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The re-use of scientific data has the potential to greatly increase communication, collaboration and synthesis within and among disciplines, and thus is fostered, supported and encouraged. Permission to use this dataset is granted to the Data User free of charge subject to the following terms:

1) Acceptable use. Use of the dataset will be restricted to academic, research, educational, government, recreational, or other not-for-profit professional purposes. The Data User is permitted to produce and distribute derived works from this dataset provided that they are released under the same license terms as those accompanying this Data Set. Any other uses for the Data Set or its derived products will require explicit permission from the dataset owner.
2 ) Redistribution. The data are provided for use by the Data User. The metadata and this license must accompany all copies made and be available to all users of this Data Set. The Data User will not redistribute the original Data Set beyond this collaboration sphere.
3 ) Citation. It is considered a matter of professional ethics to acknowledge the work of other scientists. Thus, the Data User will properly cite the Data Set in any publications or in the metadata of any derived data products that were produced using the Data Set. Citation should take the following general form: Creator, Year of Data Publication, Title of Dataset, Publisher, Dataset identifier. For example:

Shaver, G. 1989. Above ground biomass in acidic tussock tundra experimental site, 1989, Arctic LTER, Toolik, Alaska. Arctic LTER, Marine Biological Lab, Woods Hole, Ma 02543. 1989gsttbm http://ecosystems.mbl.edu/arc/terrest/biomass/index.shtml 

4 ) Acknowledgement. The Data User should acknowledge any institutional support or specific funding awards referenced in the metadata accompanying this dataset in any publications where the Data Set contributed significantly to its content. Acknowledgements should identify the supporting party, the party that received the support, and any identifying information such as grant numbers. For example:

Data sets were provided by the Arctic LTER. 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.

5 ) Notification. The Data User will notify the Data Set Contact when any derivative work or publication based on or derived from the Data Set is distributed. The Data User will provide the data contact with two reprints of any publications resulting from use of the Data Set and will provide copies, or on-line access to, any derived digital products. Notification will include an explanation of how the Data Set was used to produce the derived work.
6 ) Collaboration. The Data Set has been released in the spirit of open scientific collaboration. Data Users are thus strongly encouraged to consider consultation, collaboration and/or co-authorship with the Data Set Creator.

By accepting this Data Set, the Data User agrees to abide by the terms of this agreement. The Data Owner shall have the right to terminate this agreement immediately by written notice upon the Data User's breach of, or non-compliance with, any of its terms. The Data User may be held responsible for any misuse that is caused or encouraged by the Data User's failure to abide by the terms of this agreement.

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Dataset URLs:METADATA: HTML, Rich Text, XML(EML compliant)
DATA: Comma Delimited, Excel file with Metadata and data
Dataset ID:20092013MCM_TKsoil.01
Dataset Title:Surface soil characteristics for six thermokarst chronosequences near Toolik Field Station and Noatak National Preserve, Alaska
Investigator 1: 
First Name:Michelle
Last Name:Mack
Organization:University of Florida
Address line 2:Department of Biology
Address line 3:
City:Gainesville
State:FL
Zip Code:32611
Country:US
Investigator 2: 
First Name:Edward
Last Name:Schuur
Organization:University of Florida
Address line 2:Department of Biology
City:Gainesville
State:FL
Zip Code:32611
Country:US
Associate Investigators:
Keywords:Retrogressive thaw slump, NE-14 lake, I-minus 1 lake, Itkillik river, Toolik Field Station, Noatak National Preserve
Abstract:Surface organic and mineral soil layers were sampled in retrogressive thaw slump disturbance scars and nearby undisturbed tundra to estmate the influence of this thermo-erosional--thermokarst--disturbance type on soil carbon (C) and nitrogen (N) pools. Within six independent sites, we identified multiple thaw slump scars and determined time after disturbance for each scar by (1) aging the population of tall deciduous shrubs rooted in the mineral soil and (2) by dating the basal layer of the re-accumulating soil organic matter. Within each scar or paired undisturbed tundra site, we sampled replicate soil profiles volumetrically and analyzed samples for horizon depth, coarse, fine and rock fractional contribution, pH, bulk density, moisture content, and C and N concentration.
For questions about the Metadata and data contact the Investigators.
For information about this web site contact:
Arctic LTER Information Manager
The Ecosystems Center
Marine Biological Lab
7 MBL St
Woods Hole, MA 02543
Phone (508) 289 7496
Email: arc_im@mbl.edu
Online URL: http://ecosystems.mbl.edu/ARC/
DATA FILE INFORMATION:
Data File URL http://metacat.lternet.edu/das/dataAccessServlet?docid=knb-lter-arc.10464&urlTail=thermokarst/soil/data/2009-2013_MCM_TKsoil.csv
Data File Name 2009-2013_MCM_TKsoil
Beginning Date 6/19/2009
End Date 7/28/2013
Number of Data Records 385
Other Files to Reference
Availability Status Type 1
Quality Control Information
Maintenance Description Starting on 09/2009, we conducted a monthly update and data entering check. On 02/2013, we conducted a QC/QA for all the raw data entered and calculations
Log of Changes: Updated Metadata sheet, added units to missing numbers, corrected column names from data to metadata sheets. (JD Dec.2013)
 
