Management effects on plant community and functional assemblages in Chicago’s vacant lots

Abstract

Question We ask whether 11‐year mowing patterns and presence of fencing influence plant community diversity and functional assemblage in urban vacant lots. Location This study took place in 34 vacant lots on the south and west sides of Chicago, IL, USA. Urban vacant lots are an excellent study system in which to investigate the effects of management in cities: they are ubiquitous in many cities and they experience a range of management, particularly mowing and fencing. Methods We used municipal data to classify infrequent and intensive mowing regimes and assessed presence or absence of fencing in situ. In our sites, these management strategies are independent. We used individual permutational analysis of variance (PERMANOVA) models to assess the effects of these management strategies on plant community composition. We then assessed species richness of plants with various traits using six individual two‐way ANOVA models with interaction terms. Our predictor variables included management strategies (mowing intensity and fencing) and three plant traits (growth form [graminoid, forb, or woody], life duration (annual, biennial, or perennial), and biogeographic origin [native or introduced]). Results We found 120 plant species in the vacant lots. Most of these species were perennial, introduced forbs. We found no discernable effects of mowing intensity on plant community composition or richness of plants in the three functional groups. However, when we compared the species found along fences to those in lot interiors, we found significantly different plant communities. Fence line communities had significantly more native and woody species than lot interiors. Conclusions Plant communities differ at very fine spatial scales within an individual vacant lot, and this pattern is related to the presence of fences. Overall, vacant lots support diverse plant communities which can differentially contribute to wildlife habitat depending on management strategy.