Effects of cattle husbandry on abundance and activity of methanogenic archaea in upland soils

Abstract

In the present study, we tested the hypothesis that animal treading associated with a high input of organic matter would favour methanogenesis in soils used as overwintering pasture. Hence, methane emissions and methanogen populations were examined at sections with different degree of cattle impact in a Farm in South Bohemia, Czech Republic. In spring, methane emission positively corresponded to the gradient of animal impact. Applying phospholipid etherlipid analysis, the highest archaeal biomass was found in section severe impact (SI), followed by moderate impact (MI) and no impact. The same trend was observed for the methanogens as showed by real-time quantitative PCR analyses of methyl coenzyme M reductase (mcrA) genes. The detection of monounsaturated isoprenoid side chain hydrocarbons (i20:1) indicated the presence of acetoclastic methanogens in the cattle-impacted sites. This result was corroborated by the phylogenetic analysis of mcrA gene sequences obtained from section SI, which showed that 33% of the analysed clones belonged to the genus Methanosarcina. The majority of the sequenced clones (41%) showed close affiliations with uncultured rumen archaeons. This leads to the assumption that a substantial part of the methanogenic community in plot SI derived from the grazing cattle itself. Compared to the spring sampling, in autumn, a significant reduction in archaeal biomass and number of copies of mcrA genes was observed mainly for section MI. It can be concluded that after 5 months without cattle impact, the severely impact section maintained its methane production potential, whereas the methane production potential under moderate impact returned to background values.

Evaluating the lingering effect of livestock grazing on functional potentials of microbial communities in Tibetan grassland soils

“…Grazing induced increases in the number of copies of the mcrA gene and soil CH 4 emissions (Radl et al 2007). In our study, the relative abundance of the CH 4 -producing mcrA gene increased at the 3200-m site, but CH 4 -oxidizing genes decreased at both sites (see Supplementary Fig.…”

“…However, grassland recovery after grazing is a common land-use management strategy in many places around the world. Grassland recovery has been shown to fully restore plant growth and certain eco-processes (e.g., CH 4 emissions) if grazed at moderate intensity, but grazing at high intensity leads to soil deterioration (Cao et al 2004;Pappas and Koukoura 2013;Radl et al 2007). Therefore, it is necessary to examine functional potentials of microbial communities in post-grazing grassland soils.…”

“…The DNA copy number of the methyl coenzyme M reductase (mcrA) gene increased immediately in response to grazing, concurrent with an increase of methane (CH 4 ) emissions (Radl et al 2007). Additionally, grazing increased the abundance of the ammonia-oxidizing gene (amoA), which was attributed to increased conversion of urea into ammonia in animal excrement (Radl et al 2014;Xie et al 2014).…”

“…Livestock grazing is a dominant economic activity in the Tibetan Plateau (Cao et al 2004); however, it imposes marked and lasting impacts on above-and below-ground ecosystems of land surfaces via a number of mechanisms such as trampling, defoliation, defecation, and urination (Bardgett and Wardle 2003;Hamilton and Frank 2001;Radl et al 2007;Ruess and Mcnaughton 1987). As a result, the magnitude of soil carbon (C) and nitrogen (N) pools could be altered by reallocating C and N between roots and shoots, or by recycling C and N through the animal excreta pathway (Hamilton and Frank 2001;Ruess and Mcnaughton 1987).…”

Microbial biomass in sediments affects greenhouse gas effluxes in Poyang Lake in China

“…In particular, N 2 O effluxes varied linearly with fungi biomass in freshwater sediments (Takaya 2009;Seo & DeLaune 2010;Mouton et al 2012). However, although it has been reported that microbial biomass influenced GHG emissions in terrestrial soils (Radl et al 2007;Burke et al 2012;Narvaez et al 2013), few studies have focused on investigating the effects of microbial biomass on GHG emissions in lake sediments.…”