RESEARCH LOCATION:                                                      
Location Name Site 1 Site 2 Site 3 Site 4 Site 5 Site 6 Site 7 Site 8 Site 9 Site 10 Site 11 Site 12 Site 13 Site 14 Site 15 Site 16 Site 17 Site 18 Site 19 Site 20 Site 21 Site 22 Site 23 Site 24 Site 25 Site 26  
Geographic Description Transect (50 m) in the undisturbed tundra (control 1) of retrogressive thaw slump (RTS) NE14, associated with lake NE-14. Transect (50 m) in Lobe 1 of RTS NE14, associated with lake NE-14. Transect (50 m) in Lobe 2 of RTS NE-14, associated with lake NE-14. Transect (50 m) in the undisturbed tundra (control 2) of RTS NE-14, associated with lake NE-14. Transect (50 m) in Lobe 3 of RTS NE-14, associated with lake NE-14. Transect (50 m) in the undisturbed tundra (control) of RTS Itkillik 1, associated with the Itkillik River. Transect (50 m) in Lobe 1 of RTS Itkillik 1, associated with the Itkillik River Transect (50 m) in the undisturbed tundra (control) of RTS Itkillik 2, associated with the Itkillik River. Transect (50 m) in Lobe 1 of RTS Itkillik 2, associated with the Itkillik River. Transect (50 m) in the undisturbed tundra (control) of RTS Itkillik 3, associated with the Itkillik River. Transect (30 m) in Lobe 1 of RTS Itkillik 3, associated with the Itkillik River. Transect (50 m) in the undisturbed tundra (control 1) of RTS I-minus 1, associated with lake I-minus 1. Transect (50 m) in the undisturbed tundra (control 2) of RTS I-minus 1, associated with lake I-minus 1. Transect (40 m) in Lobe 1 of RTS I-minus 1, associated with the I-mins 1 lake. Transect (40 m) in Lobe 2 of RTS I-minus 1, associated with lake I-minus 1. Transect (28 m) in Lobe 3 of RTS I-minus 1, associated with associated with lake I-minus 1. Transect (50 m) in Lobe 4 of RTS I-minus 1, associated with lake I-minus 1. Transect (50 m) in Lobe 5 of RTS I-minus 1, associated with lake I-minus 1. Transect (50 m) in Lobe 6 of RTS I-minus 1, associated with lake I-minus 1. Transect (50 m) in Lobe 7 of RTS I-minus 1, associated with lake I-minus 1. Transect (40 m) in the undisturbed tundra (control) of RTS Loon Lake, associated with Loon Lake in the Noatak National Preserve. Transect (10 m) in Lobe 1 of RTS Loon Lake, associated with Loon Lake in the Noatak National Preserve. Transect (50 m) in Lobe 2 of RTS Loon Lake, associated with Loon Lake in the Noatak National Preserve. Transect (45 m) in Lobe 3 of RTS Loon Lake, associated with Loon Lake in the Noatak National Preserve. Transect (15 m) in Lobe 4 of RTS Loon Lake, associated with Loon Lake in the Noatak National Preserve. Transect (45 m) in Lobe 5 of RTS Loon Lake, associated with Loon Lake in the Noatak National Preserve.  
Location Bounding Box                                                      
West Bounding Coordinate                                                      
East Bounding Coordinate                                                      
North Bounding Coordinate                                                      
South Bounding Coordinate                                                      
OR if single point location                                                      
Latitude 68.677903 68.678833 68.679417 68.679244 68.6785 68.633222 68.632611 68.666256 68.66675 68.671592 68.673667 68.553 68.562267 68.553417 68.553778 68.554483 68.559117 68.560483 68.56055 68.56065 67.927667 67.928467 67.927817 67.92905 67.928378 67.929883  
Longitude -149.621064 -149.623278 -149.625361 -149.627725 -149.628139 -149.7985 -149.798639 -149.817472 -149.817944 -149.844794 -149.844333 -149.574444 -149.571017 -149.573639 -149.57475 -149.57545 -149.573283 -149.5742 -149.563533 -149.569767 -161.963717 -161.961333 -161.96455 -161.959283 -161.962161 -161.95645  
Elevation In Meters In Meters In Meters In Meters In Meters In Meters In Meters In Meters                                      
Link to Google Map View on Google Map View on Google Map View on Google Map View on Google Map View on Google Map View on Google Map View on Google Map View on Google Map                                      
                                                       
