Bambi

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Bambi Smokey Bear New Realities for Forest
Management in the 21st Century
Walter Carson1, Henry Schumacher1, Rachel
Collins2, Mary Beth Adams3 1University of
Pittsburgh, 2Univ Wisconsin, 3USFS NE Forest
Research Station
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Final Exam Wed. Dec. 13, 12-150 in A224 Langley
Hall This room

• Dramatic shifts in tree species composition in
  eastern deciduous forests over the past 100
  years.
• Loss of American chestnut
• Regional failed oak and hickory regeneration
• Massive clear-cutting
• Rise of the Swamp Thing
• Current loss of American beech

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Introduction to the problem

• Shifts in composition have coincided with
• A century of fire suppression (Smokey Bear)
• Increased deer populations (Bambi)
• Alteration of canopy gap dynamics (Clear-cutting)

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Research questions

• What ecological processes (e.g. light, deer,
  fire) have caused these changes in species
  composition?
• Does one process drive the patterns, or does more
  than one process interact to drive these changes?
• The Deer Camp vs. The Fire Camp.

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3 general conceptual models of forest
regeneration dynamics

• Shade Tolerance Model (STM)
• Mammalian Browsing Model (MBM)
• Fire Tolerance Model (FTM)

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Shade tolerance model (STM)

• As disturbance severity increases, absolute and
  relative abundance of shade-intolerant species
  increases.
• Light is the most limiting resource in
  understory
• Species shade tolerance drives regeneration

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Shade Tolerance Model

• Species have different life-history strategies.
• Trade-off between high-light growth and low-light
  survival (shade tolerance)
• Physiological constraints prevent super-species

Kobe et al. 1995
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Shade Tolerance Model

• Shade tolerant species
• American beech, sugar maple, hemlock
• Intermediate shade tolerant species
• Oaks, hickories, red maple, black cherry
• Shade intolerant species
• Yellow/Black birch, Pin cherry, Tulip poplar,
  Aspen

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Mammalian browsing model (MBM)

• Pre- and post-disturbance communities will be
  composed of browse-tolerant species.
• Assumes that mammalian browsers have a major
  impact on species composition, over the past and
  now.

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Deer populations are much higher than historic
estimates
1500 A.D. 3.5 Deer km-1 McCabe McCabe
(1997) Todays densities 3 deer km-1 6 deer
km-1 12 deer km-1 gt18 deer km-1
www.qdma.com
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Mammalian Browsing Model

• High deer abundances lead to an understory of
  browse-tolerant species.
• Deer prevent browse-intolerant species from
  regenerating.
• Browse-tolerance may interact with shade-tolerance

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Hay-scented Fern in Allegheny National Forest
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High plant diversity only found on refugia
BOULDERS!!
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Fire Tolerance Model (FTM)

• Fire increases the absolute and relative
  abundance of fire-tolerant species and decrease
  the abundance of fire-intolerant species

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Fire Tolerance Model

• Natural anthropogenic fires common for 1000s of
  years
• Re-occurring fires should promote fire tolerant
  species
• Fire-tolerant species have adaptations to fire

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Fire Tolerance Model

• Fire and oak hypothesis
• Abrams (1992, 2003)
• Oak abundance and fire frequency correlated
  (gt7,000 yrs)
• Delcourt Delcourt (1987)

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Lightning strike density (per sq.km/yr)
Lightning storms rare in west, common in southeast
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Forest Dynamics Project, WV

• Investigate the individual and interactive
  effects of
• Light availability
• Deer browsing
• Understory fire

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Study Sites

• 2 sites in West Virginia
• MeadWestvaco Research Forest
• Dominated by sugar maple
• 10-20 oak canopy
• 17 deer km-1 (4x)
• USFS Fernow Forest
• Oak dominated
• 8 deer km-1 (2x)

USFS Fernow
MeadWestvaco Research Forest
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Treatment layout in each Stand (40 ha)
16 research plots per stand
Fire
No Fire
20m x 20m subplot
canopy gap
fence
plot
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Data collected

• Censuses
• 1997 (pre-treatment)
• 1999, 2000, 2004 (post-treatment)
• gt20,000 individuals tagged at each site

• Definitions
• Canopy (gt10cm DBH)
• Saplings (1-10cm DBH)
• Seedlings (20-140cm Height)

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Density Deer mask the effects of disturbance
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Density Deer mask the effects of disturbance
72 pioneers
81 pioneers
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Density by species Are species compositions
changing?
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STM As disturbance severity increases, absolute
and relative abundance of shade-intolerant
species increases.

• STM supported in the ABSENCE of deer.
• Gaps shifted species compositions only when deer
  were absent.

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MBM Pre- and post-disturbance communities will
be composed of browse-tolerant species.

• In presence of deer, MBM made most accurate
  predictions.
• Deer disproportionately reduced shade intolerant
  species especially in gap fire treatments.

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FTM Fire will increase the absolute and relative
abundance of fire-tolerant species and decrease
the abundance of fire-intolerant species

• Fire-tolerant species did not increase in
  relative abundance after fires.
• Deer control the species composition following
  fire.
• Fire shifted species compositions only when deer
  were absent.

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Deer mask the effects of gaps fire
Fire Gap without deer browsing
Fire Gap with deer browsing
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Are we going to lose the major masting species
in the Eastern Deciduous forest

• Chestnut and chestnut blight
• Beech and beech bark disease
• Oaks and hickories (fire and deer)

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Acknowledgements

• MeadWestVaco Corp.
• Pat Keyser, Vic Ford, Bruce Brenneman
• USDA Forest Service
• Tom Schuler, Mark Ford, Gary Bustemente, Gary
  Willison, Tim Sherm
• University of Pittsburgh
• EE Grad Student Community Faculty
• Funding
• USDA Forest Service, USDA NRI, Phipps
  Conservatory, Garden Club of Allegheny County,
  Mead-Westvaco, Babcock Charitable Trust
• Field Workers