Just weeds? Comparing assessed and perceived biodiversity of urban spontaneous vegetation in informal greenspaces in the context of two American legacy cities.

Legacy cities are increasingly understood as drivers of various informal landscape patterns and processes which arise from the conditions of economic contraction and neglect. This study finds that the presence of urban spontaneous vegetation (USV) contributes to the biodiversity of informal urban greenspaces (IGS) in two American legacy cities—Detroit and Flint, Michigan. A mixed-method research design was used to compare quantitative measures of in-situ biodiversity (Simpson’s Index), to perceptual measures of biodiversity and landscape preference using an online survey (N=53). Results of a linear mixed model analysis show a statistically significant (p < 0.0001) quadratic (curvilinear) relationship between these variables, with respondents reporting higher preference for intermediate levels of IGS biodiversity as compared to IGS sites containing lower or higher biodiversity. This tendency, which is confirmed by several previous studies is referred to herein as the threshold effect.