A multi-criteria drought resistance assessment of temperate Acer, Carpinus, Fraxinus, Quercus, and Tilia species

Abstract

A rapidly warming climate with growing frequency of hot droughts urges Central Europe’s forestry sector to adapt to increasing climatic stress. One option is to choose native minor timber species with assumed higher stress tolerance; yet, information on the drought resistance of many species is scarce. We examined the drought resistance of adult trees of Norway maple (Acer platanoides), European hornbeam (Carpinus betulus), Common ash (Fraxinus excelsior) and Little-leaved lime (Tilia cordata) at leaf, branch, stem and root levels, combining studies on leaf water status, branch xylem hydraulics, fine root vitality and radial stem growth, for deriving an evidence-based drought resistance ranking of the species. Results were compared to Sessile oak (Quercus petraea), a fairly drought-resistant major timber species. All species showed constant growth rates despite increasing climatic aridity, indicating low climate vulnerability. Foliage loss after the severe 2018/19 drought increased in the sequence Quercus < Fraxinus < Acer < Tilia < Carpinus. The water potential at leaf turgor loss (P_TLP) was no suitable indicator of the species’ climate-sensitivity of growth or drought-induced foliage loss. The growth performance of Tilia demonstrates that some angiosperm trees can achieve a fairly high degree of drought resistance through plant-internal water storage and high leaf tissue elasticity, despite a small hydraulic safety margin and high P_TLP. Drought resistance as deduced from growth performance and defoliation after severe drought decreased in the sequence Quercus > Fraxinus & Acer > Tilia > Carpinus. We conclude that Acer, Carpinus, and Tilia (and Fraxinus, despite being often Hymenoscyphus-infected) are suitable timber species for Central Europe’s forestry sector in a drier and warmer climate.