Trait Based Comparison of <scp> <i>Ageratina adenophora</i> </scp> and Co‐Occurring Herbaceous Species Across Forest Ecosystems in Champawat, Kumaun Himalaya

ABSTRACT The success of invasive species like Ageratina adenophora is frequently related to their functional trait advantages and ecological flexibility. Hence, this study evaluated the morphological trait‐based performance of A. adenophora in relation to its co‐occurring herbaceous species across four sites in the Champawat district of the Kumaun Himalaya, representing two forest types: Banlekh (site 1), dominated by Quercus leucotrichophora , and Chowki (site 2), Gauri (site 3), and Shaktipur (site 4), which are characterised by Cedrus deodara forests. Four species, that is, Ajuga parviflora , Apluda mutica , Cyperus rotundus , and Erigeron karvinskianus , were chosen from Banlekh, from Chowki, Anaphalis busua from Gauri, and, A. parviflora , Anaphalis busua , and Viola canescens , were chosen from Shaktipur for the comparison based on their association and growth with A. adenophora . Plant morphological and leaf traits were assessed during January, 2025 across all these four sites following standard methods. The results showed that A. adenophora steadily unveiled the highest population density, peaking at Shaktipur (88.65 individuals/m 2 ) and Chowki (80.12 individuals/m 2 ), far surpassing nearby species such as A. parviflora (11.5 ind./m 2 ) and C. rotundus (33.33 ind./m 2 ). Morphologically, A. adenophora reached maximum shoot length (23.05 cm in Shaktipur), plant height (90.77 cm), and stem volume (13.28 cm 3 in Banlekh), often exceeding neighbouring herbs by 30%–90%. It also maintained longer roots (66.05 cm in Banlekh), with values up to 99.2% greater than co‐occurring species in Shaktipur. A. adenophora demonstrated higher specific leaf area (up to 1177.96 cm 2 /g at Gauri), superior stem mass fraction (up to 61.62%), and a higher root: shoot ratio (up to 0.83), reflecting an avaricious resource use approach. Leaf biomass was also higher (e.g., 2.57 g in Chowki, 53.33% more than A. busua ) significantly, and above and belowground biomass values commonly topped those of co‐occurring species by over 90%, especially in Banlekh and Chowki. In spite of infrequent trait setbacks in Shaktipur, A. adenophora demonstrated steady inexpensive dominance. These results confirm that both superior trait values and phenotypic plasticity contribute to the prevalent invasion of A. adenophora . This study underscores the importance of trait‐based assessments for understanding invasion dynamics and supervisory targeted biological management.