Disclaimer ThispaperisoneofaseriesofFAOdocumentsonforestrelatedhealthandbiosecurityissues.The purposeofthesepapersistoprovideearlyinformationaboutongoingactivitiesandprogrammes, andtostimulatediscussion. Thedesignationsemployedandthepresentationofmaterialinthisinformationproductdonotimply theexpressionofanyopinionwhatsoeveronthepartoftheFoodandAgricultureOrganizationofthe UnitedNations(FAO)concerningthelegalstatusofanycountry,territory,cityorareaorofits authorities,orconcerningthedelimitationofitsfrontiersorboundaries.Thementionofspecific companiesorproductsofmanufacturers,whetherornotthesehavebeenpatented,doesnotimply thatthesehavebeenendorsedorrecommendedbyFAOinpreferencetoothersofasimilarnature thatarenotmentioned. Commentsandfeedbackarewelcome. Forfurtherinformation,pleasecontact: GillianAllard ForestryOfficer(ForestProtectionandHealth) ForestAssessment,ManagementandConservationDivision ForestryDepartment FAO VialedelleTermediCaracalla 00153Rome,Italy Tel:+390657053373 Email:[email protected] Acknowledgements TheauthorswouldliketothankFAOForestryDepartmentpersonnel,NoraBerrahmouni,JimCarle, ThomasHofer,DougMcGuireandPietervanLierop,forreviewingthisdocumentandproviding valuablecomments,andRobertoCenciarelliandTulliaBaldassarriHögervonHögersthalforthe designandlayout. Coverphotos: Lightningstrikes,Canberra,Australia(flickr/PRESCOTT) Deadvegetationindroughtstrickenarea,Senegal(FAO/CH.ERRATH/12787) Chile’sLonquimayVolcanoerupting(FAO/R.GRISOLIA/21843) Icecoverstreesandpowerlinesafteramajorstorm,Canada(B.MOORE) Floodedforest,Hungary(FAO/M.KERESZTES/FO6082) ©FAO2011 ForestHealthandBiosecurityWorkingPapers Abioticdisturbancesandtheirinfluenceonforesthealth Areview BeverlyA.MooreandGillianAllard 2011 ForestAssessment,Managementand ConservationDivision WorkingPaperFBS/35EFAO,Rome, ForestryDepartment Italy Contents Foreword...................................................................................................................................iv EXECUTIVESUMMARY....................................................................................................................1 INTRODUCTION.............................................................................................................................3 METEOROLOGICALEVENTS..............................................................................................................6 Cyclones(synonymshurricanesandtyphoons)..................................................................6 Storms(wind,snow,ice,hail,dustandsand)...................................................................11 Tornadoes...........................................................................................................................14 Thunderstormsandlightning.............................................................................................16 CLIMATOLOGICALEVENTS.............................................................................................................1 Drought...............................................................................................................................17 HYDROLOGICALEVENTS................................................................................................................19 Floodsandflashfloods.......................................................................................................19 Avalanches..........................................................................................................................20 Landslidesandmudslides..................................................................................................22 GEOPHYSICALEVENTS..................................................................................................................24 Tsunamis.............................................................................................................................24 Earthquakes........................................................................................................................25 Volcaniceruptions..............................................................................................................26 ANTHROPOGENICEVENTS.............................................................................................................29 Fire......................................................................................................................................29 Oilspills...............................................................................................................................31 Airpollution........................................................................................................................32 Radioactivecontamination................................................................................................34 