Biological invasions in rapidly urbanizing areas: a case study of Beijing, China

Abstract

Urbanization is widely recognized as a major factor promoting biological invasions worldwide. In this article, we provide insights into the patterns of biological invasions in Beijing, one of the largest and quickly urbanizing cities of the world, by developing a comprehensive list of naturalized and invasive flora and their associate traits (e.g., distribution, life form, habitat, or geographic origin). One hundred and twelve naturalized (including 48 invasive) plants have been identified within the Beijing Municipality. Most of the naturalized and invasive plants belong to four families (Asteraceae, Poaceae, Amaranthaceae, and Euphorbiaceae) and are annual herbs that preferentially grow in disturbed sites. North and South America are the main contributors to the naturalized and invasive flora of Beijing. As expected, those Beijing districts that have recently experienced the highest human population growth, urban expansion, and the largest economic growth are also those with the highest number of naturalized and invasive species. Urban expansion is predicted to continue in the near term making additional invasions likely that will significantly increase the proportion of introduced species in Beijing's flora. An integrated management strategy for the whole municipality is urgently needed that includes comprehensive scientific research that documents the extent of invasions and their effects on Beijing's economy and environment.

Variations of urban greenness across urban structural units in Beijing, China

“…For example, the urban greening area per capita in Beijing is only 50% of that in Paris, and only 17% of that in London (BSRC, 2009). Secondly, 53% of the green space in Beijing is made up of alien plant species (Zhao et al, 2010a;Wang et al, 2011).…”

Studying the patterns of alien and native floras of some habitats in Srinagar city, Kashmir, India

“…The dominance of herbaceous plant species, with annual and perennial lifespan, is in agreement with findings of Khuroo et al (2007) who also reported preponderance of annual (32% of all alien species) and perennial herbs (27% of all alien species) in alien flora of Kashmir Himalaya. Wang et al (2011) also reported the preponderance of herbaceous habit in naturalised plant species recorded in Beijing Municipality, China. The dominance of alien plant species with herbaceous habit found in urban landscapes of Kashmir valley is presumably due to high anthropogenic disturbance.…”

“…'Casual or naturalised' alien plant species were those alien plant species about which adequate field information was not available (Wu et al 2004). We used the term 'invasive' for those alien species that cause apparent damage or pose potential threats to species, ecosystems or to the economy (IUCN (International Union for the Conservation of Nature) (1999); Wang et al 2011).…”

“…Many alien species thrive in urban environments probably due to the 'urban heat island effect' (Ricotta et al 2009;Wang et al 2011). Because of the considerable potential exhibited by alien plants to disperse propagules to long distances (Pyšek and Hulme 2005), there is an understandable concern that urban areas may act as source centres from which alien plant species will spread into the wider surrounding environments (Catling and Porebski 1994;Sullivan et al 2005;Houlahan et al 2006) and hence could become detrimental to regional biodiversity.…”

Espacios verdes urbanos y diversidad vegetal a diferentes escalas espacio-temporales: el ejemplo de Beijing, China

“…One hundred and twelve naturalized (including 48 invasive) plants were identified within the Beijing Municipality. Although these numbers can be regarded as "modest" compared to other large Asian cities such as Shanghai, Hong Kong, or Singapore (see Table 3 in Wang et al, 2011), they represent a significant fraction of the alien species richness reported for the entire country: namely, up to one-quarter of the total naturalized flora of China (420 to 861 species; Wu et al, 2010;Jiang et al, 2011) and one-fifth of the invasive flora of China (270 to 488 plant species; Weber et al, 2008;Xu et al, 2012). Moreover, finding 112 naturalized species represents a ca.…”