uid=ARC,o=lter,dc=ecoinformatics,dc=org all public read 2003-2009gscurveparameters.06 Arctic LTER Program Gus Shaver

The Ecosystems Center Marine Biological Laboratory 7 MBL St. Woods Hole MA 02543 USA

Arctic LTER Program

The Ecosystems Center Marine Biological Lab 7 MBL St Woods Hole MA 02543 USA

(508) 289 7496 arc_im@mbl.edu http://ecosystems.mbl.edu/ARC/ Mark van Wijk Associated Researcher Lorna Street Associated Researcher Brooke Kaye Associated Researcher Jim Laundre

The Ecosystems Center Marine Biological Laboratory 7 MBL St. Woods Hole MA 02543 USA

Associated Researcher Mathew Williams Associated Researcher Cath Thompson Associated Researcher Carrie McCalley Associated Researcher Beth Bernhardt Associated Researcher Bob Douma Associated Researcher Celine Ronfort Associated Researcher Kerry Dinsmore Associated Researcher Robert Bell Associated Researcher Peter van Buuren Associated Researcher Craig Menzies Associated Researcher Jen Peters Associated Researcher Scott Graham Associated Researcher 2010 Ecosystem CO2 flux light response curves were measured on 1m x 1m plots ( some 0.3m x 0.3m plots in 2006 and some 0.7m x0.7m plots in 2009) across the arctic. This file contains the best fit parameters that describe these light response curves, together with corresponding NDVI data for each curve. Survey plots were located in the Toolik Lake LTER fertilization experiment in Alaska; at Imnavait Creek, Alaska; at Paddus, Latnjajaure and the Stepps site near Abisko in northern Sweden; at various sites in Adventdalen, Svalbard; in the Zackenberg valley, Northeast Greenland; at BEO near Barrow, Alaska and at the Anaktuvuk River Burn in Alaska. Measurements were made during the growing seasons 2003 to 2009. ITEX flux survey carbon dioxide exchange light response curves best fit parameters NDVI primary production Acceptance and utilization of LTER data requires that: The Principal Investigator be sent a notice stating reasons for acquiring any data and a description of the publication intentions. The Principal Investigator of the data set be sent a copy of the report or manuscript prior to submission and be adequately cited in any resultant publications A copy of any resultant publications should be sent to: Principal Investigator Ecosystems Center Marine Biological Laboratory Woods Hole, MA 02543 http://ecosystems.mbl.edu/ARC/meta_template.php?FileName=./terrest/tracegas/xlsfiles/2003-2009gscurveparameters.html Toolik Lake (68 degrees 38N, 149 degrees 34W) -149.61058 -149.61058 68.62405 68.62405 Imnavait Creek (68 degrees 37N, 149 degrees 18W) Alaska, U.S. -149.31 -149.31 68.6167 68.6167 "Stepps" site (68 degrees 18N, 18 degrees 51E) near Abisko, Sweden. 18.85 18.85 68.3 68.3 Paddus (68 degrees 19N, 18 degrees 51E) near Abisko, Sweden. 18.85 18.85 68.3167 68.3167 Latnjajaure (68 degrees 21N, 18 degrees 30E) near Abisko, Sweden. 18.5 18.5 68.35 68.35 Adventdalen (78 degrees 13N, 15 degrees 38E) Svalbard, Norway. 15.6333333333333 15.6333333333333 78.2166666666667 78.2166666666667 Zackenberg research area zone 1a (74º28’ N, 20º34’ W), Northeast Greenland. -19.4333333333333 -19.4333333333333 74.4666666666667 74.4666666666667 Barrow ( 71° 18' N, 156° 36' W) Alaska, USA. -156.6 -156.6 71.31 71.31 Anaktuvuk River Burn (68° 56-59' N, 150° 12-16' W) Alaska, USA. -150.2125 -150.2125 68.9966666666667 68.9966666666667 2003-07-05 2009-08-17 Version 1: Checked file and created eml and html files. Feb 2006 Jiml Version 2: Added Zackenberg 2006 curve parameters. Inserted new column for “plot size” because 2006 data include measurements made on 0.3m x 0.3m plots. Changed time format for all data to e.g. 1124 not 11:24. Changed date in file name from 2005 to 2006. Oct 2006 LStreet Version 3: Added LTERNET Data Access server proxy for Excel and comma delimited data files. Version 4: Updated LTERNET Data Access server proxy link for Excel and comma delimited data files. Changed from knb to das in url. Version 5: Added Toolik and Barrow 2009 data. Changed file name from 2006 to 2009. Added Comments column. Version 6: Updated metadata form to newer version (without site sheet). Missing values changed to #N/A. CH 25Jan2013 Updated to newer metadata with site sheet. CH March 2013. Data Manager

