Arctic tundra fires: natural variability and responses to climate change

Hu, Feng Sheng; Higuera, Philip E.; Duffy, Paul; Chipman, M. L.; Rocha, A. V.; Young, Adam M.; Kelly, Ryan; Dietze, Michael C.

doi:10.1890/150063

Cited by 152 publications

(153 citation statements)

References 57 publications

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“…Our results indicate that regions characterized by warmer and drier climates support both burnable biomass and frequent fire‐conducive weather conditions necessary for fuel drying, ignition, and fire spread. The importance of summer warmth and moisture availability is consistent with annual‐scale models from both boreal forest (Duffy et al , Balshi et al ) and tundra ecosystems (Hu et al , ), which highlight warmer and drier summer conditions as key determinants of annual flammability. This congruence in the importance of summer climate at annual and multi‐decadal timescales suggests that both Alaskan tundra and boreal forest are characterized by climate‐ rather than fuel‐limited fire regimes.…”

Section: Discussionsupporting

confidence: 76%

Climatic thresholds shape northern high‐latitude fire regimes and imply vulnerability to future climate change

Young

Higuera

Duffy³

et al. 2016

Ecography

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Boreal forests and arctic tundra cover 33% of global land area and store an estimated 50% of total soil carbon. Because wildfire is a key driver of terrestrial carbon cycling, increasing fire activity in these ecosystems would likely have global implications. To anticipate potential spatiotemporal variability in fire‐regime shifts, we modeled the spatially explicit 30‐yr probability of fire occurrence as a function of climate and landscape features (i.e. vegetation and topography) across Alaska. Boosted regression tree (BRT) models captured the spatial distribution of fire across boreal forest and tundra ecoregions (AUC from 0.63–0.78 and Pearson correlations between predicted and observed data from 0.54–0.71), highlighting summer temperature and annual moisture availability as the most influential controls of historical fire regimes. Modeled fire–climate relationships revealed distinct thresholds to fire occurrence, with a nonlinear increase in the probability of fire above an average July temperature of 13.4°C and below an annual moisture availability (i.e. P‐PET) of approximately 150 mm. To anticipate potential fire‐regime responses to 21st‐century climate change, we informed our BRTs with Coupled Model Intercomparison Project Phase 5 climate projections under the RCP 6.0 scenario. Based on these projected climatic changes alone (i.e. not accounting for potential changes in vegetation), our results suggest an increasing probability of wildfire in Alaskan boreal forest and tundra ecosystems, but of varying magnitude across space and throughout the 21st century. Regions with historically low flammability, including tundra and the forest–tundra boundary, are particularly vulnerable to climatically induced changes in fire activity, with up to a fourfold increase in the 30‐yr probability of fire occurrence by 2100. Our results underscore the climatic potential for novel fire regimes to develop in these ecosystems, relative to the past 6000–35 000 yr, and spatial variability in the vulnerability of wildfire regimes and associated ecological processes to 21st‐century climate change.

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Section: Discussionsupporting

confidence: 76%

Climatic thresholds shape northern high‐latitude fire regimes and imply vulnerability to future climate change

Young

Higuera

Duffy³

et al. 2016

Ecography

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170

149

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“…Wildfire is a dominant disturbance type in the boreal forest (Kasischke & Turetsky, 2006), but until recently, it has been relatively rare in Arctic tundra because of cold and wet conditions. Increased temperature and evapotranspiration have increased tundra fire in some regions Hu et al, 2015Hu et al, , 2010Rocha et al, 2012;Turetsky et al, 2011), and by the end of the century, tundra wildfire frequency and extent are projected to increase by 60% to 480% (Abbott et al, 2016;Flannigan et al, 2009;Kloster et al, 2012). Wildfire in the permafrost zone can dramatically alter fundamental ecosystem properties, such as surface albedo, plant community composition, net primary productivity, nutrient cycling, and lateral export (Goetz et al, 2005;Larouche et al, 2015;Loranty et al, 2018;Mack et al, 2011).…”

