Prokaryotic community shifts during soil formation on sands in the tundra zone

Abstract

14A chronosequence approach, i.e., a comparison of spatially distinct plots with different stages of 15 succession, is commonly used for studying microbial community dynamics during paedogenesis. 16 The successional traits of prokaryotic communities following sand fixation processes have 17 previously been characterized for arid and semi-arid regions, but they have not been considered 18 for the tundra zone, where the environmental conditions are unfavourable for the establishment 19 of complicated biocoenoses. In this research, we characterized the prokaryotic diversity and 20 abundance of microbial genes found in a typical tundra and wooded tundra along a gradient of 21 increasing vegetation -unfixed aeolian sand, semi-fixed surfaces with mosses and lichens, and 22 mature soil under fully developed plant cover. Microbial communities from typical tundra and 23 wooded tundra plots at three stages of sand fixation were compared using quantitative 24 polymerase chain reaction (qPCR) and high-throughput sequencing of 16S rRNA gene libraries. 25The abundances of ribosomal genes increased gradually in both chronosequences, and a similar 26 trend was observed for the functional genes related to the nitrogen cycle (nifH, bacterial amoA, 27 nirK and nirS). The relative abundance of Planctomycetes increased, while those of 28 Thaumarchaeota, Cyanobacteria and Chloroflexi decreased from unfixed sands to mature soils. 29According to β-diversity analysis, prokaryotic communities of unfixed sands were more 30 heterogeneous compared to those of mature soils. Despite the differences in the plant cover of 31 the two mature soils, the structural compositions of the prokaryotic communities were shaped in 32 the same way. 33 34 35 3 36 4 61structure during soil formation [20]. In comparison to bacteria, fungi are less adapted to life on 62 barren substrates and depend strongly on plants during the early stages of colonization [21]. 63The diversity of soil microorganisms changes during the process of soil formation; however, 64 there is no distinct and universal pattern of prokaryotic diversity shifts with the successional 65 stage of paedogenesis [2,3,20,22]. Previous studies have shown that at the earliest stages of soil 66 formation after the retreat of glaciers (0 -100 years), the bacterial diversity was relatively low, 67 whereas it increased with the age of soil [2] or was the highest in middle-aged soils [3]. In 68 contrast, in a longer timescale of ecosystem development (60 -120 000 years), the diversity of 69 the soil prokaryotic community decreased with the site age [22]. The patterns of prokaryotic 70 diversity change among chronosequences of soil formation have been mostly studied for glacier 71 retreats but not for soils formed on aeolian sand dunes. 72The aim of this research was to reveal the traits of microbial community succession during sand 73 fixation in the tundra zone. Two chronosequences of soil formation on aeolian sands with similar 74 initial stages and different mature vegetation (typical tundra ...

Following the flow—Microbial ecology in surface‐ and groundwaters in the glacial forefield of a rapidly retreating glacier in Iceland

“…Microorganisms are the primary producers in newly emerged soils, providing an organic carbon and nitrogen source for plants to further colonize these environments (Brown & Jumpponen, 2014; Zhelezova et al, 2019). Bacteroidota have been proposed as the pioneers of newly formed soils after glacier retreat (Rime et al, 2015; Sun et al, 2016).…”