Urbanization drives cross‐taxon declines in abundance and diversity at multiple spatial scales

Abstract

The increasing urbanization process is hypothesized to drastically alter (semi‐)natural environments with a concomitant major decline in species abundance and diversity. Yet, studies on this effect of urbanization, and the spatial scale at which it acts, are at present inconclusive due to the large heterogeneity in taxonomic groups and spatial scales at which this relationship has been investigated among studies. Comprehensive studies analysing this relationship across multiple animal groups and at multiple spatial scales are rare, hampering the assessment of how biodiversity generally responds to urbanization. We studied aquatic (cladocerans), limno‐terrestrial (bdelloid rotifers) and terrestrial (butterflies, ground beetles, ground‐ and web spiders, macro‐moths, orthopterans and snails) invertebrate groups using a hierarchical spatial design, wherein three local‐scale (200 m × 200 m) urbanization levels were repeatedly sampled across three landscape‐scale (3 km × 3 km) urbanization levels. We tested for local and landscape urbanization effects on abundance and species richness of each group, whereby total richness was partitioned into the average richness of local communities and the richness due to variation among local communities. Abundances of the terrestrial active dispersers declined in response to local urbanization, with reductions up to 85% for butterflies, while passive dispersers did not show any clear trend. Species richness also declined with increasing levels of urbanization, but responses were highly heterogeneous among the different groups with respect to the richness component and the spatial scale at which urbanization impacts richness. Depending on the group, species richness declined due to biotic homogenization and/or local species loss. This resulted in an overall decrease in total richness across groups in urban areas. These results provide strong support to the general negative impact of urbanization on abundance and species richness within habitat patches and highlight the importance of considering multiple spatial scales and taxa to assess the impacts of urbanization on biodiversity.

Contrasting impacts of urban and farmland cover on flying insect biomass

“…The estimated effect of urban areas was still negative after accounting for potential stops during sampling ( Figure 4). Our results are consistent with a recent meta-analysis combining data from multiple studies to show an overall negative effect of urbanisation for arthropod diversity and abundance (Fenoglio, Rossetti & Videla, 2020) and the decline of insect diversity with urbanisation at multiple spatial scales (Piano et al, 2020). In large part, this may be due to the reduced biomass and productivity per unit area in urban habitats where much of the landscape is impervious surface, such as cement or rooftops, on which vegetation does not grow.…”

“…Arguably one of the most extreme land cover changes imposed by human activities is urbanisation (Seto, Güneralp & Hutyra, 2012). Across several insect taxa, Piano et al (2020) found that urbanisation was associated with a decline in insect diversity at multiple spatial scales in Belgium. Similarly, a recent meta-analysis combining studies from across the world found a mean negative effect of urbanisation on terrestrial arthropod diversity and abundance, although the effect may differ among insect orders (Fenoglio, Rossetti & Videla, 2020).…”

High species turnover shapes anuran community composition in ponds along an urban-rural gradient

“…However, similar results were found by Rádková et al (2014) and Specziár et al (2018) among invertebrate communities in aquatic environments in non-urban context. Our results suggest that urbanization is acting as an environmental filter (Piano et al 2019), leading to the replacement of species not adapted to urban conditions by species that are more efficient in exploiting urban resources (McKinney 2006, Menke et al 2011. As a result of such turnover of species, communities in ponds in highly urbanized areas are similar to each other, a process known as biotic homogenization Lockwood 1999, Olden andRooney 2006).…”

CityScapeLab Berlin: A Research Platform for Untangling Urbanization Effects on Biodiversity

“…Ultimately, the spatial scale also matters for taxa that are potentially subject to urbanization drivers because urban biodiversity components starkly differ in their radius of activity, from soil biota to bats, birds, or large mammals such as wild boars that can move on a regional scale [73]. Urban biodiversity research, thus, needs to bridge spatial scales [74].…”

“…Different groups of animals and plants respond differently to urbanization [46,74,88] as do different functional groups [43,89]. Yet, multi-taxon analyses are rare [74,89], and some groups of taxa (e.g., birds and vascular plants) are overrepresented in urban studies [36,45]. Seibold et al [89], thus, not only argue for multi-taxon studies, but for integrating different trophic levels in multi-trophic studies.…”