Data from: Arctic and boreal paleofire records reveal drivers of fire activity and departures from Holocene variability ...

• Main Authors: Hoecker, Tyler, Higuera, Philip, Kelly, Ryan, Hu, Feng Sheng
• Format: Dataset
• Language: English
• Published: Dryad 2020
• Subjects: boreal ecosystem; Fire frequency; Arctic; Barrett; Livingstone; Climate change; Tundra; Alaska
• Online Access: https://dx.doi.org/10.5061/dryad.0gb5mkkxv; https://datadryad.org/stash/dataset/doi:10.5061/dryad.0gb5mkkxv

Boreal forest and tundra biomes are key components of the Earth system because the mobilization of large carbon stocks and changes in energy balance could act as positive feedbacks to ongoing climate change. In Alaska, wildfire is a primary driver of ecosystem structure and function, and a key mechanism coupling high-latitude ecosystems to global climate. Paleoecological records reveal sensitivity of fire regimes to climatic and vegetation change over centennial-millennial time scales, highlighting increased burning concurrent with warming or elevated landscape flammability. To quantify spatiotemporal patterns in fire-regime variability, we synthesized 27 published sediment-charcoal records from four Alaskan ecoregions, and compared patterns to paleoclimate and paleovegetation records. Biomass burning and fire frequency increased significantly in boreal forest ecoregions with the expansion of black spruce, ca. 6-4 thousand years before present (yr BP). Biomass burning also increased during warm periods, ... : All 27 lake-sediment charcoal records were developed with virtually identical methods, originally published by: Higuera et al. 2007, 2009, 2011 a/b, Kelly et al. 2013 and Barrett et al. 2013. Sediment cores were collected from small (< 10 ha), deep (> 5 m) lakes with simple basin shapes and minimal inlets or outlets, using a polycarbonate tube fitted with a piston and/or a modified Livingstone coring device. Core tops were sampled in the field at continuous 0.5-1.0 cm intervals, and in the laboratory, cores were sampled in contiguous 0.25-0.5 cm intervals, with 0.5-3.0 cm3 samples taken for charcoal analysis. Samples were treated with sodium metaphosphate, oxidized with sodium hypochlorite or hydrogen peroxide, and sieved to isolate macroscopic charcoal (> 150-180 um). Charcoal particles were counted at 10-40x with a stereomicroscope, and CHAR (pieces cm-2 year-1) was derived as the product of charcoal concentrations (pieces cm-3) and sediment accumulation rates (cm yr-1). Sediment accumulation ...