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Month: February 2023

“Oak Resilience”: investigating ecological measures to combat oak decline

Oaks can live up to a thousand years and grow to trees of impressive magnitude. They are of great importance, economically and ecologically. Oak wood is hard and resistant and provides a valuable resource for the market. And with over a thousand species of beetles, butterflies, birds and bats, fungi and more living on oaks, these trees are a real biodiversity hotspot.

Since the mid-1980s, however, the condition of oaks in Europe has deteriorated dramatically. This is due to an interaction of climatic extremes, such as drought or late frost, herbivorous insects and mildew. Among these stress factors, insect damage by early defoliators is of particular importance. Oaks generally show a strong ability for regeneration and can regrow their foliation even after complete defoliation. However, if severe defoliation in spring occurs repeatedly or in combination with a second stressor, the oaks’ energy reserves cannot be restored and the tree is lost.

The critical question is: how can we make oaks more resilient? And are there ecological means to combat oak decline? In Germany, committed people from forestry practice and science have joined forces to find solutions. The project “Oak Resilience” investigates the resilience of the native pedunculate oak and sessile oak and looks into predatory parasites –called parasitoids­– of the most important early defoliators in oaks, the winter moth Operophtera brumata, the mottled umber moth Erannis defoliaria and the oak leafroller moth Tortrix viridana. Parasitoid insects are natural antagonists of defoliating insects and are an important regulatory force in the ecosystem. The project will develop recommendations for silvicultural measures to support these natural regulating forces in order to strengthen the oak’s vitality and forest resilience in general. The project is led by Wald und Holz NRW and funded by the FNR (Agency for Renewable Resources; FKZ 22017517). Watch this video to get an introduction to the project – and check our Resilience blog for upcoming project results in 2023.

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Healthy trees translate to healthy citizens

New FORWARDS project will provide crucial information on European forests’ vulnerability to climate change

Climate change has already had a deleterious impact on forests ecosystems and silviculture in various parts of the world. But healthy trees translate to healthy citizens: everyone benefits from forests’ clean air, safe food and water, and recreational space.

With a total budget of €14m funded by the European Commission’s HorizonEurope (plus additional funding by Switzerland and the UK) and more than 19 partners (incl. European Forest Institute) involved, the FORWARDS project (ForestWard Observatory to Secure Resilience of European Forests) will provide timely and detailed information on European forests’ vulnerability to climate change. The project will also deliver science-based knowledge to guide management using the principles of climate-smart forestry, ecosystem restoration, and biodiversity conservation. With its activities, FORWARDS aims at supporting European forests and society to transform, adapt, and mitigate climate-induced changes.

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Re-spiritualizing forests… What in heaven does this mean?!

“In the forests are things you could lie in the moss for years pondering about.” (Franz Kafka) 

With this quotation from a famous local poet, we started our SINCERE project workshop in 2019 in the city of Prague. Experts and enthusiasts of spiritual and cultural values of forests from across Europe and Asia came together for three days to discuss how the “spiritual values of forests” have been relevant in the past as well as the present.  

The result is an exploratory study, based on knowledge from 18 inter-disciplinary experts including natural and social scientists, recently published in Ecology & Society. Funeral forests, forest therapy, and forest bathing: these are all “new” trends, especially in Europe. What is the spiritual fuss over forests about? That’s what we wanted to find out! 

But this spiritual interest in forests is not new at all. Humans have had a close relationship with forests and have been intrigued by their magical nature since forever. Societies depended on forests also for their spiritual development, e.g., sacred natural sites (sacred groves), of which some still exist today. We also know that forests and trees are often central in myths and folklore – thinking about the Brothers Grimm fairytales, but also myths including the mystical and magical power of certain tree species such as the oak…. (and again, even in art and films today such as Lord of the Ring’s Treebeard character and Avatar). 

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Experiencing an excursion through the eyes of a forest modeler 

For the RESONATE project, my task aims at developing high resolution future forest trajectories and disturbance maps for the European continent. Continental scale modelling always comes along with trade-offs regarding the detailed processes. Taking this into account, we follow a bottom-up approach, where we use detailed information from local process-based forest simulations to train deep neural networks. For this, we collected forest simulations under different climate scenarios from hundreds of locations across Europe, covering large gradients of environmental and climatic conditions. By combining simulations from different regions, we can explore the relationship between forest dynamics and climate signals using deep neural networks. These neural networks learn to represent forest dynamics depending on environmental and climate conditions, allowing us to upscale the forest dynamics to continental scale. We believe that with this approach we will make a step towards better capturing local scale dynamics at the macroscale.  

But guess what, forest modeling means we spend most of the time in front of our screen, working on code and data that eventually allow a glimpse into the future of forest ecosystems. Although I spend a lot of my leisure time hiking, cycling and sometimes ski touring in the mountains, professionally I spend very little time in the field. Therefore, I was really happy to join the excursion as part of a conference we organized in Berchtesgaden some months ago. The occasion to go to the field with colleagues who spend a lot of time there and visit the system that I am currently modelling is very special and of course informative. And for me, coming from a macroecology background, it is also particularly important to see gradients in the mountain landscape and discuss their impact on vegetation processes as well as disturbances.

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