DOI: 10.25921/s487-vv02
title: NOAA/WDS Paleoclimatology - Dunnette fire data from Chickaree Lake, Rocky Mountain National Park, Colorado - IMPD USCHK001

description: Wildfires can significantly alter forest carbon (C) storage and nitrogen (N) availability, but the long-term biogeochemical legacy of wildfires is poorly understood.

We obtained a lake-sediment record of fire and biogeochemistry from a subalpine forest in Colorado, USA, to examine the nature, magnitude, and duration of decadal-scale, fire-induced ecosystem change over the past c. 4250 yr. The high-resolution record contained 34 fires, including 13 high-severity events within the watershed.

High-severity fires were followed by increased sedimentary N stable isotope ratios (d15N) and bulk density, and decreased C and N concentrations – reflecting forest floor destruction, terrestrial C and N losses, and erosion. Sustained low sediment C : N c. 20–50 yr post-fire indicates reduced terrestrial organic matter subsidies to the lake. Low sedimentary d15N c. 50–70 yr post-fire, coincident with C and N recovery, suggests diminishing terrestrial N availability during stand development. The magnitude of post-fire changes generally scaled directly with inferred fire severity.

Our results support modern studies of forest successional C and N accumulation and indicate pronounced, long-lasting biogeochemical impacts of wildfires in subalpine forests. However, even repeated high-severity fires over millennia probably did not deplete C or N stocks, because centuries between high-severity fires allowed for sufficient biomass recovery.

description: Contact person: Philip E. Higuera;
 Contact person email address: phiguera@uidaho.edu;
 Sampling date: 2010-08;
 Water depth (cm): 790;
 Sampling device: modified Livingstone piston corer;
 Diameter (cm): 5.0 and 7.6 cm diameter;

 Supplemental Material Data File Content Details (26 files total):  
 Contents:
 I. Biogeochemical Data Files           (file count: 1)
 II. Biogenic Silica Data Files         (file count: 1)
 III. Charcoal Data Files               (file count: 3)
 IV. Chronology Data Files              (file count: 14)
 V. Loss-on-ignition Data Files         (file count: 1)
 VI. Magnetic Susceptibility Data Files (file count: 3)
 VII. Pollen Data Files                 (file count: 3)
 
 Note: All 27 Supplemental Material Data Files of this dataset, listed below, begin with the IMPD code for this dataset: "usck001", and are locate at:
       http://www.ncei.noaa.gov/pub/data/paleo/firehistory/charcoal/northamerica/supplemental/
 
 I. Biogeochemical Data Files (file count: 1)
 
 A. uschk001-ch10-biogeochemdata.csv
 Biogeochemical Data
 This file contains the same information as Dunnette et al. 2014 Supporting Information, CH10_biogeochemData.csv
 
 This file includes the following raw data (by column):
 1. core_ID: Sediment core identifier
 2. drive_ID: Drive identifier
 3. top_sam #: Top sample number
 4. bot_sam #: Bottom sample number
 5. top_cm: Top depth of sample (cm)
 6. bot_cm: Bottom depth of sample (cm)
 7. top_age: Top age of sample (cal. yr before CE 1950)
 8. bot_age: Bottom age of sample (cal. yr before CE 1950)
 9. d15N: Nitrogen isotopic composition (delta 15N; per mil)
 10. %N: Percent Nitrogen (by weight)
 11. d13C: Carbon isotopic composition (delta 13C; per mil)
 12. %C: Percent Carbon (by weight)
 13. C:N_atomic_ratio: Ratio of %C to %N (atomic)
 14. bulk_density: Bulk density (dry g wet cm-3)
 15. C_acc: Carbon accumulation rate (g cm-2 yr-1)
 16. MS_SI : Magnetic susceptibility (SI units)
 
 Missing Values: NaN
 Checksum values:
 635 rows (with headers), 16 columns
 Column 3 (top_sam #): 58551
 Column 5 (top_cm): 201836
 Column 10 (%N): 626.83
 Column 15 (C_acc): 341.58
 
 
 II. Biogenic Silica Data Files (file count: 1)
 
 A. uschk001-ch10-bsi-data.csv
 Biogenic Silica Data File
 This file contains the same information as Dunnette et al. 2014 Supporting Information, CH10_BSiData
 
