Time Is Not Money: Income Is More Important Than Lifestage for Explaining Patterns of Residential Yard Plant Community Structure and Diversity in Baltimore

Abstract

Plant biodiversity is affected by limiting resources such as water, nutrients, and sunlight. In urban settings, such as residential yards, however, limiting resources may also include the social factors of time and money spent on yard care. To examine the role that these precious human resources play in determining plant community structure and diversity, we surveyed homeowners and their yards in 12 neighborhoods across Baltimore City and Baltimore County, Maryland, visiting a total of 96 residential properties. We chose neighborhoods based on residents' median income (a proxy for money) and lifestage (a proxy for time) as determined by ESRI's Tapestry dataset [older (>65 and most likely retired with more free time) versus younger (<65 and most likely working with less free time)]. At each residential yard, we studied four major plant types: lawn species, flowering herbaceous plants (excluding grasses), trees, and invasive species. For the flowering plants, we documented the number, size, and color of flowers, and calculated total floral area. We found that residential yards harbored high plant diversity with 89 tree species, 82 lawn species, and 80 flowering plant genera. Lawn richness was not related to the neighborhood-level lifestage of the residents or their income,; rather, all lawns were equally weedy. Consistently, we found that yards in higher income neighborhoods and larger yards had greater abundance of plants and greater diversity of flowering herbaceous plants, trees, and invasive species, whereas lifestage was rarely associated with plant diversity. Additionally, we found front yards had greater floral area than back yards, while back yards had greater tree abundance and tree diversity than front yards. Finally, we found that residents who spent more time doing yard work had more flowering plants, flower colors, and floral genera. Overall, yards in highincome neighborhood, and large yards had the greatest plant biodiversity, indicating that money is the more precious human resource for creating and maintaining biodiverse residential yards.

Spatial contagion structures urban vegetation from parcel to landscape

“…The region has a humid continental climate (mean annual | 91 temperature = 9.6℃; mean annual precipitation = 1,233 mm; PRISM Climate Group, 2015) and was historically covered with mesic forests. Forty-four per cent of the land area is residential (Ossola et al, 2019a), which is consistent with other urban areas in western countries such as Baltimore, MD (Avolio et al, 2020b), Chicago, IL (Lewis et al, 2019), Adelaide, (Australia; Ossola et al, 2021), Edinburgh (Scotland), Belfast (Northern Ireland), Cardiff (Wales) and Leicester and Oxford (England;Loram et al, 2007), and represents more than twice as much land area as parks and open spaces (18.43%; Ossola et al, 2019b). Backyards compose 14% of all urban land area and contain ~21% of all tree canopy cover; front yards cover ~8% of the area and have ~8% of the study area's tree canopy cover (Ossola et al, 2019b).…”

“…Social theory (Carrico et al, 2012;Cialdini et al, 1990Cialdini et al, , 1991Grove et al, 2006;Hyman, 1942;Locke et al, 2018;Merton & Kitt, 1950) and prior empirical findings (Avolio et al, 2020a;Larsen & Harlan, 2006;Larson et al, 2009;Locke et al, 2018) suggest pressures for conformity are greater in more-visible front yards. Paradoxically, greater spatial autocorrelation in backyards is reasonable: in our study system, backyards have abundant tree canopy that form large contiguous patches that may partly explain the relative high autocorrelation (Ossola et al, 2019b).…”

“…Yards are the non-building portions of residential land. In the United States, about 11% of all land is residential (Theobald, 2014), and within urban areas, residential land is often the dominant land use (Avolio et al, 2020b;Loram et al, 2007).…”

“…Boston, residential yards, spatial autocorrelation, spatial contagion, urban ecology, urban forestry Baltimore City and County, front yards had greater floral diversity, while backyards had more trees and greater tree diversity (Avolio et al, 2020b). In larger yards, mowing an entire yard can be less common, leaving more room for wooded areas (Visscher et al, 2014).…”

Residential yard management and landscape cover affect urban bird community diversity across the continental USA

“…Socioeconomic processes are major drivers of management and preferences (Avolio et al 2015). In addition, legacies of systemic racism, for example, redlining, further define differences in types and amount of vegetation such as canopy cover, their associated land management and subsequent ecological patterns and processes (Avolio et al 2020, Schell et al 2020. Landscaping preferences for colorful and showy plants, and those easy to maintain also influence landscape heterogeneity (Larson et al 2016, Avolio et al 2018, Cavender-Bares et al 2020.…”