Managing mountain forests undergoing changing disease / disturbance dynamics
PA: Kalkalpen National Park, Austria (Northern Limestone National Park, Austria)
Active participants (names and institutions):
Thomas Dirnböck, Environment Agency Austria
Johannes Kobler, Environment Agency Austria
Ralf Kiese, Karlsruhe Institute of Technology, Germany
David Kraus, Karlsruhe Institute of Technology, Germany
Edwin Haas, Karlsruhe Institute of Technology, Germany
Rüdiger Grote, Karlsruhe Institute of Technology, Germany
Mihai Tanase, University of Melbourne, Australia
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). 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. As a result, tree mortality is increasing (Senf et al. 2018), possibly more so for tree species with low water use efficiency. These perturbations are and 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). Mountain forest management has developed a large palette of measures to increase wood production and forest stability, yet climate change driven disturbances are a new challenge for forest managers.
Various sources of information such as airborne images, long-term field and LiDAR data were used to initialize and calibrate two ecosystem models for the Kalkalpen National Park in Austria. In their modelling effort, Thom et al. (2017) showed that expected climate change will very likely increase bark beetle disturbances during the 21st century, thereby reducing the climate regulation function of the landscape. Using the same data source, we detailed the landscape carbon cycle, revealing that the cumulative carbon sink over the last 15 years was between 16 per cent and 37 per cent higher if accounting for the effect of tree regeneration and of ground vegetation compared to simulations without these components (Dirnböck et al. in prep). Capitalizing, particularly from the potential of tree regeneration to its full extent will very likely be difficult considering the current degree of damage by ungulate browsing in Austria (Reimoser and Reimoser 2010, Hangler 2017).
Apart from the above findings, two methodological issues were resolved. First, we could show that although varying altitudes and aspects within small distances in mountainous areas complicate the accurate quantification of forest carbon dynamics at larger scales, modelling with a resolution of 100 x 100 m was suitable (Kobler et al. 2019). Second, we assessed the potential of EO products for the upscaling of plot data to the landscape. Albeit LiDAR products can reasonably predict forest structure and composition, upscaling of more complex carbon cycle parameter, such as gross primary production (GPP) or the net carbon sink (NEP, NEE), improved significantly when augmented with an extended set of predictor variables related to site and soil conditions (Kobler et al. in prep).
Hangler, J. 2017. Wildschadensbericht 2016. Bundesministerium für Land- und Forstwirtschaft, Umwelt und Wasserwirtschaft, Vienna, Austria.
Reimoser, F., and S. Reimoser. 2010. Ungulates and their management in Austria. Pages 338356 in M. Apollonio, A.
Andersen, and P. Putman, editors. European Ungulates and their Management in the 21th Century. Cambridge University Press.
Seidl, R., M.-J. Schelhaas, W. Rammer, and P. J. Verkerk. 2014. Increasing forest disturbances in Europe and their impact on carbon storage. Nature Clim. Change 4:806-810.
Senf, C., D. Pflugmacher, Y. Zhiqiang, J. Sebald, J. Knorn, M. Neumann, P. Hostert, and R. Seidl. 2018. Canopy mortality has doubled in Europes temperate forests over the last three decades. Nature Communications 9:4978.
Thom, D., W. Rammer, and R. Seidl. 2017. The impact of future forest dynamics on climate: interactive effects of changing vegetation and disturbance regimes. Ecological Monographs 87:665-684.
Zang, C., C. Hartl-Meier, C. Dittmar, A. Rothe, and A. Menzel. 2014. Patterns of drought tolerance in major European temperate forest trees: climatic drivers and levels of variability. Global Change Biology 20:37673779.
Dirnböck et al. (in prep for Landscape Ecology). Substantial understory contribution to the C sink of a European temperate mountain forest landscape.
Kobler, J., B. Zehetgruber, T. Dirnböck, R. Jandl, M. Mirtl, and A. Schindlbacher. 2019. Effects of aspect and altitude on carbon cycling processes in a temperate mountain forest catchment. Landscape Ecology. https://doi.org/10.1007/s10980-019-00769-z
Kobler et al. (in prep for Remote Sensing of the Environment). Upscaling of model-derived GPP, TER, Ra, NEE and aboveground biomass with LiDAR and extended data.
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Last update: May, 2019