Higher growth synchrony and climate change-sensitivity in European beech and silver linden than in temperate oaks

AimClimatic changes affect the growth dynamics of temperate trees, but these effects might differ between co-occurring ring- and diffuse-porous species as well as between mesic and xeric rear-edge populations. We explore whether recent climate warming has increased the climate sensitivity and within-stand synchrony of growth in these groups differently. LocationThe natural beech-oak ecotone in Western Romania at the dry margin of beech occurrence. TaxaThree ring-porous oak species (Quercus petraea, Q. frainetto and Q. cerris), and diffuse-porous European beech (Fagus sylvatica) and silver linden (Tilia tomentosa). MethodsWe correlated tree-ring records with monthly and seasonal climate data (period 1940-2017). Regional growth synchrony was assessed through the analysis of inter-series correlation of growth within populations and among populations using mixed models. ResultsIn all five species including two south-east European oak taxa and silver linden, water availability in summer was the most important climatic determinant of radial growth. This factor has gained in importance since the onset of rapid warming after 1980, while the impact of other climate factors in spring and summer has decreased. Within-population growth synchrony as a measure of overall climatic stress has increased, or remained stable, since 1980 in beech and silver linden, but has decreased in the oak species, matching declining growth trends in beech and linden and increasing (or stable) trends in the oaks. Main ConclusionsThe patterns of growth synchrony provide valuable information on tree species' drought susceptibility in efforts to select suitable tree species for climate change-adapted forestry. The climate vulnerability of beech is higher than that of the more drought-resistant oak species due to its marked summer-drought sensitivity of growth.

Automated summary

This study investigated whether climate sensitivity and growth synchrony of temperate trees have changed under recent climate warming. The results showed that water availability, especially in summer, was the most important factor affecting radial growth in all five species. Recent climate warming has increased the impact of water availability on growth while decreasing the influence of other climate factors in spring and summer. Within-population growth synchrony has increased or remained stable in beech and silver linden, but decreased in oak species. These findings have implications for selecting climate change-adapted tree species in forestry.