PhD defense: Davide Barsotti

Davide Barsotti defends his thesis:

"Development of plant and fungal communities in afforested agricultural soils
Effects of time, tree species, environment, and restoration"

Supervisors:
Professor Inger Kappel Schmidt, IGN
Assistant professor Sebastian Kepfer Rojas, IGN

Assessment Committee:
Professor Kris Verheyen, Ghent University - Belgium
Professor Bente Jessen Graae, NTNU - Norway
Associate professor Rasmus Kjøller (chair), BIO

Summary:
Many of the factors shaping species communities in planted forests across Denmark and central Europe are altered by the former agricultural use. This results in the formation of different communities compared to pristine forest, causing concerns for the long-term conservation of habitat specialists.
The Silva Nova project, which funded this PhD, aimed at exploring the use of soil inoculation in planted forests to reduce former land use legacy effects and enhance ecosystem function. This PhD project focused on drawing a baseline of knowledge on the development of plant and fungal communities in post-agricultural forests without interventions, and to explore the effectiveness of soil transplants to restore fungal diversity. The thesis includes three research papers: the first two cover the study of a chronosequence spanning the first 50-60 years of development of plant and fungal communities under oak, beech and Norway spruce without active biodiversity restoration measures. The third paper describes an assisted dispersal experiment to evaluate the effectiveness of transferring forest floor from old forests to younger plantations to accelerate the recovery of fungal communities.
Overall, plant communities remained very different from the old forest even in the oldest chronosequence stages, although the number of forest specialist species increased over time. The development of plant communities was primarily limited by dispersal, with environmental factors playing a secondary role. Fungal communities rapidly became ectomycorrhizal- and basidiomycete-dominated like the old forests, however they also maintained a different species composition. Ectomycorrhizal fungi, nearly absent from agricultural sites, were abundant even in the youngest forest sampled. Both plant and fungal communities showed land use legacy effects and lacked species found in the old-forest. Tree species had small impact on the plant community but produced a distinct fungal community in Norway spruce stands. Introducing old-forest soil increased the similarity to the donor site even using just small amounts of inoculum, with saprotrophic fungi benefiting the most. The experimental inoculation results varied and were affected by site conditions, highlighting the importance of local contexts.
This thesis demonstrates that afforestation has the potential to provide new habitats for specialized forest communities on the long term. Nevertheless, dispersal limitation and land use legacies are confirmed as major obstacles and may prevent or delay the restoration of biodiversity typical of old forest. Active restoration measures such as soil inoculation may accelerate the recovery but require careful planning and more research.

A digital version of the PhD thesis can be obtained from the PhD secretary at phd@ign.ku.dk before the defence. After the defence the thesis will become available from the Royal Danish Libary at kb@kb.dk.