The Ecosystems Center Marine Biological Lab 7 MBL St Woods Hole MA 02543 USA

(508) 289 7496 arc_im@mbl.edu http://ecosystems.mbl.edu/ARC/ ARC LTER

The Ecosystems Center Marine Biological Lab 7 MBL St Woods Hole MA 02543 USA

(508) 289 7496 arc_im@mbl.edu http://ecosystems.mbl.edu/ARC/ RESEARCH LOCATIONS: Imnavait Creek, Alaska 2003: Measurements were made on 8 flux plots in different vegetation types along the topographic sequence of the west facing slope of Imnavait Creek catchment. A light response curve was measured on each plot several times during early July and several times during late July/early August. Imnavait Creek, Alaska 2004: Measurements were made on 15 plots along the topographic sequence of the west facing slope of Imnavait Creek catchment, in the same area as 2003. A light response curve was measured on each plot once in late June/early July and once in August. Toolik Lake, Alaska 2004. Measurements were made on a total of 20 flux plots in treatment (N +P) and control blocks of the LTER fertilization experiment at Toolik Lake, including the moist acidic tussock, non-acidic tussock, non acidic non-tussock, inlet wet sedge and heath sites. Light curves were measured on each plot once in late June/early July and once in August. Abisko, Sweden 2004. Measurements were made on 11 plots at the "Stepps" site, each measured once in July and once in August. Measurements were made on 13 plots at Paddus and 12 plots at Latnjajaure, once in July and August. Abisko, Sweden 2005. 15 plots were located at the "Stepps" site, measurements were made on 3 occasions through June/ early July and once in mid August. During the 3rd phase of measurements in June we conducted a diurnal series on five of the plots, measuring a light curve once every 4 hrs for 28 hrs. Svalbard 2005. Measurements were made on 41 plots at various sites in Adventdalen, one light curve was measured on each plot during July. Zackenberg 2006. Data were collected on 35 1 x 1m plots and 25 0.3 x 0.3m plots across a range of vegetation types. 13 of the 0.3 x 0.3m plots were located within 1m x 1m plots (identified by plot name with suffix "b1, b2 or b3"), the remainder were independent of the 1 x 1m plots (B14-25). A light curve was measured on each plot once, all measurements were made from 8 July through 1 Aug 2006. Toolik 2009: Data were collected on nine 1m x 1m flux plots, three in each vegetation type. Vegetation types included moist acidic tundra (MAT), dry heath (HTH) and wet sedge (WSG). Each plot was measured at approximately 2 weeks intervals from mid-June to mid-August 2009. Anaktuvuk River Burn 2009: Data was collected on five 0.7m x 0.7m flux plots along a burn severity gradient in mid-June 2009. Barrow 2009: Data was collected on thirteen 0.7m 0.7m flux plots along a moisture gradient during late-July to early-August 2009. EXPERIMENTAL DESIGN AND METHODS: We measured net CO2 flux using a Licor 6400 photosynthesis system (Li-Cor Inc., Lincoln, Nebraska, USA) connected to a plexiglass chamber. For most sites, the chamber measured 1m x 1m x 0.25m, but a 0.3 x 0.3 x 0.15m was used in 2006 and a 0.7 x 0.7 x 0.25m was used in 2009 due to limited accessibility at these sites. In Alaska in late season 2004 and at Zackenberg from 25th July 2006 onwards, we used a LiCor 6200 photosynthesis system. Flux data from the LiCor 6200 were corrected for the effects of water vapor build-up according to Hooper et al 2002. At each plot we took measurements to create a light response curve: 2-3 measurements were made at ambient light conditions, followed by 2 flux measurements at each of 3 successive shading levels, with finally 3 measurements under complete darkness. We shaded the chamber by layering 3 fine mesh net cloths and used a tarpaulin to block all light from the chamber. Flux measurements under complete darkness represent ecosystem respiration. At each light level a flux measurement lasted 