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Environmental factors impact species richness differently across taxonomic groups, and understanding the geographic patterns and drivers influencing alpine plant richness remains limited. This study compiled global distribution data of 404 species of Gentiana, an alpine genus, and analyzed the relative effects of different environmental factors and several previously proposed models on the variation of Gentiana richness. By evaluating the effects of range size and regions on the relationships between Gentiana richness and environmental factors, we found that all tested environmental factors had weak effects on richness variation for all species and wide‐ranging species, while habitat heterogeneity was the best predictor for narrow‐ranging species. Habitat heterogeneity was the main driver of richness variation in Europe and Asia, but not in North America. The multiple regression model that included variables for energy, water, seasonality, habitat heterogeneity and past climate change had the highest explanatory power, but it still explained less than 50% of the variation in species richness for all Gentiana species at both global and regional scale, except for Europe. The limited explanatory power of environmental factors in explaining species richness patterns for all species, along with the variations observed among regions, suggest that other factors, such as evolutionary processes and biogeographic history may have also influenced the geographic patterns of Gentiana species richness. In conclusion, our results indicate a limited influence of climate factors on alpine species richness, while habitat heterogeneity, along with its impacts on speciation and dispersal, likely play significant roles in shaping the richness of alpine Gentiana species. [ABSTRACT FROM AUTHOR]

• The exponent (z) of the SAC model was used in urban ecosystems to characterize beta diversity. • We found the species composition of native plants was more heterogeneous than non-natives. • The beta diversity of all species groups was best explained by alpha diversity and urbanization. • Urban spontaneous plants diversity was determined by both the current state and historical processes of urbanization. Urbanization has significantly reshaped regional biodiversity structure globally. Previous studies suggested that urban communities of spontaneous plants are well adapted to the urban environment. However, a perspective of urbanization that accounts for the joint impacts of the current state (as expressed by urbanization intensity) and the historical progress of urbanization (as expressed by urbanization rate) to reveal the mechanisms underlying the biodiversity patterns of spontaneous plants in cities is still lacking. Here we present data and analysis of spontaneous plants sampled in 709 patches within 82 sites of built-up areas from nine cities distributed across climatic and floristic zones in Yunnan province, a biodiversity hotspot in China. We used the exponent (z) of a species accumulation curve (SAC) model to characterize beta diversity among patches in a site, and found a higher beta diversity of native species compared with non-natives, indicating that the species composition of native plants is more heterogeneous. The beta diversity of all species groups was best explained by the constant c of the SAC (a proxy of alpha diversity), followed by the urbanization intensity (as expressed by the proportion of sealed surface and patches' Shannon diversity index), and urbanization rate (as expressed by the sealed surface expansion rate). Moreover, beta diversity of non-native species was additionally negatively correlated with altitude. Our results suggest that the interplay of natural environmental factors and human-induced urbanization shape diversity of urban spontaneous plants in Yunnan province. Our findings emphasize that urban spontaneous plants diversity is not only a reflection of the current state of urbanization, but also a consequence of historical processes of urbanization. [ABSTRACT FROM AUTHOR]

• Patterns of spontaneous species richness are explained by multiply theories. • Richness patterns of both invasive and non-invasive had similar drivers. • Patch area, dispersal limitation and edge effects explained all richness patterns. • The patch-matrix perspective also applies to urban green spaces. • Incorporation of our results into urban planning can benefit biodiversity hotspots. Urban green space provides refuges for species that are unintentionally introduced by humans and which do not belong to the remnants of natural habitats in urban areas. However, the quantitative relationships between urban green space properties and these spontaneous species are unclear. To address this, we surveyed plant species occurring in urban green patches in Kunming city, which is located in a biodiversity hotspot in southwest China. We classified spontaneous plants into native, non-native and invasive plant species. A total of 386 spontaneous species belonging to 278 genera and 92 families were recorded in 190 patches. Most of the recorded species were herbaceous plants (76.2 %). While invasive species constituted a relatively small proportion of the total species pool (17.9 %), six out of ten of the most frequently occurring species were invasive. Regression models inspired by the theory of Island Biogeography show that total, native, non-native and invasive spontaneous species richness in urban green patches were best explained by the size of the 'island' (patch area), dispersal limitations (as expressed by 'distance to city boundary') and edge effects (as shown by the landscape shape index). While the set of drivers of spontaneous plants is similar for the different groups of species, the relative importance of each driver varies among them. Our study provides quantification of drivers of biodiversity patterns in urban green space. Based on this understanding, planning and management of urban green space can be adapted to maximize spontaneous plant conservation in rapidly urbanizing biodiversity hotspot regions. [ABSTRACT FROM AUTHOR]