Climatic Controls on Wildfire Regimes and Vegetation from 15-10 ka in the Pacific Northwest (USA)
Abstract
The time period from ~15-10 ka spans the last glacial to interglacial transition and is a period of relatively large climate changes, including abrupt changes, such as occur at the start of the Bølling-Allerød interval at ~14.7 ka. These climate changes affected both vegetation and wildfire regimes. Here we examine simulated climate, wildfire, and vegetation interactions for ~15-10 ka for the Pacific Northwest (PNW) region of the USA. We use climate data from the CCSM3 TraCE simulations, and these climate data are also used to simulate vegetation and wildfire-related data with LPJ-GUESS, a dynamic global vegetation model, and to calculate surface water-balance variables with SPLASH, a bioclimatic model. The simulated climate, vegetation, and wildfire data are compared with observed vegetation (i.e., pollen and plant macrofossils) and wildfire (i.e., charcoal) data from three lakes in the west coast region of the PNW (Battle Ground Lake, Bluff Lake, Little Lake) and from two lakes in the northern Rocky Mountains region of the PNW (Burnt Knob Lake, Cygnet Lake). Our results show that simulated air temperature for these regions generally increased for all months from 15 ka to 10 ka. Simulated precipitation and moisture-related variables (e.g., actual evapotranspiration) generally decreased in spring and summer months for the west coast region and generally increased in the northern Rocky Mountains region. Simulated vegetation biomass generally decreased for the two northernmost west coast region lake sites and increased for the southernmost west coast region site and at the northern Rocky Mountains lake sites. For the west coast region, increased summer air temperature coupled with decreased summer precipitation is associated with simulated increases in wildfire frequency. For the northern Rocky Mountain region, increased summer air temperature and precipitation is associated with simulated decreased wildfire frequency from ~15-12 ka followed by increased wildfire frequency from ~12-10 ka as simulated vegetation biomass increases to near modern levels. Improving our understanding of these climate-wildfire-vegetation interactions will contribute to interpretations of paleorecords and projections of potential future changes in vegetation and wildfire regimes for the PNW.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2020
- Bibcode:
- 2020AGUFMPP0470006S
- Keywords:
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- 0473 Paleoclimatology and paleoceanography;
- BIOGEOSCIENCES;
- 1630 Impacts of global change;
- GLOBAL CHANGE;
- 4307 Methods;
- NATURAL HAZARDS;
- 4313 Extreme events;
- NATURAL HAZARDS