Plant-mediated methane and nitrous oxide fluxes from a carex meadow in Poyang Lake during drawdown periods

Abstract

Aims Plants have been suggested to have significant effects on methane (CH 4 ) and nitrous oxide (N 2 O) fluxes from littoral wetlands, but it remains unclear in subtropical lakes. Methods We conducted in situ measurement of CH 4 and N 2 O fluxes for two years. To distinguish between the effects of shoots and roots, three treatments (i.e., intact plants as control, shoot clipping, and root exclusion) were used. Effects of plant biomass, temperature, and soil moisture on CH 4 and N 2 O fluxes were analyzed. Results The mean ecosystem CH 4 emission rate was 36 μg CH 4 m −2 h −1 for drying periods, but 8219 μg CH 4 m −2 h −1 for drying-wetting transition periods. CH 4 fluxes were positively correlated with below-ground and total biomass, but not with above-ground biomass. Clipping did not significantly alter CH 4 flux rate, but root exclusion decreased the CH 4 flux by 116 % as compared to the control. N 2 O emissions were similar for both the drying and drying-wetting transition periods, with a mean rate of 20 μg N 2 O m −2 h −1 . Both clipping and root exclusion significantly increased N 2 O fluxes as compared to the control. Conclusions There was no significant correlation between CH 4 and N 2 O fluxes. Roots dominated plantmediated enhancement in CH 4 fluxes, but played almost an equal role as shoots in plant-regulated suppression on N 2 O fluxes in this Carex meadow during drawdown periods.

Warming Increases Nitrous Oxide Emission from the Littoral Zone of Lake Poyang, China

“…In this study, the littoral zone of Lake Poyang was an N2O source during the uninundated period, with a mean flux rate of 8.9 ± 1.1 μg N2O m −2 h −1 . This result confirms our first hypothesis and is also in line with the result reported by Hu et al (2016) in the south littoral zone of Lake Poyang [30]. Moreover, N2O flux in the littoral zone of Lake Poyang was much lower than that of Lake Huahu in the Qinghai-Tibetan Plateau [49], which may be attributed to the lower available nitrogen and the non-waterlogged conduction in this study site during the sampling period.…”

“…A recent study found that plant biomass can explain 17-30% of N 2 O flux variation in the littoral zone of Lake Poyang [30]. In addition, we found that warming increased the content of soil NH + 4 -N and soil NO − 3 -N, which were the two main substrates supporting the processes of nitrification and denitrification.…”

“…Previous studies have reported a great variability of N 2 O emission or uptake from different wetlands due to various environmental factors [15,30,[43][44][45][46][47][48][49]. Overall, swamps, peatlands, and marshes in cold regions usually acted as an N 2 O sink or an N 2 O source, while most littoral wetlands emitted N 2 O and showed high variation among different locations (Table 3).…”

“…Despite not considering two other GHGs-CO 2 and CH 4 -in this study, the contribution of N 2 O to climate warming should not be ignored due to its large global warming potential. Hu et al (2016) also concluded that N 2 O should be integrated into the estimation of net GHG emission for the same lake [30]. In addition, warming effects on GHG fluxes will not always be consistent for a continuous long-term period [18].…”

Plant-microbe-mediated decrease of greenhouse gases under dynamic wetland hydrology

“…Additionally, vegetation can alter soil redox potentials by facilitating transport of oxygen into roots zones (Chanton, 2005;Sundberg et al, 2007) and transporting methane from root zones into the atmosphere (Carmichael et al, 2014;Hu et al, 2015).…”