Modeling the effects of forest succession on fire behavior potential in southeastern British Columbia

S.W. Taylor, G.J. Baxter and B.C. Hawkes

Natural Resources CanadaCanadian Forest Service

Historical Background

• dry forests in western North America were historically exposed to high-frequency,

low- intensity fire regimes

• favoring the development of grasslands and open stands of fire-tolerant tree species: ponderosa pine, Douglas-fir, western larch

• fire suppression, logging and forest grazing have resulted in forest in-growth and

expansion

Rocky MountainTrench

1900s

1990s

B.C. Government photos

19521952 19921992

Issues

• loss of habitat for some wildlife species

• reduction in forest grazing

• decline in forest health

• increased potential for catastrophic crown fires

0 200 400 600 800 1000 1200

Temperature (C)

0

5

10

15

20

Height Above Flame (m)

12

34

5

Temperatures above flame front by fire intensity class

Heat Transfer

h

IT 3/29.3

0 2000 4000 6000 8000 10000

Critical surface fire intensity (kW/m)

0

5

10

15Crown Base Height (m)

Crown Fire Initiation

*Foliar moisture content = 100%

Crown fire

Surface fire

2

3

4

6

5

Crown fire threshold by fire intensity class

few planning tools to guide ecosystem restoration and fuels management programs

need to develop techniques to project future change and effects of management practises

Rationale

Objectives

Develop methods to assess historical change and project future change in:

• forest cover

• fuel conditions

• fire behavior potential

Study areas

Methods

crown closure, fuel type, terrain classification map historic and contemporary air photos sample stand characteristics stand projection using PROGNOSIS growth model fire weather climatology and fire behavior normals determine fire behavior potential over time

CoverClass

Description CrownClosure (% )

FBP System Fuel Type

0 Grassland 0-5 O-1b Standing deadgrass

1 Treedgrassland

6-15 O-1b Standing deadgrass

2 Openforest

16-40 C-7 Ponderosa pineDouglas-fir

3 Closedforest

40-55 C-3 Mature jack orlodgepole pine

4 Denseforest

> 55 C-4 Immature jack orlodgepole pine

Forest and fuel type classification

DBH

0

50

100

SPH

13 10 15 20 25 30 35 45 55

0 - 5 %

DBH

0

50

100

SPH

13 10 15 20 25 30 35 40 45 50

16 - 40 %

DBH

0

50

100

SPH

13 10 15 20 25 30 35 40 45 50 55

> 55 %

DBH

0

50

100

SPH

13 10 15 20 25 30 35 40 45 50

6 - 15 %

DBH

0

50

100

SPH

13 10 15 20 25 30 35 40 45 50 55

41 - 55 %

Douglas-firPonderosa pineLodgepole pineWestern larchTrembling aspen

Stand description

Stand projection

1990 2000 2010 2020 2030 2040

Year

0

20

40

60

80

100

Percent Cover

O1234

Crown closure class

Cover Class (ha)

0 1 2 3 4

FBP System Fuel Type (ha)

Year O-1b O-1b C-7 C-3 C-4

1952 7 055 8 274 9 128 2 602 2 040

1992 3 083 3 840 9 879 5 274 4 804

2032 0 0 3 095 4 791 18 991

Inventory projection

J F M A M J J A S O N D

MONTH

-20

-10

0

10

20

30

Tem

pera

ture

(C

)

0

20

40

60

80

100

Pre

cip

itati

on

(m

m)

CRANBROOK A Elev 939 m

{22 yrs of observations}

Mean annual temp 5.6 C

Absolute maximum 36.6 C

Mean daily max of the hottest month 25.7 C

Mean annual precip 384 mm

Mean daily min of the coldest month -12.9 C

Absolute minimum 25.7 C

Climatology

FBP System Crown-fraction-burned (% )

Fuel type < 10 10-50 >50

0-1b 100 0 0

C-7 89 4 7

C-3 75 5 20

C-4 39 9 52

Fire behavior normals

* level ground

< 10 10 - 50 > 500

20

40

60

80

100

Percent

1952

Normal fire seasoncrown fraction burned class frequencies

< 10 10 - 50 > 500

20

40

60

80

100

Percent

1992

< 10 10 - 50 > 500

20

40

60

80

100

Percent

2032

Fire behavior projection

Normal fire seasonfire intensity class frequencies

1 2 3 4 5 60

10

20

30

40

Percent

1952

1 2 3 4 5 60

10

20

30

40

Percent

1992

1 2 3 4 5 60

10

20

30

40

Percent

2032

Fire behavior projection

Results

Grassland and open forest • decreased by 50% during 1952-92• will be eliminated by 2036 without

management

Area of closed forest doubled during 1952-92

Area susceptible to crown fire with >50% CFB

• increased from 7 to 14% during 1956-96• projected to increase to 29% by 2032

* Results are preliminary - regeneration model needs calibration

• dynamic fuel and fire behavior models

• integrate fire behavior and ignition potential in more sophisticated risk measures

• quantify preparedness and control costs associated with fire risk

• further develop fuel management planning tools

Research Needs

Fuels Management Planning Tools

Tactical models

• fire behavior and effects • stand projection and simulation

Strategic models

• inventory projection• forest estate • landscape level

Tactical ModelsFire Behavior Prediction SystemSCORCH Tree Mortality Model

Tactical ModelsForest Vegetation Simulator (PROGNOSIS)Fuel Dynamics and Fire Effects Model

FVS Fuel Dynamics and Fire Effects Model Sample Output

Strategic Models

Simulate forest dynamics and management activities on vegetation growing stock and related attributes

fssimWoodstock

Acknowledgements

Funding for this project was provided in part by Forest Renewal British Columbia

We would like to acknowledge the cooperation of:BC Ministry of Forests

Cranbrook Forest District, Nelson Forest Region

BC Parks Okanagan District, Thompson River Dist.

Time for questions ?

Thank you !