The role of roads and urban area in occurrence of an ornamental invasive weed: a case of Rudbeckia laciniata L

Abstract

Road density and proportion of urban area are considered to be useful indicators of invasion risk from non-native plants. However, the mechanisms behind the relationship between these indicators and establishment of non-native species have rarely been addressed explicitly. To identify these mechanisms, we used a species distribution model (MaxEnt) for an invasive ornamental weed Rudbeckia laciniata using road density and proportion of urban area as explanatory variables, along with soil moisture and solar radiation. Overall model performance is relatively high (AUC = 0.91). Road density explained most R. laciniata occurrence, followed by the proportion of urban area. The occurrence probability of R. laciniata increased monotonically with road density, but the rates of increase constantly fell. The occurrence probability also increased with urban area when the proportion of urban area was small, but started to decrease when the proportion of urban area reached 0.2. Our results suggest that both road density and proportion of urban area are important factors in determining R. laciniata establishment but work differently.