RESEARCH LOCATIONS:
Imnavait Creek, Alaska 2003: Measurements were made on 8 1m x 1m flux plots in different vegetation types along the topographic sequence of the west facing slope of Imnavait Creek catchment.

Imnavait Creek, Alaska 2004: Measurements were made on 15 1m x 1m plots along the topographic sequence of the west facing slope of Imnavait Creek catchment, in the same area as 2003.

Toolik Lake, Alaska 2004: Measurements were made on a total of 20 flux plots in treatment (N +P) and control blocks of the LTER fertilisation experiment at Toolik Lake, including the moist acidic tussock, non-acidic tussock, non acidic non-tussock, inlet wet sedge and heath sites.

Abisko, Sweden 2004: 11 plots were located at the Stepps site, 13 plots at Paddus and 12 plots at Latnjajaure in a range of vegetation types.

Abisko, Sweden 2005: Measurements were made on 15 plots at the Stepps site.

Svalbard 2005: Measurements were made on 41 plots at various sites in Adventdalen.

Zackenberg 2006: Measurements were made on 35 1m x 1m plots and 25 0.3m x 0.3m plots at various sites within 2km of ZERO research station - in research zone 1a.

Toolik 2009: Measurements were made on 94 plots across three vegetation types: moist acidic tussock, dry heath, and wet sedge. Each plot was measured at approximately 2 weeks intervals from mid-June to mid-August 2009.

Anaktuvuk River Burn 2009: Measurements were made on five plots along a burn severity gradient during mid-June 2009.

Barrow 2009: Measurements were made on thirteen 0.7m 0.7m flux plots along a moisture gradient during late-July to early-August 2009.

EXPERIMENTAL DESIGN AND METHODS:

GPS co-ordinates of the ITEX flux plots were taken using a differential GPS unit at the following sites:
-Imnavait Creek, Toolik 2003 (A. Rennermalm, Princeton University)
-Stepps site, Abisko 2004 (A. Fox, Durham University)

GPS co-ordinates were taken using a handheld Garmin Etrex GPS unit at the following sites:
-Paddus and Latnjajaure, Abisko 2004
-Stepps site, Abisko 2005
-Svalbard, Abisko 2005
-Zackenberg, Northeast Greenland 2006.
-Barrow 2009
-Anaktuvuk River Burn: UNB1 and SV2 plots.

GPS for other Anaktuvuk River Burn sites was assigned based on known GPS coordinates of eddy flux plots for moderate and severe burns.

CALCULATIONS: none

COMMENTS: Differential GPS points given to 7 decimal places (Toolik and Abisko Stepps 2004). All other GPS data given to 5 decimal places.

Vegetation at Zackenberg is categorised as "Cassiope heath", "Vaccinium heath", "Dryas heath", "Salix snow bed", "Fen", "Grassland" or "Abrasion plateau" according to the descriptions and mapping by Bay 1998.

FOR MORE INFORMATION CONTACT: Gus Shaver, The Ecosystems Center, Woods Hole, MA, 02543, USA

REFERENCE CITATIONS:
Bay, C. (1998) Vegetation mapping of Zackenberg Valley Northeast Greenland. Danish Polar Center.

Street, L.E., Shaver, G.R., Williams, M., van Wijk, M.T. (in press) What is the relationship
between changes in canopy leaf area and changes in photosynthetic CO2 flux in arctic ecosystems? Journal of Ecology

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.

OTHER DATA FILES TO REFERENCE:
2003-2009gsflux.dat CO2 and H2O flux data.
2004-2009gscoversp.dat. Percent cover of flux plots by species.
2004-2009gscoverft.dat. Percent cover of flux plots by functional type.
2003-2009gscurveparameters.dat. Best fit parameters describing the light response curves measured on each plot.
2003-2009gssoiltemp.dat. Soil temperature and volumetric water content of flux plots.

FORMAT OF DATA FILE: ASCII

See Methods.