45 - 60 secs in total, CO2 concentrations in the chamber being recorded by the Licor every 2-3 secs. Incident radiation, average temperature and NDVI were also measured on each plot for each light curve. A saturating (Michaelis-Menton type) function is fitted to the measured data. Best fit parameters describing each light curve are calculated by minimizing the sum of squared errors between measured and modeled NEP values. In 2003, all flux data from a plot on one day are grouped into one light curve. We measured NDVI on each flux plot using either a portable 2 channel field sensor (Skye Instruments) or Unispec spectral analyzer (PP Systems) or both: Toolik 2003: Skye sensor Toolik 2004: Unispec and Skye sensor Abisko 2004: Unispec and Skye sensor (Unispec only at Stepps site phase 2) Abisko and Svalbard: Unispec and Skye sensor (Unispec only during June at Abisko) Zackenberg: Unispec Toolik 2009: Unispec Barrow 2009: Unispec The unispec spectral analyzer measures reflected light intensity in 256 portions of the visible spectrum from ~300nm to ~1100nm. A foreoptic cable transmits light reflected from the target to the instrument, a measurement scan lasts for ~10ms. 9 scans were measured in a regular grid for each of the flux plots. The end of the fiber optic was kept approximately 1m vertically above the ground surface resulting in a view of the vegetation of approx. 20cm diameter. For the 0.3m x 0.3m plots, 3 scans were taken from directly above the plot with a field of view of approximately 30cm diameter. The average of these three scans was then taken. Incident radiation was measured using a reference standard in order that reflectance from the vegetation could be calculated as a percentage of incoming solar radiation. The program Multispec5.1.5.exe was used to compile Unispec reflectance spectra from the raw target spectra. The skye NDVI sensor measures total radiation reflected from the vegetation (without measuring incident radiation) in the wavebands 570nm-680nm and 725nm - 1100nm. NDVI is then calculated as below. Calculations: The light response curve is modeled as a rectangular hyperbola: NEP = Re - [(Pmax*PAR)/(K + PAR)] where Re = ecosystem respiration [µmol C m-2 ground s-1] Pmax = theoretical light saturated photosynthesis [µmol C m-2 ground s-1] K = half saturation constant [µmol PAR m-2 ground s-1] The initial slope of the light response curve (light use efficiency or E0) and the light compensation point (LCP) are calculated from these parameters as: E0 = (Pmax/K) LCP = (RE*K)/(Pmax-RE) where Re = ecosystem respiration [µmol C m-2 ground s-1] Pmax = theoretical light saturated photosynthesis [µmol C m-2 ground s-1] K = half saturation constant [µmol PAR m-2 ground s-1] E0 = ecosystem light use efficiency [µmol C µmol-1 PAR] LCP = ecosystem light compensation point [µmol PAR m-2 ground s-1] NDVI = (RII-RI)/ (RI + RII) where RI = average reflectance from 570nm to 680nm RII = average reflectance from 725nm to 1000nm COMMENTS: all times are given as local times. Sorting variables and curve ID numbers match the flux data from which the curve is calculated, in the ITEX CO2 flux data file 2003-2009gsflux.dat FOR MORE INFORMATION CONTACT: Gus Shaver, The Ecosystems Center, Woods Hole, MA, 02543, USA REFERENCE CITATIONS: Hooper D.U., Cardon Z. G., Chapin III F. S. Durant, M. (2002) Corrected calculations for soil and ecosystem measurements of CO2 flux using the LI-COR 6200 portable photosynthesis system. Oecologia 132:1–11 Street, L.E., Shaver, G.R., Williams, M., van Wijk, M.T. (2007) What is the relationship between changes in canopy leaf area and changes in photosynthetic CO2 flux in arctic ecosystems? Journal of Ecology, 95, 139-150. Williams, M., Street, L.E., van Wijk, M.T., and Shaver, G.R. (2006) Identifying Differences in Carbon Exchange among Arctic Ecosystem Types. Ecosystems, 9, 288-304. FORMAT OF DATA FILE: ASCII pers-1 See Methods Gus Shaver

