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The re-use of scientific data has the potential to greatly increase communication, collaboration and synthesis within and among disciplines, and thus is fostered, supported and encouraged. Permission to use this dataset is granted to the Data User free of charge subject to the following terms:

1) Acceptable use. Use of the dataset will be restricted to academic, research, educational, government, recreational, or other not-for-profit professional purposes. The Data User is permitted to produce and distribute derived works from this dataset provided that they are released under the same license terms as those accompanying this Data Set. Any other uses for the Data Set or its derived products will require explicit permission from the dataset owner.
2 ) Redistribution. The data are provided for use by the Data User. The metadata and this license must accompany all copies made and be available to all users of this Data Set. The Data User will not redistribute the original Data Set beyond this collaboration sphere.
3 ) Citation. It is considered a matter of professional ethics to acknowledge the work of other scientists. Thus, the Data User will properly cite the Data Set in any publications or in the metadata of any derived data products that were produced using the Data Set. Citation should take the following general form: Creator, Year of Data Publication, Title of Dataset, Publisher, Dataset identifier. For example:

Shaver, G. 1989. Above ground biomass in acidic tussock tundra experimental site, 1989, Arctic LTER, Toolik, Alaska. Arctic LTER, Marine Biological Lab, Woods Hole, Ma 02543. 1989gsttbm http://ecosystems.mbl.edu/arc/terrest/biomass/index.shtml 

4 ) Acknowledgement. The Data User should acknowledge any institutional support or specific funding awards referenced in the metadata accompanying this dataset in any publications where the Data Set contributed significantly to its content. Acknowledgements should identify the supporting party, the party that received the support, and any identifying information such as grant numbers. For example:

Data sets were provided by the Arctic LTER. This material is based upon work supported by the National Science Foundation under Grants #DEB-981022, 9211775, 8702328; #OPP-9911278, 9911681, 9732281, 9615411, 9615563, 9615942, 9615949, 9400722, 9415411, 9318529; #BSR 9019055, 8806635, 8507493.

5 ) Notification. The Data User will notify the Data Set Contact when any derivative work or publication based on or derived from the Data Set is distributed. The Data User will provide the data contact with two reprints of any publications resulting from use of the Data Set and will provide copies, or on-line access to, any derived digital products. Notification will include an explanation of how the Data Set was used to produce the derived work.
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While substantial efforts are made to ensure the accuracy of data and documentation contained in this Data Set, complete accuracy of data and metadata cannot be guaranteed. All data and metadata are made available "as is". The Data User holds all parties involved in the production or distribution of the Data Set harmless for damages resulting from its use or interpretation.

Dataset URLs:METADATA: HTML, Rich Text, XML(EML compliant)
DATA: Comma Delimited, Excel file with Metadata and data, Dataset via LTER Data Poral
Dataset ID:2010_nb_ndvi-4sites.01
Dataset Title:Weekly Normalized Difference Vegetation Index (NDVI) data from Roche Moutonnee, Toolik Field Station, Imnavait, and Sag river DOT sites, in the northern foothills of the Brooks Range, Alaska, summer 2010.
Investigator 1: 
First Name:Natalie
Last Name:Boelman
Organization:Lamont-Doherty Earth Observatory and Department of Earth and Environmental Sciences,
Address line 2:Columbia University
Address line 3:61 Route 9W
City:Palisades
State: NY
Zip Code:10964
Country:USA
Investigator 2: 
First Name:Shannan
Last Name:Sweet
Organization:Lamont-Doherty Earth Observatory and Department of Earth and Environmental Sciences,
Address line 2:Columbia University
Address line 3:61 Route 9W
City:Palisades
State: NY
Zip Code:10964
Country:USA
Associate Investigators:
Keywords:normalized difference vegetation index, Roche Moutonnee, Imnaviat, Toolik Field Station, shrub tundra, spectral radiance, reflectance, teambird
Abstract:Weekly Normalized Difference Vegetation Index (NDVI) data from Roche Moutonnee, Toolik Lake Field Station, Imnavait Creek and Sagavanirktok River DOT sites in the northern foothills of the Brooks Range, Alaska. Located south of the Arctic LTER and Toolik Lake Field Station. Data collected from May to July 2010. Methods and further data published in Ecography by Rich, et al. 2013.
For questions about the Metadata and data contact the Investigators.
For information about this web site contact:
Arctic LTER Information Manager
The Ecosystems Center
Marine Biological Lab
7 MBL St
Woods Hole, MA 02543
Phone (508) 289 7496
Email: arc_im@mbl.edu
Online URL: http://ecosystems.mbl.edu/ARC/
DATA FILE INFORMATION:
Data File URL http://metacat.lternet.edu/das/dataAccessServlet?docid=knb-lter-arc.10496&urlTail=multi-trophic_impacts/NDVI/data/2010_nb_ndvi-4sites.csv
Data File Name 2010_nb_ndvi-4sites
Beginning Date 5/24/2010
End Date 7/26/2010
Number of Data Records 512
Other Files to Reference
Availability Status 1
Quality Control Information
Maintenance Description
Log of Changes: Metatdata entered and data reviewed by S.Sweet, uploaded and formatted JD (Dec.2013)
 
