Abstract

In this study we examined the responses of the dominant understorey plant species, Vaccinium myrtillus, in a Swedish boreal forest to nitrogen applications and repeated damage by clipping. Four years of clipping V. myrtillus reduced its abundance, regardless of whether the clipping was combined with fertilization or not. The treatments also induced changes in growth form and concentration of phenolic compounds in the shoots. Repeated damage to the shrub caused reductions in both the length and diameter of the shoots, while fertilization alone increased their diameter. Fertilization also decreased the concentration of condensed tannins in shoots of V. myrtillus, while clipping had no significant effect in this respect. Condensed tannin concentrations were higher in shoots given the combined fertilization and clipping treatment than in shoots that were fertilized but not clipped. The effect on tannins is in accordance with the predictions of the CNB-hypothesis. Among the seven individual phenolic compounds analysed only one, a cinnamic acid derivate, showed a significant effect of the treatments. Repeated damage resulted in decreased concentration of this phenolic acid. In addition there was a tendency towards treatment effects on both nitrogen and carbon concentration of the V. myrtillus shoots, but none of these effects were statistically significant. The treatment-induced changes in V. myrtillus also affected the food preferences of grey-sided voles (Clethrionomys rufocanus), resulting in the following order of preference among the treatments: 1) fertilization and clipping, 2) fertilization, 3) control and 4) clipping. Not only biochemical changes, but also changes in growth form were found to influence the preferences, as the voles avoided the smallest shoots. This size-dependent feeding may partly explain the observed differences in their preferences. Thus, induced changes in growth form need to be considered when conclusions about changes in herbivores' preference are made

Published in

Oikos
2003, Volume: 103, number: 1, pages: 133-141
Publisher: BLACKWELL MUNKSGAARD

SLU Authors

• Witzell, Johanna

  • Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences
    

• Dahlgren, Jonas

  • Department of Forest Resource Management, Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Environmental Sciences related to Agriculture and Land-use
Forest Science


Publication identifier

DOI: https://doi.org/10.1034/j.1600-0706.2003.12680.x

Permanent link to this page (URI)

https://res.slu.se/id/publ/1123