 This file includes the following raw data (by column):
 1. top_cm: top depth of sample (cm)
 2. bot_cm: bottom depth of sample (cm)
 3. top_age: top age of sample (cal. yr before CE 1950)
 4. bot_age: bottom age of sample (cal. yr before CE 1950)
 5. %BSi: Percent biogenic silica (by weight)
 6. d15NAIR: Nitrogen isotopic composition (delta 15N; per mil)
 7. %N: Percent Nitrogen (by weight)
 8. d13CVPDB_17O_corrected: Carbon isotopic composition delta 13C; per mil)
 9. %C: Percent Carbon (by weight)
 10. C:N_atomic_ratio: Ratio of %C to %N (atomic)
 11. bulk_density: Bulk density (dry g / wet cm3)
 
 Missing Values: None
 Checksum values:
 41 rows (with headers), 11 columns
 Column 3 (top_cm): 69935
 Column 5 (%BSi): 1042.45
 Column 10 (C:N): 591.52
 
 
 III. Charcoal Data Files (file count: 3)
 
 Three files, described below, provide the raw input data, the parameters used, and the output data for charcoal analysis via the program CharAnalysis (see Dunnette et al. 2014, Materials and Methods, and https://sites.google.com/site/charanalysis/).
 
 A. uschk001-ch10-char-data.csv
 The raw input data
 This file contains the same information as Dunnette et al. 2014 Supporting Information, CH10_charData.csv,.
 This file also contains the same information as the charcoal data file for this dataset, which is located at: http://www.ncei.noaa.gov/pub/data/paleo/firehistory/charcoal/northamerica/uschk001.txt
 
 This file includes the following raw data (by column):
 1. cmTop: top depth (cm) of the sample
 2. cmBot: bottom depth (cm) of the sample
 3. ageTop: estimated age at top of sample (cal. yr before CE 1950)
 4. ageBot: estimated age at bottom of sample (cal. yr before CE 1950)
 5. charVol: volume of sediment subsample from which charcoal was prepared (cm3)
 6. charCount: pieces of charcoal counted in the sample (#)
 Missing values: None
 Checksum values:
 1202 rows (with headers), 6 columns
 Column 3 (ageTop): 2446519
 Column 6 (charCount): 38218
 
 B. uschk001-ch10-char-params.csv
 The parameters used
 This file contains the same information as Dunnette et al. 2014 Supporting Information, CH10_charParams.csv
 
 See CharAnalysis User's Guide for description of parameters file, available at the web site link above.
 Missing values: -9999 (column 3) or blank cell (all others)
 Checksum values:
 26 rows (with headers), 5 columns
 Column 3 (Parameters): -39779
 
 C. uschk001-ch10-char-results.csv
 The output data for charcoal analysis
 This file contains the same information as Dunnette et al. 2014 Supporting Information, CH10_charResults.csv
 
 This file includes the following derived data (reflecting interpolation):
 1. cmTop_i: top depth (cm) of interpolated sample
 2. ageTop_i: bottom depth (cm) of interpolated sample
 3. charCount_i: pieces of charcoal in interpolated sample
 4. charVol_i: volume of interpolated sample
 5. charCon_i: charcoal concentration in interpolated sample (pieces/cm3)
 6. charAcc_i: charcoal accumulation rate, based in interpolated concentration and age (pieces/cm2 yr)
 7. charBkg: background charcoal, Cback, smoothed based on methods selected in _charParams.csv file, (pieces/cm2 yr)
 8. charPeak: peak charcoal, Cpeak, based on methods selected in _charParams.csv file, (pieces/cm2*yr)
 9. thresh1: threshold value (pieces/cm2 yr) based on first threshold entered in _charParams.csv file
 10. thresh2: same as thresh1, but for second threshold entered
 11. thresh3: same as thresh1, but for third threshold entered
 12. threshFinalPos: positive threshold value (pieces/cm2 yr), based on fourth threshold value entered in *charParams.csv file 
 13. threshFinalNeg: negative threshold value (pieces/cm2 yr), based on fourth threshold value entered in *charParams.csv file
 14. SNI: signal-to-noise index values, based on threshdFinalPos values
 15. threshGOF: P value from KS goodness-of-fit test between fitted noise distribution and empirical data below the sample-specific threshold
 16. peaks1: samples that exceed thresh1 values are identified by "1"; only the first sample is identified
 17. peaks2: same as peaks1, but for the second threshold value
 18. peaks3: same as peaks1, but for the third threshold value
 19. peaksFinal: same as peaks1, but for the final threshold value
 20. peaksInsig.: peaks that exceeded threshFinalPos (the final threshold), but did not pass the minimum-count test are identified with a "1"
 21. peakMag: peak magnitude is the total pieces of charcoal accumulated in a given peak (pieces/cm2*peak); if a peak is only one sample long, then peak magnitude is simply CHAR minus the positive threshold. If a peak is more than one sample long, then each sample exceeding threshFinal is summed
 22. smPeak Frequ: frequency of peaks (from peaksFinal) smoothed over time, as set in *_charParams.csv file
 23. smFRIs: fire return intervals (from peaksFinal) smoothed over time, as set in *_charParams.csv file
 
