Plant biodiversity in residential yards is influenced by people’s preferences for variety but limited by their income

Abstract

Residential yards are a unique component of the urban environment and harbor high cultivated plant biodiversity; however, why and how people create yards with so many plant species is not well understood. To investigate this pattern, we studied the relationships between residents’ preferences, income, and yard plant biodiversity in the Salt Lake Valley, Utah, USA where most of the urban vegetation is intentionally cultivated. We conducted in-person interviews, distributed written surveys, and inventoried the biodiversity (i.e., genus and species richness) of ornamental herbaceous flowering plants and lawn plants in residential yards located in neighborhoods across income levels. We found that 95% of surveyed residents valued having ‘plants that create variety in the yard’ (‘variety’ left open to interpretation) and that 47% of interviewed residents expressed an emotional connection to variety. On average, general plant variety was more important to residents than high plant biodiversity (i.e., a specified type of variety), but they also exhibited a preference for neat monoculture lawns lacking in biodiversity and other types of variety. Residents’ preferences for general plant variety, and biodiversity specifically, were not necessarily reflected in their yards. Higher income households had greater flowering plant variety in terms of number of different flower colors, inflorescence types, and genera, but lower lawn species biodiversity due to a reduction in weedy species. Overall, our study shows that most residents in this region prefer plant variety in their yards more than biodiversity specifically, and that people with higher incomes can better achieve these preferences.