Team of researchers from the Global Change Research Institute of the Czech Academy of Sciences and the University of Helsinki has revealed that boreal trees emit nitrous oxide (N2O) to the atmosphere being thus relevant sources of this important greenhouse gas. The results were published in Nature Communications in November 2019.
Nitrous oxide, contributing to global climate change, is naturally produced in soils and exchanged with the atmosphere at the soil surface. This gas can be transported into the atmosphere also via vegetation. Even though trees are known to emit N2O into the atmosphere, they have so far been overlooked in N2O inventories of forest ecosystems. The authors studied natural fluxes of N2O from soil and stems of main tree representatives of boreal forests in Southern Finland (pine, spruce, birch). Whole-year measurements revealed clear seasonality in stem N2O flux following tree physiological activity. Stem N2O emissions peak during the vegetation season and remain low but significant to the annual totals during winter dormancy. At an annual scale, all studied boreal trees are net N2O sources, with spruce being the strongest emitter. The authors underline the role of trees in the seasonal dynamics of ecosystem N2O exchange and highlight the urgent need to include the exchange potential of trees in the forest ecosystem greenhouse gas inventories.
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Machacova K, Vainio E, Urban O, Pihlatie M (2019) Seasonal dynamics of stem N2O exchange follow the physiological activity of boreal trees. Nature Communications 10: 4989, DOI: 10.1038/s41467-019-12976-y.