uid=BNZ,o=lter,dc=ecoinformatics,dc=org all public read knb-lter-bnz.348.9 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 Kathryn G. Crummer Research Associate

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

(352) 846-9620 (352) 392-3993 Associated investigator 2009-01-01 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. This dataset reports aboveground biomass and aboveground net primary productivity for three sites across a gradient of permafrost thaw, as well as foliar nitrogen and foliar stable nitrogen isotopes for a subset of the plant species. aboveground production net primary production foliar nitrogen nitrogen isotopes plant biomass Biogeochemistry

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http://www.lter.uaf.edu/data_detail.cfm?datafile_pkey=348 Site information unavailable -149.2535833 -149.2535833 63.87836111 63.87836111 2004-07-25 2004-07-31

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. There were 12 quadrats per site that were 70x70 cm.

FIELD: We quantified differences in plant species composition, aboveground biomass, and aboveground NPP among these three sites to determine how vegetation could change in response to permafrost thawing. To do this, we coupled intensive destructive harvests of the tundra vegetation with more extensive surveys of plant biomass distribution at the sites. For the harvests, we separated the aboveground tundra ecosystem by plant species and plant part, and then used allometric relationships that we derived in order to extend this information to the broader surveys. Foliar nitrogen and 15N were measured by collecting leaves from a subset of the species. LAB: We measured the concentration of foliar nitrogen (N) from six species common to all sites as an index of changes in ecosystem nutrient availability among sites. To compare leaves among sites, we analyzed the fully-developed, new leaf cohort for each species. Each sample was the composite of mature leaves from multiple individual plants within a quadrat, and there were six quadrats analyzed at every site, with the exception of Betula nana in the Extensive and Moderate sites, which was only found and analyzed in 3 and 4 quadrats respectively. Leaves were dried at 60?C and ground, and the N concentration was measured using a Costech elemental analyzer. Because increased plant growth can sometimes offset increases in soil N availability, we multiplied the concentration of foliar N by the green photosynthetic biomass (total canopy N) as another metric of change in nutrient availability across sites. Nitrogen isotopes were measured on the same samples with a Finnigan Delta XL plus continuous flow mass spectrometer.

geoReference 2004-07-25 2004-07-31

Single timpoint measurements for both destructive harvest of quadrats and for point framing. This was done at peak biomass

348_Healy04_BiomassNPP.txt Healy biomass NPP data fro Ted Schuur 348_Healy04_BiomassNPP.txt 1 \n \n column \t http://metacat.lternet.edu/das/dataAccessServlet?docid=knb-lter-bnz..&urlTail=/ascii/files/348_Healy04_BiomassNPP.txt Site Site Name of site that chamber is located in string Name of site that chamber is located in Chamber Chamber Chamber number string Chamber number Species/Fxn Group/ Total Species/Fxn Group/ Total Species ID, Functional Group Name, or Sum Total for Chamber string Andpol Andromeda polifolia Betnan Betula nana Carbig Carex bigelowii Empnig Empetrum nigrum Erivag Eriophorum vaginatum Leddec Ledum decumbens Rubcha Rubus chamaemorus Vaculi Vaccinium uliginosum Vacvit Vaccinum vitis-idaea Fxn Grp Fxn Grp Functional Group or Sum Total for Chamber string Functional Group or Sum Total for Chamber g/m2 all g/m2 all total of plant parts weight per area float gramsPerSquareMeter real g/m2 lf g/m2 lf leaf or photosynthetic part weight per area float gramsPerSquareMeter real g/m2 NPP g/m2 NPP net primary productivity on an annual basis per area float gramsPerSquareMeter real %AG %AG percent contribution to total aboveground biomass of the chamber float percent real 0.000 100.000 none - cell left empty Missing Value %PS %PS percent contribution to total photosynthetic biomass of the chamber float percent real 0.000 100.000 none - cell left empty Missing Value delta 15N delta 15N 15/14N isotope ratio of new foliage or graminoid blade from same site - NOT SAME CHAMBER float permil real none - cell left empty Missing Value delta 13C delta 13C 13/12C isotope ratio of new foliage or graminoid blade from same site - NOT SAME CHAMBER float permil real none - cell left empty Missing Value %N %N %N content of new foliage or graminoid blade from same site - NOT SAME CHAMBER float percent real 0.000 100.000 none - cell left empty Missing Value %C %C %C content of new foliage or graminoid blade from same site - NOT SAME CHAMBER float percent real 0.000 100.000 X if measured and in error, cell left empty if not measured Missing Value