Urban plant diversity in Kazakhstan: Effects of habitat type, city size and macroclimate

Questions Urbanisation has accelerated the spread of alien and apophytic species around the world including the drylands of continental inland Asia. However, few studies have examined the patterns and drivers of urban plant diversity in this region. We ask how habitat type, city size and macroclimate affect species richness and composition of alien, apophytic and non-apophytic indigenous plants in cities of the steppe and forest-steppe zones of Kazakhstan. Location Ten cities in central and northeastern Kazakhstan, Middle Asia. Methods Using a standardized sampling protocol, we recorded spontaneously occurring vascular plant species in 1-ha plots in seven habitat types (central square, boulevard, residential area, park, early-successional vacant site, mid-successional vacant site and railway station) in five large (>100,000 inhabitants) and five small (<100,000 inhabitants) cities. We used linear mixed-effect models to quantify the effects of habitat type, city size and macroclimate on species richness and the proportion of alien, apophytic and non-apophytic indigenous plants. Results Plant species richness differed significantly among habitat types, with the lowest richness in central squares, and the highest in railway stations and residential areas. Apophytic species were most numerous in railway stations and alien species in residential areas. The richness of alien, apophytic and non-apophytic indigenous species varied more among habitats than among cities. The proportion of apophytes increased linearly with annual precipitation. The largest differences in species composition were between disturbed sites in city centres (squares, boulevards and parks) and early-successional, mid-successional and railway station sites. Large and small cities also differed in species composition. Conclusions Plant diversity in cities of northern Kazakhstan depends mainly on habitat type and less on macroclimate. Overall, cities in inland continental Asia follow patterns of urban species diversity observed in other Asian and European cities.