Temperate Deciduous Forests in Europe under Climate Changewhat can we learn from Romanian beech and oak forests for the future of German forests?

The nemoral (temperate) deciduous forests cover large parts of Central Europe and have important functions for landscape ecology (climate, water, soil, carbon storage) and nature conservation (biodiversity). They supply us with timber, a highly versatile raw material that can be used for anything from building to energy production. Moreover, these forests provide many more goods such as mushrooms, truffels and game meat and are the perfect place to relax, to enjoy nature and to practice recreational activities.

The multiple ecosystem functions and services depend on the composition and vitality of the forests. Climate-related disturbance events and climate-sensitve, vector-borne diseases and global environmental change influence the dynamics and interactions in forest ecosystems. Climate change as determinant in environmental factors has profound consequences on forest growth, the stability and resilience of temperate deciduous forests. Regionalized global climate models (GCMs) have projected to reach + 2.8 ° C average annual temperatures by 2080 for Central Europe for medium greenhouse gas / mid-range anthropogenic radiation levels (RCP 4.5) and a significant increase in climate-induced extreme weather events.

One focus of the project is that tree species of the Central European (sub-) mesophytic beech and mixed beech-oak forests (“competitors”) in Western Romania reach its dry climatic limits and finally of drought-tolerant tree species of the thermophilous Pannonian-Danubian Balkan oak-bitter oak forests (“stress-tolerators”). In a `space for time substitution´approach, three selected altitude transects in Western Romania are examined, which include the following attributes:

  • altitudes between 200 and 750/800 m
  • 90 plots per transect,
  • colline oak level/Balkan oak-bitter oak forests of < 300 m asl; colline-submontane transitional level of mixed oak forests, beech-durmast oaks forests (incl. silver linden stands) from 300-600 m asl; submontane beech level / beech stands at > 600 m asl.

mixed beech-durmast oak stand in Western Romania

In the vicinity of its heat and dryness limited “rear edge occurrences”, the “competitors” form drought-adapted / acclimatized modifications. Beyond that, the light-based stress-tolerators develop remarkable varieties of adaptations. Of particular interest is therefore the Quercus petraea complex.

abundant natural regeneration of durmast oak of mixed oak-stands in Western Romania