Responses of Denitrification Rate and Denitrifying Bacterial Communities Carrying nirS and nirK Genes to Grazing in Peatland

Grazing lowers soil multifunctionality but boosts soil microbial network complexity and stability in a subtropical grassland of China

“…Grazing changed the soil's physical property, chemical property, and ecto-enzyme activity This study found that grazing evidently elevated the SH (Shan et al, 2011;Zhang et al, 2019;Liu et al, 2021), BD, pH (Blank et al, 2006;Ajorlo et al, 2011;Rong et al, 2022), ACa, AMg (Jusoff, 1988;Blank et al, 2006), (Niu et al, 2016;Sigcha et al, 2018;Chen et al, 2021;Fenetahun et al, 2021;Rong et al, 2022; Figure 1). The buffalo squeezed the soil pores that include those pores originally storing water and air, through treading, which caused soil compaction (Ludvíková et al, 2014), elevated the bulk density (Li et al, 2008;Zhan et al, 2020;Fenetahun et al, 2021;Wade et al, 2022) and soil hardness, and reduced soil water infiltration (Daniel et al, 2002). Soil compaction is a global environmental issue of increasing importance occurring in grasslands and other lands (Anneke et al, 2010).…”

“…Some studies found that grazing promoted nutrient cycling (Zhang et al, 2021a) and enhanced soil net nitrogen (N) mineralization and N nitrification (Zhou et al, 2017;Dong et al, 2020b), NH 4 + (Lai and Kumar, 2020), NO 3 − (Wang et al, 2016) and available phosphorus (P) (Hao and He, 2019), potassium (K), and calcium (Ca) (Arevalo et al, 1998) and have a positive impact on the availability of soil nutrients (Faghihinia et al, 2020;Xu et al, 2022). Other studies showed that grazing diminished the net mineralization rate (Shan et al, 2011) and decreased available soil N and P (Hao and He, 2019;Liu et al, 2021;Yu et al, 2021), K (Fenetahun et al, 2021), Ca, and magnesium (Binkley et al, 2003). Because nutrient availability has a very important effect in soil microbiome (Fierer, 2017;Wang Z. et al, 2019;Ding et al, 2020), we assumed that the grazing-triggered alterations in available elements may also shift the microbial NP limitations and the attributes of soil microbiome.…”

“…A large body of field experiments and meta-analyses have been carried out to measure the influences of grazing on the soil's physical environment, available elements, and element limitations (Zhang et al, 2018a;Chai et al, 2019;Fenetahun et al, 2021;Liu et al, 2022;Van Syoc et al, 2022;. Grazing could decrease soil porosity (Tang et al, 2019) and increase soil bulk density (Binkley et al, 2003;Davidson et al, 2017;Zhang et al, 2018b;Sun et al, 2019;Lai and Kumar, 2020;Fenetahun et al, 2021). These could result in a decline in the air and water permeability (Daniel et al, 2002;Zhang et al, 2018b) and soil moisture (Hou et al, 2014;Liu et al, 2021).…”

“…These could result in a decline in the air and water permeability (Daniel et al, 2002;Zhang et al, 2018b) and soil moisture (Hou et al, 2014;Liu et al, 2021). However, grazing also increased soil pH (Binkley et al, 2003;Hao and He, 2019;Fenetahun et al, 2021;. Since soil pH, O 2 , and water were most crucial driving forces of soil microorganisms (Fierer, 2017), and grazing compressed the living niche for soil microbiome (Chai et al, 2019;Proesmans et al, 2022) and negatively affected the growth of microbes (Zhan et al, 2020), we speculated that the changes caused by grazing may have a far-reaching impact on the attributes of soil microorganisms.…”

“…Although increasing numbers of studies have reported the influences of grazing on soil's physical environment, available elements (Fenetahun et al, 2021;, and element limitations (Liu et al, 2022), studies about the effects of grazing on the microbial community compositions and the microbial networks are relatively scant (Magalí et al, 2019). Although evidence is mounting that dissecting the relative importance of plants and soils for the impact of the microbiome (Ding et al, 2020;Chen et al, 2021), the linkages of soil physical environment, available elements, and element limitations with the niche width, structure, function, and network of soil microorganism remain relatively scarce, which hinders our understanding of the mechanisms by which grazing changes the soil microorganisms.…”