Larix decidua and additional light affect the methane balance of forest soil and the abundance of methanogenic and methanotrophic microorganisms

Abstract

Due to the activity of methane-oxidizing bacteria, forest soils are usually net sinks for the greenhouse gas methane (CH4). Despite several hints that CH4 balances might be influenced by vegetation, there are only few investigations dealing with this connection. Therefore, we studied this soil–plant–microbe interaction by using mesocosm experiments with forest soil and Larix decidua, a common coniferous tree species within the Alps. Gas measurements showed that the presence of L. decidua significantly reduced CH4 oxidation of the forest soil by ∼10% (−0.95 µmol m−2 h−1 for soil vs −0.85 µmol m−2 h−1 for soil plus L. decidua) leading to an increased net CH4 balance. Increased light intensity was used to intensify the influence of the plant on the soil's CH4 balance. The increase in light intensity strengthened the effect of the plant and led to a greater reduction of CH4 oxidation. Besides, we examined the impact of L. decidua and light on the abundance of methanogens and methanotrophs in the rhizosphere as compared with bulk soil. The abundance of both methane-oxidizing bacteria and methanogenic archaea was significantly increased in the rhizosphere compared with bulk soil but no significant response of methanogens and methanotrophs upon light exposure was established.

Microbial community composition in the rhizosphere of Larix decidua under different light regimes with additional focus on methane cycling microorganisms

“…Generally, forest soils show on average the highest sink capacity to oxidize CH 4 of well aerated soils 41 , making it the second largest sink for atmospheric CH 4 after tropospheric chemical oxidation 42 . Besides abiotic influencing factors for methanotrophs like temperature, pH and soil moisture 43 , atmospheric CH 4 uptake showed to be sensitive towards vegetation type and plant species 44 , 45 . Different tree species can affect the methanotrophic community composition and the oxidation capacity of forest soils 16 , 22 .…”

Abundance and biogeography of methanogenic and methanotrophic microorganisms across European streams

“…Quantitative PCR (qPCR) was conducted using the SensiFast TM SYBR No‐Rox Kit (Bioline, UK) on a Corbett Life Science Rotor‐GeneTMQ system (Qiagen). Total mcrA ‐genes of MA were determined using the primer set mlas/mcrA‐rev (469bp) (Steinberg and Regan, 2009) and the abundance of pmoA gene of type Ia and type II methane‐oxidizing bacteria with the primer pairs A189f/Mb601r (432bp) and II223f/II646r (444bp) (Kolb et al., 2003; Cai et al., 2016; Praeg et al., 2020; see Table S3, Appendix S2 for cycling conditions). Detailed qPCR‐related information is given in the supplement (Method S5, Appendix S3).…”

“…In contrast to the sequencing, the qPCR approach does not include ANME and the quantified group targeted with the pmoA is thus abbreviated as MOB (without archaea). Thereby, the separate investigation of type I and type II MOB provides (more) detailed information on methanotrophic physiology (Trimmer et al., 2015) and total methanotrophs can be quantified to a large extend by the aforementioned primer pairs (Cai et al., 2016; Kolb et al., 2003; Praeg et al., 2020). Thus, gene copies of type Ia and type II MOB were summed to represent an approximation to the total MOB gene copy number.…”

Water and Carbon Dynamics, Ecosystem Stability of Forest and Grassland in Response to Climate Change

“…This is consistent with research on night-time CH 4 flux in farmland and wetland ecosystems Zhang et al, 2019). The maximum values of diurnal average CH 4 fluxes during the growth season were all less than those of the non-growth season, mainly because of the larger precipitation and net radiation, the latter of which enhanced plants' activities and reduced the oxidation of CH 4 (Praeg et al, 2019). Obvious daily changes were observed during the sunny days in both the growth and the non-growth season.…”