uid=BNZ,o=lter,dc=ecoinformatics,dc=org all public read knb-lter-bnz.366.8 Edward A.G. Schuur

University of Florida Department of Botany 220 Bartram Hall Gainesville FL 32611 United States

(352) 392-7913 (352) 392-3993 tschuur@ufl.edu http://ecology.botany.ufl.edu/ecosystemdynamics/schuur/ Bonanza Creek LTER Data Manager

Boreal Ecology Cooperative Research Unit University of Alaska Fairbanks P.O. Box 756780 Fairbanks AK 99775 USA

907-474-6364 907-474-6251 jpdowning@alaska.edu http://www.lter.uaf.edu Caitlin Elizabeth Pries-Hicks PhD Student in the Schuur Lab

Department of Biology, University of Florida, PO Box 118526, 217 Bartram Hall Gainesville FL 32611 United States

(413) 530-8481 Associated investigator 2009-03-02 In this larger study, we are asking the question: Is old carbon that comprises the bulk of the soil organic matter pool released in response to thawing of permafrost? We are answering this question by using a combination of field and laboratory experiments to measure radiocarbon isotope ratios in soil organic matter, soil respiration, and dissolved organic carbon, in tundra ecosystems. The objective of these proposed measurements is to develop a mechanistic understanding of the SOM sources contributing to C losses following permafrost thawing. We are making these measurements at an established tundra field site near Healy, Alaska in the foothills of the Alaska Range. Field measurements center on a natural experiment where permafrost has been observed to warm and thaw over the past several decades. This area represents a gradient of sites each with a different degree of change due to permafrost thawing. As such, this area is unique for addressing questions at the time and spatial scales relevant for change in arctic ecosystems. In this data set, thaw gradient site soil carbon and nitrogen inventories are reported by depth layer for both organic and mineral horizons. The inventories include % Carbon, % Nitrogen, bulk density, gC/m2, gN/m2, 13C, and 14N. carbon balance permafrost Biogeochemistry

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http://www.lter.uaf.edu/data_detail.cfm?datafile_pkey=366 Site information unavailable -149.2535833 -149.2535833 63.87836111 63.87836111 2004-05-27 2004-06-01

Cores were not always sectioned into the depth layers listed on the data sheet for carbon and nitrogen analysis. To get the section data into standardized depth layers, bulk density and depth weighted averages of the %C, %N, 13C, and 14N were calculated. For inventories (cC/m2 or gN/2), the amount in the depths being combined into the standardized depth layer were simply added. When data for a section was missing (happened only twice and then only for bulk density, the average of the layers above and below were used). In the file, missing data in the organic layers mean that the organic layer was shallower than that depth layer, not that there were any missing data.

Completed

Bonanza Creek LTER Data Manager

Boreal Ecology Cooperative Research Unit University of Alaska Fairbanks P.O. Box 756780 Fairbanks AK 99775 USA

907-474-6364 907-474-6251 jpdowning@alaska.edu http://www.lter.uaf.edu Bonanza Creek LTER

Boreal Ecology Cooperative Research Unit University of Alaska Fairbanks P.O. Box 756780 Fairbanks AK 99775 USA

907-474-6364 907-474-6251 Bonanza Creek LTER

The study site at the Eight Mile Lake watershed is located in the northern foothills of the Alaska Range. Permafrost temperature has been monitored annually on a gentle north-facing slope at this site, in a 30 m deep borehole that was installed in 1985 before the permafrost started to thaw. While permafrost thaw can sometimes result in water ponding depending on local topography, this landscape consists largely of relatively well-drained uplands. In this watershed, we monitored three sites that represented differing amounts of change as a result of permafrost thaw based on observations of ground subsidence and depth of thaw. Our minimal thaw site had the shallowest summer thaw depth and the least ground surface subsidence, and the vegetation was typical moist acidic tundra, dominated by the tussock-forming sedge, Eriophorum vaginatum, with coexisting deciduous and evergreen shrubs, and an understory of mosses and lichens. A second site, located adjacent to the borehole, had moderate summer thaw depths and increased ground subsidence. Here the vegetation composition was similar to our minimal thaw site, but with increased biomass of all plant groups. Lastly, an extensive thaw site was located in an area where permafrost degradation had occurred at least several decades prior to the establishment of the borehole; thermokarst can already be observed in air photos of the area taken in 1954. This site had the deepest summer thaw depth and the most ground subsidence, and the plant biomass has shifted to dominance by shrubs, including blueberry (Vaccinium uliginosum) and cloudberry (Rubus chamaemorus), at the expense of sedges. Six soil cores were taken at each gradient site. Tussocks were avoided during coring.

FIELD: Cores were collected in the spring of 2004 (while the ground was still frozen) from the extensive, moderate, and minimal thaw gradient sites at 8 Mile Lake in Healy, AK. The top organic layers were collected using the "Brownie method" by cutting out the soil with a knife. Deeper layers were sampled with a gas-powered drill corer. The dimensions of the brownies (height, width, length) and cores (length and diameter) were measured. Cores were broken into transportable sections in the field and frozen. LAB: Cores were weighed (for bulk density) and then further divided into standardized depth layers where possible. A subsample was taken and dried at 60C for moisture content. That subsample was ground and then run on a Costech (ECS4010) Elemental Analyzer in line with an Isotope Ratio Mass Spectrometer for %c. %N, 13C, and 14C.

geoReference 2004-05-27 2004-06-01

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366_Healy_Soil_C_and_N_inventory.txt 366_Healy_Soil_C_and_N_inventory.txt 1 \n \n column \t http://metacat.lternet.edu/das/dataAccessServlet?docid=knb-lter-bnz..&urlTail=/ascii/files/366_Healy_Soil_C_and_N_inventory.txt Site Site Name of site for measurement. string Ext Extensive Thaw Mod Moderate Thaw Min Minimal Thaw Core Core Core replicate. There are 6 per site. integer Core replicate. There are 6 per site. Horizon Horizon Whether this layer is part of the organic or mineral soil (20% C is the cutoff) string O organic M mineral Layer Layer Layer is soil that the data in this row pertain to. string centimeter real Depth Depth Depth of soil layer integer centimeter real %N %N Percent nitrogen by mass float percent real %C %C Percent carbon by mass float percent real delta14N delta14N Ratio of 14N in the soil relative to a standard float permil real delta13C delta13C Ratio of 13N in the soil relative to a standard float permil real gN/m2 gN/m2 Amount of N in that layer of soil on an areal basis float gN/m2soil real gC/m2 gC/m2 Amount of C in that layer of soil on an areal basis float gC/m2soil real BulkDensity BulkDensity Bulk density of the soil float gdrysoil/m3soil real