Buckle Up: The under-appreciated role of large wildfires in the West Cascades. Daniel Donato Washington DNR & University of Washington May 2018

Transcription

1 Buckle Up: The under-appreciated role of large wildfires in the West Cascades Daniel Donato Washington DNR & University of Washington May 2018

2 Wind Disturbances About the author Old-growth development J. Walstad Insect Volcano M. Simard Fire R. Van Pelt

3 Central Premise Very large fires will visit the west side, sooner or later (climate change or not) (management or not)

4 Eagle Creek Fire ~25,000 acres stand-replacement severity

5 Historic fire regimes Infrequent high severity Moderate frequency mixed severity Frequent low severity FROM: Draft Synthesis of Science to Inform Land Management Within the Northwest Forest Plan Area (January 2017)

6 Life & times of a Doug-fir/hemlock forest ~ years Van Pelt (2007)

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13 Circa year At least 1 million acres burned on the Olympic Peninsula, and 3 to 10 million acres burned in western Washington -Henderson et al. 1989

14 Circa year At least 1 million acres burned on the Olympic Peninsula, and 3 to 10 million acres burned in western Washington -Henderson et al. 1989

15 How big are westside fires?

16 Some background Research Question: How much late-successional habitat should we strive for? Whole landscape? Probably not then what?

17 Wanna know about old-growth in the West Cascades?

18 Wanna know about old-growth in the West Cascades? Gotta know about fire

19 Historic fire regimes Infrequent high severity Moderate frequency mixed severity Frequent low severity FROM: Draft Synthesis of Science to Inform Land Management Within the Northwest Forest Plan Area (January 2017)

20 Life & times of a Doug-fir/hemlock forest ~ years Van Pelt (2007)

21 Approach: model the fires & succession on landscape over time ~ years Van Pelt (2007) Halofsky et al. 2013, 2017

22 West Cascade landscape dynamics Fires 100 Percent of land area Years

23 West Cascade landscape dynamics Fires 100 Percent of land area Years

24 West Cascade landscape dynamics Fires Early-seral 100 Percent of land area Years

25 West Cascade landscape dynamics Fires Early-seral Late-seral 100 Percent of land area Years

26 In the process, we learned something about westside fires

27 A little fire math West Cascades area = 6,000,000 acres Fire rotation = 500 years (time it takes for whole thing to burn)

28 A little fire math West Cascades area = 6,000,000 acres Fire rotation = 500 years (time it takes for whole thing to burn) If one fire per 500 years Fire size =

29 A little fire math West Cascades area = 6,000,000 acres Fire rotation = 500 years (time it takes for whole thing to burn) If one fire per 500 years Fire size = 6,000,000 acres

30 A little fire math West Cascades area = 6,000,000 acres Fire rotation = 500 years (time it takes for whole thing to burn) If 2 fires per 500 years (250-year intervals) Fire size =

31 A little fire math West Cascades area = 6,000,000 acres Fire rotation = 500 years (time it takes for whole thing to burn) If 2 fires per 500 years (250-year intervals) Fire size =

32 A little fire math West Cascades area = 6,000,000 acres Fire rotation = 500 years (time it takes for whole thing to burn) If 2 fires per 500 years (250-year intervals) Fire size = 3,000,000 acres

33 A little fire math West Cascades area = 6,000,000 acres Fire rotation = 500 years (time it takes for whole thing to burn) If 5 fires per 500 years (100-year intervals) Fire size =

34 A little fire math West Cascades area = 6,000,000 acres Fire rotation = 500 years (time it takes for whole thing to burn) If 5 fires per 500 years (100-year intervals) Fire size =

35 A little fire math West Cascades area = 6,000,000 acres Fire rotation = 500 years (time it takes for whole thing to burn) If 5 fires per 500 years (100-year intervals) Fire size = 1,200,000 acres

36 A little fire math West Cascades area = 6,000,000 acres Fire rotation = 500 years (time it takes for whole thing to burn) If 20 fires per 500 years (25-year intervals) Fire size = 300,000 acres

37 Even more math Fire frequency (annual probability) Fire likelihood ,000 1,000,000 1,500,000 2,000,000 Fire size (acres) Power Law of event sizes

38 Even more math Fire frequency (annual probability) Fire likelihood ,000 1,000,000 1,500,000 2,000,000 Fire size (acres) Fire frequency (annual probability) Fire likelihood , ,000 1,000,000 10,000,000 Fire size (acres) Power Law of event sizes

