Urban-rural distribution patterns and environmental adaptation strategies of herbaceous plants in a karst city of China

Studying herbaceous plants across urban-to-rural gradients is key for urban biodiversity conservation because they exhibit high sensitivity to human disturbances. Our research focused on the karst landscapes of Guiyang where we studied the herbaceous species in both urban and rural zones comprising forested and wasteland areas. We evaluated species richness, abundance, functional traits, niche width and CSR (Competitive, Stress-tolerant, Ruderal) strategies. We found that alien plant diversity peaked in urban wastelands, while the diversity of native species was higher in forests. Urban plants generally had broader niche widths compared to their rural counterparts. In urban settings, alien species were taller, whereas native forest dwelling species exhibited larger leaves and had shorter statures. Urban specialists displayed larger specific leaf areas (SLA) with reduced dry matter content, indicating lower S-selection and higher R-selection. Further analysis disclosed significant intraspecies adaptive variations along the gradient. For instance, the native Achyranthes aspera exhibited larger leaf areas and reduced stress tolerance in rural forests, while the alien Erigeron canadensis showed smaller leaves and enhanced plant height in urban settings. These adaptations suggest that in urban areas, harsh and unpredictable environments lead plants to adopt strategies like increased niche width and SLA while decreasing dry matter content to enhance survival. However, in more stable rural contexts, species tend to develop lower SLA and higher dry matter content, optimizing resource use and achieving competitive dominance. These findings provide valuable insights for sustainable urban planning and biodiversity conservation, contributing to the establishment of greener urban environments.