Phipps Conservatory and Botanical Gardens Pittsburgh, Pennsylvania, United States
Background/Question/Methods
Urban green spaces are increasingly important for providing ecological, environmental, and cultural services, including biodiversity conservation and human wellbeing. However, a large portion of urban greenspace is often managed as highly manicured grassy lawns and dominated by one or a few perennial grass species (often nonnative) that provide few ecosystem services and support significantly less biodiversity. Managing urban green spaces as biodiverse perennial native meadows can offer several ecosystem benefits. Relatively little is known about the effect of green space management regimes on plant biodiversity and urban soil health.In this study, we systematically sampled two types of green spaces – meadows and lawns in 2020 and 2021 at four different urban locations in Pittsburgh, Pennsylvania, USA. We compared plant species richness (alpha diversity), and soil chemical [soil organic matter (SOM), nitrate nitrogen (NO3-N), phosphorus (P) and total nitrogen (N) and carbon (C)] and biological [total soil microbial biomass (MBC), and intra-radical arbuscular mycorrhizal (AM) fungal biomass] attributes between meadows and lawns. We hypothesized that managing urban green spaces as meadows would increase alpha diversity and improve soil health.
Results/Conclusions
Results showed that urban meadows support a significantly higher alpha diversity (p< 0.001) compared to lawns in both the measurement years. Likewise, C/N ratios and AM fungal biomass were significantly higher in meadows (p< 0.01). However, SOM, NO3-N, P, and total N and C were higher in lawns (p< 0.01). In addition, we found significant positive relationships between plant species richness and C/N ratios and AM fungal biomass. These results imply that diverse plant communities in meadows may assimilate nitrogen more efficiently and buffer eutrophication in downstream water. Furthermore, these meadows likely improve plant nutrient retention, soil stability, and resistance to adverse environmental conditions by harboring higher AM fungal communities in the soils. Despite the accumulation of higher SOM and C in the lawns, elevated NO3-N, P, and N is a cause of concern as excess phosphorus and nitrogen contaminate surface and groundwater that run downstream, increasing eutrophication. Our results provide some evidence that urban green space management can have predictable effects on plant diversity, soil microbial communities, and soil nutrients. These results can also have significant policy implications if urban green spaces can sustainably optimize ecosystem benefits while reducing negative environmental impacts.