 Missing values: NaN
 Checksum values:
 458 rows (with headers), 23 columns
 Column 2 (age Top_i): 1014540
 Column 6 (char Acc_i): 753.8938
 Column 19 (peaks Final): 36S
 
 
 IV. Chronology Data Files (file count: 14)
 
 A. uschk001-ch10_14Cdates.zip 
 Chronology Data - .zip archive includes the .B00` files output from CALIB
 This file contains the same information as Dunnette et al. 2014 Supporting Information, CH10_14Cdates.zip.
 
 B. uschk001-ch10-210pb-data.xls
 Chronology Data - Microsoft Excel format file containing Pb210 Data, Pb210 Params, and PB210 Results (210Pb Ages, and 210Pb Age Model). 
 This file contains the same information as Dunnette et al. 2014 Supporting Information, CH10_210Pb_data.xls.
 
 c. uschk001-ch10-210pb-input-data.csv
 Chronology Data - 210Pb Data 
 This file contains the same information as Dunnette et al. 2014 Supporting Information, CH10_210Pb_data.xls, tab: Pb210Data.
 
 D. uschk001-ch10-210pb-params.csv
 Chronology Data - 210Pb Parameter Choices 
 This data is also contained in usck001-ch10-210pb-data.xls tab: Pb210Params. 
 This file contains the same information as Dunnette et al. 2014 Supporting Information, CH10_210Pb_data.xls, tab: Pb210Params. 
 
 E. uschk001-ch10-210pb-results-ages.csv
 Chronology Data - 210Pb Ages
 This data is also contained in usck001-ch10-210pb-data.xls tab: Pb210Results, table within tab: 210Pb Ages.
 This file contains the same information as Dunnette et al. 2014 Supporting Information, CH10_210Pb_data.xls, tab: Pb210Results, table within tab: 210Pb Ages.
 
 F. uschk001-ch10-210pb-results-age-model.csv
 Chronology Data - 210Pb Age Model
 This data is also contained in usck001-ch10-210pb-data.xls tab: Pb210Results, table within tab: 210Pb Age Model. 
 This file contains the same information as Dunnette et al. 2014 Supporting Information, CH10_210Pb_data.xls, tab: Pb210Results, table within tab: 210Pb Age Model.
 
 G. uschk001-ch10-age-depth-data.csv
 Supplemental Material: Chronology Data - age-depth data
 This file contains the same content as Dunnette et al. 2014 Supporting Information, CH10_ageDepthData.csv.
  
 This file includes the following raw data (by column):
 1. Top depth of sample (cm)
 2. Calibrated age at sample top (cal yr BP)
 3. Upper 95% confidence intervals for data in column two
 4. Lower 95% confidence intervals for data in column two
 5. Sedimentation rate (cm/yr)
 6. Upper 95% confidence intervals for data in column five
 7. Lower 95% confidence intervals for data in column five
 8. Sample resolution (yr/sample)
 9. Upper 95% confidence intervals for data in column eight
 10. Lower 95% confidence intervals for data in column eight
 Missing values: None
 Checksum values:
 1596 rows (with headers), 10 columns
 Column 1 (sampleCm): 642150.9
 Column 2 (calAge): 4679522
 Column 5 (sedAcc): 211.236
 Column 8 (sampleRes): 6860.85
 
 H. uschk001-ch10-age-depth-data.xls
 Chronology Data - age-depth data in Microsoft Excel file format
 This file contains the same content as Dunnette et al. 2014 Supporting Information, CH10_ageDepthData.xls.
 
 I. uschk001-ch10-age-depth-input-data-tab
 Chronology Data - age-depth input data  
 This file contains the same content as Dunnette et al. 2014 Supporting Information, CH10_ageDepthData.xls, Tab: InputData
 This file also contains the same content as uschk001-ch10-age-depth-data.xls, Tab: InputData (described above).
 
 J. uschk001-ch10-age-depth-input-params-tab
 Chronology Data - age-depth input parameters  
 This file contains the same content as Dunnette et al. 2014 Supporting Information, CH10_ageDepthData.xls, Tab: InputParams
 This file also contains the same content as uschk001-ch10-age-depth-data.xls, Tab: InputParams (described above).
 
