Dynamics and Adaptation of Natural Forests to Climate Change

Increased frequency of drought years with alarming forest decline is challenging forestry and society. The longevity of forest ecosystems as well as the extent and ecological diversity of forest areas hinder the attribution of causes and effects of the decline. Foresters, organisations and public are struggling for adequate reactions to the crisis. While areas left to natural forest development (NFD) have often been perceived in terms of biodiversity conservation, climate change calls for reconsidering their role as a reference for forest management. NFD-areas are the only ones, where mortality of trees and stands and their effect on forest development can be observed without interference of timber harvesting. Further, they are indispensable for deciding whether managed or natural forests exhibt higher resistance and resilience towards climate change and to what degree silvicultural adaptation measures can be replaced by self-organised forest dynamics. An integrated analysis of the development of NFD areas in conjunction with adjacent managed forests promises answers to related pressing questions.

The project quantifies extent, intensity and ecological consequences of drought and heat damages in NFD and compares them to adjacent managed forests. It is tested whether and under which preconditions forests show a self-organised adaptation to climate change. Recommendations for implementing natural processes into adaptation strategies will be made. NFD represent an important reference system for biodiversity conservation and close-to-nature forestry. Many unmanaged forests have been designated several decades ago as natural forest reserves and core zones of national parks. The devlopment of forest decline in the drought years 2018 and 2019 and subsequent changes in disturbance regimes and gap dynamics shows that they deserve a key role in detecting climate change effects and in adapting forests to climate change (Fig. 1). The project assesses this potential including the transfer to managed forests and dervies recommendations for risk management and adaptation strategies.

The four work packages (WP1-4, Fig. 2) will answer the following questions:

• What is the significance of NFD areas for forest management and climate change research?
  
• Can findings from unmanaged forests support the adaptation of managed forests to climate change and, if yes, to what extent?
  
• How do conclusions differ by site and forest types?
  
• Do effects of recent extreme events on forest growth, structure and biodiversity differ between NFD and managed forests?
  
• Are NFD more resilient towards climate chnage than managed forests?
  
• Which requisites of NFD (deadwood, biotope trees, gaps) increase resistance and resilience of forest stands and can contribute to the stabilisation of managed forests?
  
• What is the contribution of disturbances to biodiversity, in particular of insects (in the context of "insect decline"), and how should disturbances be managed with regard to biodiversity?
  

In WP5 results will be synthesized and discussed with forest managers and stakeholders in a workshop. The scientific results can form the basis of climate adaptation strategies for managed forests as well as of concrete recommendations for forest management. This concerns the magement intensity and resilience of forests (improved climate adaptation by requisites from natural forests) and the handling of biotic and abiotic disturbances (intensity of salvage logging, reforestation and successsion with/without planting). The range of the study transect from the lowlands to the subalpine belt will allow a differentation by climatic conditions and forest types. Finally, these recommendations will bei discussed and refined in a second, concluding workshop with practitioners and stakeholders.