Different functional characteristics can explain different dimensions of plant invasion success

1. The success of invasive plant species can be evaluated using different dimensions, such as, range size, abundance, and impact. These different dimensions do not always covary but are rarely separated, suggesting an urgency to disentangle the functional mechanisms behind them. 2. A dataset of leaf traits and four dimensions of invasion success (i.e., range size, local abundance, impact on native plant abundance, and impact on native plant diversity) were compiled for 395 non-native plant species in the US and Europe. Associations among dimensions of invasion success and between leaf traits and dimensions were analyzed with general linear models (LMs) and supplemented by phylogenetic generalized least square (PGLS) models, which control for the phylogenetic relatedness across species. 3. The pair-wise associations between most pairs of invasion dimensions were weak or neutral. The only exception was the association between impact on native plant abundance and impact on native plant diversity, which was strongly positive. Traits of species that have large range sizes were associated with a high metabolic rate; whereas, traits of species that were abundant or had a strong impact at the local scale were associated with low metabolic rate. In addition, traits of species with a large range size or having strong impacts on native plant abundance were associated with acquisitive strategies; whereas, traits of species with a high local abundance or strong impacts on native plant diversity were associated with conservative strategies. 4. Synthesis: Different dimensions of invasion success were associated with different functional traits. Invasion success at the regional scale was related to traits that promote rapid colonization; whereas, invasion success at the local scale was related to traits that are potentially less preferred by herbivores. Some locally successful invaders even possessed traits that facilitate a high stress tolerance and conservative strategy, which were similar to locally abundant native species. Therefore, an ambiguous definition of \u201cinvasion success\u201d in mechanism-related studies may produce inconsistent or even controversial conclusions, highlighting the importance of separately studying different dimensions of invasion success

Comparison of two simplified versions of the Gielis equation for describing the shape of bamboo leaves

Bamboo is an important component in subtropical and tropical forest communities. The plant has characteristic long lanceolate leaves with parallel venation. Prior studies have shown that the leaf shapes of this plant group can be well described by a simplified version (referred to as SGE-1) of the Gielis equation, a polar coordinate equation extended from the superellipse equation. SGE-1 with only two model parameters is less complex than the original Gielis equation with six parameters. Previous studies have seldom tested whether other simplified versions of the Gielis equation are superior to SGE-1 in fitting empirical leaf shape data. In the present study, we compared a three-parameter Gielis equation (referred to as SGE-2) with the two-parameter SGE-1 using the leaf boundary coordinate data of six bamboo species within the same genus that have representative long lanceolate leaves, with >300 leaves for each species. We sampled 2000 data points at approximately equidistant locations on the boundary of each leaf, and estimated the parameters for the two models. The root–mean–square error (RMSE) between the observed and predicted radii from the polar point to data points on the boundary of each leaf was used as a measure of the model goodness of fit, and the mean percent error between the RMSEs from fitting SGE-1 and SGE-2 was used to examine whether the introduction of an additional parameter in SGE-1 remarkably improves the model’s fitting. We found that the RMSE value of SGE-2 was always smaller than that of SGE-1. The mean percent errors among the two models ranged from 7.5% to 20% across the six species. These results indicate that SGE-2 is superior to SGE-1 and should be used in fitting leaf shapes. We argue that the results of the current study can be potentially extended to other lanceolate leaf shapes

Dimensions of invasiveness: Links between local abundance, geographic range size, and habitat breadth in Europe\u2019s alien and native floras

Understanding drivers of success for alien species can inform on potential future invasions. Recent conceptual advances highlight that species may achieve invasiveness via performance along at least three distinct dimensions: 1) local abundance, 2) geographic range size, and 3) habitat breadth in naturalized distributions. Associations among these dimensions and the factors that determine success in each have yet to be assessed at large geographic scales. Here, we combine data from over one million vegetation plots covering the extent of Europe and its habitat diversity with databases on species\u2019 distributions, traits, and historical origins to provide a comprehensive assessment of invasiveness dimensions for the European alien seed plant flora. Invasiveness dimensions are linked in alien distributions, leading to a continuum from overall poor invaders to super invaders-abundant, widespread aliens that invade diverse habitats. This pattern echoes relationships among analogous dimensions measured for native European species. Success along invasiveness dimensions was associated with details of alien species\u2019 introduction histories: earlier introduction dates were positively associated with all three dimensions, and consistent with theory-based expectations, species originating from other continents, particularly acquisitive growth strategists, were among the most successful invaders in Europe. Despite general correlations among invasiveness dimensions, we identified habitats and traits associated with atypical patterns of success in only one or two dimensions - for example, the role of disturbed habitats in facilitating widespread specialists. We conclude that considering invasiveness within a multidimensional framework can provide insights into invasion processes while also informing general understanding of the dynamics of species distributions