CSR strategy composition of urban spontaneous plants:A case from Yangling, China

Urban spontaneous plants are advocated as a novel type of urban green infrastructure due to their high ecological value and low maintenance costs. However, their widespread application is limited by the inherent instability and insufficient knowledge about species-specific functional traits and intra-community ecological interactions. The CSR (Competition-Stress-Ruderal) strategy framework could serve as a methodological tool to classify plant functional groups and survival strategies, thereby facilitating a mechanistic understanding of individual spontaneous plant species' adaptive characteristics. Therefore, this study investigated 196 spontaneous plant species in Yangling, China, with the systematic sampling method, and their CSR strategy composition was analyzed. The results indicate that the CSR strategy composition of urban spontaneous plants is dominated by the R-strategy, followed by the C-strategy, with S-strategy being the least prevalent. The intermediate ecological strategy was R/CSR (C:S:R = 30:21:47%). There are no significant differences in the composition of ecological strategies among plants of various life forms. However, perennial plants invest more in C-strategy, while annual and biennial plants invest more in R-strategy. Native plants are more concentrated in the central area of the CSR strategy triangle diagram, whereas exotic species are more widely and evenly distributed within the triangle. The investment in C strategy by exotic species was significantly higher than that of native species. The investment in C strategy was significantly increased among invasive species, and the probability of invasion species increases when R-strategy is combined with C-strategy. The proportion of invasive species dominated by S-selection is extremely low. This study indicates that the CSR strategy of urban spontaneous plants is shaped by urban vegetation history and urban habitats. The CSR strategy can effectively indicate the survival strategies of urban spontaneous plants and their invasive statuses. In urban landscape design, plants can be selected to match the habitat characteristics based on their strategies, and the CSR strategy can be used as one of the bases for assessing the invasion risk of exotic plants.