RESEARCH LOCATION:          
Location Name Roche Moutonnče (ROMO) Toolik Lake Field Station (TLFS) Imnavait Creek (IMVT) Sag River Department of Transportation (SDOT)  
Geographic Description Near Roche Mountonnee (68 degrees 38’N, 149 degrees 33’W, elevation ~ 820 m) northern foothills of Brook Range, Alaska, U.S.A. Near Toolik Field Station (68 degrees 65’N, 149 degrees 58’W, elevation ~ 730 m) in the northern foothills of Brook Range, Alaska, U.S.A. Near Imnavait Creek (68 degrees 62’N, 149 degrees 30’W, elevation ~ 910 m) in the northern foothills of Brook Range, Alaska, U.S.A. Near the Sagavanirktok River (68 degrees 46’N, 148 degrees 52’W, elevation ~ 510 m) in the northern foothills of Brook Range, Alaska, U.S.A.  
Location Bounding Box          
West Bounding Coordinate          
East Bounding Coordinate          
North Bounding Coordinate          
South Bounding Coordinate          
OR if single point location          
Latitude 68.3752904462 68.6455515506 68.6200002679 68.764564446  
Longitude -149.328436734 -149.576251046 -149.300313174 -148.90027451  
Elevation 820.329 731.782 911.128 510.33  
Link to Google Map View on Google Map View on Google Map View on Google Map View on Google Map  
           
 
TAXONOMIC COVERAGE:
Organisms studied
 
Methods:Datasets were collected in early May through the end of July in 2010 at four field sites in the vicinity of the Arctic Long Term Ecological Research (LTER) site at Toolik Field Station in the northern foothills of the Brooks Range, Alaska (68ş38’ N, 149ş34’ W, elevation 760 m). Sites were chosen in May 2010 to represent the most common shrub tundra types in the foothills of the Brooks Range. The Toolik Lake Field Station (TLFS) and Sagavanirktok River-Department of Transportation camp (SDOT) sites were deglaciated ~65,000 yr BP, following the Itkillik I glaciation (Hamilton 2002). The Imnavait Creek (IMVT) site was deglaciated ~120,000 yr BP, following the Sagavanirktok River glaciation (Hamilton 2002). Each of the three sites included two 20,000 m2 plots: one graminoid dominated plot (Open plot) and one woody deciduous shrub dominated plot (Shrub plot). Together, the Open and Shrub plots represent a natural gradient of increasing shrub dominance, because the same deciduous shrubs (B. nana and S. pulchra) are found in all plots, however their percent cover and stature increase from low percent cover and short stature in Open plots to higher percent cover and taller stature in Shrub plots (Boelman et al. 2011, Rich et al. 2013).

The Open plots at all three sites are similar to one another and are characterized by tussock- forming sedges interspersed with a variety of dwarf shrubs, forbs, and mosses, with maximum deciduous shrub heights of approximately 16 cm (IMVT), 23 cm (TLFS) and 28 cm (SDOT) (Rich et al. 2013). The three Shrub plots differ from one another and represent a gradient of shrub statures, with maximum deciduous shrub heights of approximately 22 cm (IMVT), 35 cm (TLFS) and 84 cm (SDOT) (Rich et al. 2013). Differences among Shrub plots are related to topography and water flow. The IMVT Shrub plot, which has the shortest shrubs of the three sites, is associated with water movement because it is located in an area with water tracks, and the site represents vegetation typical of water track tundra as described in Chapin et al. (1988). The TLFS Shrub plot, which has medium stature shrubs, is located at the outlet of Toolik Lake, where proximity to a large body of water, substrate conditions, and the presence of large rocks may promote root lengthening and shrub growth. The TLFS Shrub plot represents vegetation typical of shrub tundra described in Shaver & Chapin (1991). The SDOT Shrub plot, which has tall and structurally complex shrubs, is a riparian community (Rich et al. 2013). The Shrub plot at SDOT has the deepest thaw depths among all of our plots and represents vegetation typical of riverside shrub tundra as described in Giblin et al. (1991), which tend to have deeper thaw depths compared to other tundra vegetation communities (Shaver & Chapin 1991). The Roche Mountonnee site (ROMO) has not been described in a publication yet, but the Shrub plot is vegetated by tall (> 100 cm) riparian shrubs, primarily Salix alaxensis, with scattered forbs, and has dry, rocky soils. The Open plot at ROMO is similar to the Open plots described above.

