| In temperate Europe, pedunculated- and sessile oak are foundational species ranking among the most important trees for endangered invertebrates, lichens, fungi, and birds. Much of their value as habitat for many groups of organisms is attributed to their long lifespan and their unique wood traits. Therefore, many oak-dominated forests have been set aside for nature conservation purposes.
However, decreasing oak dominance and oak regeneration failure are occurring worldwide, putting oak-associated biodiversity and ecosystem services at risk. Not much is known about the stand and light conditions necessary for promoting natural regeneration of oak and its recruitment into the overstory. This gap in knowledge stifles strategies to prevent regeneration failure, and perpetuates the habitat degradation prevalent in these ecosystems.
Our international project aims to discover stand development pathways that lead to oak dominance in mixed broadleaf stands of ranging site productivities. This will be accomplished with a well-replicated field study laid out over the whole area of interest in southern Sweden. This study is designed to define relationships between stand structure and light availability, along with a robust study of stand development designed to reconstruct the dynamics of stand structure and growth of oak regeneration into the canopy. Effective restoration and sustainability of mixed oak forest habitats requires a much stronger knowledge of factors governing oak stand development, specifically the pathways that enable regeneration to recruit into the canopy. Completion of the proposed experimentation will enable us to answer the following research questions:
(1) How does structural complexity in mixed oak stands change along a gradient of site productivity?
(2) How does structural complexity influence light availability in oak stands relative to site productivity?
(3) What stand structures are most favorable to sustaining growth and recruitment of natural oak regeneration into the canopy of forests valued for conservation?
Results of this research will be foundational to writing science-based, practical guidelines for managing stand structure to create and sustain critical, oak-dominated habitats valued for biodiversity conservation. This project is a 4-year (August 2021 – July 2025) long PhD project (main supervisor Magnus Löf - SLU, co-supervisors Björn Nordén - NINA, Jorge Aldea - SLU and Emile Gardiner - USDA FS). The PhD student will be recruited to the department Southern Swedish Forest Research Centre at SLU in Alnarp. The department will also support the project with 25% of the salary costs for the PhD over four years, which means that it will be fully funded if supported by the foundation.
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