CONCLUSIONS.............................................................................................................................36 References...............................................................................................................................37 iii Foreword TheUnitedNationsdeclared2011tobetheInternationalYearofForestswhichaimstoincrease publicawarenessofforests’importantecological,economicalandsocialfunctions.Forestsprovide shelterforpeopleandhabitattobiodiversity.Theyareasourceoffood,medicineandcleanwater andplayavitalroleinmaintainingastableglobalclimateandenvironment.Withsuchimmeasurable values,protectingtheworld’sforestsfromdevastatingdisturbancesiscrucial. Disturbancesareanaturalandintegralpartofforestecosystems.Whentheyexceedtheirnormal rangeofvariation,however,theimpactsonforestscanbeextremeaffectingentirelandscapes, causinglargescaletreemortalityandcompletedestructionofundergrowthandsoils.Globalclimate changeisexacerbatingmanyoftheseimpactsbymakingforestsmorepronetodamagebyaltering thefrequency,intensityandtimingofsomeeventssuchascyclones,landslides,insectanddisease outbreaks,andheatwavesanddroughtswhichincreasetheriskoflargescalefires. Muchmoreinformationisavailableontheimpactsofbioticdisturbances,suchaspestoutbreaks,on foreststhanontheimpactsofabioticdisturbances,thosecausedbynonlivingfactorssuchasstorms, droughtandtsunamis.FAO’sGlobalForestResourcesAssessment(FRA),carriedoutatfiveyear intervals,providesthedataandinformationneededtosupportpolicies,decisionsandnegotiationsin allmatterswhereforestsandforestryplayapart.Forthefirsttimeever,countrieswereaskedto reportontheareaofforestdamagedbyabioticdisturbancesforFRA2010.Informationprovidedwas sparse,mostlyqualitativeanddidnotallowforanytrendanalysis.Tosupplementtheinformationin FRA2010,andinacknowledgementoftheincreasingimportanceofabioticinfluencesonforest health,FAOpreparedthismoredetailedstudy. Abioticdisturbancesareexpectedtoincreaseinintensity,quantityandfrequency.Adaptiveforest managementisthereforeessentialtoprotecttheworld’sforestsresources.Effectivemanagement practicesandpoliciesarebuiltuponrelevantandtimelyinformationandaccuratedataon disturbancesandtheirimpactsonforests.Thispaperisafirststepinsynthesizingsuchinformationto assistwiththemanagementandprotectionofforesthealth.Takingcareoftheworld’sforestsand effectivelymanagingthemnotonlyensuresthattheymeettheirobjectivesbutalsoreducestherisk ofdamagefromfutureabioticdisturbancesandaddressesglobalclimatechangeconcerns. JoseAntonioPrado Director,ForestAssessment,Management andConservationDivision FAOForestryDepartment iv EXECUTIVESUMMARY Abioticdisturbances,disturbancescausedbynonlivingfactors,areanaturalandintegralpartof forestecosystemsthathavemajorimpacts,positiveandnegative.Theyinfluenceforeststructure, compositionandfunctioningandcanbeimportantformaintainingbiologicaldiversityandfacilitating regeneration.Whendisturbancesexceedtheirnormalrangeofvariation,however,theimpactson forestscanbeextremeaffectingentirelandscapes,causinglargescaletreemortalityandcomplete destructionofundergrowthandsoils.Globalclimatechangeisexacerbatingmanyoftheseimpactsby makingforestsmorepronetodamagebyalteringthefrequency,intensityandtimingofsomeevents suchascyclones,storms,landslides,insectanddiseaseoutbreaks,andheatwavesanddroughts whichincreasetheriskoflargescalefires. Thispaperreviewsthecurrentknowledgeontheimpactsofabioticdisturbances.Eventsare discussedwithinfivecategories: Meteorological–cyclones,storms(wind,snow,iceandhail,dustandsand),tornadoes,and thunderstormsandlightning; Climatological–drought; Hydrological–floodsandflashfloods,avalanches,landslidesandmudslides; Geophysical–tsunamis,earthquakesandvolcaniceruptions; Anthropogenic1–fire,oilspills,airpollutionandradioactivecontamination. Almost4000abioticdisturbanceeventsoccurredfrom2000to2009,killingoveronemillionpeople, impactingover2.5billionpeopleandcostingalmostatrillionUSdollars(overUS$971billion)(IFRC andRCS,2010).Whileconsiderableinformationmayexistonindividualevents,oftenlittle informationisreadilyavailableonthespecificimpactsofaneventonforests.Globalreportingon suchimpacts,particularlyquantitativeinformationonareasaffected,islowandsporadic.Thedata thatisavailablehowever,indicatesthesignificance,magnitudeandseverityofabioticdisturbances. Forexample,abioticfactorsdamaged1.2millionhectaresofforestinSwedenin2005.The majorityofthedamageoccurredasaresultofamajorstormthatcausedseverewindthrowinthe southofthecountry. TropicalCycloneSidrhitBangladeshin2007affectingapproximately8.7millionpeople(FAO,2008) anddamagednearly1.5millionhousesand4.1milliontrees.Approximately20000–25000 hectaresoftheSundarbanmangroveforests,aUNESCOWorldHeritageSite,incurredsevere