 
TAXONOMIC COVERAGE:
Organisms studied
 
Methods:Study Sites

Five of the six retrogressive thaw slump (RTS) sites (NE-14, I-minus 1 and the Itkillik series) are located in the vicinity of the Toolik Field Station (TFS; N68 38N, W149 36W), which is 720 m above sea level in the foothills province of the Brooks Range, AK (see figure 1, appendix figure A1). Sites were accessed via helicopter from TFS or by foot from the Dalton Highway. Vegetation in this region includes moist acidic tundra (MAT) (tussock sedge, dwarf-shrub, moss tundra; (Walker et al 2002), which is defined by the presence of the tussock-forming sedge Eriophorum vaginatum, moist non-acidic tundra (MNT) (Non-tussock sedge, dwarf-shrub, moss tundra; (Walker et al 2002), and low shrub tundra.

The fourth site (Loon Lake) is located in the vicinity of the Noatak National Preserve (NNP, N6780268839, W1558501628551), which is on the south slope of the Brooks Range in northwestern Alaska (see figure 1). This site was accessed via bush plane from Kotzebue, and then via helicopter from a central field camp. Although MAT and MNT dominates much of the NNP, the tree Picea glauca also occurs at low density (Suarez et al 1999).
To locate sites, we used helicopter over-flights, aerial photographs, Google Earth images (2009) and field surveys. Re-vegetated sites at I-minus 1 were located with LiDAR based on changes in slope topography (Krieger 2012). Once sites were identified, we visually classified disturbance features within sites, henceforth referred to as lobes, as recently disturbed (observed active headwall migration and bare mineral soil exposed due to sediment movement), intermediate aged (mature tall shrubs and some moss cover established) and old (little to no mineral soil exposed, and relatively continuous vegetation cover). Lobes ages (in years after disturbance) were assigned later based on dating of shrubs and soil organic matter (described in an accompanying archived dataset).

Within sites, all lobes were located on the same geologic surface: NE-14 and I-minus 1 were located on the drift of Itkillik phase II (till and ice-contact deposits), Itkillik series on undifferentiated lacustrine deposits, and Loon Lake on Holocene floodplain deposits (alluvium) (Hamilton 2003). Lobes within most sites were close (<500 m) so that the climate and the pool of organisms capable of colonizing were likely similar. The only exception was the Itkillik site with three lobes located along the bank of the Itkillik River and separated by as much as 1 km.

