highly significantp < 0.01
There was a highly significant positive correlation between Pn and Tr, WUE, and Gs (0.586 < r < 0.784, p < 0.01).
There was a highly significant positive correlation between Pn and Tr, WUE, and Gs (0.586 < r < 0.784, p < 0.01).
Additionally, all Pn, Tr, and Gs exhibited a decreasing trend from the outer to the inner positions within the same canopy layer across all planting densities.