Late Holocene tundra fires and linkages to climate and vegetation in northern Alaska

Charcoal particles in lake-sediments can reveal past fires and linkages to climate and vegetation change. We use analyses of charcoal accumulation rates from two lakes (Lake I4 and Kirk Lake) on the Alaskan North Slope to reconstruct past fire activity, and charcoal morphology to identify changes in fuel sources. This dataset contains 1) chronological data for both lake-sediment cores used to construct age-depth models (Pb-210 and radiocarbon), 2) magnetic susceptibility measurements for both cores, 3) macroscopic charcoal particle counts for both sites at three size fractions (90-125µm, 125-250µm, and >250µm), and 4) charcoal morphology (classes defined in associated Arctic Science publication). ,  210Pb data was generated vis gamma spectrometry on a Mirion HPGe small anode germanium (SAGe) well detector. Activities for 210Pb (46.5 keV) and 226Ra (calculated from average of 214Pb (351.9 keV) and 214Bi (609.3 keV) activities) presented. 
Radiocarbon ages were measured from macrofossil material extracted from cores and submitted to the National Ocean Sciences Accelerator Mass Spectrometry (NOSAMS) for AMS 14C dating. Reported 14C ages were calibrated with the INTCAL 20 dataset  using CALIB version 8.2. 
Magnetic susceptibility was measured on split core surfaces (continuous measurements) on a Geotek MSCL-S system with a Barrington MS-C point meter. 
Charcoal particles were sieved from measured volumes of wet sediment with a sieve cascade of 90, 125, and 250 µm, and particles counts were enumerated for each size fraction. 
Charcoal morphologies for all particles >90 µm were identified (see publication for full methodology and references). Morphotypes..., # Late Holocene Tundra Fires and Linkages to Climate and Vegetation in Northern Alaska

Dataset DOI: [10.5061/dryad.tb2rbp0dd](10.5061/dryad.tb2rbp0dd)

## Description of the data and file structure

Charcoal counts (three size fractions), charcoal morphology, and chronological control from two sites on the Alaskan North Slope, near Toolik Field Station. Sites are Lake I4 (Toolik LTER designation) and Kirk Lake (informal name). Data was collected to provide insight into fire history in the region over the past 7000 years. Please see publication for methodological details (Frank-Depue, L., and M.L. Chipman, 2025, *Arctic Science*).

## Files and Variables

**Frank-Depue_and_Chipman_2025_DRYAD.xlsx**: Tabs within this excel file and descriptions listed below.

***Metadata***: this tab contains study and site information, a list of all variables and abbreviations, and missing value designations for all data tabs

***Chronology-Data-Lake-I4***: chronological data for Lake I4, core RTS7U2

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