Tree species growth response to climate in mixtures of Quercus robur/Quercus petraea and Pinus sylvestris across Europe - a dynamic, sensitive equilibrium

Quercus robur/Quercus petraea and Pinus sylvestris are widely distributed economically important tree species in Europe co-occurring on mesotrophic, xeric mesic sites. Increasing dry conditions may reduce their growth, but growth reductions be modified by mixture, competition site conditions. The annual diameter monospecific mixed stands along an ecological gradient with mean temperatures ranging from 5.5 °C to 11.5 was investigated this study. On 36 triplets (108 plots), trees were cored the year-ring series cross-dated, resulting of 785 804 for Q. spp. P. sylvestris, respectively. A generalized additive model a logarithmic link fit data random effects intercept at triplet, year level slope covariate age each tree; Tweedie-distribution used. final explained 87 % total variation increment both species. Significant covariates age, climate variables (long-term mean, monthly), local variables, relative dbh, stand structure interactions thereof. Tree declined density increased social position. It positively influenced mixture structural diversity (Gini coefficient); significant only. influence potential evapotranspiration (PET) spring autumn positive non-linear, whereas sharply decreased increasing PET June, which proved most influential month whole gradient. Interactions position (relative dbh) July September April sylvestris. or not significant. Climatic found agree well previous results intra-annual studies indicate that captures causal factors well. Furthermore, interaction between dbh might longer duration higher classes. Analysis across time space showed highly dynamic patterns, competitive advantages changing annually spatial patterns showing no large-scale trends pointing prevalence factors. In mixed-species stands, have same competitivity long-term, is year. Climate warming will shift advantages, direction site-specific.