Background and Aims It is frequently assumed that phenotypic plasticity can be very advantageous for plants, because it may increase environmental tolerance (fitness homeostasis). This should, however, only hold for plastic responses that are adaptive, i.e. increase fitness. Numerous studies have shown shade-induced increases in specific leaf area (SLA), and there is wide consensus that this plastic response optimizes light capture and thus has to be adaptive. However, it has rarely been tested whether this is really the case.Methods In order to identify whether SLA plasticity does contribute to the maintenance of high biomass of plant species under shaded conditions, a meta-analytical approach was employed. The data set included 280 species and 467 individual studies from 32 publications and two unpublished experiments.Key Results Plants increased their SLA by 55Á4 % on average when shaded, while they decreased their biomass by 59Á9 %. Species with a high SLA under high-light control conditions showed a significantly greater ability to maintain biomass production under shade overall. However, in contrast to the expectation of a positive relationship between SLA plasticity and maintenance of plant biomass, the results indicated that species with greater SLA plasticity were less able to maintain biomass under shade.Conclusions Although a high SLA per se contributes to biomass homeostasis, there was no evidence that plasticity in SLA contributes to this. Therefore, it is argued that some of the plastic changes that are frequently thought to be adaptive might simply reflect passive responses to the environment, or result as by-products of adaptive plastic responses in other traits.

Most naturalised and invasive alien plant species were originally introduced to regions for horticultural purposes. However, many regions now face an invasion debt from ornamental alien species, which have not yet naturalised. In this regard, climate change represents a threat as it may lower the barriers to naturalisation for some ornamental alien species. Identifying those species is extremely important for anticipating impending invasions. To identify predictors of naturalisation, we modelled the effects of climate, nursery availability and species characteristics on the current European naturalisation success of 2,073 ornamental aliens commonly planted in European gardens. We then used the resulting model together with climate projections for 2050 to forecast future naturalisation risks for the 1,583 species not yet naturalised in Europe. We found that non‐European naturalised range size, climatic suitability, propagule pressure, having a dioecious sexual system and plant height jointly explained current naturalisation success in Europe. By 2050, naturalisation probability projections increased by more than 0.1 for 41 species, and only decreased by more than 0.1 for one species. Policy implications. Using predictions based on our integrated model of alien ornamental naturalisation success, we identified species with high future naturalisation risk and species with high projected increases in naturalisation potential in Europe under climate change. This species list allows for prioritisation of monitoring and regulation of ornamental plants to mitigate the invasion debt.

(2017) 'The eects of climate warming and disturbance on the colonization potential of ornamental alien plant species.', Journal of ecology., 105 (6). pp. 1698-1708. Further information on publisher's website:https://doi.org/10.1111/1365-2745.12798 Publisher's copyright statement: This is the accepted version of the following article: Haeuser, E., Dawson, W. van Kleunen, M. (2017). The eects of climate warming and disturbance on the colonization potential of ornamental alien plant species. Journal of Ecology., which has been published in nal form at https://doi.org/10.1111/1365-2745.12798. This article may be used for non-commercial purposes in accordance With Wiley Terms and Conditions for self-archiving.Additional information: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders. Accepted ArticleThis article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process, which may lead to differences between this version and the Version of Record. Accepted ArticleThis article is protected by copyright. All rights reserved.the current invasion potential of many alien ornamental species. However, with ongoing disturbance and climate change, this barrier may be reduced for some species. 2.Here we tested how colonization ability (a prerequisite for invasion) of frequently planted alien ornamentals depends on disturbance and heating, and on their species characteristics.We sowed seeds of 37 non-naturalized alien herbaceous garden-plant species into native grassland plots with and without disturbance, and with and without infrared heating lamps.To assess whether their responses differ from those within the regional wild flora, we also sowed 14 native species and 12 naturalized alien species. During two years, we assessed the likelihoods of germination, first-year survival, second-year survival and flowering of these 63 study species.3. The heating treatment, which also reduced soil moisture, decreased all measures of colonization success, but more so for sown native species than for the non-naturalized and naturalized alien ones. The disturbance treatment increased colonization success, and because heating decreased productivity of the undisturbed grassland plots, it also increased invasibility of these plots. Average colonization success of non-naturalized aliens was reduced by heating, but some species were not affected or performed even better with heating, particularly those with an annual life span and a high seed mass. Winter hardiness improved colonization ability of non-naturali...

Ornamental horticulture is the most important pathway for alien plant introductions worldwide, and consequently, invasive spread of introduced plants often begins in urban areas. Although most introduced ornamental garden-plant species are locally not naturalized yet, many of them have shown invasion potential elsewhere in the world, and might naturalize when climate changes. We inventoried the planted flora of 50 public and 61 private gardens in Radolfzell, a small city in southern