In May 2010, two 100 m transects were established within each Open and Shrub plot, for a total of 12 transects (n = 6 Open; and n = 6 Shrub). For non-destructive vegetation sampling over multiple years, ten quadrats (1 m2) were established at 10 m intervals along each transect (ten quadrats per transect).

Quadrat-level spectral radiance measurements were made with a field portable spectroradiometer (FieldSpec3, Analytical Spectral Devices, Boulder, CO, USA) throughout the growing seasons of 2010. The spectroradiometer has a 25? full angle cone of acceptance field-of-view (FOV) fibre optic with a spectral range of from 350 to 1050 nm. The spectral sampling interval of the spectroradiometer is 1.4 nm. Radiance measurements were preceded by a calibration scan of a 99% reflectance white standard (Spectralon, LabSphere, North Sutton, NH, USA) to normalize for changes in light conditions between measurements. The foreoptic was held approximately 1 m above the top of the canopy, so that each measurement’s circular footprint was approximately 0.15 m2. Spectral measurements were made in the 1 m2 quadrats along each of the plots described above. Five measurements were collected within each 1 m2 quadrat in order to ensure that the spatial heterogeneity of each quadrat was captured, which resulted in 50 spectra for each transect. All spectral measurements were converted to reflectance values, and were interpolated to 1 nm intervals.
We employ the normalized difference vegetation index (NDVI); NDVI was calculated from visible red (R: 650 to 690 nm) and near-infrared (NIR: 750 to 850 nm) reflectance using the equation: NDVI = (NIR – R) / (NIR + R). The five NDVI values associated with each quadrat were averaged to give a mean quadrat NDVI value. These were then averaged for the 2 transects in each plot (Open and Shrub), for a representative index for each cover type at each site (n = 4 Open; n = 4 Shrub).

Reference Citations:
Boelman, N.B., Gough, L., McLaren, J.R., and Greaves, H., 2011: Does NDVI reflect variation in the structural attributes associated with increasing shrub dominance in arctic tundra? Environmental Research Letters, 6: 035501.
Chapin, F.S. III, Fetcher, N., Kielland, K., Everett, K.R., and Linkins, A.E., 1988: Productivity and nutrient cycling of Alaskan tundra: enhancement by flowing soil water. Ecology, 69: 693-702.
Giblin, A.E., Nadelhoffer, G.R., Shaver, G.R., Laundre, J.A., and McKerrow, A.J., 1991: Biogeochemical diversity along riverside toposequence in arctic Alaska. Ecological Monographs. 61: 415-435.
Hamilton, T.D., 2002: Glacial geology of Toolik Lake and the Upper Kuparuk River regions. Biological Papers of the University of Alaska. Walker, D.A. (Ed.). Fairbanks, AK: Institute of Arctic Biology, 1-25.
Rich, M.E., Gough, L., and Boelman, N.T., 2013: Arctic arthropod assemblages in habitat of differing shrub dominance. Ecography, 36: 1-10.
Shaver, G.R., and Chapin, F.S. III., 1991: Production: biomass relationships and element cycling in contrasting arctic vegetation types. Ecological Monographs, 61: 1-31.

Data Table

Variable Name Variable Description Data Type Units DateTime Format Code Information Missing Value Code
Site Research site code from Methods above: ROMO = Roche Mt; TLFS = Toolik Lake Field Station; IMVT = Imnavait Creek; SDOT = Sagavanirktok river DOT text        
Cover Cover type from Methods above: Open = graminoid/evergreen tundra; Shrub = deciduous shrub tundra text        
Year year datetime   yyyy    
Date date datetime   dd-mmm-yy    
NDVI index of canopy greenness/Normalized Difference Vegetation Index number dimensionless     N/A=Missing or Not Measured

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