CH₄ and N₂O emissions from a forest‐alas ecosystem in the permafrost taiga forest region, eastern Siberia, Russia

Abstract

[1] 'Alases' are mature thermokarst depressions covered by grassland distributed in taiga forests in central Yakutia, eastern Siberia, following thermokarst formation initiated in early Holocene. Alases are important land-cover class in the central Yakutia lowland occupying 17% of the total land area. CH 4 and N 2 O fluxes were measured temporally in a typical alas which have a pond at the center during the growing season of two years. Seven monitoring plots represented various vegetation types: a larch forest (F), a dry grassland (DG), four wet grasslands (WG) flooded temporarily or continuously, and a pond surface (P) flooded continuously without vegetation. The pond flooding area reached its maximum just after snow-melting and decreased during the summer. The F and DG plots were small CH 4 sinks. The wet plots (including WG and P) were large CH 4 sources (cumulative value of growing season: 17 to 864 kg CH 4 -C ha À1 ), and emission rates vary drastically depending on flooding conditions. All plots were slight sources or sinks of N 2 O except for the WG plots (0.16 to 1.7 kg N 2 O-N ha À1 ) where peak emissions were observed after the flooding ended. The global warming potentials (time horizon of 100 years) of the cumulative N 2 O emissions from the plots were lower than those of each CH 4 emissions. Estimated total CH 4 emission from the whole WG area (7.93 ha) accounted for 88% of the emission from the whole alas (28.9 ha). The current permafrosttaiga region in central Yakutia could be a net CH 4 source owing to the presence of alases.

Humic substances elemental composition of selected taiga and tundra soils from Russian European North-East

“…-Soil organic matter mineralization as well as possible CO 2 emission from soils has been paid great attention for its important effect on the global carbon cycle and ecosystems stability (Roulet 2000;Zamolodchikov et al 2005). Permafrost thaw and degradation nowadays is the global process, which results in soil organic matter redistribution, alteration and mineralization (Takakai et al 2008). Recent studies provide evidence of a high and long-term mineralisation potential of Arctic SOM under increased temperatures (Elberling et al 2013;Schädel et al 2014;Schuur et al 2015).…”

Actinobacterial Nitrate Reducers and Proteobacterial Denitrifiers Are Abundant in N 2 O-Metabolizing Palsa Peat

“…Palsa development is affected by various environmental factors, such as wind erosion, vegetation cover, snow cover, and ground water table depth (63). High-latitude peatlands have been intensively studied with respect to their capacity to emit methane due to the large amount of stored carbon in peat soils, but nitrous oxide (N 2 O) emissions from permafrost regions were generally considered to be insignificant (12,58,66). However, recent studies document significant but variable N 2 O emissions from permafrost systems including palsas (17,45,58).…”

Biogeochemical insights into microbe–mineral–fluid interactions in hydrothermal chimneys using enrichment culture

“…reported in our study are generally lacking in microbial diversity survey of active hydrothermal chimneys, with the notable exception of few clones detected at the Suiyo Seamount, Izu-Bonin Arc (Higashi et al 2004) and at the Mariner field, Lau Basin (Takai et al 2008). To date, most of the detected phylotypes are related to cultivated species of sulfur reducers, sulfur oxidizers and sulfate reducers.…”

“…It has been well documented that the steep temperature and geochemical gradient within the chimney wall generate specific micro-habitats that can host large and diverse microbial populations (Nakagawa et al 2005;Page et al 2008;Takai et al 2008;Karl 1995). The physiological and phylogenetical diversities of these prokaryotes have been investigated using both cultural and molecular approaches to determine their ecological role and importance for biogeochemical cycles of carbon, sulfur, nitrogen and iron (Yamamoto and Takai 2011;Byrne et al 2009b;Slobodkin et al 2001;Reysenbach and Cady 2001;Kashefi et al 2002).…”