Wealth, water and wildlife: Landscape aridity intensifies the urban luxury effect

Abstract

Aim: Urban biodiversity, and its associated ecosystem services, is an important component of the quality of life of urban residents. The "luxury effect" posits a positive association between biodiversity and socioeconomic status in urban areas, and is thus reflective of environmental injustice, as the benefits associated with biodiversity are not equitably shared across society. We aimed to determine the generality of the luxury effect, and to identify the factors causing its variation across published studies. Location: Urbanized landscapes globally. Time period: Current. Major taxa studied: Terrestrial animals and plants. Methods: We tested the luxury effect across a sample of 337 estimates of the relationship between biodiversity measures and socioeconomic status from 96 studies via a metaanalysis, addressing three hypotheses: (a) the luxury effect is more pronounced where water availability is limited, (b) the luxury effect is more pronounced in developing than developed countries, (c) the luxury effect is stronger in exotic compared to native species. Results: There was a significant overall luxury effect: there was a positive association between terrestrial biodiversity measures and socioeconomic status. The strength of the luxury effect was greater in arid areas. There was limited support for a stronger luxury effect in exotic species, but no support for any association with development status. Main conclusions: Many key and emerging climate impacts are concentrated in urban areas. Therefore, the degree of environmental injustice represented by the luxury effect may be amplified in the future, especially in arid regions. The objective to increase urban biodiversity through more equitable management and provision of water resources could form part of a wider strategy for sustainable development of cities to promote environmental justice, enhancing the quality of life of urban residents across all sectors of society. Challenges remain to ensure that any such strategy prioritizes conservation goals for native biodiversity.

South African raptors in urban landscapes: a review

“…For example, a worldwide study on the impact of urbanisation on avian functional diversity showed 20% less functional diversity on average in urban areas than surrounding natural habitats (Sol et al 2020). However, most research is conducted in the Global North, and conclusions might not always apply to Africa, which is characterised by developing countries with strong socio-economic and socio-cultural gradients, as well as a more tropical climate and different time and pace of urbanisation scenarios (Gupta 2002;Seto et al 2010;McHale et al 2013;Chamberlain et al 2020).…”

Urban areas have lower species richness, but maintain functional diversity: insights from the African Bird Atlas Project

“…This feeds into the globally observed trend of a decline in species diversity as the amount of urban land cover increases across landscapes (Batáry et al 2018). This general pattern is also seen in bird communities of developing countries (van Rensburg et al 2009;MacGregor-Fors and Schondube 2011;Silva et al 2015;Chamberlain et al 2018), although some notable exceptions arise depending on the quality of the surrounding natural (rural) vegetation type and water availability (Dures and Cumming 2010;Chamberlain et al 2020). Unfortunately, it is difficult to ascribe causality to the variety of different ecological and environmental factors that are affecting bird diversity across our urbanrural gradient.…”

“…Given that Africa's population is the fastest growing in the world and expected to increase from the current 1.2 billion people to >1.8 billion by 2035 (Institute for Security Studies 2020), there is growing need to focus on biodiversity in these rapidly urbanising African landscapes (Magle et al 2012). Additionally, in Africa, which is characterised by developing countries with strong socio-economic gradients, as well as a more tropical climate and uniquely structured cityscapes, we expect that urban influences on biodiversity will be markedly different to what is known from cities of the Global North (Becker and Morrison 1988;Gupta 2002;Seto et al 2010;McHale et al 2013;Chamberlain et al 2020).…”

“…Similarly, a landmark study attempting to describe characteristics of the 'urban bird' essentially answers this question for only the United Kingdom (Evans et al 2011). Therefore, despite a focus on urban ecological research and several key reviews emerging in recent years (Faeth et al 2011;Beninde et al 2015;Batáry et al 2018;Chamberlain et al 2020), information for African cities is still largely lacking and limits our ability to make informed decisions around how African avifauna respond to this rapid land transformation.…”

A southern perspective on urban birds

“…The luxury effect predicts a positive relationship between human wealth and biodiversity. This is supposedly amplified in arid cities (Chamberlain et al 2020), as neighbourhoods age, and might be reduced in tropical areas (Leong et al 2018). Also these findings highlight the need for research in more tropical cities to unravel global patterns.…”