School of Conservation Sciences

Analyses of the spatial distribution of wood cricket (Nemobius sylvestris) on

the Isle of Wight (UK)

PhD by: Niels Brouwers (Bournemouth University)Supervised by: Dr. Adrian Newton (Bournemouth University)

Dr. Sallie Bailey (Forestry Commission)Dr. Kevin Watts (Forest Research)

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Index

• Introduction• Objective• Research Questions• Study Area• Method• Results• Discussion

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Introduction

• Background– Woodland conservation– Restoration and expansion– Forest Habitat Networks

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Objective

• To determine what factors influence wood cricket (Nemobius sylvestris) distribution on a landscape and local scale.

1 cm

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Research Questions:

• Where is wood cricket situated on the Isle of Wight?

• Is wood cricket presence related to the factors: woodland type, age, area, shape and nearest neighbour distance?

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Study Area

Surface Area: 381 km²

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Method

• Summer 2005

(Mid-July/Mid-September)• Walk survey• Woodlands

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13%46%

Results: Distribution

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Broadleaved Coniferous Mixed

Woodland type

0

20

40

60

80

100

Pe

rce

nta

ge

of

wo

od

lan

ds

(%

)

Results: Woodland Type

• Pearson Chi-Square: χ² = 1.146, n = 215, P = 0.564

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Secondary Ancient

Woodland age

0

20

40

60

80

100

Pe

rce

nta

ge

of

wo

od

lan

ds

(%

)

Results: Woodland Age

• Pearson Chi-Square: χ² = 4.585, n = 144, P = 0.032

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Present Not present

Wood cricket presence

0

10

20

30

40

50

60

Wo

od

lan

d a

rea

(h

a)

a

b

Results: Woodland Area

• Mann-Whitney test, Z = -3.175, n = 215, P = 0.001

vs.

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Results: Woodland Shape

• Mann-Whitney test: Z = -3.254, n = 215, P = 0.001

Present Not present

Wood cricket presence

1.0

2.0

3.0

4.0

5.0

Sh

ap

e i

nd

ex

72

75

a

b

vs.

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Results: N. N. Distance

• Mann-Whitney test: Z = -6.478, n = 215, P = 0.000

0

5

10

15

20

25

30

35

100

200

300

400

500

750

1000

1500

2000

2500

3000

4500

6000

6500

Distance (m)

Pe

rce

nta

ge

of

wo

od

lan

ds

(%

)

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Results: Logistic Regression

Variables Wald df Significance (P) R² adjusted

Area 3.158 1 0.076 n.s. 0.037

Shape 10.003 1 0.002 0.072

Distance 18.100 1 0.000 0.291

Logistic regression models        

Distance + Area 16.086 1 0.000 0.380

Distance + Shape 11.181 1 0.001 0.367

Distance + Area + Shape 4.305 2 0.038 0.404

Spearman rank correlation:_____________________________________Area vs. Shape: r = 0.604, P = 0.000Area vs. Distance: r = 0.139, P = 0.041Distance vs. Shape: r = 0.098, P = 0.153

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Discussion

• Summary: – Type (ns)– Age (s)– Area (s)– Shape (s)– N. N. Distance (s)

– Logistic regression

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Discussion

• Distance and Area– Unexplained variation– Habitat variables

• Conservation effort– Landscape scale planning– Target

• Large fragments • Aggregations

better than

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Thank you for your attention