Urbanization erodes ectomycorrhizal fungal diversity and may cause microbial communities to converge

Abstract

Urbanization alters the physicochemical environment, introduces non-native species and causes ecosystem characteristics to converge. It has been speculated that these alterations contribute to loss of regional and global biodiversity, but so far most urban studies have assessed macro-organisms and reported mixed evidence for biodiversity loss. We studied five cities on three continents to assess the global convergence of urban soil microbial communities. We determined the extent to which communities of bacteria, archaea and fungi are geographically distributed, and to what extent urbanization acts as a filter on species diversity. We discovered that microbial communities in general converge, but the response differed among microbial domains; soil archaeal communities showed the strongest convergence, followed by fungi, while soil bacterial communities did not converge. Our data suggest that urban soil archaeal and bacterial communities are not vulnerable to biodiversity loss, whereas urbanization may be contributing to the global diversity loss of ectomycorrhizal fungi. Ectomycorrhizae decreased in both abundance and species richness under turf and ruderal land-uses. These data add to an emerging pattern of widespread suppression of ectomycorrhizal fungi by human land-uses that involve physical disruption of the soil, management of the plant community, or nutrient enrichment.

Anthropogenic disturbance equalizes diversity levels in arbuscular mycorrhizal fungal communities

“…An equalizing effect of disturbance on levels of AM fungal alpha diversity is also consistent with recent findings on other microbes (ectomycorrhizal fungi, archaea and bacteria; Epp Schmidt et al, 2017) that reported biotic homogenization resulting from biodiversity loss in some communities, but not others. Our currently limited knowledge about the distribution and ecology of AM fungal taxa makes it difficult to specify mechanisms underlying the selection of functional traits that might drive equalization of diversity levels.…”

“…However, as suggested by Epp Schmidt et al. (), a mechanism analogous to that influencing plants (i.e. the exclusion of an important number of late successional specialist species from naturally rich communities, which is compensated in naturally poor communities by the arrival of new pioneer species) may also influence these soil organisms.…”

“…Our currently limited knowledge about the distribution and ecology of AM fungal taxa makes it difficult to specify mechanisms underlying the selection of functional traits that might drive equalization of diversity levels. However, as suggested by Epp Schmidt et al (2017), a mechanism analogous to that influencing plants (i.e. the exclusion of an important number of late successional specialist species from naturally rich communities, which is compensated in naturally poor communities by the arrival of new pioneer species) may also influence these soil organisms.…”

“…There is an increasing body of literature showing that anthropogenic disturbance influences soil microbial communities (Caruso, Hempel, Powell, Barto, & Rillig, ; De Vries et al., ; Lekberg et al., ; Tsiafouli et al., ). It has been proposed that microbes may exhibit analogous patterns to those observed in plants (Epp Schmidt et al., ; Gossner et al., ), such that an effect of anthropogenic activity on community diversity and composition operates via facilitation of disturbance‐tolerant, generalist taxa. Indeed, such patterns have recently been recorded among soil fungi at the regional scale (Mueller, Rodrigues, Nüsslein, & Bohannan, ).…”

Open‐source data reveal how collections‐based fungal diversity is sensitive to global change

“…First, urban locations were found, for our analyses utilizing a 50‐km 2 grid, exclusively at lower latitudes. Consistent with previous research (Schmidt et al., ), mean diversity in urban systems was reduced for both fungal nutritional modes (Fig. ), with greater negative impacts to ectomycorrhizal fungal diversity in urban systems compared to forests (Appendices ).…”