39 Solving for frequency/size

40 Solving for frequency/size

41 100-year flood Solving for frequency/size

42 Solving for frequency/size 100-year event 500-year event

43 Solving for frequency/size Event type (interval) Fire Size (acres) 25-year 50-year 100-year 200-year

44 Solving for frequency/size Event type (interval) Fire Size (acres) 25-year ~27, year ~110, year ~445, year ~1,730,000

45 Solving for frequency/size Event type (interval) Fire Size (acres) 25-year ~27, year ~110,000 Eagle Creek Fire 100-year ~445, year ~1,730,000

46 Results -- Fire Sizes

47 Results -- Fire Sizes Maximum fire/episode sizes (acres) More Fire frequency Less Fire rotation Shorter Longer 1,700,000

48 Results -- Fire Sizes Maximum fire/episode sizes (acres) More Fire frequency Less Fire rotation Shorter Longer 1,700,000 3,500,000 4,700, ,000 1,700,000 2,200, ,000 1,200,000 1,500,000

49 Not the first to suggest this Year ~1700 fire episode: >1 million acres on Olympic Peninsula, 3 to 10 million acres in western Washington (Henderson et al. 1989) 1902 Yacolt complex >1 million acres (Natl. Int. Fire Center [nifc.gov]) 1933 Tillamook burn 350,000 acres (Kemp 1960)

50 Early land surveys Spies et al. in review (summarizing Plummer 1902, etc.)

51 The M.O. of large westside fires Three factors coincide: 1) 2) 3)

52 The M.O. of large westside fires Three factors coincide: 1) Exceptional summer drought (e.g. 2015) 2) 3)

53 The M.O. of large westside fires Three factors coincide: 1) Exceptional summer drought (e.g. 2015) 2) Ignition source 3)

54 The M.O. of large westside fires Three factors coincide: 1) Exceptional summer drought (e.g. 2015) 2) Ignition source 3) Synoptic east wind event

55 The M.O. of large westside fires Three factors coincide: 1) Exceptional summer drought (e.g. 2015) 2) Ignition source 3) Synoptic east wind event hours

56 The M.O. of large westside fires Three factors coincide: 1) Exceptional summer drought (e.g. 2015) 2) Ignition source 3) Synoptic east wind event hours Tillamook Burn: Yacolt Burn: 200,000 acres in 24 hrs 30 miles in 36 hrs

57 The M.O. of large westside fires Three factors coincide: 1) Exceptional summer drought (e.g. 2015) 2) Ignition source 3) Synoptic east wind event hours Tillamook Burn: Yacolt Burn: 200,000 acres in 24 hrs 30 miles in 36 hrs Biscuit Fire

58 What about Fire suppression? Fuels management? Climate change?

59 What about Fire suppression? Ineffective on large events Fuels management? Climate change?

60 What about Fire suppression? Ineffective on large events Fuels management? Climate change? Event type (interval) Fire Size (acres) 25-year 27, year 110, year 440, year 1,700,000

61 What about Fire suppression? Ineffective on large events Fuels management? Climate change?

62 What about Fire suppression? Fuels management? Ineffective on large events Largely irrelevant here Climate change?

63 What about Fire suppression? Fuels management? Climate change? Ineffective on large events Largely irrelevant here Buckle up!

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66 Cascadia Subduction Fires

67 Black Swan Theory: The world is structured by rare, unpredictable, extreme events that can only be rationalized in hindsight

68 One event can direct landscape (and management) for next century

69 Results -- Smaller landscape West Cascades region (2.7 million ha) Landscape (20,000 ha) LSR, timber block, municipal watershed, etc. Percent of land area B E Year of simulation

70 Results -- Smaller landscape West Cascades region (2.7 million ha) Landscape (20,000 ha) LSR, timber block, municipal watershed, etc. Percent of land area B E Year of simulation

71 So What do we do?

72 So What do we do?

73 So What do we do? Big events are part of the system; built-in resilience

74 So What do we do? Big events are part of the system; built-in resilience Climate adaptation management options are few, or ineffective (e.g. fuel management)

75 So What do we do? Big events are part of the system; built-in resilience Climate adaptation management options are few, or ineffective (e.g. fuel management) Fire suppression is a reasonable strategy

76 So What do we do? Big events are part of the system; built-in resilience Climate adaptation management options are few, or ineffective (e.g. fuel management) Fire suppression is a reasonable strategy KEY: Post-disturbance plans in place

77 DRM; oregonhikers.org Thanks