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Landscape variables

In Östergötland County, protected areas were positively correlated with the abundance of T. depsarium at a 500 meter scale. The area of clear-cuts within 1000 meters from the trapping site could explain the presence of the beetle in Östergötland County. For volume pine, a tendency for a negative correlation can be seen at 100 meters. However, at 2000 m, there is a strong tendency for a positive relationship between the amount of pine wood and beetle occurrence.

Three negative binomial Generalized Linear Models (GLZs) with the landscape variables in Östergötland County only. The response variable was “individuals”, and the explanatory variables were protected areas, cut areas and volume pine at 100, 500, 1000 and 2000 meters from each trap, respectively. In protected areas, unsuitable habitats were excluded as far as possible. Clear-cut areas were 5-15 years old (cut in 1999-2009). Volume pine refers to volume wood of alive Scots pine trees.

Explanatory variables, Östergötland

Estimate

SE

z-value

p-value

Protected areas (ha) 100 m

-0.808

0.798

-1.013

0.311

Protected areas (ha) 500 m

0.182

0.088

2.074

0.038

Protected areas (ha) 1000 m

-0.066

0.035

-1.890

0.059

Protected areas (ha) 2000 m

0.008

0.007

1.206

0.228

Clear-cut areas (ha) 100 m

0.129

1.863

0.069

0.945

Clear-cut areas (ha) 500 m

-0.375

0.202

-1.857

0.063

Clear-cut areas (ha) 1000 m

0.169

0.069

2.457

0.014

Clear-cut areas (ha) 2000 m

-0.010

0.020

-0.520

0.603

Volume pine (m3/ha) 100 m

-0.010

0.005

-1.837

0.066

Volume pine (m3/ha) 500 m

2.66E-04

<0,001

0.562

0.574

Volume pine (m3/ha) 1000 m

-9.00E-05

<0,001

-0.432

0.666

Volume pine (m3/ha) 2000 m

7.76E-05

4.03E-05

1.927

0.054
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Last updated: 05/11/15