Identification of drought-tolerant tree species through climate sensitivity analysis of radial growth in Central European mixed broadleaf forests

Abstract

Climate warming and a rise in evaporative demand expose forests to increasing stress, challenging silvicultural planning in many temperate forest regions. As some major timber species are drought susceptible, the choice of native broadleaf minor timbers with assumed higher drought tolerance is a promising alternative option. However, their growth performance and vitality in a warmer and drier climate are not well known. We studied tree-ring chronologies of the Central European minor timbers Acer platanoides L., Fraxinus excelsior L., and Tilia cordata Mill. in comparison to the widely planted Quercus petraea Matt. Liebl in different mixed stands along a precipitation gradient in Central Germany and analyzed the sensitivity of radial growth to climatic drivers and severe drought events with the aim to compare the species’ drought tolerance. While growth responded in all four species positively to summer (or spring) precipitation and negatively to higher summer temperature and climatic aridity, climate sensitivity of growth decreased in the period 1967–2016, proving non-stationarity. Superposed epoch analysis revealed larger growth reduction during severe drought in the diffuse-porous species (A. platanoides, T. cordata) than the ring-porous species (Q. petraea, F. excelsior), but resilience was high in all species. Moreover, none of the species showed negative growth trends with recent climate warming, and drought sensitivity was not higher at drier sites, suggesting a considerable acclimation and adaptation potential to increasing drought stress. As all four species proved to be fairly drought tolerant, they deserve broader consideration in silvicultural concepts targeted at adapting production forests to climate warming.