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: nbockino@uwyo.edu

Ryan Sims

My Mom, Alida

Michael Straw

CSU

Bridger-Teton NF

UWYO