 K. uschk001-ch10-age-depth-pb210-data-tab
 Chronology Data - age-depth pb21 data
 This file contains the same content as Dunnette et al. 2014 Supporting Information, CH10_ageDepthData.xls, Tab: pb210Data
 This file also contains the same content as uschk001-ch10-age-depth-data.xls, Tab: pb210Data (described above).
 
 L. uschk001-ch10-age-depth-calib-dates-tab
 Chronology Data - age-depth input parameters  
 This file contains the same content as Dunnette et al. 2014 Supporting Information, CH10_ageDepthData.xls, Tab: calibDates
 This file also contains the same content as uschk001-ch10-age-depth-data.xls, Tab: calibDates (described above).
 
 M. uschk001-ch10-age-depth-chron-tab
 Chronology Data - age-depth input parameters  
 This file contains the same content as Dunnette et al. 2014 Supporting Information, CH10_ageDepthData.xls, Tab: chronology
 This file also contains the same content as uschk001-ch10-age-depth-data.xls, Tab: chronology (described above).
 
 N. uschk001-ch10_radiometric-samples.csv
 Chronology Data - radiometric samples.
 This file contains the same content as Dunnette et al. 2014 Supporting Information, CH10_radiometricSamples.csv.
 This file also contains the same content as the Chronology section of this dataset for the Charcoal, Loss-on-ignition, and Magnetic Susceptibility data files, respectively named uschk001.txt, uschk001.loi, and uschk001.mag, and all located at http://www.ncei.noaa.gov/pub/data/paleo/firehistory/charcoal/northamerica/
 
 
 V. Loss-on-ignition Data Files (file count: 1)
 
 A. uschk001-ch10-loi-data.csv
 Loss-on-ignition data
 This file contains the same content as Dunnette et al. 2014 Supporting Information, CH10_LOI_Data.csv.
 This file also contains the same content as the Data section of the Loss-on-ignition file for this dataset, located at: http://www.ncei.noaa.gov/pub/data/paleo/firehistory/charcoal/northamerica/uschk001.loi
     Note: for usck001.loi, core_ID, drive_id, top_sam#, and bot_sam# have been concatenated into the last column with heading, Notes. 
 
 This file includes the following raw data (by column):
 1. core_ID: Sediment core identification number
 2. drive_ID: Drive identifier
 3. top_sam #: Top sample number
 4. bot_sam #: Bottom sample number
 5. top_cm: top depth of sample (cm)
 6. bot_cm: bottom depth of sample (cm)
 7. top_age: top age of sample (cal. yr before CE 1950)
 8. bot_age: bottom age of sample (cal. yr before CE 1950)
 9. d15N: Nitrogen isotopic composition (delta 15N; per mil)
 10. %N: Percent nitrogen (by weight)
 11. d13C: Carbon isotopic composition (delta 13C; per mil)
 12. %C: Percent carbon (by weight)
 13. C:N_atomic_ratio: Ratio of %C to %N (atomic)
 14. bulk_density: Bulk density (dry g wet cm-3)
 15. LOI_550: Loss on ignition at 550 C (% organic matter; multiply by 100)
 16. LOI_1000: Loss on ignition at 1000 C (% organic matter; multiply by 100)
 
 Missing Values: None
 Checksum values:
 124 rows (with headers), 16 columns
 Column 3 (top_samp #): 12010
 Column 5 (top_cm): 31833.7
 Column 10 (%N): 161.05
 Column 15 (LOI_550): 38.63
 
 
 VI. Magnetic Susceptibility Data Files (file count: 3)
 
 Three files (Cuschk001-ch10-ms-char-data.csv, uschk001-ch10-ms-char-params.csv, uschk001-ch10-ms-char-results.csv, described below) provide the raw input data, the parameters used, and the output data for peak analysis of magnetic susceptibility (MS) data, using the program CharAnalysis (see Materials and Methods in main text, and web site https://sites.google.com/site/charanalysis/). The column headers for all files are the same as for charcoal analysis (CH10_char* files), but NOTE that the units for MS have been manipulated to be able to be used in CharAnalysis (see below).
 
 A. uschk001-ch10-ms-char-data.csv
 Raw input data
 This file contains the same content as Dunnette et al. 2014 Supporting Information, CH10_MS_charData.csv.
 This file also contains the same content as the Data section of the Magnetic Susceptibility file for this dataset, locted at: http://www.ncei.noaa.gov/pub/data/paleo/firehistory/charcoal/northamerica/uschk001.mag, minus the "dummyVar" column. 
 
