Zvirgzdins, Andis
- Southern Swedish Forest Research Centre, Swedish University of Agricultural Sciences
Abstract
Silver birch (Betula pendula Roth) has traditionally played a secondary role in Swedish forestry, dominated by coniferous species such as Norway spruce (Picea abies L.) and Scots pine (Pinus sylvestris L.). However, the increasing need for more diversified and climate-resilient forestry, combined with the availability of genetically improved planting material through breeding programmes, has renewed interest in birch as a viable alternative. This thesis investigated key aspects of establishing and managing planted silver birch, with a particular focus on spacing, browsing by cervids, thinning strategies, and modelling growth of genetically improved material. The research questions were explored through short-term field trials, long-term experiments, and surveys in Sweden and Latvia, complemented by interviews with private forest owners in Sweden. Establishment-related results showed that diameter growth increases with wider spacing. Yet, higher initial density may also serve as a tool to manage the local browsing risk. Light-to-moderate browsing did not significantly reduce survival or height growth of silver birch, indicating on species’ ability to compensate for early-stage browsing. However, the negative impact of browsing on tree quality suggests that protective measures depending on browsing risk are required. Management-related results demonstrated that heavy thinning resulted in the strongest individual tree diameter growth, albeit at the cost of total stand volume production. Furthermore, simulations of basal area development under varying levels of genetic gain revealed that improved material can substantially enhance stand productivity and reduce rotation length of planted silver birch stands. Overall, this thesis demonstrated that silver birch can be a viable alternative in Swedish forestry, offering high growth potential and resilience to browsing when properly managed. Thinning can further increase stand value by promoting high-quality timber, provided this aligns with the management goals.
Keywords
silver birch; plantations; establishment; browsing; cervids; management; diameter growth; volume production; modelling; genetically improved material; vårtbjörk; planteringar; etablering; viltbete; hjortdjur; skötsel; diameter-tillväxt; volymproduktion; modellering; genetiskt förbättrat material
Published in
Acta Universitatis Agriculturae Sueciae
2025, number: 2025:71
Publisher: Swedish University of Agricultural Sciences
SLU Authors
UKÄ Subject classification
Forest Science
Publication identifier
- DOI: https://doi.org/10.54612/a.r942kj7bmg
- ISBN: 978-91-8124-055-9
- eISBN: 978-91-8124-101-3
Permanent link to this page (URI)
https://res.slu.se/id/publ/142472