Effect of Tending on the Ecological Stoichiometry of Nitrogen, Phosphorus and Potassium in the Leaves and Branches of Disanthus cercidifolius var. Longipes

Disanthus cercidifolius var. longipes is a second-class protected wild plant in China. The effects of thinning and nurturing on the ground diameter, tree height growth, and the ecological stoichiometric characteristics of nitrogen (N), phosphorus (P) and potassium (K) in the leaves and branches of D. cercidifolius var. longipes have not been fully understood. By taking the community of D. cercidifolius var. longipes in Qianjiangyuan National Forest Park as the object of study, the four-treatment and three-replicate permanent plot was established, including no nurturing (control), upper nurturing, lower nurturing, and full nurturing. The annual growth of ground diameter and tree height of the plant was monitored. The N, P, and K contents in the leaves and branches were sampled and analyzed, and their stoichiometry was calculated. The results showed that nurturing promoted the growth of D. cercidifolius var. longipes. Compared with the control, the annual growth of ground diameter and tree height significantly increased by 20.0%−40.0% and 20.0%−90.0% (P＜0.05). After full nurturing, the P content in the leaves significantly decreased (P＜0.05), while the K content significantly increased (P＜0.05). The N content in the branches significantly decreased after full nurturing (P＜0.05), and the K content also significantly decreased after upper story nurturing (P＜0.05). The N∶P and K∶P in the leaves of D. cercidifolius var. longipes plant significantly increased after lower and full nurturing (P＜0.05), while the N∶K in the leaves significantly decreased (P＜0.05). The upper story thinning significantly increased the N∶P and N∶K in the branches (P＜0.05). There were 10 pairs of elements and stoichiometric ratios in the leaves that showed significant or extremely significant level correlations (P＜0.05 or P＜0.01), and only N∶P and N∶K in the branches showed significant correlations (P＜0.05). In summary, nurturing promoted the growth of D. cercidifolius var. longipes, and changed the accumulation and distribution of N, P, and K in leaves and branches.