Degradation Reduces Microbial Richness and Alters Microbial Functions in an Australian Peatland

Abstract

Peatland ecosystems cover only 3% of the world’s land area; however, they store one-third of the global soil carbon (C). Microbial communities are the main drivers of C decomposition in peatlands, yet we have limited knowledge of their structure and function. While the microbial communities in the Northern Hemisphere peatlands are well documented, we have limited understanding of microbial community composition and function in the Southern Hemisphere peatlands, especially in Australia. We investigated the vertical stratification of prokaryote and fungal communities from Wellington Plains peatland in the Australian Alps. Within the peatland complex, bog peat was sampled from the intact peatland and dried peat from the degraded peatland along a vertical soil depth gradient (i.e., acrotelm, mesotelm, and catotelm). We analyzed the prokaryote and fungal community structure, predicted functional profiles of prokaryotes using PICRUSt, and assigned soil fungal guilds using FUNGuild. We found that the structure and function of prokaryotes were vertically stratified in the intact bog. Soil carbon, manganese, nitrogen, lead, and sodium content best explained the prokaryote composition. Prokaryote richness was significantly higher in the intact bog acrotelm compared to degraded bog acrotelm. Fungal composition remained similar across the soil depth gradient; however, there was a considerable increase in saprotroph abundance and decrease in endophyte abundance along the vertical soil depth gradient. The abundance of saprotrophs and plant pathogens was two-fold higher in the degraded bog acrotelm. Soil manganese and nitrogen content, electrical conductivity, and water table level (cm) best explained the fungal composition. Our results demonstrate that both fungal and prokaryote communities are shaped by soil abiotic factors and that peatland degradation reduces microbial richness and alters microbial functions. Thus, current and future changes to the environmental conditions in these peatlands may lead to altered microbial community structures and associated functions which may have implications for broader ecosystem function changes in peatlands.

Unraveling microbial processes involved in carbon and nitrogen cycling and greenhouse gas emissions in rewetted peatlands by molecular biology

“…Metals Manganese and iron are less studied TEAs in the context of peatland rewetting. A small number of studies have explored the role of manganese in the C cycle in general, one referring to Mn playing a role in C decomposition in forest ecosystems (Keiluweit et al 2015) and another showing associations between Mn and proportions of fungal and microbial communities in an Australian peatland (Birnbaum et al 2023). Humic and fulvic substances, abundant in peatlands, contain iron and there is increasing evidence for a role of Fe in the C cycle of peatlands both via microbial and abiotic processes.…”

Diversity and Functional Potential of Prokaryotic Communities in Depth Profile of Boreo-Nemoral Minerotrophic Pine Swamp (European Russia)

“…Forests 2023, 14,2313 3 of 25 functional organization of the peatland microbial communities [23]. This is a strong argument in favor of studying the microbial communities of complete peatland profiles.…”

“…It should be noted that studies on the identification of bacterial diversity based on the analysis of 16S rRNA gene fragments were carried out mainly for ombrotrophic peatlands (bogs) [13,[16][17][18][19][20][21][22][23]. In Russia, the priority of studying bogs is associated with their predominance, both in terms of occupied area and peat reserves, over all other types of peatlands.…”

“…It should be noted that most studies of peatland bacterial communities using metabarcoding are limited to the study of one or several layers [18,19,[29][30][31]. There are very few works that consider the entire profile [20,23,32,33].…”

“…It should also be noted that microbial communities in the profile of peatlands function in two zones in which the ecological conditions are very different: the acrotelm with the predominance of aerobic conditions and the catotelm with the predominance of anaerobic conditions. A change in the profile of abiotic conditions leads to changes in the structural and functional organization of the peatland microbial communities [23]. This is a strong argument in favor of studying the microbial communities of complete peatland profiles.…”