Nitric oxide (NO) is a significant contributor to air pollution, and forest soil is a significant source of NO emissions. However, due to a lack of high-frequency NO emission measurements, there are significant uncertainties in global forest soil NO emission.
In Northeast China, forest soil NO emission has been ignored during the period of augmented nitrogen (N) deposition over the last few decades.
Prof. Fang Yunting’s team from the Chinese Academy of Sciences’ Institute of Applied Ecology conducted a long-term and automated soil NO measurement experiment in Qingyuan Forest, Northeast China, to quantify NO emission from forest soils and determine its controlling factors.
They discovered that the average annual soil NO emission from the study forest was 0.42 0.04 kg N ha-1.
They demonstrated that temperature was the most important factor in the daily emission scale by combining four empirical models (Temperature model, soil water-filled pore space model, Q10=2 theoretical model, and the interactive model of temperature and WFPS). With an apparent temperature sensitivity of 3.67, temperature regulated NO emission with a significant exponential relationship and explained more than 70% of the variation in daily NO emission.
They also discovered that soil moisture (WFPS) promoted NO emission after longer droughts in the growing seasons.
This study provides a better mechanistic understanding of forest soil NO emission in Northeast China, which can help develop more accurate N biogeochemical models and improve soil NO emission estimation globally.
The study was published in Agricultural and Forest Meteorology under the title “A strong temperature dependence of soil nitric oxide emission from a temperate forest in Northeast China.”