Lundgren, Andreas
- Department of Ecology, Swedish University of Agricultural Sciences
Abstract
The boreal forest biome is a valuable carbon sink as well as a producer of several ecosystem services. In recent years, forests around the boreal biome have exhibited declining productivity in terms of tree growth. The declining growth may be a consequence of a variety of factors. In this thesis, I use the findings from four studies (IIV) to explore forest growth in relation to two specific factors: climatic variables and clearcut forestry, as well as the interaction between the two. In the first study (I), I use data collected by the Swedish National Forest Inventory to show that tree growth-responses to climatic variables differ depending on local climatic factors. Specifically, trees growing in already warm regions are likely to decrease in growth with increasing temperature while the opposite is true for those growing in colder regions. Areas of high soil moisture may slightly mitigate the detrimental temperature-effect in warm regions. In the second study (II), I compare tree growth-responses to climatic variables between forests that were clearcut ~60 years earlier and forests that likely have never been clearcut. Tree growth in previously clearcut forests revealed to be more unstable between years and respond stronger to climatic variability. As an example, during the extreme drought year of 2018, the clearcut forests experienced worse growth declines than the non-clearcut forests. In the third study (III), I used a soil incubation experiment and found that the respiration rate from soils of recent clearcuts are more sensitive to warming than that of mature forests. However, the increase in respiration rate due to warming was highly transient, and the effect disappeared as the incubation proceeded, likely indicating differences in labile and recalcitrant substrates as a potential driver of the temperature sensitivity. The fourth study (IV) shows long-term differences between clearcut and nonclearcut forests in soil microbial communities important for decomposition, but these differences do not seem to correlate with aggravated nutrient limitations or long-term productivity declines. In conclusion, both climatic variables and clearcutting likely affect growth in the boreal forest, yet their effects are not unidirectional.
Keywords
boreal; climate; clearcut; tree growth; decomposition
Published in
Acta Universitatis Agriculturae Sueciae
2026, number: 2026:25
Publisher: Swedish University of Agricultural Sciences
SLU Authors
UKÄ Subject classification
Forest Science
Publication identifier
- DOI: https://doi.org/10.54612/a.63ptc5rpq7
- ISBN: 978-91-8124-242-3
- eISBN: 978-91-8124-272-0
Permanent link to this page (URI)
https://res.slu.se/id/publ/146348