Homeowner preferences drive lawn care practices and species diversity patterns in new lawn floras

Households intensively manage lawns to create uniformly green, low diversity plant communities. Because lawns occupy a large proportion of urban green space, they are a crucial case for understanding how people manipulate urban vegetation. In this study, I focused on 58 homeowners who purchased a newly constructed home and yard in the Seattle Metropolitan Statistical Area, USA, to see how preferences, lawn care regimes and new lawn floras develop within a multi-scalar urban environment. A typical homeowner watered 3 times in spring, watered 24 times in summer, applied fertilizer twice, mowed 21 times and edged 15 times. Most new lawn turfgrasses were Lolium perenne, Poa pratensis and/or Festuca spp. Mean species richness was 6.5 ± 5.3 species. The most frequent species were non-native and cosmopolitan (turfgrasses, Hypochaeris radicata, Taraxacum officinale and Trifolium repens). Five variables increased the probability of homeowners managing their lawns as turfgrass monocultures: living in a neighborhood with larger yards, summer watering frequency, fertilizer frequency, valuing space for children and valuing wildlife habitat. Valuing an easy to manage yard decreased the turfgrass monoculture probability. In polyculture yards, having a larger lawn was positively correlated with non-turfgrass species richness, but elevation was negatively correlated. Homeowners who valued space for children appeared to have more intensive lawn care regimes than those who valued wildlife habitat or easy to manage yards. Although lawn floras result from complex interactions of the environment and households, urban characteristics appeared to be weaker drivers of diversity than homeowner preferences and lawn care.