Jensen, Joel
- Department of Crop Production Ecology, Swedish University of Agricultural Sciences
Abstract
Mixed-species forestry is a promising strategy for addressing global challenges such as climate change mitigation, biodiversity conservation, and sustainable timber production. In this thesis, I investigate the large-scale effects of species mixing in young tree stands on soil carbon (C) storage and accumulation, soil organic matter (SOM) chemistry and stability, aboveground productivity, and the mechanisms driving these outcomes. Drawing on data from TreeDivNet, a global network of tree diversity experiments, I assessed the roles of functional traits and environmental context. Willow species identity and diversity influenced SOM chemistry and thermal stability, while species identity affected soil C accumulation at one of two sites. In nine European experiments, topsoil C stocks were generally higher in mixtures than in monocultures, particularly in colder, less fertile, and more climatically stable sites. Fungal richness was positively associated with soil C stocks, though it did not vary significantly across diversity levels. At the global scale, aboveground productivity increased with species richness, plateauing at four to five species and becoming more stable at higher richness. Functional diversity promoted productivity, while structural diversity had a negative effect except at high richness. Selection effects predominated over complementarity effects, with acquisitive species (high leaf nitrogen, low wood density) performing best in mixtures. Across eleven experiments in Europe and Brazil, woody and litterfall biomass were higher in mixtures. Increases in woody biomass were associated with shifts in specific leaf area and leaf area index. Overall, this thesis emphasizes the importance of functional traits and environmental context in designing mixed-species plantations to optimize for both climate mitigation and productivity.
Keywords
tree species diversity; functional traits; functional diversity; environmental context-dependency; soil carbon accumulation; soil organic matter chemistry; climate change mitigation; biodiversity
Published in
Acta Universitatis Agriculturae Sueciae
2025, number: 2025:41
Publisher: Swedish University of Agricultural Sciences
SLU Authors
UKÄ Subject classification
Forest Science
Publication identifier
- DOI: https://doi.org/10.54612/a.2kmifmq5mk
- ISBN: 978-91-8046-476-5
- eISBN: 978-91-8046-526-7
Permanent link to this page (URI)
https://res.slu.se/id/publ/132981