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Drought is expected to increase in future climate scenarios. Although responses to drought of individual functional traits are relatively well‐known, simultaneous changes across multiple traits in response to water scarcity remain poorly understood despite its importance to understand alternative strategies to resist drought.We grew 52 herbaceous species in monocultures under drought and control treatments and characterized the functional space using seven measured above‐ and below‐ground traits: plant height, leaf area, specific leaf area, leaf dry matter content, specific root length, average root diameter, and root dry matter content. Then, we estimated how each species occupied this space and the amount of functional space occupied in both treatments using trait probability density functions. We also estimated intraspecific trait variability (ITV) for each species as the dissimilarity in trait values between the individuals of each treatment. We then mapped drought resistance and ITV in the functional space using generalized additive models.The response of species to drought strongly depended on their traits, with species that invested more in root tissues and conserved small size being both more resistant to drought and having higher ITV. We also observed a significant trend of trait displacement towards less conservative strategies. However, these changes depended strongly on the trait values of species in the control treatment, with species with different traits having opposing responses to drought. These contrasting responses resulted in lower trait variability in the species pool in drought compared to control conditions. Our results suggest strong trait filtering acting on conservative species as well as the existence of an optimal part in the functional space to which species converge under drought.Our results show that changes in species trait‐space occupancy are key to understand plant strategies to withstand drought, highlighting the importance of individual variation in response to environmental changes, and suggest that community‐wide functional diversity and biomass productivity could decrease in a drier future. Knowing these shifts will help to anticipate changes in ecosystem functioning facing climate change. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

Aim: Plants that host root‐symbiotic nitrogen‐fixing bacteria have an important role in driving terrestrial ecosystem processes, but N‐fixing ability is unequally distributed among plant taxa and ecosystems. Here we explore the large‐scale distribution of N‐fixing plant species worldwide. Location: Global. Time period: Present. Major taxa studied: Vascular plants. Methods: We estimated root‐symbiotic N‐fixing plant species diversity (as Shannon entropy) and relative richness (log‐ratio of N‐fixing to non‐fixing plant species) for c. 7,800 km2 hexagonal grid cells using the NodDB and Global Biodiversity Information Facility (GBIF) databases. Additionally, we explored the distributions of plant species associated with rhizobia, actinobacteria or cyanobacteria (relative to other plant species), and the relative richness of N‐fixing trees (log‐ratio of N‐fixing to non‐fixing trees). We related N‐fixing plant species distribution to environmental (climate, soil) and biogeographical (biome, realm) variables using multiple linear regression. Results: N‐fixing plant diversity and relative richness showed unimodal relationships with latitude. Diversity of N‐fixing plants was highest in warm and wet climates, but in dry biomes and in Australasia. The relative richness of N‐fixing plants was highest in warm and dry climates, in tropical and temperate grasslands and in Eurasia. Plants associated with cyanobacteria were more widely distributed near the equator, while those associated with rhizobia were more prevalent at the edge of the tropics, and those associated with actinobacteria at higher latitudes (especially in boreal forests). The relative richness of N‐fixing tree species was highest in cold and dry areas and in boreal forests, with contrasting peaks in the Northern and Southern Hemispheres. Main conclusions: The distribution of N‐fixing plant species exhibits regional hotspots and coldspots related to both environmental conditions and biogeographical history. Global N‐fixing plant distributions are different for the key root‐symbiotic bacterial groups. Information about N‐fixing plant distribution can improve global models of ecosystem functions and contribute to understanding how plants respond to global change. [ABSTRACT FROM AUTHOR]

Tall plant species disperse further distances than do short species, within and across dispersal syndromes, yet the driver underpinning this relationship is unclear. The ability of taller plants to invest more in dispersal structures may explain the positive relationship between plant height and dispersal distance. Here, we quantify the cross-species relationships between presence of dispersal structures, dispersal investment plant height and dispersal distance., Plant height, dispersal syndrome and dispersal investment data were collated for 1613 species from the literature, with dispersal distance data collated for 114 species., We find that species with high dispersal investment disperse further than do species with low dispersal investment. Tall species have a greater probability of having dispersal structures on their seeds compared with short species. For species with dispersal structures on their seeds, plant height is very weakly related to dispersal investment., Our results provide the first global confirmation of the dispersal investment-distance hypothesis, and show dispersal investment can be used for predicting species dispersal distances. However, our results and those of previous studies indicate plant height is still the best proxy for estimating species dispersal distances due to it being such a readily available plant trait. [ABSTRACT FROM AUTHOR]

When a plant is introduced to a new ecosystem it may escape from some of its coevolved herbivores. Reduced herbivore damage, and the ability of introduced plants to allocate resources from defence to growth and reproduction can increase the success of introduced species. This mechanism is known as enemy release and is known to occur in some species and situations, but not in others. Understanding the conditions under which enemy release is most likely to occur is important, as this will help us to identify which species and habitats may be most at risk of invasion. We compared in situ measurements of herbivory on 16 plant species at 12 locations within their native European and introduced Australian ranges to quantify their level of enemy release and understand the relationship between enemy release and time, space and climate. Overall, plants experienced approximately seven times more herbivore damage in their native range than in their introduced range. We found no evidence that enemy release was related to time since introduction, introduced range size, temperature, precipitation, humidity or elevation. From here, we can explore whether traits, such as leaf defences or phylogenetic relatedness to neighbouring plants, are stronger indicators of enemy release across species.