Forest rejuvenation - the process in which new trees establish themselves and start to grow - is very important for the future forest structure, biodiversity, growth and resilience of the forest. When new trees start to grow, it marks the beginning of an important process. This phase is crucial for the future forest. Predicting forest regeneration at European scale was very limited to date. Existing approaches often rely on where species are currently found, rather than modeling the ecological processes that drive regeneration
Huge Dataset
To overcome this limitation, the researchers collected a huge and unique dataset of forest inventories in 11 European countries. They looked at 95,000 forest locations. They analyzed how climate and weather conditions influence regeneration, but also how the current forest structure affects it. The model that came out predicts which species will grow where, as well as the number of young trees that will come up and in what type of forest they thrive. This model represents a big step for long-term forest management.
Climate is crucial
The analysis shows that climatic conditions are very important for the success of saplings. Rejuvenation of the forest is successful under stable climatic conditions and a lot of rain? high precipitation. But this process will be a lot less successful if the weather is extreme or the temperature is high. It also shows that deciduous tree species do have better chances at slightly higher temperatures than normal, which also shows their adaptability.
Mixed forests rejuvenate
Prof. Gert-Jan Nabuurs: "The composition of the young trees was again very dependent on the composition of the old forest. This is worrying because a large proportion of European forests often consist of only one coniferous species. Mixed forests showed more rejuvenation. We also learn from this that the current drought is not just affecting the big trees (less growth), but rather the small ones. One extreme drought can cause certain species to drop out and with that you define that piece of forest for decades to come."
Predict future forests
Louis König, researcher: "this study provides tools to predict what the future forest will look like. We can use this to better guide long-term management. Management will have to give more space to deciduous species and mixed forests. This requires good knowledge of management and future favorable species in that location.