Aspect and topography varied somewhat among lobes within sites. Although the three lobes in NE-14 had similar southern aspects, they differed in slope. The two older sites had ~10% less slope than the active site due to stabilization of the headwalls. The three Itkillik sites had south-eastern aspects according to location on the Itkillik River and slopes were similar among lobes. I-minus 1 site is on the shore of the eponymous lake, and lobes 1-3 had northern aspects, while 4-7 had southern aspects. Slopes were similar among lobes. Finally, all Loon Lake lobes had North-western aspects and similar slopes.
In all sites, undisturbed (control) tundra was randomly selected from the area surrounding the site for comparison. At NE-14, we selected two spatially independent undisturbed areas. At I-minus 1, we selected two undisturbed areas on the south, and one on the north aspect of the lake. For the Itkillik series, we paired an undisturbed area with each disturbed lobe. Only one undisturbed area was sampled in Loon Lake because of helicopter time constraints. In almost all cases, undisturbed sites were gently sloped and had similar aspects to disturbed lobes and generally located upslope from the RTS disturbances.
Within the centre of each disturbed lobe or undisturbed area, we established a 50 m by 4 m belt transect along the contour, where we sampled soils and surveyed vegetation. We sampled a larger area (50 x 10 m along the above transect) for shrub and soil age. If the disturbed lobe was not wide enough to fit a single 50 m transect, two parallel transects were established that covered the same 100 or 500 m2 area. Our primary goal within each lobe was to sample the zone that was not currently affected by active deposition of new material from the headwall or sidewalls or by inundation from the associated lake or river (edge effects). GPS coordinates were recorded for each transect (appendix table A1).

For NE-14, Itkillik and Loon Lake sites, the vegetation of the surrounding undisturbed tundra was classified as MNT: non-tussock sedge, dwarf-shrub, moss tundra, with peaty non-acidic soils (Walker et al. 2002). Frost boils (barren patches of cryoturbated soil) were common. Vegetation at the I-minus 1 site was classified as MAT (Walker et al 2002). Vegetation within disturbed lobes was variable but was dominated by deciduous shrubs (Salix alexensis, S. pulchra, S. glauca, and Betula nana).

Soil C and N pools

Along each transect, we sampled surface soils at 10 m intervals and took additional measurements of organic layer depth at 5 m intervals. At each sample point, we dug a ~30 x 30 cm pit to the organic-mineral interface and removed an organic profile from the exposed wall. Mineral soil was sampled from the organic-mineral interface to 15 cm depth with a 7 cm internal diameter corer. Soils were wrapped in tinfoil to preserve structure and returned on ice to the lab at Toolik Field Station where preliminary processing took place.

At the field station, we sectioned organic soils into depth increments (0-5 cm and 10 cm increments thereafter) with an electric knife. Each increment was weighed and homogenized by hand to remove >2 mm diameter coarse woody debris, roots, rhizomes, and rocks. Gravimetric water content was determined by drying organic soils at 60?C for 48 hours and mineral soils at 110?C for 48 hours.
We measured soil pH on a 1:1 ratio of air-dried, homogenized soil and DI water. The mixture was allowed to settle for 30 minutes before submerging a calibrated pH electrode (Thermo Orion, Beverly, MA, USA).

To determine bulk soil C and N content, a subsample of the homogenized soil fraction was dried at 60?C for 48 hours, ground to a fine powder on a Wiley-mill (Thomas Scientific, Swedesboro, NJ) with a #40 mesh screen, and analysed using an ECS 4010 elemental analyser (Costech Analytical, Valencia, California, USA).

