DOI: 10.5061/dryad.q2b8t.1
title: Data from: Fire-regime complacency and sensitivity to centennial- through millennial-scale climate change in Rocky Mountain subalpine forests, Colorado, U.S.A.

description: 1. Key uncertainties in anticipating future fire regimes are their
 sensitivity to climate change, and the degree to which climate will impact
 fire regimes directly, through increasing the probability of fire, versus
 indirectly, through changes in vegetation and landscape flammability. 2.
 We studied the sensitivity of subalpine forest fire regimes (i.e., fire
 frequency, fire severity) to previously documented climate variability
 over the past 6000 years, utilizing pollen and macroscopic charcoal from
 high-resolution lake-sediment records in Rocky Mountain National Park,
 Colorado. We combined data from the four lakes to provide composite
 records of vegetation and fire history within a 200 km2 study area. 3.
 Rates of forest burning were relatively complacent to millennial-scale
 summer cooling and decreased effective moisture. Mean return intervals
 between fire episodes, defined over 500-year periods, generally varied
 between 150-250 years, consistent with tree-ring-based estimates spanning
 recent centuries. Variability around these long-term means, however, was
 significantly correlated with variability in summer moisture (i.e., more
 burning with drier summers), inferred from existing lake-level and
 supporting paleoenvironmental records. 4. The most pronounced change in
 fire regimes was in response to decreased subalpine forest density ca.
 2400 cal. year BP, itself a response to regional cooling. This indirect
 impact of climate was followed by a decrease in charcoal production per
 fire, a proxy for crown-fire severity, while the long-term rate of burning
 remained unchanged. Over the last 1500 years, increased summer evaporation
 and drought frequency were associated with increased fire severity,
 highlighting a direct link between fire and climate. 5. Synthesis:
 Subalpine forest fire history reveals complacency and sensitivity of fire
 regimes to changing vegetation and hydroclimate over the past 6000 years.
 Complacency is highlighted by non-varying fire frequency over millennia.
 Sensitivity is evident through changes in biomass burned per fire (and
 inferred fire severity), in response to climate-induced changes in forest
 density and, more recently, increased summer drought. Overall, the paleo
 record suggests that (i) fire severity may be more responsive to climate
 change than fire frequency in Rocky Mountain subalpine forests, and (ii)
 the indirect impacts of climate on vegetation and fuels are important
 mechanisms determining fire-regime response to climate change.
description: Charcoal data from Lone
 Pine, Odessa, Sand Beach, and Thunder lakes.Raw and analyzed
 charcoal data from Lone Pine, Odessa, Sand Beach, and Thunder lakes.
 Correspondence Author: Philip E. Higuera. College of Natural Resources,
 Box 441133. University of Idaho, Moscow, ID 83844-1133. USA. E-mail:
 phiguera-at-uidaho-dot-edu. File List: LP07_charData.csv.
 LP07_charParams.csv. LP07_charResults.csv. OD06_charData.csv.
 OD06_charParams.csv. OD06_charResults.csv. SB06_charData.csv.
 SB06_charParams.csv. SB06_charResults.csv. TL06_charData.csv.
 TL06_charParams.csv. TL06_charResults.csv.charcoalData.zip