Summary 1.The search for characteristics that promote invasion success constitutes one of the most challenging tasks in invasion ecology. So far the main focus in multispecies studies of plant invasion success has been on single traits. Only few generalizations have emerged from this work and single traits yielded very limited explanatory power for invasion success. Here we hypothesize that the consideration of ecological strategies, determined by different combinations of traits, will improve explanatory power. 2. To test this hypothesis we analysed the relative importance of 40 traits for species' invasion success in the German neophytic flora. Success was expressed as map grid cell frequency. After quantifying the relevance of single traits, we quantified the importance of different trait combinations for invasion success by calculating a multiple trait model, with explicit consideration of trait interactions. In all analyses we considered the effects of phylogeny. 3. In general, neither single traits nor phylogenetic relatedness held much explanatory power. In contrast, the amount of variation explained in the multiple trait model was distinctly higher, mainly due to the incorporation of trait interactions. Thus, particular combinations of trait attributes rather than distinctive attributes per se appear to be associated with invasion success. 4. In single trait analysis, traits associated with flowering and reproductive biology, and with ecological tolerance and the residence time of the species were significantly associated with invasion success. Multiple trait analysis revealed that the relationship between the length of flowering season and invasion success was contingent upon pollination modes. Moreover, the success of polyploids and of species with certain vegetative reproductive trait attributes depended on the species' flowering phenology. 5. Synthesis . Our results indicate that different ecological strategies, determined by particular combinations of traits, can facilitate plant invasion success. Our findings highlight the importance of incorporating trait interactions when testing for characteristics that promote plant invasion success. Improved explanatory power of traits suggests that our new approach can provide an important step forward in the risk assessment and management of new arrivals in regional floras.

This paper explores the differences in the trait compositions of non-indigenous (neophytic) and native plant species for selected traits in Germany. Our set of functional traits addresses species' reproductive biology, life history, morphology and ecophysiology. To take account of broadscale heterogeneity across the country we compared the relative frequencies of neophytes and natives with particular trait attributes at the scale of grid cells (c. 130 km 2 each). Subsequently, we compared the differences at the grid cell scale to the differences in the corresponding comparisons at the scale of the entire country. Finally, we explored how variation in the trait compositions of the nonindigenous species across the country relates to variation in the trait compositions of the natives. We found remarkable differences in the trait compositions of neophytes and natives at the grid cell scale.Neophytes were over-represented in insect-and selfpollinated species and in species with a later and longer flowering season. Furthermore, the proportions of species with mesomorphic or hygromorphic leaf anatomy, of annual herbs and of trees as well as of non-clonals and polyploids were significantly higher in neophytes than in natives. These differences at the grid cell scale could vary distinctly from the corresponding differences observed at the country scale. This result highlights the complexity of the invasion process and suggests an importance of spatial scale for the comparisons. Correlation analysis indicated, that for traits relating to plant morphology and ecophysiology, the relative frequencies of the non-indigenous species increased with those of the natives. This suggests that favourable environments for natives with particular attributes constitute an increased suitability for neophytes with these attributes as well. Our study provides a step forward towards an integrated understanding of traits in plant invasions across spatial scales and broad-scale heterogeneity and underlines the necessity to understand the role of functional traits in plant invasions with reference to spatial scale and in the context of the environment.

Variation in plant functional traits has been related to variation in environmental conditions. In particular, the relationship between leaf traits and climate has received much attention. This paper presents a functional‐trait‐centred approach to identify potential impacts of climate and land use change on plant species assemblages. Using species atlas data, we modelled the relative frequencies of species with different leaf anatomies (LARF) as a function of observed climate and land use data on a regular spatial grid across Germany. Subsequently, we projected the geographical distribution of LARF with simulated climate and land use data for the late 21st century under two future scenarios. We used a conditional autoregressive regression model to account for spatially structured variation in LARF that remained unexplained by the environmental factors considered. We found a clear relationship between the climatic gradient of water availability and shifts in LARF: increasing water deficit was associated with a decreasing proportion of species with hygromorphic leaves in the composition and increasing proportions of species with scleromorphic and mesomorphic leaves. The variation in LARF due to land use was only small. Under future environmental scenarios the proportion of species with hygromorphic leaves was projected to decrease in all parts of Germany, whereas the proportions of species with sclero‐ and mesomorphic leaves were projected to increase on average. In particular, Germany's south‐western and north‐eastern areas were projected to experience functional change in LARF. Our study highlights the relationship between functional traits and plant species vulnerability to climate change. Our results suggest that the functional‐trait‐centred approach can provide a powerful additional modelling tool to estimate potential impacts of climate change on plant species assemblages.