Soil bulk density was calculated for each organic and mineral soil depth increment as the mass (g) per unit volume (cm3) of < 2mm dry soil. Carbon and N pools were calculated for each depth increment as the element concentration times the bulk density scaled to a meter squared. The total organic layer pool is the sum of all depth increments within a profile. Organic layer bulk density was calculated as an average for each profile by dividing the summed soil mass by the summed volume. Total layer %C and %N were similarly calculated for each profile by dividing the summed C or N pool by the summed soil mass. Total layer pH was calculated for each profile by (1) multiplying hydrogen ion concentration in each layer by the mass of soil in the layer, (2) summing the layers, and (3) dividing the sum by the total soil mass. Statistics were performed on hydrogen ion concentrations and back-transformed to pH for reporting.

Data Table

Variable Name Variable Description Data Type Units DateTime Format Code Information Missing Value Code
Site name Site name based on ARCSS Thermokarst project naming conventions text        
Transect Position of each lineal transect used for sampling: T0=control transect located outside RTS in the undisturbed tundra, T0a = second control transect located outside the RTS in undisturbed tundra; T1-7=transects located inside the RTS text        
State Disturbance status: Undisturbed indicates no evidence of disturbance from retrogressive thaw slump; disturbed indicates that transect is within a retrogressive thaw slump feature. text        
Distance (m) Sampling distance from zero end of a 50 m transect number meter      
Soil horizon Soil horizon sampled: Org=organic soil horizon, Min=mineral soil horizon text      
Depth range (cm) Sample depth increment from surface to base of the organic soil horizon, or from the surface of the mineral soil horizon to permafrost or rock text        
Depth (cm) Depth increment in centimeters number centimeter      
Adjusted depth (cm) Soil depth scaled to 15 cm for mineral soils number centimeter      
Dry mass ratio (dry g/wet g) Dry mass of a homogenized soil (<2mm diameter fraction) subsample divided by its wet mass number gramPerGram     "-1111=missing data"
Gravimetric water content ((wet g-dry g)/dry g) Wet mass of a homogenized soil (<2mm) subsample minus its dry mass divided by its dry mass number gramPerGram     "-1111=missing data"
Bulk Density (g/cm^3) Dry mass per unit field measured volume of homogenized (< 2mm) soil number gramPerCentimeterCubed     "-1111=missing data"
pH Soil pH number number     "-1111=missing data"
%N Concentration of nitrogen (%) in homogenized (<2mm) soil on a dry mass basis number percent     "-1111=missing data"
%C Concentration of carbon (%) in homogenized (<2mm) soil on a dry mass basis number percent     "-1111=missing data"
Raw soil mass (g/m^2) Mass of homogenized (<2mm) soil per meter squared for sampled increment number gramPerMeterSquared      
Raw C pool (gC/m^2) Mass of carbon in homogenized (<2mm) soil per meter squared for sampled increment number gramPerMeterSquared      
Raw N pool (gN/m^2) Mass of nitrogen in homogenized (<2mm) soil per meter squared for sampled increment number gramPerMeterSquared      
Adjusted soil mass (g/m^2) Mass of homogenized (<2mm) soil per meter squared for depth adjusted sample increment number gramPerMeterSquared      
Adjusted C pool (gC/m^2) Mass of carbon in homogenized (<2mm) soil per meter squared for depth adjusted sample increment number gramPerMeterSquared      
Adjusted N pool (gN/m^2) Mass of nitrogen in homogenized (<2mm) soil per meter squared for depth adjusted sample increment number gramPerMeterSquared      
Coarse organic debris density (g/cm^3) Dry mass per unit field measured volume of coarse organic debris (>2mm diameter fraction) number gramPerMeterSquared      
COD pool (g/m^2) Mass of carbon in coarse organic debris (>2mm) per meter squared for sampled increment number gramPerMeterSquared      
COD C pool (gC/m^2) Mass of nitrogen in coarse organic debris (>2mm) per meter squared for sampled increment number gramPerMeterSquared      
Adjusted COD pool (g/m^2) Mass of carbon in coarse organic debris (>2mm) per meter squared for depth adjusted sample increment number gramPerMeterSquared      
Adjusted COD C pool (gC/m^2) Mass of nitrogen in coarse organic debris (>2mm) per meter squared for depth adjusted sample increment number gramPerMeterSquared      
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