Final Report Summary - SAGE (Simulating adaptation of forest management to changing climate and disturbance regimes)
Forest disturbance regimes have intensified distinctly in recent decades, and climate change is expected to further increase the frequency and severity of natural disturbances. Adaptation is thus necessary to mitigate detrimental effects of disturbance change on the sustainable provisioning of ecosystem services. However, while we’re beginning to understand the responses of individual disturbance agents to a changing climate, our knowledge on disturbance regimes (i.e. multiple agents interacting in space and time) is still limited. The development of adaptation strategies is further complicated by remaining deficiencies in our conception of forests as coupled human and natural systems. While forest models are increasingly able to simulate climate change impacts dynamically, human responses to these ecosystem changes are still widely represented as static prescriptions in such models, neglecting the adaptive capacity in silviculture. The overall objective of SAGE was to foster adaptation to changing climate and disturbance regimes in forest management. We studied disturbance regimes and management responses empirically, and subsequently integrated them in a dynamic simulation framework that allows for scenario analyses under expected future climate conditions.
We found that forest disturbances from wind, bark beetles, and wildfire have approximately tripled in Europe between 1970 and 2010, increasing by an additional 1 Million m³ of damaged timber on average per year. Projections under different management strategies and climate scenarios suggest a further increase until 2030, and considerable negative impacts on forest carbon storage. At the local scale we found that recent unprecedented beetle outbreaks in Central Europe were to a large degree driven by regional-scale drivers (i.e. factors that are beyond the control of stand-scale management), and were temporally synchronized by summer drought events. Furthermore, disturbance interactions have contributed significantly to recent extensive disturbance events in Central Europe, and amplify the future climate sensitivity of the disturbance regime in the region.
These changes in disturbance regimes have a largely negative impact on ecosystem services, reducing provisioning, regulating, cultural, as well as supporting services provided to humans by forest ecosystems. Consequently, forest managers are particularly sensitive to changes in the disturbance regime. In a questionnaire study conducted in Austria many managers stated that they already perceive climate-induced changes in their forests, and a subset of them will also actively adapt their management in response to these changes (while another subset states that climate change impacts do not influence their management decisions).
However, disturbances also increase the species diversity in forests, and even an increasing disturbance activity – as expected under climate change – will likely still benefit the overall diversity of forest ecosystems in Central Europe. This is of high relevance as we identified increased structural and compositional diversity as a key mechanism of resilience in forest ecosystems. Carbon uptake and storage, for instance, suffers less from disturbances in species-rich forests compared to species-poor forests. Also, increased structural diversity after disturbance reduces the risk for further large-scale disturbance events. Furthermore, not only diversity in species and structures but also diversity in management responses (e.g. in multi-owner landscapes) can aid the adaptation to changing conditions, as it creates response diversity and counteracts homogenization and synchronization on the landscape. Disturbances can catalyze the adaptation of forest ecosystems to a rapidly changing climate, by creating niches for new, and better climate-adapted species.
Overall, the project contributed to a better understanding of the causes and consequences of changing disturbance regimes. It provides the crucial scientific underpinning for developing local, place-based adaptation strategies for sustainable forest management under changing climate and disturbance regimes. It furthermore significantly advanced our ability to simulate disturbance interactions and management responses to disturbances. All simulation code and executables developed during the project can be downloaded from the website http://iLand.boku.ac.at which also contains an extensive online documentation.
We found that forest disturbances from wind, bark beetles, and wildfire have approximately tripled in Europe between 1970 and 2010, increasing by an additional 1 Million m³ of damaged timber on average per year. Projections under different management strategies and climate scenarios suggest a further increase until 2030, and considerable negative impacts on forest carbon storage. At the local scale we found that recent unprecedented beetle outbreaks in Central Europe were to a large degree driven by regional-scale drivers (i.e. factors that are beyond the control of stand-scale management), and were temporally synchronized by summer drought events. Furthermore, disturbance interactions have contributed significantly to recent extensive disturbance events in Central Europe, and amplify the future climate sensitivity of the disturbance regime in the region.
These changes in disturbance regimes have a largely negative impact on ecosystem services, reducing provisioning, regulating, cultural, as well as supporting services provided to humans by forest ecosystems. Consequently, forest managers are particularly sensitive to changes in the disturbance regime. In a questionnaire study conducted in Austria many managers stated that they already perceive climate-induced changes in their forests, and a subset of them will also actively adapt their management in response to these changes (while another subset states that climate change impacts do not influence their management decisions).
However, disturbances also increase the species diversity in forests, and even an increasing disturbance activity – as expected under climate change – will likely still benefit the overall diversity of forest ecosystems in Central Europe. This is of high relevance as we identified increased structural and compositional diversity as a key mechanism of resilience in forest ecosystems. Carbon uptake and storage, for instance, suffers less from disturbances in species-rich forests compared to species-poor forests. Also, increased structural diversity after disturbance reduces the risk for further large-scale disturbance events. Furthermore, not only diversity in species and structures but also diversity in management responses (e.g. in multi-owner landscapes) can aid the adaptation to changing conditions, as it creates response diversity and counteracts homogenization and synchronization on the landscape. Disturbances can catalyze the adaptation of forest ecosystems to a rapidly changing climate, by creating niches for new, and better climate-adapted species.
Overall, the project contributed to a better understanding of the causes and consequences of changing disturbance regimes. It provides the crucial scientific underpinning for developing local, place-based adaptation strategies for sustainable forest management under changing climate and disturbance regimes. It furthermore significantly advanced our ability to simulate disturbance interactions and management responses to disturbances. All simulation code and executables developed during the project can be downloaded from the website http://iLand.boku.ac.at which also contains an extensive online documentation.