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Harvard Forest Data Archive
Light Environment in Hemlock Removal Experiment at Harvard Forest since 2004Related Publications
- Lead: Aaron Ellison
- Investigators: Audrey Barker Plotkin, Rachel Stahr
- Contact: Aaron Ellison
- Start date: 2004
- End date: 2020
- Status: ongoing
- Location: Simes Tract (Harvard Forest)
- Latitude: +42.47
- Longitude: -72.22
- Elevation: 200 to 240 meter
- Taxa: Acer spp. (maple), Betula spp. (birch), Pinus strobus (white pine), Quercus spp. (oak), Tsuga canadensis (eastern hemlock)
- Release date: 2021
- EML file: knb-lter-hfr.107.30
- DOI: digital object identifier
- EDI: data package
- DataONE: data package
- Related links:
- Canopy Photographs
- Ecosystem Response to Hemlock Woolly Adelgid in Southern New England since 1998
- Understory Vegetation in Hemlock Removal Experiment at Harvard Forest since 2003
- Landscape Response to Hemlock Woolly Adelgid in Southern New England 1997-2004
- Study type: long-term measurement
- Research topic: large experiments and permanent plot studies
- LTER core area: disturbance
- Keywords: canopy cover, hemlock, hemlock woolly adelgid, leaf area index, light
The impending loss of hemlock trees due to hemlock woolly adelgid (Adelges tsugae) infestation is expected to lead to changes in the light environment of the forest understory. These changes will both drive succession and will themselves be altered by successional processes. The light reaching the forest floor is measured using hemispherical canopy photographs. Photographs were taken in December 2004 and May 2005 (both deciduous-tree leaf-off condition), prior to the application of the logging and girdling treatments, and then in September 2005 (deciduous tree leaf-on condition) after logging and girdling. Subsequent photographic series will be taken annually in spring (leaf-off) and summer/fall (leaf-on).
Every 15 m in each of the 8 experimental plots in the Simes Tract (i.e., at coordinates [15,15], [15,30], ... , [75, 60], [75.75]), we take a photograph of the canopy using a Nikon 8mm fish-eye lens mounted on a Nikon F3 (non-digital) camera. The camera is mounted on a tripod and positioned 1-2 m above ground. The camera is leveled (using self-leveling gimbals) and oriented with magnetic north at the top of the negative. For archival purposes, we use Kodak T-max 100 or T-max 400 black-and-white negative film. Negatives are individually cut, mounted, labeled, and scanned (300 dpi) for analysis. Original negatives (in acid-free slide sheets) and scans (on compact disks) are deposited in the Harvard Forest archives. Digital scans are analyzed using HemiView 2.1 SR1 software for canopy photograph analysis (Delta-T Devices, Ltd., UK: http://www.delta-t.co.uk).
For analysis purposes, latitude was set at 42.47, longitude was set at -72.22, altitude was set at 200m a.s.l., declination was set at -14 degrees. Lens calibration file (Linear 180) was provided within the software.
Beginning in September 2008, canopy photos were taken digitally using a Nikon D-3 digital camera body. We continue to use the same lens (Nikon 8mm AI fisheye lens) for images. From 2010 onward, Plot 7 no longer includes photo points [75,15], [75,30], [75,45], [75,60], and [75,75]
Key references for software and analysis
Anderson, M. C. 1964. Light relations of terrestrial plant communities and their measurment. Biological Reviews 39: 425-486.
Delta-T Devices, Ltd. 1999. HemiView Manual Revision Number 2.1. Delta-T Devices, Ltd., Cambridge, U.K.
Rich, P.M. 1989. A manual for analysis of hemispherical canopy photography. Los Alamos National Laboratory Report LA-11733-M.
Rich, P.M., D.B. Clark, D.A. Clark, and S.F. Oberbauer. 1993. Long-term study of solar radiation regimes in a tropical wet forest using quantum sensors and hemispherical photography. Agricultural and Forest Meteorology 65: 107-127.
The file hf107-02-sites.csv can be imported into HemiView software, version 2.1, to pre-define locations at Harvard Forest where canopy photos have been taken.
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.
Ellison A. 2021. Light Environment in Hemlock Removal Experiment at Harvard Forest since 2004. Harvard Forest Data Archive: HF107.
hf107-01: light data
- date: date photograph taken
- leaf: deciduous trees’ leaves off or on
- 0: leaves off
- 1: leaves on
- treatment: treatment
- girdle: girdled
- log: logged
- hemlock.control: hemlock control
- hardwood.control: hardwood control
- block: block
- 1: valley: plots 1-3, 8
- 2: ridge: plots 4-7
- plot: plot number of the Simes Tract Hemlock Removal Experiment
- x: x-coordinate location, in meters, of the sample. Each plot of the Simes Tract is 90 x 90 m. (unit: meter / missing value: NA)
- y: y-coordinate location, in meters, of the sample. Each plot at the Simes Tract is 90 x 90 m. (unit: meter / missing value: NA)
- gsf: estimated proportion of global radiation (direct plus diffuse) under a plant canopy relative to that in the open (range: 0 – 1). (unit: number / missing value: NA)
- dsf: estimated proportion of direct solar radiation reaching a given location, relative to that in a location with no sky obstruction (range: 0 – 1). (unit: number / missing value: NA)
- isf: estimated proportion of diffuse solar radiation reaching a given location, relative to a location with no sky obstruction (range: 0 – 1). (unit: number / missing value: NA)
- tot.be: estimated total radiation below the canopy, corrected for interception surface orientation (units: MJ m-2 yr-1) (range: greater than 0). (unit: megajoulePerMeterSquaredPerYear / missing value: NA)
- dir.be: estimated direct radiation below the canopy, corrected for interception surface orientation (units: MJ m-2 yr-1) (range: greater than 0). (unit: megajoulePerMeterSquaredPerYear / missing value: NA)
- lai: estimated leaf area index for the entire canopy (range: greater than 0) (unit: number / missing value: NA)
- gndcover: estimated overall fraction of ground covered by canopy (range: 0 – 1). (unit: number / missing value: NA)
- lai.dev: estimated uniformity of the canopy across the image (range: greater than 0) (unit: number / missing value: NA)
- threshold: user-specified value used to classify the image into black and white pixels (range 0 – 255) (unit: number / missing value: NA)
- SiteName: short version of site name
- Description: longer description of site name
- Lat: latitude in degrees N (unit: number / missing value: NA)
- Long: longitude in degrees W (unit: number / missing value: NA)
- Alt: elevation in m a.s.l (unit: number / missing value: NA)
- Decl: declination (degrees W of N) (unit: number / missing value: NA)