Oaks for future forests and forestry in Slovenia: Quercus robur versus Quercus petraea

Forests are at the forefront of our efforts to mitigate climate change and achieve the UN’s Sustainable Development Goals (SDGs), to ensure a sustainable life on Earth. However, combined with biotic stress, the expected increase in frequency and intensity of extreme weather events will affect tree growth and viability, thereby altering the stability and productivity of natural and managed forests. In addition, tree species distribution ranges and forest composition are likely to change, affecting global timber supply, demand and production. Therefore, knowledge of the functional and structural traits of a tree species and of the effects that climatic variables and silvicultural management decisions have on tree performance is a key factor in assessing and preserving the sustainability of forests. This project focuses on two temperate, ecologically and economically important oak species in Slovenia: Q. robur versus Q. petraea; their future distribution and growth potential. For disentangling climate-growth relationship of the two species, reliable identification of these sympatric and hybridising species is needed as a first step. Thus, our national data on morphological distinctions need to be reviewed, supported with advanced genetic analyses and compiled in a common database. Secondly, environmental experiments on young trees of Q. robur and Q. petraea will reveal more detailed species-specific functional-structural response to identical natural environmental conditions (including the effects of abiotic and soil microbial factors) during regeneration, the critical phase of new forest establishment. This part will be done in the Krakovo lowland oak forest, where in recent years the decline and mortality of Q. robur has been regularly reported. Therefore, evaluation and comparison of the growth variability of Q. robur and Q. petraea on this plot is critical for future projections of the distribution of the two oak species. Finally, the available equipment (eddy covariance tower) in the Krakovo oak forest and tree-ring data from this project will be used (1) to assess forest functioning in different environmental conditions and (2) to model future potential of tree growth and ecosystem carbon sequestration in endangered Q. robur lowland stands. The project will be organized in five working packages (WPs), which will cover all planned activities. WP5, dedicated to management, communication and dissemination of project results will support all WPs, while WPs 1–4 are thematic: WP1: Tools for identification of Q. robur and Q. petraea; WP2: Monitoring in mature oak stands; WP3: Young tree performance in natural conditions; WP4: Upscaling to the ecosystem and regional levels – modelling and measurements, and WP5: Project management and dissemination. The research comprises data review and unification (i.e., morphological data for updating the tree species determination key, site selection), experimental work (performance of young Q. robur and Q. petraea trees in natural conditions) and modelling (future performance of the studied oak species in Slovenia and future carbon sequestration strength for the studied ecosystem). The experimental work will be divided into two parts: (1) analysing mature oak stands (WP1, WP2 and WP4) and (2) environmental experiments on young trees (WP3 and WP4). The proposed research subject is complex as it combines state-of-the-art knowledge of different research groups that study forest ecosystems at different spatio temporal scales, combining both novel and well-established methodologies from the fields of forest genetics, tree biology, ecophysiology, mycology and dendroecology. We intend to use data and results obtained in the previous studies and by that maximally exploit and justify funding of previous projects.