1 Introduction
Subtropical moss peatlands have important ecological functions, such as
biodiversity maintenance, carbon storage and water conservation, and are
characterized by their rarity (Li et al. 2018). Microtopography affects
the formation and characteristics of moss peatlands, and different
microtopography forms different types of moss peatlands (bogs and fens),
which are usually occupied by different dominant moss plants (Page et
al. 2016; Li et al. 2019). For example, in the Yunnan-Guizhou Plateau of
China, the typical subtropical moss peatlands form ombrotrophicPolytrichum bogs (PBs) in the plateau area
and minerotrophic Sphagnum fens (SFs) in the low-lying area.
Driven by economic interests, moss peatlands all over the world are
faced with the disturbance threats of human activities such as
agricultural reclamation (Kandel et al. 2018), drainage and
afforestation (Sloan et al. 2019), peat mining (Vitovcova et al. 2022;
Pospisilova et al. 2023) and fire (Lynda et al. 2023). Drainage and
afforestation poses the greatest threat to the patchy moss peatlands in
the subtropical region, which greatly reduces their area and causes them
to lose their ecological function. Therefore, the protection and
restoration of subtropical moss peatlands are urgently needed (Wang et
al. 2021).
Soil microorganisms are important drivers of element cycling in peatland
ecosystems (Andersen et al. 2013). Studies have found that the most
common bacteria in peat are representatives of Proteobacteria and
Acidobacteria, which have good adaptability to acidic environments and
exhibit a variety of different lifestyles (Lin et al. 2012; Andersen et
al. 2013; Urbanová et al. 2014). Other important bacterial groups
typically found in peatlands include Actinobacteria, Verrucomicrobia,
Planctomycetes, Chloroflexi, Firmicutes and Chlamydiae. The study of
peatlands in different climate zones has found that although there are
common dominant groups in different peatlands, the correlation between
microbial communities and environmental factors is different. In
primitive peatlands, the composition and function of soil microbial
communities have been shown to vary according to the hydrological
conditions, nutritional status, and vegetation composition of a site
(Andersen et al. 2013). For example, the relative abundances of
Acidobacteria and Proteobacteria showed opposite changes with changes in
pH and substrate availability (Smit et al. 2001; Hartman et al. 2008;
Urbanová et al. 2014). For example, the water table has been shown to
affect the structure of peatland microbial communities or their α
diversity (Tian et al. 2019). Other environmental factors, such as
nitrogen content (Pankratov et al. 2008), organic matter content,
moisture, and phosphorus (Elliott et al. 2008), have also been shown to
have an impact on the microbial communities of peatland ecosystems.
Compared with high-latitude and tropical peatlands, there are few
studies related to subtropical moss peatlands due to their rarity (Alam
et al. 2022; Ifo and Garcin 2022; Wilkinson et al. 2023). A few studies
have reported that the microbial community of Sphagnum peatlands
is affected by microhabitats, and it has been found that groundwater
level and total nitrogen content have significant effects on the soil
bacterial community of Sphagnum peatlands (Tian et al. 2019).
There are few reports on the differences in soil microbial structure and
function of different types of subtropical moss peatlands (bogs and
fens) and their influencing factors.
Studies of northern peatlands have shown that fens have greater
microbial diversity due to additional nutrient input from groundwater,
higher pH, and different quality litter compared to nutrient-poor acidic
bogs, which mainly obtain nutrients from precipitation (Galand et al.
2005; Kim et al. 2008; Urbanová et al. 2011; Gupta et al. 2012; Lin et
al. 2012). Urbanová and Bárta (2016) studied the effects of long-term
drainage on different types of peatlands (bogs, fens, swamps) in the
Czech Republic and found that fens and swamps were more affected, while
bogs were less affected, and the soil microbial structure and function
of the three types of peatlands became similar after long-term drainage
and suggested that the subsurface microbial community in the drainage
sites seems to be driven primarily by the biogeochemical characteristics
of peat rather than plant community composition. Compared with long-term
drainage disturbance, vegetation is more homogeneous, and long-term
drainage and afforestation will make the soil microbial community
structure and function of affected bogs and fens more similar to each
other (Sloan et al. 2019). Are there significant differences in soil
microbial community structure and function between SFs and PBs in the
subtropics? Compared with the two types of natural moss peatlands, which
swamp forest formed by long-term drainage and afforestation has greater
changes than in the soil microbial community? The answers to the above
questions will enrich our understanding of the characteristics of
different types of moss peatlands in subtropical regions, help us
scientifically assess how easy it is for different types of peatlands
affected by drainage and afforestation to recover, and provide a
theoretical basis for the protection and restoration of moss peatlands
in subtropical regions.
This study selected typical subtropical moss peatlands and theCryptomeria swamp forest (CSF) formed by long-term drainage and
afforestation in the Yunnan-Guizhou Plateau of China as the research
objects. By collecting the topsoil (0-10 cm) that is easily disturbed or
strongly affected by climate change, 16S rRNA gene Illumina sequencing
technology was used to study the differences in soil bacterial community
composition and structure between natural SF, PB and CSF habitats and
combined with soil physicochemical properties to explore the important
environmental factors affecting the soil bacterial community. We
hypothesized that (1) SF has a higher diversity of the soil bacterial
community than PB. (2) Compared with PB, the differences in soil
bacterial communities between CSF and SF were greater, and this
difference was caused by the differences in soil water and nutrients
between the different types of peatlands (soil water and nutrients are
important factors in this difference).