Volume 2, Issue 2 p. 131-139

Effects of leaf beetle damage on stem wood production in coppicing willow

Christer Björkman

Christer Björkman

Department of Entomology, Swedish University of Agricultural Sciences, PO Box 7044, S-750 07 Uppsala, Sweden

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Solveig Höglund

Solveig Höglund

Department of Entomology, Swedish University of Agricultural Sciences, PO Box 7044, S-750 07 Uppsala, Sweden

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Karin Eklund

Karin Eklund

Department of Entomology, Swedish University of Agricultural Sciences, PO Box 7044, S-750 07 Uppsala, Sweden

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Stig Larsson

Stig Larsson

Department of Entomology, Swedish University of Agricultural Sciences, PO Box 7044, S-750 07 Uppsala, Sweden

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First published: 24 December 2001
Citations: 48
Christer Björkman. Tel: + 46 18 67 1532; fax: + 46 18 67 2890; e-mail: [email protected]

Abstract

1 The effect of defoliation by larvae of the leaf beetle Phratora vulgatissima on current-year stem wood production of resprouting Salix viminalis was investigated for two years. Adjacent subplots with varying levels of defoliation within one large willow plantation in south Sweden were studied in the two years.

2 High defoliation levels reduced stem wood production by an average of 32 and 39% in the two years, respectively.

3 Medium defoliation levels reduced stem wood production by 16% in one year. In the other year, the stem wood production of medium-defoliated stools did not differ significantly from stools exposed to low defoliation, i.e. there was full compensatory growth.

4 The main difference between the year with compensatory growth and the one without was that overall productivity was higher in the year with compensation. This finding forms the basis for a mechanistic model by which compensation could be accomplished. We propose that the major contribution to full compensation comes from an increased growth among intermediate-sized shoots of medium-defoliated stools relative to the corresponding shoots in stools exposed to low defoliation.