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Reciprocal Disturbance Interactionsin Pinus albicaulis Ecosystems
Nancy Bockino – M.S. CandidateDaniel Tinker – Advisor
University of Wyoming Department of Botany
• Ecosystem Introduction– Function– Disturbance
• Quantitative Analysis & Results
• Implications– Ecosystem– Management
Black Bear Harvesting ConesPhoto: Ryan Sims
Seed Dispersal VectorClark’s NutcrackerPhoto: A. Wilson
Whitebark Distribution
Greater Yellowstone Ecosystem –
Northwest Wyoming
Ecological Background
Ecological Background
Photo from Allen Carroll
Mountain Pine BeetleNative insect
Ecological BackgroundBlister Rust Exotic Pathogen
Photo Susan Hagle, USFS
Which tree & stand characteristics determine beetle selection and
the resulting mosaic of mortality?
Project Objectives
Quantify 1. Whitebark characteristics related to beetle selection
2. Beetle host-selection patterns
3. Relationship between blister rust & beetle selection
Provide1. Summary of whitebark condition in the GYE
2. Predictions of beetle selection
3. Ecosystem familiarity to aid restoration strategies
Study Sites
# Site Name Stand Type
1Breccia Pure Whitebark
Breccia Non-Host
2Mt. Leidy Pure Whitebark
Mt. Leidy Non-Host
3Teewinot Pure Whitebark
Teewinot Non-Host
4Sylvan
PassWhitebark &
Lodgepole
Teewinot
Breccia
Mt. Leidy
Sylvan Pass
Three Stand Types
Pure Whitebark
Whitebark & Alternate Beetle HostWhitebark & Non-Beetle Host
Data Collection
Each Tree
SpeciesTree Diameter
Blister Rust (Six & Newcomb, 2005)Crown ColorLive or Dead
Beetle Entrance Sites
Within A Stand (2-3 ha)• 24 plots systematically distributed
•Variable radius• Tree = replicate
Whitebark Status in theGreater Yellowstone Ecosystem
Sample Size 1,947
Dead 52 %
Blister Rust Symptomatic 83 %
Selected by Beetle 69 %
Rust & Beetle 61 %
Step 1: Chi-Square
Category Selected by Beetle
Characteristic Breccia Mt. Leidy Teewinot Sylvan Pass
Whitebark Density in Pure stands medium medium medium NA
Blister Rust Severity heavy heavy heavy NA
Tree Species(whitebark vs
lodgepole)NA NA NA whitebark
Step 2: Selection Ratio
(# preferred host attacked ÷ total attacked) (# preferred host available ÷ total available)
• Accounts for: 1. stand density 2. species composition
3. sequence of attack• Selection Ratio 1.0 = No Preference • Host characteristics
blister rust severity tree species
=
Step 2: Selection RatioSylvan Pass
Host Characteristic
Mean Selection
Ratio
Deviates from 1.0?
Species = whitebark
1.3 yes*
Rust severity =
heavy1.28 yes*
Beetles prefer:1. whitebark over lodgepole 2. whitebark with heavy blister rust
Teewinot
Mt. LeidyBreccia
Selection Ratio 1.0 = No Preference
*α = 0.05
Step 2: Selection Ratio
1.01.0
Response Variable
• Binary – Selected OR Not Selected
Predictor Variables
1. Stand type (pure vs. non-host mix)
2. Blister rust severity (light vs. heavy)
3. Tree diameter
Step 3: Multiple Logistic Regression
Step 3: Multiple Logistic Regression
Heavy/Pure
Heavy/Non-Host
Light/Pure
Light/Non-host
Conclusions
1. Beetles select whitebark over lodgepole
2. Blister rust influences selection probabilityPositive relationship between heavy rust & beetle selection.
Interactions Between Blister Rust & Beetle Selection Enhance Disturbance Severity
• “Barometer of change”• Spatial & temporal
prioritization of restoration sites
• Alteration of genetic structure of remaining
seed source• Redirection of
succession
Implications
Acknowledgements Funding sources:
Joint Fire Science Program Grant # H1200040001UWYO – NPS Research Grant Wyoming Native Plant Society
Dan TinkerKen GerowDavid LeggCory BolenBill RommeKelly McCloskey – Grand Teton NPLiz Davey Andy Norman
Contact Info: [email protected]
Ryan Sims
My Mom, Alida
Michael Straw
CSU
Bridger-Teton NF
UWYO