Key European tree species are expected to contract their ranges under changing climate, thus there is a need to assess range shifts for other native tree species that could fill their forest niche. Recent studies have focused on economically important species, revealing a wide range of shifts in their distribution worldwide and highlighting several pathways for potential future changes. We aimed to quantify changes in projected ranges and threat levels by the years 2041-60 and 2061-80, for 20 European temperate forest tree species under four climate change scenarios. We compared ten standard stock tree species with ten alternative stock species, that are less frequent and less preferred by managers. We combined distribution data from several sources for each tree species and developed species distribution models using MaxEnt and seven bioclimatic variables. We applied these models to projections of future climate from four global circulation models, under four Shared Socioeconomic Pathways and for near and middle terms: 2041-60 and 2061-80. We also assessed the relationships between predicted range contraction and their functional traits. Analysis of MaxEnt models divided the studied tree species into three groups: non-threatened (Sorbus torminalis, Ulmus minor, Tilia platyphyllos, Acer pseudoplatanus, Prunus avium, and Carpinus betulus), partially threatened (U. laevis, Betula pendula, Quercus robur, Q. petraea, A. platanoides, Fagus sylvatica, Fraxinus excelsior, T. cordata, Alnus glutinosa, and U. glabra), and the most threatened (Abies alba, Larix decidua, Picea abies, and Pinus sylvestris). For the last group, almost half of the range contraction will occur earlier (2041-2060) compared to our previous predictions (2061-2080). The proportion of range contraction decreased with increasing specific leaf area, leaf area, leaf nitrogen content, seed mass, and specific stem density while it increased with increasing height. Our study provides novel predictions of shifts in climatic optima under the most recent climate change scenarios, which would be useful for evidence-based conservation and management of European forests. The near-term predicted threats to the main standard stock tree species call for intensified preparation for incoming changes. We recommend splitting the silvicultural risks over a wider range of tree species, also including alternative stock species.

Juglans regia L. is a species of great importance for environmental management due to attractive wood and nutritious fruits, but also high invasive potential. Thus, uncertainties connected with its range shift are essential for environmental management. We aimed to predict the future climatic optimum of J. regia in Europe under changing climate, to assess the most important climatic factors that determine its potential distribution, and to compare the results obtained among three different global circulation models (GCMs). We used distribution data from the Global Biodiversity Information Facility and completed it with data from the literature. Using the MaxEnt algorithm, we prepared a species distribution model for the years 2061–2080 using 19 bioclimatic variables. We applied three emission scenarios, expressed by representative concentration pathways (RCPs): RCP2.6, RCP4.5, and RCP8.5 and three GCMs: HadGEM2-ES, IPSL-CM5A-LR, and MPI-SM-LR. Our study predicted northward shift of the species, with simultaneous distribution loss at the southern edge of the current range, driven by increasing climate seasonality. Temperature seasonality and temperature annual range were the predictors of highest importance. General trends are common for the projections presented, but the variability of our projections among the GCMs or RCPs applied (predicted range will contract from 17.4 to 84.6% of the current distribution area) shows that caution should be maintained while managing J. regia populations. Adaptive measures should focus on maintaining genetic resources and assisted migration at the southern range edge, due to range contraction. Simultaneously, at the northern edge of the range, J. regia turns into an invasive species, which may need risk assessments and control of unintended spread.

Despite increasing use of trait-based approaches in community ecology, most studies do not account for intraspecific variability of functional traits. Although numerous studies investigated functional traits of species with high economic value, the intraspecific and interspecific (caused by species identity) trait variability of forest understory herbs is still poorly understood. We aimed to assess the variability of specific leaf area (SLA), total leaf area, aboveground biomass and leaf mass fraction among 167 forest understory plant species, and the level of variability explained by species identity and collection site. We hypothesized that the level of intraspecific variability of SLA is underestimated in commonly used trait databases and that the interspecific variability (caused by species identity) is greater than intraspecific variability (site-specific). Our study revealed higher interspecific than intraspecific variability of the traits studied. We also confirmed that level of intraspecific variability available in the LEDA database is underestimated. We confirmed that species identity was the main factor determining the values of all the traits studied, and site-specific random effects explained lower amounts of variation in traits. Use of trait values from databases not acknowledging intraspecific variability is biased by uncertainty about this variability. For that reason, our analysis used mean trait values to reduce uncertainty of the results in the study conducted to assess human impacts on ecosystems. Thus, our study might support the assumption that level of intraspecific variability of functional traits is lower than interspecific variability.