Effects of soil warming and nitrogen deposition on leaf and soil stoichiometric characteristics of Cunninghamia lanceolata saplings北大核心CSCD

Warming and nitrogen deposition directly or indirectly affect the plant-soil element cycle under global change. To examine the effects of warming and nitrogen deposition on leaf and soil carbon (C), nitrogen (N), phosphorus (P) contents, and their stoichiometric ratios in Cunninghamia lanceolata saplings, four types of treatments were assigned: control (CT), warming (W, + 4 ºC), nitrogen deposition (N, 40 kg ha-1 a-1), and warming + nitrogen deposition (WN) treatments. The results showed that: (1) compared with CT, W treatment significantly decreased leaf P content by 54.54% and increased leaf C/P and N/P by 85.26% and 83.39%, respectively; WN treatment significantly decreased leaf C content and P content by 1.99% and 51.03%, respectively, but increased the leaf C/P by 68.01% with no significant differences in leaf N content among treatments. The leaf N/P ratio of each treatment was less than 10, but that of the W and WN treatments were closer to 10 than that of the CT treatment. Meanwhile, W and WN treatments significantly increased tree height. (2) No significant differences were observed in soil total carbon (TC), total nitrogen (TN), and total phosphorus (TP) contents among treatments. Compared with CT, W treatment significantly decreased soil C/N by 4.09%, while neither W nor WN treatment affected soil C/P and N/P. W treatment increased the available soil content compared to CT treatment. (3) The correlation analysis showed that leaf N content was significantly negatively correlated with soil C/N in the CT treatment; in the W treatment leaf N content and N/P were significantly positively correlated with soil TN and TP content, respectively. Leaf N content was significantly negatively correlated with soil TC and TN in the N treatment, and leaf contents had no significant correlation with soil C, N, and P contents or their stoichiometric characteristics in the WN treatment. This study showed that N limitation still exists in C. lanceolata saplings. Warming and the interaction between warming and nitrogen deposition could alleviate N limitation and promote the growth of C. lanceolata. © 2022 Authors. All rights reserved.