HEM and LPH Towers - Leaf Area Index

Data

• hf150-01: Hemlock leaf area index
• hf150-02: Little Prospect Hill leaf area index

Overview

• Lead: Julian Hadley
• Investigators: Liza Nicoll, Mark VanScoy
• Contact: Julian Hadley
• Start date: 1998-01-01
• End date: ongoing
• Location: Prospect Hill Tract (Harvard Forest)
• Latitude: +42.539 to +42.542
• Longitude: -72.185 to -72.180
• Elevation: 355 to 380 meters
• Taxa:
• Research topic: plot
• Study type: long-term measurement
• LTER core area: primary production
• Keywords: canopy development, carbon exchange, leaf area index, leaf development, water use
• Release date: 2009
• EML version: knb-lter-hfr.150.4
• Revisions: data updated 2009-11-18
• Related links:
• HEM Tower - Net Carbon Exchange of an Old-Growth Hemlock Forest
• HEM Tower - Physiological Model of CO2 Exchange by Hemlock Forests
• HEM and LPH Towers - Soil Respiration
• LPH Tower - Net Carbon Exchange of a Young Upper-Slope Deciduous Forest
• 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 and may be freely downloaded. 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. For more information on LTER Network data access and use policies, please see: http://www.lternet.edu/data/netpolicy.html.

• Citation:

  Hadley J. 2009. HEM and LPH Towers - Leaf Area Index. Harvard Forest Data Archive: HF150.

Detailed Metadata

hf150-01: Hemlock leaf area index

1. Date: date (YYYY-MM-DD)
2. DOY: day of year (DDD)
3. Time: time (hh:mm:ss)
4. Distance: distance from tower (meter )
5. Transect: compass direction from Hemlock tower from geographic north (degree )
6. LAI_masked: leaf area index measurement with the 5th ring masked (dimensionless )
7. SEL: standard error of mean (dimensionless )

hf150-02: Little Prospect Hill leaf area index

1. Date: date (YYYY-MM-DD)
2. DOY: day of year (DDD)
3. Time: time (hh:mm:ss)
4. Distance: distance from tower (meter )
5. Transect: compass direction from LPH tower from geographic north (degree )
6. LAI_unmasked: unmasked leaf area index measurement (dimensionless )
7. SEL_unmasked: standard error of mean of unmasked measurement (dimensionless )
8. LAI_masked: leaf area index measurement with the 5th ring masked (dimensionless )
9. SEL_masked: standard error of mean of masked measurement (dimensionless )