Responses of twig functional traits and leaf stoichiometric characteristics of two plantations to simulated nitrogen deposition in the hilly area of central sichuan

The effects of nitrogen deposition on the nutrient limitation pattern and growth strategy of forest trees have already become the research frontiers of forest ecological ecology. In order to clarify the influence of N deposition on the nutrient limitation characteristics and growth strategies of plantations in the hilly area of central Sichuan, this study took Pinus massoniana plantation and Cupressus funebris plantation as the research objects in this area, and analyzed the responses of the functional traits of the current twigs and foliar N and P stoichiometry to N addition in the two plantations. The results showed that: 1) Under nitrogen addition, the TM and MLI of the current twigs of Pinus massoniana plantation and Cupressus funebris plantation were significantly decreased. 2) Under nitrogen addition, the foliar P concentration of the two plantations was significantly decreased, and the foliar N:P was significantly increased. 3) Under nitrogen addition, the LDMC of the two plantations increased significantly, while the SLA decreased significantly. Therefore, N addition enhanced the P-limiting degree of Pinus massoniana plantation and Cupressus funebris plantation in the hilly area of central Sichuan, resulting in the inhibition of tree growth, and in this case, the two plantations tended to adopt a conservative “slow investment-return” growth strategy. And this result can provide a scientific basis for the adaptive management and ecological function restoration of plantations in this area.