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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.
6 ) Collaboration. The Data Set has been released in the spirit of open scientific collaboration. Data Users are thus strongly encouraged to consider consultation, collaboration and/or co-authorship with the Data Set Creator.

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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:2012_GS_ITEX_MaxCanopyHeight.04
Dataset Title:Maximum canopy height from 14 flux canopy and 19 point frame plots sampled near the shrub LTER sites at Toolik Field Station, Alaska, summer 2012.
Investigator 1: 
First Name:Gaius
Last Name:Shaver
Organization:Ecosystems Center at the Marine Biological Laboratory
Address line 2:7 MBL Street
Address line 3:
City:Woods Hole
State:MA
Zip Code:02543
Country:United States
Investigator 2: 
First Name:Edward
Last Name:Rastetter
Organization:Ecosystems Center at the Marine Biological Laboratory
Address line 2:7 MBL Street
City:Woods Hole
State:MA
Zip Code:02543
Country:United States
Investigator 3: 
First Name:Mathew
Last Name:Williams
Organization:University of Edinburgh
Address line 2:School of Geosciences
City:Edinburgh
State:
Zip Code:EH9 EJU
Country:United Kingdom
Investigator 4: 
First Name:James
Last Name:Laundre
Organization:Ecosystems Center at the Marine Biological Laboratory
Address line 2:7 MBL Street
Address line 3:
City:Woods Hole
Zip Code:02543
Country:United States
Investigator 5: 
First Name:Laura
Last Name:van der Pol
Organization:Ecosystems Center at the Marine Biological Laboratory
Address line 2:7 MBL Street
City:Woods Hole
State:MA
Zip Code:02543
Country:United States
Associate Investigators:
Keywords:photosynthesis, shrub canopy height, flux, point frame
Abstract:Maximum canopy height measurements for deciduous shrub canopies sampled for both 1m x 1mc hamber flux polots (n=14) and point frame plots (n=19) in the summer of 2012 near LTER shrub plots at Toolik Lake, AK. The canopies were dominated either by Salix pulchra or Betula nana species, and plot locations were preferentially selected for tall canopies (height > 75 cm). The methods for the chamber flux and point frames are outlined here briefly, though the data from these measurements are contained in separate files.
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.10149&urlTail=terrest/tracegas/data/2012_GS_ITEX_MaxCanopyHeight.csv
Data File Name 2012_GS_ITEX_MaxCanopyHeight
Beginning Date 6/23/2012
End Date 8/7/2012
Number of Data Records 33
Other Files to Reference 2012_GS_ITEX_BF3_DiffuseLightData; 012_GS_ITEX_CH_SoilData; 2012_GS_ITEX_CHFluxData; 2012_GS_ITEX_LC_ParameterSummary; 2012_GS_ITEX_MaxCanopyHeight; 2012_GS_ITEX_PercentCover; 2012_GS_ITEX_CHN_Data; 2012_GS_ITEX_PF_LAISummary; 2012_GS_ITEX_RawPinDrop_Data; 2012_GS_ITEX_ShootACiData; 2012_GS_ITEX_ShootHarvestData; 2012_GS_ITEX_ShrubCanopy_DailyLogger; 2012_GS_ITEX_InstantLogger; 2012_GS_ITEX_SunScan_LAI; 2012_GS_ITEX_SunScan_PAR; 2012_GS_PFandCH_GPS; 2012_GS_ITEX_PF_ShootLightCurve; 2003-2004gsfluxleafN; 2003-2009gscurveparameters; 2003-2009gsflux; 2003-2009gsGPSandveg; 2003-2009gsharvestLAI-N; 2003-2009gsspecieslist; 2004-2009gscoverft; 2004-2009gscoversp;
Availability Status 1
Quality Control Information
Maintenance Description This was a season-long project, though it followed similar methods to ITEX projects performed starting in 2003 that are likely to be replicated in the future for reasearch at the Toolik Field Station, AK.
Log of Changes: Updated Metadata sheet
Version 2: Updated metadata to newer version (with sites sheet). CH April 2013.
Version 3: Corrected the extension of the eml Excel file - it was saved as .xls instead of .xlsx JimL 17May13
Version 4: Corrected Distrubution URL. It had xlsfiles in the path. Jim L 19Jun14
 
