Fire in arctic tundra of Alaska: past fire activity, future fire potential, and significance for land management and ecology

Abstract

A multidecadal analysis of fire in Alaskan Arctic tundra was completed using records from the Alaska Large Fire Database. Tundra vegetation fires are defined by the Circumpolar Arctic Vegetation Map and divided into five tundra ecoregions of Alaska. A detailed review of fire records in these regions is presented, and an analysis of future fire potential was performed based on future climate scenarios. The average size of tundra fire based on the data record is 22 km2 (5454 acres). Fires show a mean size of 10 km2 (2452 acres) and median of 0.064 km2 (16 acres), indicating small fires are common. Although uncommon, 16 fires larger than 300 km2 (74 132 acres) have been recorded across four ecoregions and all five decades. Warmer summers with extended periods of drying are expected to increase fire activity as indicated by fire weather index. The implications of the current fire regime and potential changes in fire regime are discussed in the context of land management and ecosystem services. Current fire management practices and land-use planning in Alaska should be specifically tailored to the tundra region based on the current fire regime and in anticipation of the expected change in fire regime projected with climate change.

Circumpolar spatio-temporal patterns and contributing climatic factors of wildfire activity in the Arctic tundra from 2001–2015

“…During the months preceding a wildfire event, especially between spring to midsummer, surface temperature and soil moisture content were demonstrated to be important climatic factors in determining wildfire occurrence and wildfire intensity. These results are consistent with findings from recent regional studies (French et al 2015, Rocha et al 2012, Veraverbeke et al 2017, Young et al 2017. Our study extends the current state-ofknowledge on tundra wildfire-climate dynamics to a circumpolar level.…”

“…Historically, Arctic tundra ecosystems have experienced limited burning compared to boreal forest ecosystems (Kasischke and Turetsky 2006). In recent years, however, tundra ecosystems have begun experiencing an unexpectedly high frequency of wildfire events (AICC 2014, French et al 2015. The 2007 ARF was a notable tundra fire that doubled the known total area burned since 1950 (Jones et al 2009, Mack et al 2011, where such fire events had been absent or unknown for the past 5000-10 000 years , Hu et al 2010, 2015.…”

“…In 2015, two large wildfires in southwest Alaska burned ∼ 160 km 2 (D'oro 2015). These wildfires are primarily initiated by lightning strikes during thunderstorms (French et al 2015) and scientists have identified strong positive feedback loops among warming climates, increased lightning, and increased fire activities (Veraverbeke et al 2017). A strong climatefire linkage has been found in the tundra regions .…”

“…While few contemporary studies have shed light on the spatio-temporal dynamics of increased wildfire scenarios and fire-climate associations , detailed studies of Arctic wildfire dynamics have been limited to large fire events (e.g. ARF in 2007) and fires in specific geographic regions (French et al 2015, Hu et al 2010, 2015, Kasischke and Turetsky 2006, Rocha and Shaver 2011, Stocks et al 2003, Turetsky et al 2004. Also, fire events in the boreal forest have been studied more rigorously than tundra fires, partly due to the tundra's extreme environmental conditions .…”

Inference of the impact of wildfire on permafrost and active layer thickness in a discontinuous permafrost region using the remotely sensed active layer thickness (ReSALT) algorithm

“…Among terrestrial biomes, tundra and boreal ecosystems underlain by permafrost contain the largest below-ground carbon reservoirs globally [3], and these regions are also significantly impacted by wildfires [4,5]. As air temperatures rise and regional climate changes, wildfires are expected to increase in frequency over the Arctic domain [6,7]. Under favorable environmental conditions, tundra regions are susceptible to burn [8].…”