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Climatic change
warmer temperatures
more severe and extended droughts
Mature trees buffer against
effects of warmer climate,
temporal scale associated
with species longevity.
Fire resets
succession,
temporal scale
associated with fire
rotation.
Habitat changes
Broad-scale homogeneity
Truncated succession
Loss of forest cover
Loss of reugia
Fire-adapted species
New fire regimes
More frequent fire
More extreme events
Greater area burned
e disturbance pathway is quicker
Species responses
Fire-sensitive species
Annuals & weedy species
Specialists with restricted ranges
Deciduous and sprouting species
FIGURE 8.3 Conceptual.model.of.the.relative.time.scales.for.disturbance.versus.climatic.
change.alone.to.alter.ecosystems..Times.are.approximate..The.focus.here.is.on.ire,.but.much.
of.the.same.logic.applies.to.insect.outbreaks..(Adapted.from.McKenzie,.D.,.Z..Gedalof,.D.L..
Peterson,. and. P.. Mote.. 2004.. Climatic. change,. wildire,. and. conservation.. Conservation
Biology .18:890-902.).
variability.and.change.on.the.areal.extent.and.broad-scale.spatial.patterns.of.two.key.
disturbance.processes:.wildire.and.insect.outbreaks,.particularly.of.MPB.
Westwide.we.have.linked.wildire.to.climatic.variability.via.studies.of.Holocene.
charcoal.and.pollen.sediments.(Anderson.et.al..2008),.dendrochronological.recon-
structions. of. forest. ire. histories,. stand. ages,. and. climate. patterns. (e.g.,. Margolis.
et. al.. 2007),. and. statistical. models. using. twentieth-century. instrumental. records.
(McKenzie. et. al.. 2004. and. references. therein).. WMI. convened. 75. tree-ring. and.
charcoal.specialists.for.a.2005.workshop.on.Fire.History.and.Climate.Synthesis.in.
Western.North.America,.leading.to.special.symposia.at.two.international.scientiic.
meetings;.subsequent.research.papers.compose.a.special.issue.of.the. International
Journal of Wildland Fire .(Swetnam.and.Anderson.2008).
WMI.research.has.provided.important.paleoecological.context.on.late.Pleistocene.
and. Holocene. ire. regimes. in. relation. to. both. climatic. variability. and. patterns. of.
dominant.vegetation.(e.g.,.Anderson.et.al..2008;.Prichard.et.al..2009)..Synchronous.
changes.in.ire.occurrence.and.species.composition.suggest.the.central.role.of.dis-
turbance.in.structuring.forest.vegetation..Using.historical.ire-scar.records.from.sites.
ranging. from. northern. New. Mexico. to. eastern. Washington,. we. have. documented.
the.overarching.control.of.climate,.particularly.drought,.on.ire.when.examined.at.
broad.scales.(Hessl.et.al..2004;.Margolis.et.al..2007),.in.contrast.with.the.ine-scale.
controls.of.fuels.and.topography.(McKenzie.et.al..2006;.Kellogg.et.al..2008)..In.the.
southern.Rocky.Mountains,.we.have.combined.charcoal.sediment.and.tree-ring.ire.
scar.data.to.document.the.effects.of.climate.and.land.use.histories.on.overlapping.
Holocene.and.historical.ire.regimes.(Allen.et.al..2008).
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