hemlocks and the woolly adelgid

8/7/2019 Hemlocks and the Woolly Adelgid

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Hemlocks and the Woolly

Adelgid

A presentation by Maximus Thaler,

Carlos Medina and SignePorteshawver


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Invasive Species

Non native species that adversely affect a

foreign habitat

Causes? Defense free space

Enemy free space


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Subject Species

Adelges tsugae- Woolly Adelgid Tsuga canadensis Hemlock Tree


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Life Cycle


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Scope of Research

Bio mechanics focus how does the

adelgid affect water flow?

Plant focus how does the trees

condition (stress levels) affect infection?

Forest focus how will the adelgid

infestation affect the whole forest?

Increasing

Scope


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Research Questions

1 Are light stressed plants more susceptible to

infestation by A. tsugae?

2 Does A. tsugae infestation affect plant

physiology with respect to flow rate of water?

3 What plant species could potentially replace

T. canadensis in the canopy community?


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Q1 Are light stressed plants more susceptible

to infestation by A. tsugae?

Open vs. shaded trees

3 branches per cardinaldirection, chosen

randomly

Numbers of alive and

dead A. tsugae counted

in 5cm segment

Photo provided by Colleen Butler


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Hydraulic Conductance Setup

Courtesy of Bio51 Blackboard Page

Q2 Does A. tsugae infestation affect plant

physiology with respect to flow rate of water?


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Q2 Does A. tsugae infestation

affect plant physiology

with respect to flow rate of water?Pressure Source

Pressurized H2O

Branch Segment

Scale

Photos taken by Carlos Medina


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Q3 What plant species could potentially

replace T. canadensis in the canopy community?

100-m2 sampling plots set up (7.07m x

14.14m) as suggested by Brower et al.

Species within plot determined using keyprovided by Prof. Orians

Photo provided by Colleen Butler Photo provided by Colleen Butler


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Figure 2: The effect of branch radius on specific conductivity (flow rate/pressure) ofT.

canadensis branches (n=10), measured in the laboratory at Tufts University 17

November 2010.

Water flow rate through T. canadensis

depends on branch radius


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Water flow rate is not affected

by adelgid infection

Figure 3: Linear regression of specific conductivity (water flow/pressure) ofT.

canadensis branches infected (n=5) and not infected (n=5) by A. tsugae, measured inthe laboratory at Tufts University 17 November 2010.


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Higher density ofA. tsugae on shaded T. cadanensis plants than on trees in open light

environments

Figure 1: Average total number ofA. tsugae sistens found on plant segments in

shaded (n=72) and open (n=72) light environments at the Fells forest reserve on 3November 2010.


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Pinus may come to dominate in the Fells forest

Figure 4: Average relative density of understory tree

genera in 100 square meter sampling areas (n=6) on 3

November 2010 at the Fells forest reserve. Acer n=13,

Pinus n=30, Tsuga n=12, Betula n=4, Prunus n=2. Error

bars represent one standard deviation from the mean.

Figure 5: Average relative density of canopy tree

genera in 100 square meter sampling areas (n=6)

on 3 November 2010 at the Fells forest reserve.

Quercus n=6, Pinus n=7, Tsuga n=5, Betula n=15.

Error bars represent one standard deviation from

the mean.


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Hypotheses revisited

H1: A. tsugae will be more abundant on light-stressed plants.

Hypothesis supported: Plants in shaded environmentexhibited higher densities of adelgid sistens than plantsin the open

H2: A. tsugae will reduce the ability ofT.canadensis to transport water.

Hypothesis not supported: Rate of water flowdepended only upon the radius of the branch.

H3: Changing abundance ofT. canadensis willalter future community structure.

Hypothesis supported: Pinus is more common inunderstory than in canopy, suggesting it may come to

dominate.


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Future research

To better understand why A. tsugae can

spread so rapidly

To develop a treatment plan for saving

infected trees as well as determining which

trees are most susceptible

To develop a prevention plan to stop the

spread ofA. tsugae

A better grasp on physiology can serve as the

foundation of solutions to these problems.

http://wps.prenhall.com/esm_freeman_biosci_1/7

/1953/500185.cw/index.html


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hemlocks and the woolly adelgid

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