計劃焚燒澳大利亞的森林：事實.pdf

1、Prescribed burning Australias forests:the factsNeil BurrowsForestry Australia 2024 Fire SummitPrescribed burningThe introduction of fire to a defined area,under specific environmental conditions,to achieve a desired outcome.Fire at a time and place of our choosing.Fuelreduction is a common desired o

2、utcome.Prescribed burning:Strategic overview Primacy of life Integral to land management Land managers responsibility Legal,policy and moral obligations Underpinned by science Risk-based Adaptive plan,do,check Resources Partnerships Political and community supportPrescribed burning for fuel reductio

3、nTo reduce the intensity of bushfires and the size of bushfiresProxies for losses,damages and costsFirefighter safetyFire intensity a key factor in risk-based frameworksReluctant to use measures such as loss of life and house loss as KPIsOther factors outside the jurisdiction of public land managers

4、 Where and how people liveCommunity preparedness,responseFuel on private property and other landBushfire risk managementInternal stakeholders Conservation&ecosystems Parks and Visitors Conservation scienceExternal stakeholders Aboriginal cultural heritage Industry Land holders Brigades,DFES,LGAsPres

5、cribed burn programDistrict programRegional programState programConstraintsPrescribed burn implementation-overviewBurn boundary track prep.Burn security edging,raking etc.Signage,notifications,smoke alertsMonitor weatherAssemble resourcesBriefings and safety checksIntroduce fireMonitor fire behaviou

6、rMop up and patrolPost-burn assessmentPrescribed burning assists firefightersReduces fire intensity,speed,flame size and spottingSafer environment for firefighters Options for suppression strategiesAnchor points and tie-in opportunitiesBuys timePrioritise fire complexesEnhances effectiveness of aeri

7、al suppression,fuel reduced buffers etc.Controversial Claims about prescribed burning:100+years agoPoor soils-Aboriginal burningDamages timber valuesPrevention and suppression 50 years ago Causes extinctions Prevention and suppression TodayCauses extinctionsCreates a fire hazardIt doesnt work Forest

8、s can“look after themselves”.Prevention and suppressionThese claims dont accord with the facts Prescribed burning is the cornerstone of an integrated bushfire mitigation system.The Mercure Family from survived the firestorm.Photo:John WoudstraImage result for quokka northcliffe fireFact Fire is a na

9、tural environmental factorClimate,vegetation,ignition,firePre-human occupation-lightningAboriginal people used fire“This continent of smoke”.Capt.James Cook(1770)Evolution of physical and behavioural adaptationsNo extinctions due to prescribed burningLarge,high intensity fires threaten biodiversityF

10、act European settlement disrupted traditional Noongar burning practices Noongar burning vs prescribed burning.Similarities and differencesEarly foresters adopted fire exclusion policy Fuels accumulated resulting in severe bushfires 1932-1961 the big bushfire era.1961 bushfires Royal Commission expan

11、d the prescribed burning programFact Post-colonial fire exclusion policy failed.“When fire control was wrested from the Aborigines and placed in the hands of Europeans,disaster resulted”(Flannery 2002).A new policy emerged:Integrated system prescribed burning the cornerstone.High priorityExpansion o

12、f bushfire science-fire behaviour and prescribed burning guides,fire ecology,aerial ignition.Expansion of capacity equipment,people,training,etc.New systems and structures Aerial detection(spotters)FactDead fine fuel(DFF)is the driver of bushfire Mostly in surface and near surface fuel layersFuel lo

13、ad increases with time,then plateausDFF is 90%of total fuel loadUnderstorey hazard increases with time then declinesUnderstorey contributes 10%to fuel loadFire cannot sustain spread without DFF0123456781-5 5-1010-2020-3030-4040-6060+Understorey Hazard IndexFuel age class(yrs)FuelA:12yr rotation(8%PB

14、 per annum)B:Fire exclusion60+yo fuelsLoad t/ha45%of region 1855%of region 18-35100%of region 50Underst.Hazard45%of region 3.555%of region 3.5-6.5100%of region 4.5Fuel loads and understorey hazard indices in karri forests for a A)prescribed burn program that aims to maintain 45%of the region with 6y

15、o fuels,and B)fire exclusion.Fuel load and fire behaviourROS McArthur(1972)&WA Red Book direct relationship Burrows(1994)no relationship Vesta 1(Cheney et al.2012)-weak relationship Vesta 2(Cruz et al.2022)diminishes with increasing FDRIntensity,flame size,spotting I=HWR(Byram 1959)Direct relationsh

16、ip with flame depth,length.Heavy fuels promote high intensity fires,facilitating long range spotting and PyroCb events FactInverse relationshipLeft side of graph is messy as interactions between area burnt by wildfire45%of the region carrying 6yo fuels aids firefightersFactSignificant benefits of PB

17、 including reducing:Loss of human life and traumaHomes destroyedCommunities dislocatedInfrastructure and industries damagedMortality and injury to wildlifeHarm to environmental and conservation valuesDamage and suppression costs Firefighter experience and training Forest health benefitsAfter Florec

18、et al.(2016)05010015020025030005101520Cost($Millions/annum)Proportion of area prescribed burnt(%)DamagesSuppressionPrescribed burnAnnual trend in area burnt by prescribed fire and wildfire in forests and associated ecosystems in sw WA.Blue line is 8%annual target0100,000200,000300,000400,000500,0006

19、00,0001958/591961/621964/651967/681970/711973/741976/771979/801982/831985/861988/891991/921994/951997/982000/012003/042006/072009/102012/132015/162018/192021/22Area burnt(ha)YearPrescribed fire(ha)Wildfire(ha)Prescribed burning&climate changeYang et al.2014Canadell et al.2021 Globally,downward trend

20、 in area of bushfire Australian forests:upward trend in area of bushfire Drivers climate change and associated extreme weather events fuel management Will the climate change back?When?Multi-scale fuel management is more critical now than everAcknowledgmentsSome data,photos,maps and information used in this presentation were provided by Fire Management Services WA Parks and Wildlife and the Bushfire Front