Structures of Microbial Communities in Alpine Soils: Seasonal and Elevational Effects

Abstract

Microbial communities in alpine environments are exposed to several environmental factors related to elevation and local site conditions and to extreme seasonal variations. However, little is known on the combined impact of such factors on microbial community structure. We assessed the effects of seasonal variations on soil fungal and bacterial communities along an elevational gradient (from alpine meadows to a glacier forefield, 1930–2519 m a.s.l.) over 14 months. Samples were taken during all four seasons, even under the winter snowpack and at snowmelt. Microbial community structures and abundances were investigated using Terminal Restriction Fragment Length Polymorphism (T-RFLP) and quantitative PCR (qPCR) of the 16S and 18S rRNA genes. Illumina sequencing was performed to identify key bacterial groups in selected samples. We found that the soil properties varied significantly with the seasons and along the elevational gradient. For example, concentrations of soluble nutrients (e.g., NH4+-N, SO42−-S, PO43−-P) significantly increased in October but decreased drastically under the winter snowpack. At all times, the alpine meadows showed higher soluble nutrient concentrations than the glacier forefield. Microbial community structures at the different sites were strongly affected by seasonal variations. Under winter snowpack, bacterial communities were dominated by ubiquitous groups (i.e., beta-Proteobacteria, which made up to 25.7% of the total reads in the glacier forefield). In the snow-free seasons, other groups (i.e., Cyanobacteria) became more abundant (from 1% under winter snow in the glacier forefield samples to 8.1% in summer). In summary, elevation had a significant effect on soil properties, whereas season influenced soil properties as well as microbial community structure. Vegetation had a minor impact on microbial communities. At every elevation analyzed, bacterial, and fungal community structures exhibited a pronounced annual cycle.

Soil microbial biomass, activity and community composition along altitudinal gradients in the High Arctic (Billefjorden, Svalbard)

“…The studies commonly show that microbial activity decreases with increasing elevation (Schinner, 1982 -Alps;Niklińska and Klimek, 2007 -Polish Carpathians;Margesin et al, 2009 -Alps), while there are no general altitudinal patterns in soil microbial diversity and community structure. For example, the microbial community composition did not change along elevational gradients in the Swiss Alps (Lazzaro et al, 2015), while other studies have documented decreasing bacterial (Ma et al, 2004 -western China;Lipson, 2007 -Rocky Mountains;Shen et al, 2013 -northeastern China) and fungal (Schinner and Gstraunthaler, 1981 -Alps) diversity with increasing altitude. Several studies reported a mid-altitudinal peak in microbial diversity (Fierer et al, 2011 -Peru;Singh et al, 2012 -Mt.…”

Heavy Metal Pollution Structures Soil Bacterial Community Dynamics in SW Spain Polluted Salt Marshes

“…Clones obtained from the same band with coinciding results are represented by a single clone a The number represents the band number (Fig. 1) and the letter the clone b Using 16S ribosomal RNA sequences (Bacteria and Archaea) database non-polluted soils support the idea that over the plant the major determinant of microbial community may be seasonal changes (Zhao et al 2016;Lacap et al 2007;Lazzaro et al 2015;Shi et al 2015;Streten-Joyce et al 2013;Žifčáková et al 2016;Hill et al 2015;Regan et al 2014), and/or soil type structure (Singh et al 2007). …”

Emerging from the ice‐fungal communities are diverse and dynamic in earliest soil developmental stages of a receding glacier

“…SMCs follow distinct seasonal patterns across different habitats including boreal forest and arctic/alpine habitats (Schadt et al, 2003;Kuhnert et al, 2012;Lazzaro et al, 2012;Buckeridge et al, 2013;Koranda et al, 2013;Voříšková et al, 2014;Lazzaro et al, 2015;Schostag et al, 2015;Zifcakova et al, 2016) and are not at all dormant during winter. A community shift from bacteria towards cold-adapted fungi has been observed during winter (Schadt et al, 2003;Lazzaro et al, 2012;Buckeridge et al, 2013), with saprobial Ascomycota and basidiomycete yeasts-dominating fungal communities (Oberkofler and Peintner, 2008;Kuhnert et al, 2012).…”