Nitrous oxide (N2O) is one of the most important greenhouse gases, with a global warming potential that is 280 times higher than that of CO2. Tropical forests are important contributors for N2O emissions from soil to the atmosphere; however, the microbial processes responsible for soil N2O production in tropical forest soils remain unclear.
In a study published in CATENA, researchers from Xishuangbanna Tropical Botanical Garden (XTBG) employed a 40-day-long in situ 15NO3？ labeling experiment to determine the microbial processes that are responsible for N2O production in an undisturbed tropical rainforest in Xishuangbanna, southwest China.
The researchers distinguished the contributions of nitrification, denitrification, and co-denitrification to N2O emissions based on the random isotope pairing principle in a 15N-labeled nitrate field experiment.
The field experiment certified that nitrification is the most important microbial processes underlying the N2O emissions in the transition period between the dry and the rainy season.
The results indicate that denitrification resulted in more N2O emissions than co-denitrification via the higher consumption of both organic nitrogen and inherent NO3？. When extra N was added, soil N2O emissions increased. Deposited 15NO3？ contributed 3.1% to the 15N2O produced, whereas the added NH4+ and native soil N contributed 48.6%.
“To the best of our knowledge, this is the first study where the microbial processes involved in N2O emissions have been measured in situ,” said Prof. ZHANG Yiping of XTBG.
ZHANG Yiping Ph.D
Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Yunnan 666303, China