Distribution characteristics and influencing factors of carbon storage in Populus plantations with different stand ages in the Luxi Yellow River floodplain, China

To explore the relationship between carbon storage and environmental factors in <i>Populus</i> plantations of different stand ages, and to reveal the carbon sequestration mechanisms of <i>Populus</i> plantations across different age classes, this study employed field surveys and laboratory analysis to investigate the distribution patterns and influencing factors of carbon storage in trunk-branch-leaf-root-soil systems of <i>Populus</i> plantations with different stand ages (10 y, 30 y, 40 y, 50 y) in the Luxi Yellow River floodplain. The results showed that the carbon storage in trunks, branches, and roots increased gradually with increasing stand age, while the carbon storage in leaves reached a maximum of 7.52 t·hm² at 40 y, followed by a gradual decrease. Soil carbon storage increased consistently with stand age. Overall, the total carbon storage of <i>Populus</i> plantations across different age classes exhibited a linear increasing trend with advancing standage. Correlation analysis, principal component analysis, and structural equation modeling indicated that diameter at breast height (DBH), tree height (H), tree age (AGE), and stand density (SD) were the key factors affecting carbon storage in <i>Populus</i> plantations. The findings of this study can provide theoretical basis and technical support for enhancing carbon sequestration and sink capacity, as well as ecological restoration of <i>Populus</i> plantations in the Luxi Yellow River floodplain.