The Ecosystems Center Marine Biological Lab 7 MBL St Woods Hole MA 02543 USA

(508) 289 7496 gshaver@mbl.edu Lead PI Jim Laundre

The Ecosystems Center Marine Biological Lab 7 MBL St Woods Hole MA 02543 USA

(508) 289 7496 arc_imr@mbl.edu Information Manager The goal of Arctic LTER project is to predict the future ecological characteristics of the site based upon our knowledge of the controls of ecosystem structure and function as exerted by physical setting and geologic factors, climatic factors, biotic factors, and the changes in fluxes of water and materials from land to water. To achieve this goal the Arctic LTER uses several approaches: Long-term monitoring and surveys of natural variation of ecosystem characteristics in space and time. Includes: climate, plant communities and productivity, thaw depth, stream flow, chemistry of streams and lakes, temperatures of streams and lakes, lake chlorophyll lake productivity, zooplankton abundance. Experimental manipulation of ecosystems for years and decades. Includes: tundra warming, shading, and fertilizing, grazer exclusions, fertilization of lakes and streams, addition and subtraction of predators. Synthesis of results and predictive modeling at ecosystem and watershed scales. Includes: stream N cycling, lake physics, bioenergetics of fish populations, water movement and transfer of DOC and nutrients from land to water, soil respiration, cycling and storage of C in tundra under different scenarios of future climates. 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. Any opinions, findings, conclusions, or recommendations expressed in the material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation. The Arctic LTER research site (68°N and 149°W) is in the foothills region of the North Slope of Alaska and includes the entire Toolik Lake watershed and the adjacent watershed of the upper Kuparuk River, down to the confluence of these two watersheds. This area is typical of the northern foothills of the Brooks Range, with continuous permafrost, no trees, a complete snow cover for 7 to 9 months, winter ice cover on lakes, streams, and ocean, and cessation of river flow during the winter. Tussock tundra vegetation of sedges and grasses mixed with dwarf birch and low willows form the dominant vegetation type with areas of drier heath tundra on ridge tops and other well-drained sites as well as areas of river-bottom willow communities. -149.75 -149.0433 68.8 68.5 610 1360 meter 2003-2009gscurveparameters.csv Best fit parameters describing net CO2 flux light response curves measured during the ITEX CO2 flux survey 2003-2009. 2003-2009gscurveparameters.csv 1 \r\n column , " http://metacat.lternet.edu/das/dataAccessServlet?docid=knb-lter-arc.1602&urlTail=terrest/tracegas/data/2003-2009gscurveparameters.csv YEAR YEAR Year measurement taken yyyy DATE DATE Date measurement taken dd-mon-yy SITE SITE Abisko, Imnavait, Toolik, Svalbard, Zackenberg, AR Burn or Barrow Abisko, Imnavait, Toolik, Svalbard, Zackenberg, AR Burn or Barrow GROUP GROUP Location of flux plots at each site Location of flux plots at each site PLOT PLOT Individual plot identifier Individual plot identifier TREAT TREAT Control or fertilised with N and P fertiliser Control or fertilised with N and P fertiliser PHASE PHASE Measurement series (round of measurement within each year) Measurement series (round of measurement within each year) PLOT SIZE PLOT SIZE Plot size of 1m x 1m or 0.3m x 0.3m or 0.7 x 0.7m Plot size of 1m x 1m or 0.3m x 0.3m or 0.7 x 0.7m CURVE ID CURVE ID Light curve identifier Light curve identifier TIME TIME time the light curve was taken (avg indicates a combination of more than one curve in a day) time the light curve was taken (avg indicates a combination of more than one curve in a day) NDVI NDVI NDVI of flux plot dimensionless real #N/A Missing or Not Measured Pmax Pmax light saturated photosynthesis parameter micromolePerMeterSquaredPerSecond real #N/A Missing or Not Measured K K half saturation constant micromolePerMeterSquaredPerSecond real #N/A Missing or Not Measured Re Re ecosystem respiration micromolePerMeterSquaredPerSecond real #N/A Missing or Not Measured Eo Eo ecosystem initial light use efficiency micromolePerMicromole real #N/A Missing or Not Measured LCP LCP ecosystem light compensation point micromolePerMeterSquaredPerSecond real #N/A Missing or Not Measured AIRTEMP AIRTEMP average air temperature celsius real #N/A Missing or Not Measured MAX PAR MAX PAR The maximum average PAR value under which a flux measurement is recorded for that curve. micromolePerMeterSquaredPerSecond real #N/A Missing or Not Measured Comments Comments explaination of why the curve lacks parameter values explaination of why the curve lacks parameter values 446 2003-2009gscurveparameters.xls An excel file that has worksheets with the metadata and data. 2003-2009gscurveparameters.xls Microsoft Excel http://metacat.lternet.edu/das/dataAccessServlet?docid=knb-lter-arc.1602&urlTail=terrest/tracegas/xlsfiles/2003-2009gscurveparameters.xls Microsoft Excel file micro Einsteins (1E-06 moles of photons) per square meter per second (radiant flux density) micromoles of substance per micromole