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The sustainable management of green spaces in cities is crucial in achieving the challenging goal of urban sustainability. The common practice of cultivation of alien plants in urban green spaces is often associated with risk of naturalisation (i.e. escape into wild), which can have sometime adverse impacts on biodiversity and ecosystem services. To mitigate these risks, understanding patterns and processes of naturalisation of alien flora in urban green spaces becomes crucial. Here we report the floristic diversity of alien flora and correlates of its naturalisation in the green spaces of Srinagar city – one of the largest urban centres in the Himalaya. We documented 342 plant species belonging to 66 families from the green spaces of Srinagar, predominantly represented by 245 alien species (72%). Among the alien species pool, 133 species (54%) are exclusively under cultivation (non-escapes) and 112 species (46%) grow in the wild (cultivation escapes and accidentally introduced species); and of the latter, 51 were naturalised, 39 casual and 22 invasive. The cultivated alien species escaped into the wild belong to 27 families, and most prominently to the Asteraceae. Habitat-wise, plant dumping sites in the green spaces constituted the most dominant habitat of cultivation escapes. A significant relationship was revealed between the proportion of aliens under cultivation and species traits such as growth form, life span and residence time; and plant species with herbaceous growth form, annual life span and relatively longer residence time showed higher proportion of naturalisation. We found a significant correlation between abundance of the cultivation escapes and residence time (r = 0.507). The present study has generated policy-relevant data on urban green spaces of Srinagar, which can support policy regulations to steer the sustainable development of this rapidly urbanising Himalayan city. [ABSTRACT FROM AUTHOR]

Summary: Human introductions of species beyond their natural ranges and their subsequent establishment are defining features of global environmental change. However, naturalized plants are not uniformly distributed across phylogenetic lineages, with some families contributing disproportionately more to the global alien species pool than others. Additionally, lineages differ in diversification rates, and high diversification rates have been associated with characteristics that increase species naturalization success. Here, we investigate the role of diversification rates in explaining the naturalization success of angiosperm plant families.We use five global data sets that include native and alien plant species distribution, horticultural use of plants, and a time‐calibrated angiosperm phylogeny. Using phylogenetic generalized linear mixed models, we analysed the effect of diversification rate, different geographical range measures, and horticultural use on the naturalization success of plant families.We show that a family's naturalization success is positively associated with its evolutionary history, native range size, and economic use. Investigating interactive effects of these predictors shows that native range size and geographic distribution additionally affect naturalization success. High diversification rates and large ranges increase naturalization success, especially of temperate families.We suggest this may result from lower ecological specialization in temperate families with large ranges, compared with tropical families with smaller ranges. [ABSTRACT FROM AUTHOR]

Climate warming is supposed to enlarge the area climatically suitable to the naturalization of alien garden plants in temperate regions. However, the effects of a changing climate on the spread of naturalized ornamentals have not been evaluated by spatially and temporarily explicit range modelling at larger scales so far. Here, we assess how climate change and the frequency of cultivation interactively determine the spread of 15 ornamental plants over the 21st century in Europe. We coupled species distribution modelling with simulations of demography and dispersal to predict range dynamics of these species in annual steps across a 250 × 250 m raster of the study area. Models were run under four scenarios of climate warming and six levels of cultivation intensity. Cultivation frequency was implemented as size of the area used for planting a species. Although the area climatically suitable to the 15 species increases, on average, the area predicted to be occupied by them in 2090 shrinks under two of the three climate change scenarios. This contradiction obviously arises from dispersal limitations that were pronounced although we assumed that cultivation is spatially adapting to the changing climate. Cultivation frequency had a much stronger effect on species spread than climate change, and this effect was non‐linear. The area occupied increased sharply from low to moderate levels of cultivation intensity, but levelled off afterwards. Our simulations suggest that climate warming will not necessarily foster the spread of alien garden plants in Europe over the next decades. However, climatically suitable areas do increase and hence an invasion debt is likely accumulating. Restricting cultivation of species can be effective in preventing species spread, irrespective of how the climate develops. However, for being successful, they depend on high levels of compliance to keep propagule pressure at a low level. [ABSTRACT FROM AUTHOR]

Abstract: Biological invasions are a major threat for natural ecosystems. Deserts are characterized by their scarce, highly variable rainfall and thus considerably susceptible to invasions, especially by annual plants that can quickly capitalize sporadic rainfall events. In this study we evaluated the potential of an invasive winter-annual species native to the Mediterranean region (Schismus barbatus) to invade a summer-rainfall desert in the Central-Northern Monte Phytogeographical Province, Argentina, where the native annual flora is mainly composed of summer species. We recorded the number of germinated seeds from soil samples collected in four seasons (during one year) coinciding with four important life-stages of Schismus (pre-germination, post-germination I and II and post-dispersal), and contrasted our results with data obtained from the literature. Almost 33,000 Schismus seeds were estimated to germinate per m2, and about 90% percent of them germinated from samples collected in the pre-germination stage. Compared to deserts in USA and Australia, where Schismus has been a successful invader, the density of germinated seeds we observed was especially high even though the amount of rainfall for the vegetative period of Schismus was considerable lower. Our results suggest that S. barbatus has a great invasive potential in the Central-Northern Monte. The low number of annual plant populations that are able to compete for highly variable cool-season rains may be a key feature determining the invasibility of these deserts during the winter. [Copyright &y& Elsevier]

Horticulture is an important source of naturalized plants, but our knowledge about naturalization frequencies and potential patterns of naturalization in horticultural plants is limited. We analyzed a unique set of data derived from the detailed sales catalogs (1887-1930) of the most important early Florida. USA, plant nursery (Royal Palm Nursery) to detect naturalization patterns of these horticultural plants in the state. Of the 1903 nonnative species sold by the nursery, 15% naturalized. The probability of plants becoming naturalized increases significantly with the number of years the plants were marketed. Plants that became invasive and naturalized were sold for an average of 19.6 and 14.8 years, respectively, compared to 6.8 years for non-naturalized plants, and the naturalization of plants sold for 30 years or more is 70%. Unexpectedly, plants that were sold early were less likely to naturalize than those sold later. The nursery's inexperience, which caused them to grow and market many plants unsuited to Florida during their early period, may account for this pattern. Plants with pantropical distributions and those native to both Africa and Asia were more likely to naturalize (42%), than were plants native to other smaller regions, suggesting that plants with large native ranges were more likely to naturalize. Naturalization percentages also differed according to plant life form, with the most naturalization occurring in aquatic herbs (36.8%) and vines (30.8%), Plants belonging to the families Araceae, Apocynaceae. Convolvulaceac, Moraceae, Oleaceae, and Verbenaceae had higher than expected naturalization Information theoretic model selection indicated that the number of years a plant was sold. alone or together with the first year a plant was sold. was the stronges predictor of naturalization. Because continued importation and marketing of nonnative horticultural plants will lead to additional plant naturalization and invasion, a comprehensive approach to address this problem, including research to identify and select noninvasive forms and types of horticultural plants is urgently needed. [ABSTRACT FROM AUTHOR]