from tower (unit: meter / missing value: NA)
  6. transect: compass direction from Hemlock tower from geographic north (unit: degree / missing value: NA)
  7. lai.masked: leaf area index measurement with the 5th ring masked (unit: dimensionless / missing value: NA)
  8. sel: standard error of mean (unit: dimensionless / missing value: NA)

hf150-02: Little Prospect Hill leaf area index

  1. datetime: date and time
  2. date: date
  3. doy: day of year (unit: nominalDay )
  4. time: time
  5. distance: distance from tower (unit: meter / missing value: NA)
  6. transect: compass direction from LPH tower from geographic north (unit: degree / missing value: NA)
  7. lai.unmasked: unmasked leaf area index measurement (unit: dimensionless / missing value: NA)
  8. sel.unmasked: standard error of mean of unmasked measurement (unit: dimensionless / missing value: NA)
  9. lai.masked: leaf area index measurement with the 5th ring masked (unit: dimensionless / missing value: NA)
  10. sel.masked: standard error of mean of masked measurement (unit: dimensionless / missing value: NA)