 This file Includes the following raw data (by column):
 1. cmTop: top depth (cm) of the sample
 2. cmBot: bottom depth (cm) of the sample
 3. ageTop: estimated age at top of sample (cal. yr before CE 1950)
 4. ageBot: estimated age at bottom of sample (cal. yr before CE 1950)
 5. dummyVar: dummy variable set to 1, to facilitate use in CharAnalysis program
 6. MS_shifted_trans: Shifted MS data (from col. 8), transformed by dividing by the sediment accumulation rate (cm/yr). Thus, when these transformed values are multiplied by the sediment accumulation rate (cm/yr), as done in CharAnalysis, the result is the transformed MS values (column 8).
 7. MS_raw_SI: Raw magnetic susceptibility measurements (SI units)
 8. MS_shifted: Raw MS values, shifted by adding the minimum values in MS_raw_SI to each value, such that the minimum value becomes 0. CharAnalysis cannot work with negative data.
 
 Missing values: None
 Checksum values:
 1477 rows (with headers), 8 columns
 Column 3 (ageTop): 3970165
 Column 6 (setRate/MS): 0.3626761
 
 B. uschk001-ch10-ms-char-params.csv
 The parameters used
 This file contains the same content as Dunnette et al. 2014 Supporting Information, CH10_MS_charParams.csv
 
 C. uschk001-ch10-ms-char-results.csv
 Output data for peak analysis of magnetic susceptibility (MS) data
 This file contains the same content as Dunnette et al. 2014 Supporting Information, CH10_MS_charResults.csv.
 
 
 VII. Pollen Data Files (file count: 3) 
 
 A. uschk001-ch10-pollen-counts.csv
 Raw pollen data reported as pollen counts
 This file contains the same content as Dunnette et al. 2014 Supporting Information, CH10_PollenCounts.csv
 
 B. uschk001-ch10-pollen-counts.xls
 Raw pollen data reported as pollen counts (in Microsoft Excel format file)
 This file contains the same content as Dunnette et al. 2014 Supporting Information, CH10_PollenCounts.xls
 This file also contains the same content as uschk001-ch10-pollen-counts.csv
 
 uschk001-ch10-pollen-counts.csv and uschk001-ch10-pollen-counts.xls (described above), include the following raw data (by column):
 1. Sample_ID : Identification of sample, by lake (CH), year (07 or 10), core (1 or 2), and drive (A, B,C,...).
 2. Sample_number: Sample number for each drive
 3. Top_cm: Top depth of each sample (cm)
 4. age_yrBP: Age of each sample, in calibrated years before present (CE 1950)
 5. Pinus hap: Haploxilon Pinus pollen grains counted
 6. Pinud dip: Diploxilon Pinus pollen grains counted
 7. Pinus undiff: Undifferentiated Pinus pollen grains counted
 8. Picea: Picea pollen grains counted 9...112: Column heads are the taxonomic identification for each pollen grain counted
 9. Charcoal: NOT COUNTED
 10. EU: Exotic pollen grains, added as spike.
 
 Missing values: NaN.
 Checksum values:
 46 rows (with headers), 113 columns
 Column 2 (sample_number): 6143
 Column 4 (age_yrBP): 86683
 Column 10 (Pseudotsuga/Larix): 42
 Column 113 (EU): 8793
 
 C. uschk001-ch10-pollen-percentages.csv
 Pollen percentages
 This file contains the same content as Dunnette et al. 2014 Supporting Information, CH10_pollenPercentages.csv
 
 This file includes the following raw data (by column):
 1. Sample_ID : Identification of sample, by lake (CH), year (07 or 10), core (1 or 2),
 and drive (A, B, C,...).
 2. Sample_number: Sample number for each drive
 3. Top_cm: Top depth of each sample (cm)
 4. age_yrBP: Age of each sample, in calibrated years before present (CE 1950)
 5. Pinus hap: Haploxilon Pinus pollen grains counted
 6. Pinud dip: Diploxilon Pinus pollen grains counted
 7. Pinus undiff: Undifferentiated Pinus pollen grains counted
 8. Picea: Picea pollen grains counted 9...107: Columns heads are the taxonomic identification for each pollen grain counted
 
 Missing values: None.
 Checksum values:
 46 rows (with headers), 106 columns
 Column 2 (sample_number): 6143
 Column 4 (age_yrBP): 86683
 Column 10 (Pseudotsuga/Larix): 12
 Column 102 (Nuphar): 13.19