Details

Autor(en) / Beteiligte

• Albrich, Katharina
• Rammer, Werner
• Seidl, Rupert

Titel

Climate change causes critical transitions and irreversible alterations of mountain forests

Ist Teil von

• Global change biology, 2020-07, Vol.26 (7), p.4013-4027

Ort / Verlag

England: Blackwell Publishing Ltd

Erscheinungsjahr

2020

Link zum Volltext

Quelle

Wiley Online Library All Journals

Beschreibungen/Notizen

• Mountain forests are at particular risk of climate change impacts due to their temperature limitation and high exposure to warming. At the same time, their complex topography may help to buffer the effects of climate change and create climate refugia. Whether climate change can lead to critical transitions of mountain forest ecosystems and whether such transitions are reversible remain incompletely understood. We investigated the resilience of forest composition and size structure to climate change, focusing on a mountain forest landscape in the Eastern Alps. Using the individual‐based forest landscape model iLand, we simulated ecosystem responses to a wide range of climatic changes (up to a 6°C increase in mean annual temperature and a 30% reduction in mean annual precipitation), testing for tipping points in vegetation size structure and composition under different topography scenarios. We found that at warming levels above +2°C a threshold was crossed, with the system tipping into an alternative state. The system shifted from a conifer‐dominated landscape characterized by large trees to a landscape dominated by smaller, predominantly broadleaved trees. Topographic complexity moderated climate change impacts, smoothing and delaying the transitions between alternative vegetation states. We subsequently reversed the simulated climate forcing to assess the ability of the landscape to recover from climate change impacts. The forest landscape showed hysteresis, particularly in scenarios with lower precipitation. At the same mean annual temperature, equilibrium vegetation size structure and species composition differed between warming and cooling trajectories. Here we show that even moderate warming corresponding to current policy targets could result in critical transitions of forest ecosystems and highlight the importance of topographic complexity as a buffering agent. Furthermore, our results show that overshooting ambitious climate mitigation targets could be dangerous, as ecological impacts can be irreversible at millennial time scales once a tipping point has been crossed. Climate change is expected to have strong impacts on mountain forests, changing their size structure and species composition. We used a forest landscape model to simulate climate change impacts on a Central European mountain forest landscape. The forest exhibited extreme changes in structure and composition, shifting to an alternative state under stronger climate forcing. Complex mountain topography helped to buffer the impacts of climate change but changes in forest structure and composition were not easily reversible even after the climate forcing was reversed.