Epsilon Archive for Student Projects

Abstract

The study focuses on the early development of planted pedunculate oak (Quercus robur L.) in mixed broadleaf stands established on sites previously dominated by Norway spruce (Picea abies). Following the large-scale windthrow caused by the storm Gudrun in 2005, there were strong incentives to create more diverse and climate-adapted forests by spreading the risk among more species than spruce and pine. As a part of this effort, Sveaskog – the Swedish state-owned forest company – decided to plant 10% of their storm-damaged area (southern Sweden) with different broadleaf species, among them oak.

This thesis aimed to assess how different silvicultural strategies – precommercial-thinning, planting method (group vs. spot-wise) and fencing – influenced oak growth performance after 20 years of development. Field data were collected from a selection of Sveaskog’s stands, and oak trees were measured for survival, growth (height, DBH, crown ratio, crown volume), and quality. Statistical analysis included both non-parametric tests and linear mixed-effects models.

Results showed that fencing had the most consistent positive effect on growth and quality. Pre-commercial thinning had moderate effects on DBH and crown development. The planting method had only minimal influence on the measured variable. The most prevalent quality defects were crooked stems and browsing damages, particularly in unmanaged and unfenced stands.

The findings of this study highlight the challenges related to oak production under mixed stand conditions. To evaluate if these converted stands will meet their intended ecological and economic goals, long-term monitoring and silvicultural interventions are needed.