Temporal turnover of functional biodiversity in forests after disturbances (TempTurn)

• Applicant: Dr. Bettina Ohse
• Subject Area: Ecology and Biodiversity of Plants and Ecosystems
• Term: since 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 505114330

Temperate forests provide essential ecosystem functions, such as carbon sequestration, water purification, climate regulation, timber production, and recreational values. However, current and future increases in disturbances by windthrow, fire, or insect outbreaks will likely exert long-term effects on the composition of tree species and thus on the functional diversity of tree species communities. Such temporal variations in tree functional biodiversity will challenge the permanent provision of ecosystem functions in temperate forests. Yet, a thorough and systematic assessment of multi-decadal trajectories of functional biodiversity turnover in temperate forests is still lacking.The main goal of the proposed project is therefore the quantification, the improved understanding, and the prediction of temporal variations in tree functional biodiversity in temperate forests after disturbances. The proposed study will address this goal by using a combined approach of data synthesis, complementary field-observations, and modelling. First, a database will be compiled of existing multi-decadal monitoring data, complemented with filed-based re-survey data, on tree species composition and abundances after different disturbances across European temperate forests. These abundance data will be related to the tree species functional traits to quantify changes in functional biodiversity over time. I will then investigate, how functional turnover changes with time after disturbance as well as in response to different disturbance types and severities. Moreover, I will quantify the effects of three modifying factors: i) the relative importance of the post-disturbance species pool, ii) the effects of ungulate browsing, and iii) the effects of salvage logging, on post-disturbance community assembly and functional biodiversity turnover. Second, I will apply a forest modelling and simulation approach using the forest landscape model LandClim to predict species abundances under future disturbance regimes and to quantify future functional turnover rates. Effects of disturbance interactions as well as feedbacks from changes in functional biodiversity to subsequent disturbance susceptibility will be incorporated into the model. The project results will provide a systematic quantification and an improved understanding of past, current, and future temporal changes in tree functional biodiversity after climate-change related disturbances. This will pave the way towards mechanism-based predictions of the future resilience and recovery of related ecosystem functions. Moreover, the proposed project will yield a database of valuable long-term datasets on successional dynamics in temperate forests, suitable for a wide range of analyses on post-disturbance forest dynamics. Lastly, the project results will provide guidance on different management options for functional biodiversity recovery in temperate forests in the face of increasing disturbances.

• DFG Programme: Research Grants