科研之友
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摘要
As one of the main greenhouse gases, N2O has a significant impact on the Earth and human beings. To explore the influence mechanisms of heterotrophic nitrification of organic N and N2O emission process and improve global N2O flux estimation model, Pearson correlation analysis and generalized additive model (GAM) were used to analyze the influencing factors of heterotrophic nitrification rates of organic N and N2O emission rates in 135 sampling sites worldwide. The major influencing factors were included into BP neural network model to estimate the spatial distribution of heterotrophic nitrification rates of organic N and N2O emission rates in global forest soils. The results showed that soil pH and C/N were the main factors affecting heterotrophic nitrification rate of organic N. Soil C/N, water-filled pore space (WFPS), and temperature are the main factors affecting N2O emission rate during heterotrophic nitrification process. The average heterotrophic nitrification rate was 0.4241 (0.0014-0.689) μg N· g-1·d-1, and the average N2O emission rate in the heterotrophic nitrification process was 0.2936 (0.21-1.103) μg N2O·kg-1·d-1 in global forest soils. The heterotrophic nitrification rate and N2O emission rate in the heterotrophic nitrification process were higher in forest soils around 50° N. In contrast, the two rates were lower in forest soils from 30° S to 30° N. Although heterotrophic nitrification rate was high, N2O emission rate in the heterotrophic nitrification process was low in forest soils in Northeast Asia. N2O emission flux from the heterotrophic nitrification of organic N was (1.4584±0.3791) Tg N·a-1 in global forest soils, accounting for 26.04% of N2O emission from natural soils and 8.58% of global N2O emission.