Section: Introductionmentioning

confidence: 99%

Plant Uptake Offsets Silica Release From a Large Arctic Tundra Wildfire

2019

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Rapid climate change at high latitudes is projected to increase wildfire extent in tundra ecosystems by up to fivefold by the end of the century. Tundra wildfire could alter terrestrial silica (SiO 2 ) cycling by restructuring surface vegetation and by deepening the seasonally thawed active layer. These changes could influence the availability of silica in terrestrial permafrost ecosystems and alter lateral exports to downstream marine waters, where silica is often a limiting nutrient. In this context, we investigated the effects of the largest Arctic tundra fire in recent times on plant and peat amorphous silica content and dissolved silica concentration in streams. Ten years after the fire, vegetation in burned areas had 73% more silica in aboveground biomass compared to adjacent, unburned areas. This increase in plant silica was attributable to significantly higher plant silica concentration in bryophytes and increased prevalence of silica-rich gramminoids in burned areas. Tundra fire redistributed peat silica, with burned areas containing significantly higher amorphous silica concentrations in the O-layer, but 29% less silica in peat overall due to shallower peat depth post burn. Despite these dramatic differences in terrestrial silica dynamics, dissolved silica concentration in tributaries draining burned catchments did not differ from unburned catchments, potentially due to the increased uptake by terrestrial vegetation. Together, these results suggest that tundra wildfire enhances terrestrial availability of silica via permafrost degradation and associated weathering, but that changes in lateral silica export may depend on vegetation uptake during the first decade of postwildfire succession. Plain Language SummaryClimate change in the Arctic is leading to more frequent and severe wildfire in Arctic tundra ecosystems. Studying the silica (SiO2) cycle in Arctic ecosystems is important because the amount of silica exported from land to sea can control uptake by marine primary producers in Arctic coastal waters. We investigated how tundra wildfire affects silica cycling by returning to a large Arctic wildfire 10 years after the burn to collect samples of stream water, vegetation, and peat. We found that plants growing on burned landscapes contained 73% more silica in their aboveground biomass compared to unburned areas nearby. While the fire thawed permafrost underneath it, we did not observe increased levels of silica in streams draining burned areas. This pattern indicates that elevated rates of silica uptake via plants may prevent increased silica export to marine waters following tundra wildfire. We conclude that the effect of tundra fire on silica cycling depends on the recovery trajectories of terrestrial and aquatic ecosystems in the Arctic.

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“…The 2007 Anaktuvuk River fire burned more than 1,000 km 2 of moist acidic tussock tundra on the North Slope of Alaska (Bowman et al 2009, Jones et al 2009), releasing about 2.1 Tg C into the atmosphere and volatilizing an amount of nitrogen (N) equal to about 400 years of N accumulation (assuming steady-state dynamics; Mack et al 2011). 1; Rocha et al 2012, Hu et al 2015; data available online). 1; Rocha et al 2012, Hu et al 2015; data available online).…”

Section: Introductionmentioning

confidence: 99%

Modeling long‐term changes in tundra carbon balance following wildfire, climate change, and potential nutrient addition

Jiang

Rastetter

Shaver

et al. 2016

Ecological Applications

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To investigate the underlying mechanisms that control long-term recovery of tundra carbon (C) and nutrients after fire, we employed the Multiple Element Limitation (MEL) model to simulate 200-yr post-fire changes in the biogeochemistry of three sites along a burn severity gradient in response to increases in air temperature, CO concentration, nitrogen (N) deposition, and phosphorus (P) weathering rates. The simulations were conducted for severely burned, moderately burned, and unburned arctic tundra. Our simulations indicated that recovery of C balance after fire was mainly determined by the internal redistribution of nutrients among ecosystem components (controlled by air temperature), rather than the supply of nutrients from external sources (e.g., nitrogen deposition and fixation, phosphorus weathering). Increases in air temperature and atmospheric CO concentration resulted in (1) a net transfer of nutrient from soil organic matter to vegetation and (2) higher C : nutrient ratios in vegetation and soil organic matter. These changes led to gains in vegetation biomass C but net losses in soil organic C stocks. Under a warming climate, nutrients lost in wildfire were difficult to recover because the warming-induced acceleration in nutrient cycles caused further net nutrient loss from the system through leaching. In both burned and unburned tundra, the warming-caused acceleration in nutrient cycles and increases in ecosystem C stocks were eventually constrained by increases in soil C : nutrient ratios, which increased microbial retention of plant-available nutrients in the soil. Accelerated nutrient turnover, loss of C, and increasing soil temperatures will likely result in vegetation changes, which further regulate the long-term biogeochemical succession. Our analysis should help in the assessment of tundra C budgets and of the recovery of biogeochemical function following fire, which is in turn necessary for the maintenance of wildlife habitat and tundra vegetation.

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Arctic tundra fires: natural variability and responses to climate change

Cited by 152 publications

References 57 publications

Climatic thresholds shape northern high‐latitude fire regimes and imply vulnerability to future climate change

Climatic thresholds shape northern high‐latitude fire regimes and imply vulnerability to future climate change

Plant Uptake Offsets Silica Release From a Large Arctic Tundra Wildfire

Modeling long‐term changes in tundra carbon balance following wildfire, climate change, and potential nutrient addition

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