Identifying

Dutch elm disease ‘danger-spots’

on the Isle of Man

with an agent-based model

Bruce Mitchell a, Joana Barros b, Daniel Wendel c

Email a: bruce.birkbeck@ntlworld.com

b: j.barros@bbk.ac.uk c: djwendel@gmail.com

1

Suffolk, 1984

2

StarLogo TNG - code blocks

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The Isle of Man in TNG

SpaceLand

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Objective

Is there a relationship between where

a beetle cluster originates and the

number of agent elms that die?

If so, might that relationship be used

to map the island to reveal locations

where an infestation might potentially

be more or less damaging?

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Isle of Man -

Relief• Scolytus beetles can only thrive

where elms prosper

• Landscape determines elm

habitats

• On Man, there is an ‘elm-line’ of

ca. 160 metres a.s.l..

• Two ranges of hills exceed this

elevation, restricting the flow of

the disease across the island

• In the model, a ‘beetle-line’ was

set at an arbitrary 25 % higher

(200m) than the elm-line.

The combination of DEM, elm-line

and beetle-line places elevation

at the model’s centre.

• Beetles operating out of any

given disease epicentre will find

some areas accessible, others

out of range.

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A single model run …

Sets up tree, beetle, forester, bird

agents

‘Infects’ up to 1.5% of elms with

beetles

Runs an elm census at game turn

(GT) 0

Generates a single beetle cluster

Runs a beetle census at GT 60

Continues to GT 1,000

Exports results to .csv file

Resets to GT 0 and introduces next

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Model agent flow chart

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The agents

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Model system flow chart

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SL-TNG Output

For each run:

◦ cluster originates in random location;

◦ number of elms surviving to GT1000

varies

.csv run results ported to MapInfo and

SPSS for processing, then transferred

to ArcGIS Spatial Analyst

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RCNS Calculation – step one

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RCNS Calculation – step two

RCNS zones

and regions

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Data processing flowchart

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Frequency of

cell inclusion

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Cluster

median

centres and

elm survival

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Modelled

danger-spots

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Identifying Dutch elm disease ‘danger-spots’ on

the Isle of Man

with an agent-based model

Bruce Mitchell

Data Visualisation Centre

Methodology Directorate

Office for National Statistics

bruce.mitchell@ons.gov.uk

Joana Barros

Department of Geography, Environment and Development Studies,

Birkbeck, University of London,

Malet Street, London, WC1E 7HX

j.barros@bbk.ac.uk

Daniel Wendel

Lead StarLogo TNG DeveloperScheller Teacher Education Program

Massachusetts Institute of Technology

Boston, MA, USA

djwendel@gmail.com

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