Drought resistance of major tree species in the Czech Republic

In recent decades, extreme droughts have affected Central Europe, altering forest structure and function with significant socioeconomic consequences. Most Central European forests are used for timber production and provide various ecosystem services and habitats for forest-dwelling species. The extent to which recent weather extremes have impacted these forests was poorly quantified. Furthermore, the drivers of drought resistance remain uncertain, potentially misleading predictions of future forest development. In this study, we analyzed the impacts of recent droughts on the growth of managed forests in the Czech Republic based on tree-ring width of five common and commercially important tree species, European beech (Fagus sylvatica), Norway spruce (Picea abies), Scots pine (Pinus sylvestris), sessile oak (Quercus petraea), and pedunculate oak (Quercus robur). We assessed the 2015-2019 "dry period", which contains two extreme droughts. We also examined the drivers of growth reductions during three major drought events (2003, 2015, 2018) between 1995 and 2019, including the effects of tree age, size, elevation, and drought intensity. We identified drought-induced growth reductions for all five species during the "dry period" compared with the 2005-2009 "reference period", and Scots pine exhibited the highest resistance to drought (-13% growth) whereas Norway spruce showed the highest drought sensitivity (-30% growth). However, for the two recent droughts, the resistance of the three broadleaved species was higher than the two coniferous species. The effects of age and elevation on drought resistance varied with drought intensity. And European beech trees at lower elevations were significantly more negatively affected by droughts than trees at higher elevations. Our results indicate that a highly variable growth response to drought across species can be expected as climate changes. Under warmer and drier conditions, growth reductions could be more pronounced for drought-sensitive species at lower elevations, potentially threatening timber supply sustainability and other services.