Habitats Are More Important Than Seasons in Shaping Soil Bacterial Communities on the Qinghai-Tibetan Plateau

Abstract

Both habitats and seasons can determine the dynamics of microbial communities, but the relative importance of different habitats and seasonal changes in shaping the soil bacterial community structures on a small spatial scale in permafrost areas remains controversial. In this study, we explored the relative effect of four typical alpine meadow habitats (swamp wetland, swamp meadow, meadow and mature meadow) versus seasons on soil bacterial communities based on samples from the Qinghai-Tibetan Plateau in four months (March, May, July and September). The results showed that habitats, rather than seasons explained more variation of soil bacterial composition and structure. Environmental cofactors explained the greatest proportion of bacterial variation observed and can help elucidate the driving force of seasonal changes and habitats on bacterial communities. Soil temperature played the most important role in shaping bacterial beta diversities, followed by soil total nitrogen and pH. A group of microbial biomarkers, used as indicators of different months, were identified using random forest modeling, and for which relative abundance was shaped by different environmental factors. Furthermore, seasonality in bacterial co-occurrence patterns was observed. The data showed that co-occurrence relationships changed over months. The inter-taxa connections in May and July were more pronounced than that in March and September. Bryobacter, a genus of subgroup_22 affiliated to Acidobacteria, and Pseudonocardia belonging to Actinobacteria were observed as the keystone taxa in different months in the network. These results demonstrate that the bacterial community was clustered according to the seasonal mechanism, whereas the co-occurrence relationships changed over months, which indicated complex bacterial dynamics in a permafrost grassland on the eastern edge of Qinghai-Tibetan.

Microbial Diversity and Biogeochemical Cycling of Nitrogen and Sulfur in the Source Region of the Lancang River on the Tibetan Plateau

“…Overall, bacterial communities showed habitat preferences as revealed by NMDS analysis. Bacterial communities from the same habitat converged whereas they diverged from different habitats, which is in agreement with a recent finding on bacterial communities in Tibetan meadow habitats . Alphaproteobacteria were the most abundant bacterial group in all of the river water samples in the source region of the Lancang River, which has not been seen in downstream of the Lancang River, indicating their importance in aqueous systems in this area.…”

“…Bacterial communities from the same habitat converged whereas they diverged from different habitats, which is in agreement with a recent finding on bacterial communities in Tibetan meadow habitats. 15 Alphaproteobacteria were the most abundant bacterial group in all of the river water samples in the source region of the Lancang River, which has not been seen in downstream of the Lancang River, 41 indicating their importance in aqueous systems in this area. On the basis of this study and previous findings, 18,41 it seems that Proteobacteria, Bacteroidetes, Actinobacteria, Chloroflexi, Acidobacteria, and Firmicutes were the dominant bacterial groups in the sediments along the Lancang River.…”

“…The temperature change and intensified human activities have been impacting the hydrological characters of rivers and threatening the vulnerable but fragile ecosystems on the plateau. − Accumulating evidence has revealed that anthropogenic activities and climate change are affecting biogeochemical cycles and associated microorganisms on the Tibetan Plateau. , For instance, grazing increased the abundance of ammonia oxidizers and nirK denitrifiers but decreased the abundance of nirS denitrifiers in Tibetan alpine meadows . It has been reported that warming and grazing can enhance the activities of the methanotrophic community and increase the similarity of bacterial communities in the meadow on the Tibetan Plateau. , Recent studies reported temperature and nutrients played important roles in shaping bacterial communities and diversity in grasslands on the Tibetan Plateau. , Due to accelerated urbanization and extensive economic development, rapid water quality deterioration and eutrophication of Lake Hurleg on the Tibetan Plateau were also observed for the first time . However, despite the increasing research interest in the region, there is still limited information about the present microbial bacterial communities in the unique Tibetan Plateau ecosystem and how do they respond to disturbances.…”

“…13,14 Recent studies reported temperature and nutrients played important roles in shaping bacterial communities and diversity in grasslands on the Tibetan Plateau. 15,16 Due to accelerated urbanization and extensive economic development, rapid water quality deterioration and eutrophication of Lake Hurleg on the Tibetan Plateau were also observed for the first time. 17 climate change and anthropogenic activities is urgently needed to implement corresponding ecological protection programs.…”

Does revegetation cause soil microbiota recovery? Evidence from revisiting a revegetation chronosequence 6 years after initial sampling

“…Reasons for this variation remain undetermined but seasonal fluctuations in soil microbiota being one potential factor. Seasonal factors, such as temperature and precipitation, are well‐known to modulate the structure of soil bacterial communities in some land use types (Bardgett et al 2005; Lauber et al 2013; Žifčáková et al 2016; Samaritani et al 2017; although see Strickland et al 2017; Carini et al 2020; Wang et al 2021). However, further studies are needed to determine the effect of seasonal fluctuations and other factors (e.g.…”