Managing mountain forests undergoing changing disease / disturbance dynamics
Lead Author: Thomas Dirnböck (EAA)
Contributors: Ralf Kiese (KIT), Kobler Johannes (EAA), Dimitris Poursanidis (FORTH), Guy Ziv (UnivLeeds)
Mountain forests in Europe have been fundamentally changed through hundreds of years of exploitation and management. Besides large-scale clear cutting due to high wood demand from industry and households, the natural composition of trees was altered in many areas with planting monoculture conifer forests aiming for maximal economic return, mainly due to timber and pulp/paper production. Yet, these forests are less resilient to disturbances brought by direct and indirect impacts of climate change such as drought, storm events and insect infestations (e.g. bark beetle on Norway spruce) (Seidl et al. 2014, Zang et al. 2014). Monoculture forests are also less diverse as to their non-woody plant and animal species.
Climate change is already and will in future impact mountain forests in several ways. Warming will cause upward shift of suitable habitats for tree, plant and animal species (e.g. Dirnböck et al. 2011). Higher temperature together with more severe droughts will tighten water deficits during summer and thus increase the vulnerability of trees to insect infestation and natural hazards like wildfires (Seidl et al. 2014). As a result, tree mortality will increase, possibly more so for tree species with low water use efficiency. These perturbations, which are already ongoing in the forests of the European Alps (e.g. in the Limestone National Park in Austria) will fundamentally impact ecosystem services of mountain forests. Climate, tree composition and forest structure are intimately linked to forest growth, carbon and nutrient cycling (Kurz et al. 2008). Furthermore, insect outbreaks and storm events will alter biodiversity (Thom & Seidl 2015) and will be challenging the human perception of how recreation forests need to look like (Beudert et al. 2015).
Mountain forest management has developed a large palette of measures to increase wood production. Though yields have been the main concern, other measures have also evolved to optimize mountain forest stability and/or biodiversity where this is the main focus e.g. in protection forest or forest conservation areas (Duncker et al. 2012). Climate change driven disturbances are a new challenge for forest managers when they aim at maintaining forest ecosystem services and biodiversity (Thom & Seidl 2015, Thom et al. 2016). Moreover, it is feared that these measures together with management strategies aiming to increase the forest carbon sink will not be able to offset the disturbance-related reduction of the carbon storage potential in Europe’s forests (Seidl et al. 2014). In order to improve our knowledge we will carry out a case study in the Northern Limestone Alps National Park in Austria focussing on the carbon sink strength in this mountain forest landscape that is and will be prone to climate driven disturbances such as bark beetle attacks and wind throw.
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Kurz, W. A., C. C. Dymond, et al. 2008. Mountain pine beetle and forest carbon feedback to climate change. Nature 452: 987-990.
Seidl, R., Schelhaas, M.-J., et al. 2014. Increasing forest disturbances in Europe and their impact on carbon storage. Nature Climate Change 4: 806-810.
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Thom, D., Rammer, W., et al. 2016. The impacts of climate change and disturbance on spatio-temporal trajectories of biodiversity in a temperate forest landscape. Journal of Applied Ecology (in press).
Zang, C., Hartl-Meier, C., et al. 2014. Patterns of drought tolerance in major European temperate forest trees: climatic drivers and levels of variability. Global Change Biology 20: 3767-3779.