Nitrogen Addition Did Not Alter the Relationships Between the Leaf and Root Traits of Machilus Pauhoi seedlings

Abstract

Leaves and roots are important resource acquisition organs of seedlings and both are sensitive to the environment. However, it is currently unclear whether leaf and root traits have a similar response model to nitrogen (N) deposition. Furthermore, the relationships between the responses of leaf and root traits to N deposition are still unknown.Exogenous nitrogen input experiments were conducted to simulate the effects of nitrogen deposition in Shunchang County, south of China. We measured the biomass, morphological characteristics, and nutrient concentrations (total of 12 functional traits of leaves and roots) of Machilus pauhoi seedlings. The responses of leaf and root traits to N addition were analyzed. In addition, the relationships between paired leaf and root traits were analyzed.We found that the responses of the leaves and roots to short-term nitrogen deposition were not consistent. The specific leaf area (SLA) (specific root length, SRL), tissue density (TD), carbon (C) content, N content, C/N, and N/phosphorus (P) of the leaf and root did not appear to respond to N addition. However, the biomass, P content, and C/P of the leaf and root markedly responded to N addition. The nutrient concentrations of the leaf and root were correlated, while the phenotypic traits were not. Furthermore, short-term N addition did not alter the relationship between the leaves and roots.Our results show that, in the context of global change of nitrogen deposition, the correlation between the leaves and roots of a plant has a certain tolerance for nitrogen deposition, which is of great significance for the efficient cultivation of quality seedlings and understanding how terrestrial forest ecosystems respond to nitrogen deposition.