Study on carbon sequestration characteristics of 24 spontaneous herbaceous plants

To clarify the relationship between leaf traits and carbon-assimilation capacity of 24 spontaneous herbaceous species, this study selected these 24 species as materials. Eight leaf morphological and photosynthetic physiological indices were measured, and correlation analysis, principal component analysis, multiple regression analysis and cluster analysis were conducted to explore the relationship between leaf traits and carbon assimilation capacity of these spontaneous herbs.The results showed that carbon assimilation amount exhibited highly significant or significant positive correlations with leaf area, leaf dry mass and leaf area index, indicating a tight functional coordination between leaf expansion and photosynthetic carbon assimilation amount. The multiple-regression model explained 99.1% of the variance in carbon assimilation amount. Leaf area was the dominant determinant of carbon assimilation amount: for every 1 cm² increment in leaf area, carbon assimilation amount increased by an average of 0.002 59 units, and its standardized effect size was far greater than that of net photosynthetic rate. Cluster analysis classified the 24 spontaneous herbaceous species into three carbon-assimilation groups: two high-carbon species (PersiAria orientalis, Silybum marianum), sixteen moderate-carbon species (Polygonum orientale , Amaranthus cruentus, Ixeris polycephala, etc.), and six low-carbon species (Eragrostis pilosa, Mazus japonicus, Oxalis corniculata, etc.). Significant differences in leaf morphological and physiological traits were detected among the three groups. This study suggests that enlarging leaf area is a primary strategy for improving carbon-assimilation capacity in herbaceous plants at the interspecific level. The findings provide critical data support and theoretical references for carbon-sink enhancement and regulation of damaged ecosystems as well as carbon-sequestration restoration of degraded vegetation, and offer practical guidance for the utilization of spontaneous herbaceous species in urban landscapes.