2017 Fall Alaska Fire Science Workshop Fairbanks, AK

Alaskan tundra fires in a time of rapid climate change

Dan Mann1, Carson Baughman2, Ben Gaglioti3, Ben Jones2

1 Geosciences Department, University of Alaska2 US Geological Survey3 Lamont-Doherty Earth Observatory, Columbia University

NATURE (2015)

Arctic and Subarcticcontain ½ of all soil carbon worldwide1035 +- 150 Pg of C

(1 Pg = 1 billion tons)

ArcticOcean

GreenlandIce Sheet

Some of this high-latitude organic C is stored in tundra.

The tundra biome covers 11.5 million km2.

Tundra fires can contribute to global warming.

tundra fires release:

CO2

CH4

N2Oblack carbon

Forster et al (2007). IPCC. Chapter 2

annual area of tundra burned in Alaskacorrelates with climate

Frontiers Ecology Environment (2015)thresholds

Climate is changing (warmer and drier)

McAfee et al (2013) JGR-A

Key Uncertainties re tundra fire regimes

1) Fire frequency: Is it actually increasing?

2) Global effects: How does fire affect the trace-gas budget of tundra?

ARF

Mack et al (2011) SI material

3) Impacts on permafrost and geomorphology

4) Post-fire responses of biota

1) Tundra fire frequency: Is it increasing?

lake inside ANAK Fire lake outside ANAK FireChipman et al (2015) Biogeosciences

area of Anak. River Fire last burned 7000 years ago

threshold signifying a fire was determined for boreal forest fires

Rocha et al

(despite long fire-return interval suggested by existing lake-charcoal records)….

observational records suggest fire frequency isincreasing

fire

em

issi

on

s (T

gC

/yr)

On the other hand…..34 experts feel major increase in

burning of circumboreal tundra is unlikely.

Environmental Research Letters (2016)

On the other hand …. fire history of North Slope is more complex than previously thought.

Ben Jones keeps finding new fire scars.

1) Is tundra fire frequency increasing?

maybe

2) Global effects: How do fires affect the trace-gas

budget of tundra?

2013 Kucher Creek fire

trace-gas budgets

CO2CO2

How much? How fast? How does sequestration compare to release during fires?

without fire, organic C accumulates at many tundra sites

Jason Stuckey, Toolik Field Station

Mack et al (2011)

NATURE

Anaktuvuk River fire, 2007

Jason Stuckey, Toolik Field Station

Mack et al (2011)

NATURE

“

“

1 teragram = 1 trillion grams

Mack et al (2011) NATURE

“(The Anaktuvuk River fire) released….an amount of carbon similar in magnitude to the annual net C sink for the entire Arctic tundra biome….”

“(The Anaktuvuk River fire) released….an amount of carbon similar in magnitude to the annual net C sink for the entire Arctic tundra biome….”

accumulated in just 50 years

2.1 Tg C fire-1 versus 3-4 Tg C yr-1

1 teragram = 1 trillion grams

ARF burned just 1000 km2 of a biome covering 11.5 million km2.

2% of all the C sequestered in the tundra biome accumulates in the 1000 km2 area of the Anaktuvuk River Fire every year (!?)

Eriphorum grows fast, but not that fast.

2) Global effects of tundra fires remain uncertain

3) Impacts on permafrost and geomorphology

Doubling in micro-topographic relief in burn areas;340% increase in yedoma terrain…. LIDAR data.

Burning of vegetation and organic matter trigger rapid deepening of active layer

Increased ground heat flux causes rapid deepening of active layers

Noatak valley

thermokarst detachment slidesafter Anaktuvuk River fire

3) Impacts on permafrost and geomorphology

3) Impacts on permafrost and geomorphology

Could widespread tundra fires trigger an ecological regime shift?

dreaded shrubbery invasion?

4) Post-fire responses of biota?

Eriophorum vaginatum:superbly fire-adapted

Anaktuvuk River Fire2017 Site Visits

But….severe burning causes widespread establishment of grass and shrubs (and other things)

severe burn; white spruce invades

moderate severity; shrub recovery,no spruce

treeline expansion after a ca. 1920 fire in Noatak valley

Uncertainties about tundra fire regimes

1) Fire frequency: Is it increasing?

2) Global effects: How does burning affect trace gases?

3) Impacts on permafrost and geomorphology

4) Post-fire responses of biota

What we are up to inour JFSP project

Ben Jones: locating more old burns &quantifying geomorphic changes

Ben Gaglioti: improving/expanding the lake-charcoal record of tundra fires

Carson Baughman: ecologicalconsequences of burning

Acknowledgements

University of Alaska Fairbanks

Bureau of Land Management

Joint Fire Sciences Program

total C fixed in circumboreal tundra biome per year = 100 kg

C released from Anak River Fire in 2007 = 100 kg

accumulation of C in area of Anak River Fire AD 1957-2007 = 100 kg

accumulation of C in area of Anak River fire per year = 100 kg / 50 yr = 2 kg /yr

Annual C accumulation in area of Anak River Fire as % of total C fixed in tundra biome every

year = (2 kg/yr / 100 kg/yr) = 2%

these samples could be >>> AD 1950

http://www2.ocean.washington.edu/oc540/lec01-27/

Organic C of mixed ages?

Mack et al (2011)

of tree rings

most tussocks not so deeply buried in organics

Were C stocks overestimated ?

Tundra burning leaves subtle charcoal records

lake-sediment records of charcoal

grand lightning-strike transect of lake-charcoal records

Alaska Fire Service - BLM