Effects of timing, duration, and intensity of simulated browsing on Scots pine growth and stem quality

Abstract

This study examines a large number of structural and growth-related responses of young Scots pine in relation to simulated browsing from large herbivores. We combined different modes of intensity, timing, and duration of clipping for nine consecutive years from 2000 to 2008. Data on tree responses were collected yearly during this period, as well as in 2011, and were analyzed using ordination techniques and generalized linear models. A key result demonstrated is the serious effects of clipping on the youngest pines. Mortality was high when clipping started the first year, indicating that the trees are vulnerable at that stage, but after that increasing intensity and duration of clipping were the main causes of mortality. Among the different treatment factors, intensity of clipping had the largest influence on altering the final growth responses, some of the quality responses, and mortality. Timing of clipping was the most important factor for explaining the occurrence of the majority of responses related to stem structure. Duration of clipping had the largest effect on the responses that included repeated-measures data, such as height development and number of stems. We discuss the long-term consequences of browsing for the trees and the implications for forest management.

Keywords:

• browsing
• moose
• roe deer
• Scots pine

Acknowledgments

We thank Sveaskog for permission to conduct research on their land and Södra Skogsplantor for donation of pine seedlings used in the experiment. Concerning some of the statistical analyses, we acknowledge the help by Gunnar Jansson, Skogforsk.

Funding

This study was financed by the Swedish University of Agricultural Sciences; Forestry Research Institute of Sweden – Skogforsk; Swedish Governmental Agency for Innovation Systems – VINNOVA (grant to Märtha Wallgren) and Swedish Forest Agency.

Additional information

Funding

Funding: This study was financed by the Swedish University of Agricultural Sciences; Forestry Research Institute of Sweden – Skogforsk; Swedish Governmental Agency for Innovation Systems – VINNOVA (grant to Märtha Wallgren) and Swedish Forest Agency.