Pre-commercial thinning in Norway spruce-birch mixed stands can provide abundant forage for ungulates without losing volume production

• Published in: Forest ecology and management 2022-09, Vol.520, p.120364, Article 120364
• Main Authors: Ara, Mostarin, Maria Felton, Annika, Holmström, Emma, Petersson, Lisa, Berglund, Mattias, Johansson, Ulf, Nilsson, Urban
• Format: Article
• Language: English
• Subjects: administrative management; Betula; Birch; Forage; forage production; forest ecology; Forest Science; Mixed stand; Norway; Norway spruce; Picea abies; Skogsvetenskap; Ungulates
• ISSN: 0378-1127; 1872-7042; 1872-7042
• DOI: 10.1016/j.foreco.2022.120364

•Pre-commercial thinning strategies simultaneously promote the growth of Norway spruce and provide forage for ungulates.•There was higher amount of forage in stand with no PCT compared to PCT stands.•Pre-commercial thinning didn’t influence on birch browsing.•Some version of PCT strategies can be implemented to increase the forage availability in forest landscape. Mixed stands of Norway spruce and birch have the potential to simultaneously produce timber and provide large ungulates with a significant amount of forage during the regeneration phase. While the growth and yield of such mixtures are well studied, little is known about potential trade-offs between timber and forage production and which management techniques are suitable for meeting both goals. In this study, four different pre-commercial thinning (PCT) strategies were used to study the trade-offs between production and available forage for free-ranging ungulates in a Norway spruce-birch mixture. The four PCT strategies were: 1) retaining 2000 birch stems ha−1 with 2000 Norway spruce ha−1, 2) removing all birches within a 0.75 m radius around Norway spruce stems, 3) removing all birches and other broadleaves, and 4) no PCT (control). Growth of Norway spruce was higher in the 2000 birch ha−1 and full removal treatments compared to the untreated control, but these two treatments did not differ from one another in volume production of Norway spruce. We found a negative effect of PCT on forage availability but no effect on ungulate browsing. Therefore, PCT strategies that provide both sufficient birch forage and maximize volume production of Norway spruce can be implemented.