Timing, light availability and vigour determine the response of Abies alba saplings to leader shoot browsing

• Published in: European journal of forest research 2013, Vol.132 (1), p.47-60
• Main Authors: Kupferschmid, Andrea D., Bugmann, Harald
• Format: Article
• Language: English
• Subjects: Autumn; Biomedical and Life Sciences; Buds; Forest management; Forestry; Growing season; Herbivores; Life Sciences; Original Paper; Plant Ecology; Plant Sciences; Shoots; Trees
• ISSN: 1612-4669; 1612-4677
• DOI: 10.1007/s10342-012-0653-2

Herbivore browsing on tree saplings is a common phenomenon that can cause damage particularly on preferred species. In this study, the combined effects of light availability and timing of browsing on the response of 9-year-old Abies alba saplings were tested experimentally. Leader shoot clipping was applied before budburst, shortly after budburst or in autumn on saplings grown in full light or under artificial shade. Timing of clipping, light availability and tree vigour (expressed as height and tree ring width before clipping) had an effect on the height after clipping. After clipping in autumn or before budburst, fast-growing fir saplings bent up twigs to form new leader shoots and overcompensated height loss; saplings characterised by intermediate growth rates formed new shoots out of regular visible lateral buds; and slow-growing saplings had no new shoot in the first year after clipping, such that the clipping-induced height difference even increased over time. Saplings clipped shortly after budburst elongated the remaining part of the shoot in the first year and developed shoots out of the most distal lateral buds in the second growing season, leading to complete height compensation. Multi-trunking was typical for all clipped trees. We conclude that the microscale conditions under which a tree is growing (i.e. which affect tree vigour) are highly important for determining whether the height reduction imposed by browsing is offset by overcompensation or increases over time relative to unclipped trees. This response can partly be influenced by forest management via enhancing tree vigour via the light regime.