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Causes and consequences of forest reorganization: Towards understanding forest change

Periodic Reporting for period 1 - FORWARD (Causes and consequences of forest reorganization: Towards understanding forest change)

Reporting period: 2021-10-01 to 2023-03-31

Forest ecosystems around the globe are undergoing rapid reorganization. The unabated continuation of climate change, the accelerating rate of alien species introductions, and the precipitous loss of biodiversity are altering the structure and composition of forest ecosystems. As a consequence, the emergence of novel ecosystems is virtually certain. However, the trajectories to novelty and the consequences thereof remain widely unknown. This limits the ability of forest policy and management to counteract undesired developments and safeguard the supply of ecosystem services to society. The FORWARD project investigates the causes and consequences of reorganization in forest ecosystems, jointly studying the effects of global change on tree mortality and regeneration. We use a concerted combination of complementary methodological approaches operating at different spatial scales to understand why reorganization takes place, when and where it is likely to happen, and what impacts reorganization will have on biodiversity and ecosystem services. Extensive experiments are conducted both in the field and in walk-in climate chambers to answer whether compounding climatic extremes could result in bottlenecks of forest regeneration. A next-generation forest landscape model is used to investigate how climate change and alien species alter long-term forest dynamics. Based on these insights the FORWARD project generates operational early warning indicators of reorganization, and conducts in-situ tests of their generality and applicability on three continents. Also, a global synthesis effort will analyze global hotspots of forest reorganization, while regionally robust strategies for addressing reorganization in management will be developed. The FORWARD project will bring about a new level of understanding of forest change, and will provide the data, tools and strategies to tackle one of the most pressing challenges of current forestry.
In the first 18 months of the project, the FORWARD team has made the following major achievements:
– the development and publication of a conceptual framework of post-disturbance forest reorganization, setting the agenda and frame for the analyses conducted within the project (WP0);
– the setup of a suite of experiments to test interactive abiotic and biotic drivers of forest reorganization in situ (Berchtesgaden National Park) as well as in walk-in climate chambers (WP1);
– work towards the next-generation forest landscape model iLand 2.0 with focus on the implementation of forest microclimate, forest floor vegetation dynamics, and permafrost in the iLand simulation framework (WP2);
– data harmonization and model evaluation across the three FORWARD study sites, enabling consistent cross-site analyses of future trajectories of forest reorganization (WP3);
– the analysis of reorganization impacts with a specific focus on economic effects of disturbance and resilience (WP4); and
– the assessment of global hotspots of climate risks in forest ecosystems (WP5)
Overall, the FORWARD team has published 14 papers in peer-reviewed journals in the first 18 months of the project, including works in Science, PNAS, and Global Change Biology.
The project has made considerable progress beyond the state of the art, including
- the presentation of an operational framework to assess and quantify forest reorganization (;
- important insights on novel forest disturbances, e.g. the finding that forest fires could become more important also in parts of Europe not currently affected by fires, such as Central Europe (;
- a better understanding of potential future forest change in Central Europe, including the insight that climate-mediated changes in the forest disturbance regimes might be more important for future forest trajectories than the direct effects of warming (;
- an assessment of how processes important for simulating forest reorganization, such as tree mortality and regeneration, are represented in models (; and
- the identification of global climate risks to forests (

Until the end of the project we expect further progress from
- experiments on abiotic and biotic drivers of forest reorganization;
- the completion and application of a next-generation forest landscape model towards questions of forest reorganization;
- a comparison of reorganization patterns and processes across landscapes with different disturbance history and disturbance response mechanisms;
- the evaluation of specific forest management strategies in the context of changing forest disturbance regimes; and
- analyses of reorganization impacts on biodiversity and ecosystem service supply.
A concept of post-disturbance forest reorganization (Seidl & Turner 2022, PNAS 119, e2202190119)