Urban wildflower meadow planting for biodiversity, climate and society: An evaluation at King's College, Cambridge

Abstract

The biodiversity and climate crises are critical challenges of this century. Wildflower meadows in urban areas could provide important nature-based solutions, addressing the biodiversity and climate crises jointly and benefitting society in the process. King's College Cambridge (England, UK) established a wildflower meadow over a portion of its iconic Back Lawn in 2019, replacing a fine lawn first laid in 1772. We used biodiversity surveys, Wilcoxon signed rank and ANOVA models to compare species richness, abundance and composition of plants, spiders, bugs, bats and nematodes supported by the meadow, and remaining lawn, over 3 years. We estimated the climate change impact of meadow vs lawn from maintenance emissions, soil carbon sequestration and reflectance effect. We surveyed members of the university to quantify the societal benefits of, and attitudes towards, increased meadow planting on the collegiate university estate. In spite of its small size (0.36 ha), the meadow supported approximately three times more plant species, three times more spider and bug species and individuals, and bats were recorded three times more often over the meadow than the remaining lawn. Terrestrial invertebrate biomass was 25 times higher in the meadow compared with the lawn. Fourteen species with conservation designations were recorded on the meadow (six for lawn), alongside meadow specialist species. Reduced maintenance and fertilising associated with meadow reduced emissions by an estimated 1.36 Mg CO2-e per hectare per year compared with lawn. Relative reflectance increased by 25%–34% for meadow relative to lawn. Soil carbon stocks did not differ between meadow and lawn. Respondents thought meadows provided greater aesthetic, educational and mental wellbeing services than lawns. In open responses, lawns were associated with undesirable elitism and social exclusion (most colleges in Cambridge restrict lawn access to senior members of college), and respondents proved overwhelmingly in favour of meadow planting in place of lawn on the collegiate university estate. This study demonstrates the substantial benefits of small urban meadows for local biodiversity, cultural ecosystem services and climate change mitigation, supplied at lower cost than maintaining conventional lawn.