Experimental warming of a mountain tundra increases soil CO2 effluxes and enhances CH4 and N2O uptake at Changbai Mountain, China

Abstract

Climatic warming is expected to particularly alter greenhouse gas (GHG) emissions from soils in cold ecosystems such as tundra. We used 1 m2 open-top chambers (OTCs) during three growing seasons to examine how warming (+0.8–1.2 °C) affects the fluxes of carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) from alpine tundra soils. Results showed that OTC warming increased soil CO2 efflux by 141% in the first growing season and by 45% in the second and third growing season. The mean CH4 flux of the three growing seasons was −27.6 and −16.7 μg CH4-C m−2h−1 in the warmed and control treatment, respectively. Fluxes of N2O switched between net uptake and emission. Warming didn’t significantly affect N2O emission during the first and the second growing season, but stimulated N2O uptake in the third growing season. The global warming potential of GHG was clearly dominated by soil CO2 effluxes (>99%) and was increased by the OTC warming. In conclusion, soil temperature is the main controlling factor for soil respiration in this tundra. Climate warming will lead to higher soil CO2 emissions but also to an enhanced CH4 uptake with an overall increase of the global warming potential for tundra.

Combination of Warming and Vegetation Composition Change Strengthens the Environmental Controls on N2O Fluxes in a Boreal Peatland

“…This disproves our second hypothesis that warming stimulated N 2 O emission under the treatments of vascular plant removal and can be attributed to soil moisture reduction. As a result of soil moisture reduction, N 2 O easily enters into the anaerobic zone and is consumed by denitrification [31]. However, we did not find a significant relationship between soil moisture and N 2 O fluxes under the combination of warming and vascular plant removal (W-Sh-Se).…”

Impact of elevated precipitation, nitrogen deposition and warming on soil respiration in a temperate desert

“…soil NH4 + -N and soil moisture (Fig. 5), unsupported our hypothesis, but it is consistent with most research results (Wu et al, 2016;Zhou et al, 2016b;Chen et al, 2017a). In addition, large inter-annual variation was observed (CV = 41.4%) during our experiment (Table 1), while the variation of annual precipitation and air temperature were only 4.41% and 7.78%, respectively (Table 1), but close to the CV of spring root biomass of ephemeral plants (47.14%) with 24 times of aboveground biomass of spring ephemeral plants in 2016 than that in 2015 (Cui et al, 2017), which indicated that the increase of Rs in 2016 was mainly from the root respiration of ephemeral plants.…”

“…14:00 by warming, which may reduce carbon emission from soil to atmosphere. However, this is not consistent with results from a tundra ecosystem, subtropical forest or alpine regions where Rs was significantly increased by warming due to the limitation of soil temperature in these ecosystems, and no significant change in soil moisture (Noh et al, 2016;Wu et al, 2016;Zhou et al, 2016b). In addition, a significant increase in Rs was found following enhanced precipitation with warming ( Fig.…”

Key sources and seasonal dynamics of greenhouse gas fluxes from yak grazing systems on the Qinghai-Tibetan Plateau

“…Gas samples were drawn through a three-way stopcock, using a 60 ml syringe, and then transferred for storage into 500 ml aluminium foil gas-collecting bags (China Dalian Delin Gas Packing Co., Ltd). Four gas samples of approximately 250 ml were taken in each chamber at four time intervals for each sampling event (0, 10, 20 and 30 min) from 9:00 am at local time to represent daily mean flux51. Temperatures inside the chamber and at soil or manure depths of 50 mm were also recorded on each sampling occasion.…”