Stakeholders from the forestry sector in Slovakia were recently able to learn more about the preliminary results of the HoliSoils project as well as the national PROBIOFOR project (Trade-offs between biomass production and biodiversity in beech and spruce forests under changing environmental conditions) at a workshop and field visit organised by the Technical University of Zvolen. This event, which brought together more than 40 participants from the state and private forestry sector, was held on 12 October and was attended by, among others, the Administration of the Protected Landscape of the Poľana Mountains, the State Nature Protection of Slovakia, Pro Silva Slovakia, the National Forestry Centre and the Technical University of Zvolen and Slovak public media journalists.
The workshop started with four introductory lectures explaining to the participants climate change and its effects on forest ecosystems, the adaptation potential of tree species and the carbon balance of forest ecosystems. The programme continued with an excursion to the old-growth forest of Dobroc (a national nature reserve since 1913), including a visit to the test area established for the HoliSoils project.
The preliminary results that were shared with the participants can be summarised as follows:
- Norway spruce trees are more affected by extreme weather conditions than European beech and silver fir. Fir and beech trees even created a larger increment in 2022 than in 2021, which was vice versa for the spruce trees.
- Norway spruce trees strongly suffered from the drought of 2022, which together with a mild winter condition lowered its ability to protect against bark beetle invasion, leading to a large-scale disturbance in 2023.
- Soil water storage and its availability to trees was also heavily affected by the drought in 2022. As early as April, the soil water content had already dropped below 10%, touching 5%, on the test site in spruce monoculture, whereas it remained at a level of around 20–30% on the test site in the nearby mixed forest by the end of June.
- Soil CO2 fluxes were larger in the mixed forest compared to the spruce monoculture, likely due to higher microbial diversity and activity in the soil. It was also shown that the largest differences between the spruce monoculture and the mixed forest were at higher temperatures during the summer. However, during the drought, the differences were almost negligible. Carbon increment in the above- and below-ground biomass was approximately between 3.5 and 4.5 t C ha-1 yr-1, whereas the C emission from the soil was found to be around 5 – 6 t C ha-1 yr-1 in the spruce and 7 – 8 in the mixed forest. During the field trip, it was stressed that soil carbon and fluxes have to be considered when discussing the potential of forest ecosystems to sequester carbon from the atmosphere.
Journalists from the main public Slovak radio and television stations took part in the workshop. The reportage was broadcast on the RTVS Regina show on 17 October 2023.