Abstract
Atmospheric nitrous oxide (N(2)O) increase contributes substantially to global climate change due to its large global warming potential. Soil N(2)O emissions have been widely studied, but plants have so far been ignored, even though they are known as an important source of N(2)O. The specific objectives of this study are to (1) reveal the effects of nitrogen and biochar addition on plant functional traits and N(2)O emission of Cinnamomum camphora seedlings; (2) find out the possible leaf traits affecting plant N(2)O emissions. The effects of nitrogen and biochar on plant functional traits and N(2)O emissions from plants using C. camphora seedlings were investigated. Plant N(2)O emissions, growth, each organ biomass, each organ nutrient allocation, gas exchange parameters, and chlorophyll fluorescence parameters of C. camphora seedlings were measured. Further investigation of the relationships between plant N(2)O emission and leaf traits was performed by simple linear regression analysis, principal component analysis (PCA), and structural equation model (SEM). It was found that nitrogen addition profoundly increased cumulative plant N(2)O emissions (+109.25%), which contributed substantially to the atmosphere's N(2)O budget in forest ecosystems. Plant N(2)O emissions had a strong correlation to leaf traits (leaf TN, P (n) , G (s) , C (i) , Tr, WUE (L) , α, ETR (max), I (k) , Fv/Fm, Y(II), and SPAD). Structural equation modelling revealed that leaf TN, leaf TP, P (n) , C (i) , Tr, WUE (L) , α, ETR (max), and I (k) were key traits regulating the effects of plants on N(2)O emissions. These results provide a direction for understanding the mechanism of N(2)O emission from plants and provide a theoretical basis for formulating corresponding emission reduction schemes.