RESEARCH LOCATION:                  
Location Name LTER Shrub Block 1 LTER Shrub Block 2 Select Site or enter New One Select Site or enter New One Select Site or enter New One Select Site or enter New One Select Site or enter New One Select Site or enter New One  
Geographic Description Upland site; co-located in Block 1 of the Shrub LTER sites; IVO 68 38'18.8" N, 149 34' 07.2" W +/- 50m. Except for plots marked "FERT", plots are outside of the designated LTER treatments, though are exposed to the same environmental conditions. All plots were chosen by the dominant shrub canopy (either Salix pulchraor Betula nana) and preferentially selected to be 90cm+ in height. Outlet site; co-located in Block 2 of the Shrub LTER sites; IVO 68 38'008.1" N, 149 35' 017.1" W +/- 50m. Except for plots marked "FERT", plots are outside of the designated LTER treatments, though are exposed to the same environmental conditions. All plots were chosen by the dominant shrub canopy (either Salix pulchraor Betula nana) and preferentially selected to be 90cm+ in height. Enter Description Enter Description Enter Description Enter Description Enter Description Enter Description  
Location Bounding Box                  
West Bounding Coordinate                  
East Bounding Coordinate                  
North Bounding Coordinate                  
South Bounding Coordinate                  
OR if single point location                  
Latitude 68.6385555555555 68.6355833333333 In Decimal Degrees In Decimal Degrees In Decimal Degrees In Decimal Degrees In Decimal Degrees In Decimal Degrees  
Longitude -149.568666666666 -149.588083333333 In Decimal Degrees In Decimal Degrees In Decimal Degrees In Decimal Degrees In Decimal Degrees In Decimal Degrees  
Elevation 747 m 730 m In Meters In Meters In Meters In Meters In Meters In Meters  
Link to Google Map View on Google Map View on Google Map              
                   
 
TAXONOMIC COVERAGE:
Organisms studied Betula nana; Salix pulchra; Salix glauca
 
Methods:MAXIMUM CANOPY HEIGHT FOR CHAMBER FLUX AND POINT FRAME PLOTS
We measured the maximum canopy height of each 1m x 1m chamber flux and point frame plot by measuring the five highest branches in the shrub canopy. Each height is measured from the soil, defined as the end of the green plant tissue, to the heighest point on each branch. The maximum height was always measured from different individual plants, thus only one branch from any particular plant was sampled even if there might be multiple "highest" branches from a single plant. The species of each sample is recorded as "MaxHghtSPP" (replicates 1-5).

CHAMBER FLUX MEASUREMENTS
CO2 and H2O fluxes were measured using a Licor 6400 photosynthesis system (Li-Cor Inc., Lincoln, Nebraska, USA) connected to a 1m x 1m plexiglass chamber in canopies dominated either by Salix pulchra or Betula nana shrub species. The height of the chamber varied depending on the height of the canopy being measured; chamber bases were constructed of PVC pipe to accomodate canopies with heights up to 125 cm. In addition to the plexiglass chamber, we also constructed a plexiglass "sleeve" that could extend the height of the rigid portion of the chamber by 0.25m.

To set up each chamber, a location was chosen where the base would be level enough to ensure a complete seal with the plexiglass chamber and shrub branches could be moved either in or out of the chamber without creating large gaps in the canopy inside the chamber. Branches were included within the chamber if they were rooted within the chamber and excluded otherwise. Once the base was in place, we drove hollow PVC pipe legs into the permafrost and inserted an aluminum frame with foam campermount tape along the top edge for the plexiglass chamber and/or sleeve to rest upon, creating an airtight seal. The aluminum frame had taped to it semi-transparent, plastic skirt which extended to the ground (+30cm). We sealed the skirt to the tundra by weighting the skirt with heavy chains, pushing them firmly into the moss layer where possible and adding additional plastic materials as needed to ensure a good seal. We screwed the LiCor custom chamber head attachment over the holes drilled into the plexiglass chamber, again sealing with a rubber gasket. The air in the chamber was mixed using 4-8 small fans (depending on chamber height) powered by a 12v battery.

At each plot we took measurements to create two light curves: one under direct light and one under diffuse light conditions. In order to determine the fraction of diffuse light, we used a DeltaT Beam Fraction Sensor (BF3, Delta-T Devices Ltd, Burwell Cambridge, UK) which quantifies the total irradianc and total diffuse light from which the diffuse light fraction (diffuse light/total light) can be calculated. For each day of flux measurements, the BF3 logged an instantaneous reading every 30-60 seconds set up on a leveled tripod at approximately 2 m above the ground. For the purpose of correlating the diffuse light fraction with each flux measurement, the LiCor 6400 and BF3 sensor were synchronized to read the same time (+/- 1 sec) at the start of each day.

Different light levels for both diffuse and direct light curves were achieved by taking measurements under a variety of conditions: ambient light (no manipulation), successive shading levels (covering the chamber with 1-5 fine mesh net cloths), and intercepting direct light with photographic diffuser panels, as well as reflecting light into the chamber to increase the amount of diffuse light with white photographic panels. When the diffuser panels were used, they were carefully positioned to intercept all direct light that would otherwise enter the chamber. Whenwhite reflector panels were used, they were positioned on the side of the chamber opposite the sun and angled towards the chamber so as to increase the amount of diffuse light entering the chamber (these were used in conjuction with the diffuser panels). For these 'artificial' diffuse light measurements, we did not diffuse the BF3 sensor, thus the diffuse fraction calculations during these flux measurements do not represent the light conditions in the chamber. After field tests of using the diffuser and reflector panels, we determined that the panels effectively block all direct light, and thus we assume the diffuse light fraction is greater than 0.7 for these measurements. At each light level a flux measurement lasted 45 - 60 secs in total, with CO2 and H2O concentrations in the chamber recorded by the LiCor 6400 every 2 secs. After each measurement we lifted the chamber until CO2 and H2O concentrations had stabilized at ambient levels. We made an effort to obtain a wide range of flux measurements for light levels between 0-1600, and used whatever chamber light treatments were needed to achieve that based on the ambient light conditions.

