Thank God, Sylvia Were alive

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Thank God, Sylvia! Were alive!
from the wildland-urban interface
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Altered Vegetation and Disturbance
Patterns Inland Northwest Forests, 1800-2000
Paul F. Hessburg, USDA Forest Service Pacific
Northwest Research Station, Wenatchee, WA
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Diseases
Intentional burning
Many agents interacted to shape vegetation
patterns and their spatio-temporal variation.
Insects
Fires
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Settlement and management activities have altered
spatial patterns of forest structure,
composition, snags, and down wood at patch to
province scales.
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Significant change in fire, insect, and disease
disturbance regimes is directly linked to changes
in forest vegetation patterns at patch to
province scales.
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Management practices and settlement activities
did not take into account the range of spatial
patterns and temporal variations in those
patterns that enable forest ecosystems to
function in the long-term. Spatial patterns
their temporal variations matter!
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Present-Day Forests

• What were the key change agents?
• Domestic livestock grazing
• Timber harvesting, esp. selection cutting
• Road and rail construction
• Grassland conversion to agriculture
• Urban/rural development
• Aggressive fire prevention and suppression

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Lessons from the Interior Columbia Basin
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Inland Northwest Landscapes

• Summary of Key Forest Vegetation Changes
• Area of forests expanded
• Old and new forest area connectivity declined
• Forest area with fire-tolerant, early seral cover
  species, especially ponderosa pine western
  larch declined
• Forest area with late-seral, fire-intolerant
  types, especially Douglas-fir, grand fir, white
  fir increased
• Forest area with grass shrub understories
  declined, that of shade-tolerant conifer
  understories increased
• Forest area with remnant large trees declined
• Forest area with young multi-story patches
  increased
• Tree canopy cover and canopy layers increased

(Hann et al. 1997, Hessburg et al. 1999)
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Dry forests encroached on native grasslands and
meadows.
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Absent frequent burning and influenced by
grazing, PP and DF encroached on nearby meadows
grasslands.
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Ponderosa pine (PIPO) and grassland cover once
dominated.
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OF grasslands lost, young multi-story forest
remains
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Open stands of PP developed dense understories.
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Note the scattered PP overstory dense DF
understory.
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Western white pine (PIMO), ponderosa pine (PIPO),
and western larch (LAOC) cover lost to cutting
and blister rust.
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OF was relatively uncommon (75-150 MFFI), LS more
common. Forest structure is fragmented, patches
are small and numerous.
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Ponderosa pine cover declined while that of
Douglas-fir expanded. Cover type changes not
conspicuous, but
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Old and new forest patches replaced by young
forest patches.
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Topography strongly influenced historical
eastside OF settings.
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Topographically influenced OF were removed by
cutting.
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A contagious moist forest cover type mosaic
became fragmented
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Dominant OF were replaced by new forests after
cutting.
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The pattern of regeneration cutting tells the
story. Historically this watershed was mostly
composed of high quality LSOF habitat.
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Widespread selection cutting of remnant large
trees remaining after historical low and mixed
severity fires precipitated the single greatest
change in the structure of eastside forests.
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Inland Northwest Landscapes

• Related Changes in Disturbance Processes
• in the Dry and Moist Forests
• Grossly elevated fuel loadings
• Increased potential for severe crown fires, fuel
  ladders
• Increased vulnerability to insect and disease
  disturbances, especially--bark beetles,
  defoliators, dwarf mistletoes, and root diseases
• Increased likelihood of severe fire behavior,
  reduced likelihood of control and containment in
  terms of flame length, fireline intensity, fire
  rate of spread
• Increased vulnerability to severe disturbance at
  large spatial scales i.e., there is high
  contagion of vulnerability factors

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More hosts, more canopy layers, higher density,
easier dispersal
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More hosts, more canopy layers, higher density,
easier dispersal
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Dry forest illustration Historical and current
patterns of fuel loading, crown fire potential,
and flame length are related to patterns of
forest structure. Subwatershed 55, Lower Grande
Ronde Subbasin, Blue Mountains
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Severe Fire Behavior Index
Sum of standardized FL, ROS, FLI, CFP scores
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Wet forest illustration Current patterns of
fuel loading, crown fire potential, flame length,
and fireline intensity are related to patterns of
clearcutting. Subwatershed 13, Wenatchee
Subbasin, Northern Cascades The story is the
reverse of the dry forest story.
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• Framing the fire problem
• Much of the increased area in the mixed- and
  high-severity fire regimes developed in dry
  mesic forests (DF, GF, and WF zones), where
  ponderosa pine and western larch were the primary
  early seral species.
• A reasonable beginning point would be to restore
  more natural patterns of forest structure,
  composition, snags, and down wood in these dry
  forests.
• This would enable restoration of more natural
  fire, insect, and disease disturbances.

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Dry Forest Landscapes

• Suggested planning priorities for altering fuels
  fire behavior
• Historical high-severity regime areas are LOWEST
  priority events are usually weather-driven
  rather than fuel-driven.
• Historical low-severity regime areas are the
  HIGHEST priority patterns of historical
  structure and composition tolerated fires well.
  (See FireSafe principles below)
• Historical mixed-severity regime areas are an
  INTERMEDIATE priority. Reasonable hypotheses can
  be derived from reconstructions of historical
  landscapes about how much area to treat, what
  mosaics to leave, and which treatments may be
  functional fire surrogates, but testing is needed.

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Implications

• Active management is needed. Begin upland
  restoration in the wildland/urban interface.
• Managers policy-makers Consider choosing
  prescribed burning over wildfires huge smoke
  emissions trade-offs reduced uncertainty of
  outcomes.
• Manage for dynamic systems desired future
  dynamics vs. desired future conditions for
  example, dynamic LSOF forests rather than static
  reserve systems.
• Pursue strategies that restore upland patterns,
  disturbance regimes, hydrologic regimes, fish,
  aquatic habitats.
• All roads are not equal (20/80) eliminate most
  offending roads, minimize new roads learn from
  the past.
• Near term, upland restoration may not be possible
  everywhere it may be needed prioritize.