Anaktuvuk River Burn Eddy Flux Measurements, 2009 Moderate Burn Site, North Slope Alaska

Abstract: 

We deployed three eddy covariance towers along a burn severity gradient (i.e. severely-, moderately-, and un-burned tundra) to monitor post fire Net Ecosystem Exchange of CO2 (NEE) within the large 2007 Anaktuvuk River fire scar during the summer of 2008. This data represents the 2009 post fire energy and mass exchange at the moderate burn site.

Project Keywords: 

Data set ID: 

10118

EML revision ID: 

9
Published on EDI/LTER Data Portal

Citation: 

Shaver, G., Rocha, A. 2011. Anaktuvuk River Burn Eddy Flux Measurements, 2009 Moderate Burn Site, North Slope Alaska Environmental Data Initiative. http://dx.doi.org/10.6073/pasta/3d912564439309bdf17bc75866179312
People
Dates

Date Range: 

Thursday, January 1, 2009 to Thursday, December 31, 2009

Publication Date: 

2011

Methods: 

We deployed three eddy covariance towers with identical instrumentation across a burn severity gradient (Rocha and Shaver 2009). The three sites (i.e. Severe burn, Moderate burn, and Unburned) were 40 km to the west of the nearest road and were selected during a helicopter survey of the southern area of the Anaktuvuk River Fire scar in late May 2008 (Figure 1; Table 1). Because the fire had burned through September of the previous year, initial deployment of flux towers occurred prior to any significant vegetative regrowth, and our sampling campaign captured the full 2008 growing season (June 1-August 28). Each site was equipped with a Campbell Scientific® CR5000 datalogger that recorded data from micrometeorological instrumentation located on a stainless steel tripod (CM110; Campbell Scientific; Logan Utah, USA) at a height of 2.6 m. Data were stored on a 2 Gb PCMCIA card and downloaded every two to three weeks. Power for the datalogger and instrumentation was located 15 m to the east or west of the tower and consisted of a south-facing solar panel and two 12 V 80 amp-hour batteries enclosed in a polyethylene box. Towers ran continuously through the summer of 2008 with the exception of the severe burn site, which was damaged by a bear during the last week of August. The towers have been in operation since June 2008.

Environmental data were recorded as half hour averages. Net radiation was monitored with a NRLITE net radiometer (Campbell Scientific; Logan Utah, USA). Incoming and reflected solar and longwave radiation were measured with a CNR-1 Radiometer (Campbell Scientific; Logan Utah, USA), while incoming and reflected Photosynthetically Active Radiation (PAR) were measured with a silicon quantum sensor (LI-COR; Lincoln, NE, USA). Air temperature and relative humidity was measured with an HMP45C-L sensor (Campbell Scientific; Logan Utah, USA) enclosed in a naturally aspirated radiation shield, while precipitation was measured with a tipping bucket rain gauge (TE525; Campbell Scientific; Logan Utah, USA). Volumetric water content at a depth of 2.5 cm was measured with two reflectometers (CS616; Campbell Scientfic; Logan Utah, USA), soil temperature at a depth of 2 and 6 cm was measured with two averaging soil thermocouples (TCAV-L; Campbell Scientific; Logan, Utah, USA), and soil heat flux at a depth of 8 cm was measured with four soil heat flux plates (HFP01; Campbell Scientific; Logan, Utah, USA). Measurements of the soil environment were recorded on separate CR1000 dataloggers at the severely and moderately burned sites.

Turbulent fluxes of momentum, sensible heat, latent heat and CO2 were determined by the eddy covariance technique (Baldocchi et al. 1988). Half hourly CO2 and H2O fluxes were calculated as the covariance between the turbulent departures from the mean of the 10 Hz vertical wind speed measured with a 3D sonic anemometer (CSAT3; Campbell Scientific; Logan, Utah, USA) and the CO2 and H2O mixing ratio measured with an open path InfraRed Gas Analyzer (IRGA; LI7500; LI-COR; Lincoln, NE, USA). Fluxes were processed using EdiRe software (University of Edinburgh; Moncrieff et al. 1997) and reported using the meteorological sign convention where negative NEE indicates carbon uptake and positive NEE indicates carbon loss from the ecosystem. Ten Hz data were despiked, rotated to the mean wind streamlines, and corrected for the density effect due to sensible heat transfer (i.e. WPL correction; Webb et al. 1980). Turbulent fluxes of sensible and latent heat captured 78 to 80% of the available energy at each of the sites, which is consistent with energy budget closure observed for other eddy covariance studies (Wilson et al. 2002).

The moderate burn site is comprised of a mosaic of partially and completely burnt moss patches scattered across the landscape that varied in size from ~1 to 10 m2. Partially burnt moss cover was 33% and was dominated by Sphagnum [Sphagnum spp.] and feather mosses [Hylocomium spp.]. Recovering and dead tussocks formed the dominant canopy cover. Intertussock area was composed of burnt duff (30% of ground cover) and several herbaceous species (Cloudberry; Labrador tea, and Cranberry [Vaccinium vitis-idaea L.]). All tussocks were scorched in the fire and 95% of tussocks recovered after the first growing season.

References:
Rocha, A.V. and G.R. Shaver (2009) Advantages of a two band EVI derived from solar and photosynthetically active radiation fluxes. Agricultural and Forest Meteorology. 149:1560-1563, doi:10.1016/j.agrformet.2009.03.016.

Rocha, A.V. and G.R. Shaver (2011) Burn severity influences post-fire CO2 exchange in arctic tundra. Ecological Applications. 21:477-489.

Rocha, A.V. and G.R. Shaver (2011) Postfire energy exchange in arctic tundra: the importance and climatic implications of burn severity. Global Change Biology. doi:10.1111/j.1365-2486.2011.02441.x.

See Methods

Version Changes: 

Data collection and processing is complete
Version 1, May 2011: Initial data release
Version 2: Updated metadata form to newer version (with sites sheet). CH March 2013.
Version 3: Metadata error repaired - Surface temperature is in Kelvin degrees (previously listed as Celcius degrees)
Version 4: Sept 2013
-Decreased DOY values by one day. The DOY value represents the number of days completed.
-Corrected ambient vapor pressure values. Previous data was not the ambient vapor pressure
-Bad data values converted to NaN.
Version 5: Checked keywords against the LTER network preferred list and replaced non-preferred terms. Jim L 15Jan14
Version 6: Missing value needed to be NaN not NAN JimL 24Jan14
Version 7: Missing value code corrected: NAN should be NaN. Jim L 24Jan14

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