uid=ARC,o=lter,dc=ecoinformatics,dc=org all public read 2008_MCM_ARF14C.1 Arctic LTER Program Michelle Mack

University of Florida 220 Bartram Hall Department of Biology Gainesville FL 32611 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/ Edward Schuur

University of Florida 220 Bartram Hall Department of Biology Gainesville FL 32611 USA

Associated Researcher 2011 We used radiocarbon dating of the organic soil surface remaining post-fire to examine whether the fire burned into ancient and likely irreplaceable soil C pools. Suprisingly, it did not; all radiocarbon dates from burned soil surfaces contained bomb carbon, setting the maximum age of the burned soil surfaces at ~50 years. Radiocarbon soil organic layer burned 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=./burn/terrestrial/xlsfiles/2008_MCM_ARF14C.html Anaktuvuk River Fire scar (2007) -150.90848 -150.19672 69.34084 68.94963 2008-06-25 2008-08-10 Version 1: checked and generated EML and Web files. Jim L 12Jul2011 Version 2: Updated to newer metadata form (with sites sheet). Fixed discrepency with variable names. Units updated to current standards. 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/ We used radiocarbon dating of the organic soil surface remaining post-fire to examine whether the fire burned into ancient and likely irreplaceable soil C pools. Because the moss and organic soil layer accumulates vertically through time, the radiocarbon values of the remaining organic matter can provide some indication of how long it took to accumulate the organic matter above it that was consumed during the fire. Two cores were selected from each of ten sites randomly selected from the 20 sampling sites and sliced into 1 cm depth increments. Moss macrofossils were removed from the top layer under a dissecting scope. Cellulose was extracted from the macrofossils45 and the sample was converted to graphite at 650?C with an iron catalyst in a hydrogen atmosphere46. Our primary standard for 14C analysis was NIST oxalic acid II (SRM 4990C, National Institute of Standards and Technology). For a secondary standard, we used IAEA-C6 sucrose standard (International Atomic Energy Agency, Vienna, Austria). Our blank was anthracite coal cleaned with a standard acid–base–acid treatment. All standards and blanks used for 14C measurements were combusted and purified similarly to the samples. The 14C content of the graphite was measured at the W. M Keck Carbon Cycle Accelerator Mass Spectrometry Laboratory at the University of California–Irvine. Radiocarbon data are expressed as ? 14C, which is the per mil (‰) difference between the 14C/12C ratio of the sample and an international standard. Each sample was corrected for the effects of mass-dependent isotope fractionation of 14C values by correcting to a constant ?13C value of -25 ‰ and normalized to sample-specific measured ?13C values. ?13C was measured prior to graphitizing the CO2 at the University of Florida on a Delta XL isotope ratio mass spectrometer with a gas bench peripheral (Thermo Scientific, Waltham, MA), using a -10.46 ‰ PDB CO2 standard from Oztech (Stafford, Arizona, USA). In some circumstances, radiocarbon values during the bomb period (1950 to present) do not return unequivocal date estimates because of the shape of the atmospheric bomb curve (ref. 47). In a subset of those cases, we also analyzed the second, deeper 1 cm increment of organic soil for radiocarbon in order to determine the appropriate location of the surface date relative to the bomb peak. All samples had radiocarbon values above zero, so samples where the deeper segment was more enriched in radiocarbon then the surface segment were assigned to the ascending slope of the bomb peak (<1966), while samples where the deeper segment was more depleted than the surface segment were assigned to the descending slope (>1966). Literature Cited 45Gaudinski, J. B., Dawson, T. E., Quideau, S., Schuur, E. A. G., Roden, J. S., Trumbore, S. E. et al., Comparative analysis of cellulose preparation techniques for use with C-13, C-14, and O-18 isotopic measurements. Analytical Chemistry 77 (22), 7212-7224 (2005). 46Vogel, J. S., Southon, J. R., and Nelson, D. E., Catalyst and binder effects in the use of filamentous graphite for AMS. Nuclear Instruments and Methods in Physics Research Section B-Beam Interactions with Materials and Atoms 29 (1-2), 50-56 (1987). 47Levin, I. and Hesshaimer, V., Radiocarbon - a unique tracer of global carbon cycle dynamics. Radiocarbon 42 (1), 69-80 (2000). pers-1 Not yet available; online supplement for Nature paper John Hobbie

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

(508) 289 7496 jhobbie@mbl.edu Lead PI 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 2008_MCM_ARF14C.csv Burned soil surface radiocarbon values for moss macrofossils plucked from the Anaktuvuk River Fire sites 2008_MCM_ARF14C.csv 1 \r\n column , " http://metacat.lternet.edu/das/dataAccessServlet?docid=knb-lter-arc.10127&urlTail=burn/terrestrial/data/2008_MCM_ARF14C.csv State State Burned or unburned status of site Burned or unburned status of site Site number Site number Number of the site number real . code for missing values Field code Field code Code used to identify site in field notes Code used to identify site in field notes Profile number Profile number Number of the replicate profile within the site Number of the replicate profile within the site Depth Depth Depth increment of sample in cm (0=burned soil surface) Depth increment of sample in cm (0=burned soil surface) Lab sample number Lab sample number Unique number assigned to each profile x depth sample in lab Unique number assigned to each profile x depth sample in lab . code for missing values AMS DEL 14C AMS DEL 14C DELTA 14C value in per mil corrected for radioactive decay and isotopic fractionation via 13C dimensionless real . code for missing values AMS DEL 14C SE AMS DEL 14C SE Analytical standard error of the DEL 14C value dimensionless real . code for missing values 27 2008_MCM_ARF14C.xlsx An excel file that has worksheets with the metadata and data. 2008_MCM_ARF14C.xlsx Microsoft Excel http://metacat.lternet.edu/das/dataAccessServlet?docid=knb-lter-arc.10127&urlTail=burn/terrestrial/xlsfiles/2008_MCM_ARF14C.xlsx Microsoft Excel file