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We hypothesize that lower public visibility of residential backyards reduces households’ desire for social conformity, which alters residential land management and produces differences in ecological composition and function between front and backyards. Using lawn vegetation plots (7 cities) and soil cores (6 cities), we examine plant species richness and evenness and nitrogen cycling of lawns in Boston, Baltimore, Miami, Minneapolis-St. Paul, Phoenix, Los Angeles (LA), and Salt Lake City (SLC). Seven soil nitrogen measures were compared because different irrigation and fertilization practices may vary between front and backyards, which may alter nitrogen cycling in soils. In addition to lawn-only measurements, we collected and analyzed plant species richness for entire yards—cultivated (intentionally planted) and spontaneous (self-regenerating)—for front and backyards in just two cities: LA and SLC. Lawn plant species and soils were not different between front and backyards in our multi-city comparisons. However, entire-yard plant analyses in LA and SLC revealed that frontyards had significantly fewer species than backyards for both cultivated and spontaneous species. These results suggest that there is a need for a more rich and social-ecologically nuanced understanding of potential residential, household behaviors and their ecological consequences.

Human activity has altered global carbon and nitrogen cycles, leading to changes in global temperatures and plant communities. Because atmospheric carbon (C) and nitrogen (N) concentrations are affected by storage in terrestrial vegetation and soil, it is critical to understand how conversions from native to non-native vegetation may alter the C and N storage potential of terrestrial landscapes. In this study, we compared C and N storage in native California sage scrub, non-native grassland, and recovering California sage scrub habitats in the spring and fall by determining the C and N content in aboveground biomass, litter, and surface soil. Significantly more C and N were stored in intact and recovering California sage scrub than in grassland habitats. Intact and recovering sage scrub did not differ significantly in C or N storage. Our results highlight that preserving and restoring California sage scrub habitat not only provides habitat for native biodiversity, but also increases carbon and nitrogen storage potential even without restoration to intact sage scrub.

Urban biotic homogenization is expected to be especially important in residential yards, where similar human preferences and management practices across environmentally heterogeneous regions might lead to the selection of similar plant species, closely related species, and/or species with similar sets of traits. We investigated how different yard management practices determine yard plant diversity and species composition in six cities of the U.S., and tested the extent to which yard management results in more homogeneous taxonomical, phylogenetic, and functional plant communities than the natural areas they replace or than relatively unmanaged areas at the residential-wildland interface (“interstitial” areas). We categorized yards based on fertilizer input frequency and landscaping style: high-input lawns, low-input lawns, and wildlife-certified yards. We defined homogenization as decreased average β-diversity and decreased variance in α-diversity in yards when compared to natural and interstitial areas. We found that all residential yard types regardless of their management were functionally more homogeneous for both α- and β-diversity than the natural and interstitial areas. Nevertheless, wildlife-certified yards were functionally more similar to natural areas than lawn-dominated yard types. All yard types were also more homogeneous in phylogenetic α-diversity compared to natural and interstitial areas, but more heterogenous in taxonomic α-diversity. Within yards, taxonomic, phylogenetic and functional diversity were weakly correlated, highlighting the importance of examining multiple dimensions of biodiversity beyond taxonomic metrics. Our findings underscore the ecological importance of gardening practices that both support biodiversity and create residential plant communities that are functionally heterogeneous.

Residential yards contribute to human well-being and urban biodiversity. The structure, diversity, and composition of yard floras are largely determined by personal choices and landscaping priorities at local scales, but it is unclear whether these relationships hold across broader geographical areas. We investigated the relationship between homeowners’ criteria for vegetation and yard management choices, ecosystem-service based traits, and yard plant diversity (i.e., taxonomic, phylogenetic and functional) in 145 yards distributed across 6 major cities in the U.S. Individual priorities for a set of ecosystem services were collected with closed-ended questions and reduced into four main principal components using factor analyses: natural, neat, showy and low cost. Across cities, priorities for neat yards were negatively related to overall and spontaneous species richness. Priorities for showy yards were positively related to yard aesthetics (based on showiness of flowers, fruits and leaves for component plants) and spontaneous species richness. Homeowners that preferred low-cost yards had a significantly higher proportion of exotics, and yards with significantly lower functional diversity (i.e., a composite measure for plant height, seed mass, and specific leaf area). The proportion of natives was not related to homeowners’ priorities for natural yards and phylogenetic diversity was only weakly and negatively related to priorities for showy yards. Our study corroborates previous research showing that homeowners’ landscaping priorities are only partially related to their yard vegetation at the continental scale. The disconnection might be attributed to broader institutional, structural, and ecological constraints that prevent people’s personal ideals and priorities from being realized.