Climate change impacts on trees reproduction and forecasts of forest recruitment change

Project Information

ForestFuture

Grant agreement ID: 101039066

DOI

10.3030/101039066

EC signature date 5 May 2022

Start date 1 January 2023

End date 31 December 2027

Funded under

• European Research Council (ERC)

Total cost

€ 1 482 050,00

EU contribution

€ 1 482 050,00

Coordinated by

UNIWERSYTET IM. ADAMA MICKIEWICZA WPOZNANIU
Poland

Periodic Reporting for period 1 - ForestFuture (Climate change impacts on trees reproduction and forecasts of forest recruitment change)

Reporting period: 2023-01-01 to 2025-06-30

Summary of the context and overall objectives of the project

The future of our forests and the many benefits they provide, such as carbon storage, wildlife habitat, and clean air—depends on trees’ ability to reproduce successfully even as the climate changes rapidly. In many forest species, reproduction occurs in unpredictable bursts known as masting, where trees produce large, synchronized seed crops in some years and very little in others. This interannual variation is essential for overcoming seed predators and ensuring successful pollination, which in turn supports forest regeneration and long-term ecosystem functioning. However, climate change is increasingly disrupting masting patterns, potentially threatening the natural renewal of forests and the services they provide.

Our project is designed to transform our understanding of tree reproduction by uncovering the mechanisms behind masting and developing tools to predict how these processes will change in a warming world. We aim to achieve this by:
- uncovering the mechanisms of tree reproduction: through field studies, we are testing how environmental factors, such as variations in climate, stand density and trees characteristics, interact to trigger masting events.
- linking reproduction to forest regeneration: By studying long-term patterns of seed production and subsequent seedling recruitment, we seek to understand how changes in masting affect the establishment of new trees.
- predicting future reproductive trends: Leveraging extensive global datasets and innovative modeling techniques, we are developing predictive tools that can forecast changes in tree reproduction under different climate scenarios. This will help identify species and regions at risk and inform forest management strategies.

Overall, our research addresses a critical gap in our knowledge of how trees reproduce and lays the groundwork for more reliable predictions of forest dynamics. The outcomes of our work are expected to support better forest management and conservation policies, ensuring that forests continue to thrive and provide vital ecosystem services in the face of climate change.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

Our project has advanced the understanding of how climate change affects tree reproduction by uncovering mechanisms of masting and creating predictive tools for seed production.

- Seed production forecasting: We developed a sequential forecasting model that incorporates weather variables and prior seed production, improving accuracy—particularly in predicting crop failures. This tool helps forest managers optimize reforestation efforts amid changing climates.
- Trait-based masting: Using data from over 500 species, we found that interannual seed production variability is closely tied to species’ life-history traits. These results support the hypothesis that evolutionary costs of delayed reproduction strongly influence masting behavior.
- Summer solstice: We discovered that European beech synchronizes reproduction using the summer solstice as a fixed astronomical trigger. Rather than solely responding to resource cues, trees abruptly open their temperature-sensing window post-solstice, fundamentally reshaping our understanding of cue integration in masting.
- Regional and spatial analyses: Our studies show that warming increases masting frequency in temperate/boreal zones but leads to fruiting declines in tropical regions. Furthermore, seed scarcity can occur synchronously across areas up to 1800 km apart, underscoring large-scale implications for wildlife dynamics.
- General Model of Masting: We unified 30 years of research into a conceptual framework that integrates both proximate (weather cues, resource availability) and ultimate (predator satiation, pollination efficiency) drivers of tree reproduction. This model provides theoretical framework for predictions of masting under climate change.

Together, these achievements offer an improved scientific foundation for forecasting mast events and guiding sustainable forest management under future climate scenarios.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

A major breakthrough emerged from our finding that European beech aligns its reproductive timing with the summer solstice. While past studies noted that summer temperatures influence flowering uniformly in June and July, the underlying mechanism was unclear. Our research shows that beech trees open their temperature-sensing window immediately after the solstice, effectively using this astronomical event as a trigger for initiating reproduction. This discovery shifts the focus from purely resource-based cues to a combination of photoperiod and weather signals, thereby advancing ecological forecasting and offering new insights into how trees may respond to a rapidly changing climate.

Another state-of-the-art advancement is the creation of a unified framework for masting. This model synthesizes three decades of fragmented research into a coherent theory that integrates both proximate (e.g. environmental variability, weather cues, resource budgets) and ultimate (e.g. predator satiation, pollination efficiency) drivers of seed production. By bridging these aspects, the model offers a more robust, predictive tool for understanding tree reproduction across diverse species under changing climatic conditions.

European beech seeds.