Traditionally, plant biodiversity is affected by limiting resources such as water, nutrients, and sunlight. In urban settings, such as residential yards, however, limiting resources may extend to include societal factors such as time and money spent on yard care and gardening. To examine the role that these ‘precious resources’ to humans play in determining plant biodiversity, we surveyed homeowners and their yards in 12 neighborhoods across Baltimore city and Baltimore County, Maryland. We chose neighborhoods based on residents’ median income and life stage as determined by Tapestry (older [>65 and most likely retired with more time] versus younger [<65 and most likely working with less time]). We had three replicate neighborhoods of each life stage and income category. To study home-owner yard management activities and preferences, we mailed a written survey to 100 homes in each neighborhood and got back 182 surveys. We then visited eight homes in each neighborhood assess yards for biodiversity, visiting 96 homes in total. At each residential yard, we studied three major plant functional groups: lawn species, trees, and herbaceous flowering plants (excluding grasses). For the flowering plants we counted the number, size, and color of flowers.
Results/Conclusions
Across all four income and life stage categories, all residents were equally mildly satisfied with their yards. Causes for this under-whelming satisfaction were not that their yard took too much time, although residents reported spending on average 4.8 hours a week doing yard work, and not that their yards cost too much to maintain, although 33% of respondents reported paying for some form of yard work. For yard plant biodiversity, we found residential yards harbored high plant diversity; we identified 93 tree species, 95 lawn species, and 95 genera of flowering plant. Lawn richness was not affected by the life stage of the residents or their income, all lawns were equally weedy. There was higher tree diversity in higher income yards (p = 0.02) but not more trees. There were more flowering plants (p = 0.04), flowers (p = 0.003), and more colors (p = 0.01) in higher income compared with middle income yards, but there was no difference in the number of genera of flowering plants. Overall, we found that time is not money, and money is the most precious resource for maintaining diverse residential yards.