Cold season soil NO fluxes from a temperate forest: drivers and contribution to annual budgets
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Дата
2016
Науковий керівник
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Анотація
Soils, and here specifically acidic forest soils exposed to high rates of atmospheric nitrogen deposition,
are a significant source for the secondary greenhouse gas nitric oxide (NO). However, as flux estimates
are mainly based on measurements during the vegetation period, annualNOemissions budgets may
hold uncertainty as cold season soilNOfluxes have rarely been quantified. Here we analyzed cold
season soilNOfluxes and potential environmental drivers on the basis of the most extensive database
on forest soilNOfluxes obtained at the Höglwald Forest, Germany, spanning the years 1994 to 2010.
Onaverage, the cold season (daily average air temperature<3 °C) contributed to 22% of the annual
soilNObudget, varying from 13% to 41% between individual cold seasons. Temperature was the
main controlling factor of the cold seasonNOfluxes, whereas during freeze-thaw cycles soil moisture
availability determinedNOemission rates. The importance of cold season soilNOfluxes for annual
NOfluxes depended positively on the length of the cold season, but responded negatively to frost
events. Snow cover did not significantly affect cold season soilNOfluxes. Cold seasonNOfluxes
significantly correlated with cold season soil carbon dioxide (CO2) emissions. During freeze-thaw
periods strong positive correlations betweenNOandN2Ofluxes were observed, though stimulation
ofNOfluxes by freeze-thaw was by far less pronounced as compared toN2O. Except for freeze-thaw
periodsNOfluxes significantly exceeded those forN2Oduring the cold season period.Weconclude
that in temperate forest ecosystems cold seasonNOemissions can contribute substantially to the
annualNObudget and this contribution is significantly higher in years with long lasting but mild (less
frost events) cold seasons.
Опис
Ключові слова
nitric oxide, N2O,CO2, freeze-thaw, snow
Бібліографічний опис
Environ. Res. Lett. 11 (2016) 114012. – Р.1-11. doi:10.1088/1748-9326/11/11/114012