A global synthesis of plant extinction rates in urban areas

Abstract

Plant extinctions from urban areas are a growing threat to biodiversity worldwide. To minimize this threat, it is critical to understand what factors are influencing plant extinction rates. We compiled plant extinction rate data for 22 cities around the world. Two-thirds of the variation in plant extinction rates was explained by a combination of the city's historical development and the current proportion of native vegetation, with the former explaining the greatest variability. As a single variable, the amount of native vegetation remaining also influenced extinction rates, particularly in cities > 200 years old. Our study demonstrates that the legacies of landscape transformations by agrarian and urban development last for hundreds of years, and modern cities potentially carry a large extinction debt. This finding highlights the importance of preserving native vegetation in urban areas and the need for mitigation to minimize potential plant extinctions in the future.

A global analysis of the impacts of urbanization on bird and plant diversity reveals key anthropogenic drivers

“…Not surprisingly, greater proportions of intact vegetation in cities, as found in older cities, preserve plant species. These results highlight the importance of including remnant vegetation and restoring natural areas in the design of cities [49].…”

“…A median of 3.3 species km 22 was found in these cities for native plants and 4.7 species km 22 for all plants (figure 2). The density of native plant species (robust ANOVA, F 1,4 ¼ 14.4, p , 0.001) and all plant species differed among realms (robust ANOVA, F 1,4 ¼ 17.3, p , 0.001), with cities in Indo-Malaya and Australasia having the lowest densities, probably owing to urban development histories [49].…”

“…These results indicate that exotic plant species compensate more substantially for losses in the density of species in regions with colder temperatures and lower precipitation seasonality, characteristics of northern temperate regions. The loss of native species [49,52] and the Table 1. Robust regression models contrasting anthropogenic and non-anthropogenic correlates of bird and plant species density in cities worldwide.…”

Urbanization drives the evolution of parallel clines in plant populations

“…Relative to non-urban areas, urban areas have dramatically different environmental conditions, such as warmer air temperatures [2] and altered ecological communities [3]. Although urbanization can have large ecological effects on plant and animal communities [4,5], the evolutionary consequences of urbanization are still poorly understood [6][7][8]. In particular, very little is known about whether species exhibit clinal evolution along urbanization gradients and about the ecological mechanisms that cause evolution in urban ecosystems.…”

Europe’s other debt crisis caused by the long legacy of future extinctions

“…Recent empirical research has shown that, at the scale of individual habitat patches, a delayed response of species to habitat loss and fragmentation is indeed often detectable, particularly among habitat specialists (9)(10)(11). The likelihood and magnitude of extinction debt is still contentious, however (12,13), and seems to vary with the nature of environmental degradation and with the life history traits of the species concerned (14)(15)(16)(17)(18). In long-lived or less-mobile taxa (e.g., vascular plants, bryophytes, reptiles), a delayed response of populations to the deterioration and fragmentation of their habitats is especially likely and might extend over at least several decades.…”