Wintertime Greenhouse Gas Fluxes in Hemiboreal Drained Peatlands

Birgit Viru,Gert Veber,Ain Kull,Jaak Jaagus,Alar Teemusk,Martin Maddison,Ülo Mander,Mart Muhel,Mikk Espenberg

doi:10.3390/atmos11070731

Abstract

The aim of this study is to estimate wintertime emissions of greenhouse gases CO2, N2O and CH4 in two abandoned peat extraction areas (APEA), Ess-soo and Laiuse, and in two Oxalis site-type drained peatland forests (DPF) on nitrogen-rich sapric histosol, a Norway spruce and a Downy birch forest, located in eastern Estonia. According to the long-term study using a closed chamber method, the APEAs emitted less CO2 and N2O, and more CH4 than the DPFs. Across the study sites, CO2 flux correlated positively with soil, ground and air temperatures. Continuous snow depth > 5 cm did not influence CO2, but at no snow or a thin snow layer the fluxes varied on a large scale (from −1.1 to 106 mg C m−2 h−1). In all sites, the highest N2O fluxes were observed at a water table depth of −30 to −40 cm. CH4 was consumed in the DPFs and was always emitted from the APEAs, whereas the highest flux appeared at a water table >20 cm above the surface. Considering the global warming potential (GWP) of the greenhouse gas emissions from the DPFs in the wintertime, the flux of N2O was the main component of warming, showing 3–6 times higher radiative forcing values than that of CO2 flux, while the role of CH4 was unimportant. In the APEAs, CO2 and CH4 made up almost equal parts, whereas the impact of N2O on GWP was minor.

Highlights

Carbon dioxide (CO2 ), methane (CH4 ) and nitrous oxide (N2 O) are three major greenhouse gases (GHG), which influence Earth’s radiation balance
According to the principal component analysis (PCA) of the soil, water and gas emission characteristics, the abandoned peat extraction areas (APEA) (ES and LA) were under similar conditions and significantly different from peatland forests (DB and Norway spruce forest (NS)) (p < 0.001 in all comparisons), which were in turn similar to each other (Figure 2)
The APEAs differed from the forests mainly in higher water table, dissolved O2

Summary

Introduction

Carbon dioxide (CO2 ), methane (CH4 ) and nitrous oxide (N2 O) are three major greenhouse gases (GHG), which influence Earth’s radiation balance. The amount of greenhouse gases in the atmosphere has increased due to human activities. Meteorological Organization) [1], atmospheric greenhouse gas concentrations increased from 278 ppm in the pre-industrial period to 407.8 ppm for CO2 , 722 to 1869 ppb for CH4 and 270 to 331.1 for N2 O in. Snow cover significantly influences wintertime emissions of CO2 , CH4 and N2 O [2,3,4,5,6,7,8,9]. It has been reported that wintertime emissions of GHG accounted for 17–28% of CO2 [4,5,6,9,10,11]; 2–59% of CH4 [4,5,12,13,14,15,16,17,18,19]; 2–99% of

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