In addition to light measurements, we made at least three measurements in the dark for each day we took flux measurements. These were achieved by covering the chamber in an opaque tarpaulin cloth. These measurements represent the ecosystem respiration.

After each light curve we determined chamber volume by taking depth measurements from the top of the chamber base to the ground. We measured the chamber base depth with 36 measurements made at regular 20cm intervals determined by placing a 1m x1m plastic frame with a 20cm x 20cm string grid on top of the base. The volume determined by these depth measurements (chamber surface area*average depth) was added to the volume of the plexiglass chamber (and sleeve, as needed) . The surface area of the inside of the 1 m x 1 m plexiglass chamber was 0.8836m2.

POINT FRAME MEASUREMENTS
We preferentially selected tall shrub canopies dominated either by Betula nana or Salix pulchra, that is canopies that were greater than 75 cm height. Care was taken to select fairly uniform canopies, that is avoiding the edge of a shrub stand or areas where the canopy had a large gaps, suggesting the area may have been disturbed.

We used point frames constructed from a 1.1 m x 1.1 m aluminum square with holes in each corner to accomodate steel rod posts used as the legs of the point frame. In this way, the frame could rest upon the four leg posts that had been hammered into the ground and remain adjustable in each corner. The frame had a level on each side, and great care was taken to ensure that the frame was (a) unable to be pushed deeper into the ground and, (b) level on all four sides prior to taking measurements. These factors were important to the measurement to have accurate data regarding the distance from the frame and the overall height of each point sampled in the canopy.

The aluminum frame had numbered, regularly spaced holes on two opposite sides in order to accomodate a metal bar that could be placed across the frame and locked into place. [These holes on the frame are the row numbers.] The bar that was placed across the frame similarly had numbered, evenly spaced holes in order to accomodate a pin--a long (100-200cm) metal rod with a diameter of ~3.175 mm. [The holes on this bar are the pin hole numbers.] Measurements were only ever taken from odd row numbers, and alternated even/odd pin hole numbers with each row; in this way, for every plot 25 evenly spaced locations were sampled covering an area of one square meter.

The length of the pin was marked every half-centimeter so that the distance could be read easily. Measurements were made by lowering the pin through a pin hole and, once encountering a leaf or stem, recording the following: row#, pin hole#, hit#, and the species hit. If the object hit was not a leaf, the plant tissue was noted; the diameter of each stem hit was estimated in millimeters, and the length of every graminoid blade hit was recorded from the point at which it was hit to the tip. As the primary species of interest for this project were for a select number of species (B. nana, S. pulchra, S. glauca, S. reticulata, V. uliginosum, V. vitis, L. palustre), species that were not the target of interest were classified as functional groups--e.g. graminoid spp., forb, moss.

The last pin-hit recorded for each pin hole was always at the "soil" which was considered to be the transition between the green and brown plant material, often in a mossy layer.

These data can be used in conjunction with the other data collected from these same plots--leaf area index, light and A-Ci response curves of shoots taken at different segments of the canopy.

Data Table

Variable Name Variable Description Data Type Units DateTime Format Code Information Missing Value Code
YEAR year of measurement datetime   YYYY   #N/A=Missing or Not Measured
DATE date of measurement datetime   DD-MMM-YY   #N/A=Missing or Not Measured
SITE Toolik text        
GROUP Measurement location in relation to Toolik Lake LTER Shrub plots; In vicinity of Block1 =Upland, IVO Block 2 =Outlet text        
PLOT Individual plot identifier text        
TREAT none or fertilised annually (FERT) (with N and P) text        
PHASE Measurement series (round of measurements within each year); not used in this dataset number number     #N/A=Missing or Not Measured
PLOT SIZE 1m x 1m chamber or point frame size text        
MaxHght_mean mean of maximum chanopy height (cm) number centimeter     #N/A=Not Measured
MaxHght_1 replicate 1 of maximum canopy height (cm) number centimeter     #N/A=Not Measured
MaxHght_2 replicate 2 of maximum canopy height (cm) number centimeter     #N/A=Not Measured
MaxHght_3 replicate 3 of maximum canopy height (cm) number centimeter     #N/A=Not Measured
MaxHght_4 replicate 4 of maximum canopy height (cm) number centimeter     #N/A=Not Measured
MaxHght_5 replicate 5 of maximum canopy height (cm) number centimeter     #N/A=Not Measured
MaxHghtSPP_1 species of maximum canopy height 1 text        
MaxHghtSPP_2 species of maximum canopy height 2 text        
MaxHghtSPP_3 species of maximum canopy height 3 text        
MaxHghtSPP_4 species of maximum canopy height 4 text        
MaxHghtSPP_5 species of maximum canopy height 5 text        
DOM VEG Dominant canopy vegetation text        
MeasurementType Type of measurement text        
MaxHght_Comments additional notes text        

Please contact arc_im@mbl.edu with questions, comments, or for technical assistance regarding this web site.