Plant invasiveness is influenced by various ecological and environmental factors, with high phenotypic plasticity and functional trait variation playing crucial roles. Functional traits provide a conceptual framework for understanding species distribution, community assembly, and the ecological impact of invasive species. This study hypothesized that specific plant functional traits facilitate the establishment and dominance of Ageratum conyzoides in urban landscapes. We tested this hypothesis by conducting field surveys across five urban habitat types within the Northern Irrigated Plains of Punjab, Pakistan: roadside verges, urban parks, wetlands, agricultural land, and abandoned land. Key morphological and physiological traits, including plant height, specific root length, dry leaf biomass, leaf area, specific leaf area, and leaf dry matter content, were measured in each habitat type. The Competitive Advantage Index (CAI) and Community Invasibility Index (CII) were calculated for each sampling plot, and soil physicochemical and textural properties were recorded. Statistical analyses, including Tukey’s post-hoc test, principal component analysis, correlation analysis, and polynomial regression, were used to evaluate trait and soil relationships. The results revealed that A. conyzoides exhibited greater plant height, leaf area, and specific leaf area in urban parks and roadside verges, where resource availability was higher. Functional trait variation across habitat types indicated that the species prioritized rapid growth and resource acquisition in disturbed environments, while in nutrient-limited habitats it adopted a more conservative strategy. Higher CAI values were associated with increased plant height, leaf area, and specific leaf area, indicating that such traits contributed to competitive dominance. Similarly, CII was positively correlated with soil organic matter, available phosphorus, and electrical conductivity, indicating that nutrient-enriched soils promote greater invasibility. Although soil texture (sand, silt, and clay content) showed weaker correlations with CII and CAI, its inclusion in the analysis provides a more comprehensive view, suggesting that while fertility plays a dominant role, physical properties may still influence invasion dynamics through interactions with water and nutrient availability. These findings demonstrated that A. conyzoides achieved invasion success by capitalizing on high resource availability and trait plasticity, particularly in urban environments with disturbed soils. Understanding the relationships between functional traits and environmental conditions offers critical insights into invasion ecology and can guide effective management strategies to curb the spread and impact of invasive species in urban landscapes.
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