scholarly journals Geographic Patterns of Bacterioplankton among Lakes of the Middle and Lower Reaches of the Yangtze River Basin, China

2019 ◽  
Author(s):  
Chengrong Bai ◽  
Jian Cai ◽  
Lei Zhou ◽  
Xingyu Jiang ◽  
Yang Hu ◽  
...  
Keyword(s):  
Microbial Community ◽  
Stochastic Processes ◽  
Aquatic Ecosystems ◽  
Yangtze River ◽  
Yangtze River Basin ◽  
Relative Importance ◽  
Ecological Processes ◽  
Microbial Biogeography ◽  
Geographic Patterns ◽  
Rare Bacteria

AbstractIn aquatic ecosystems, microbial biogeography research is critical for unveiling the mechanisms of microbial community succession. However, little is known about the microbial biogeography among interconnected lakes. To address this deficit, we used high-throughput sequencing to explore geographic patterns and the relative importance of ecological processes that shape these patterns in abundant and rare bacterial subcommunities from 25 lakes across the middle and lower reaches of Yangtze River basin (MLYB, located in southeast China), where most of the lakes are interconnected by river networks. We found that there were significant differences in both abundant and rare bacterial subcommunities between the two lake groups that were far from each other, while were no difference among the nearby lakes in each group. Both abundant and rare bacteria followed a strong distance-decay relationship, especially for rare bacteria. These findings suggest that although the interconnectivity between lakes breaks the geographical isolation of bacteria, the dispersal capability of bacterial taxa was still limited by geographic distance. We also found that although deterministic processes and stochastic processes together drive the bacterial subcommunities assembly, the stochastic processes (based on adjusted R2 in redundancy analysis) exhibited a greater influence on bacterial subcommunities. Our results implied that bacterial dispersal among interconnected lakes was more stochastically.ImportanceUnraveling the relative importance of ecological processes regulating microbial community structure is a central goal in microbial ecology. In aquatic ecosystems, microbial communities often occur in spatially structured habitats, where connectivity directly affects dispersal and metacommunity processes. Recent theoretical work suggests that directional dispersal among connected habitats leads to higher variability in local diversity and among-community composition. However, the study of microbial biogeography among natural interconnected habitats is still lacking. The findings of this study revealed interesting phenomena of microbial biogeography among natural interconnected habitats, suggested that the high interconnectivity reduced the spatial heterogeneity of bacteria, and caused the dispersal of bacteria to be more stochastically. This study has provided a deeper understanding of the biogeographic patterns of rare and abundant bacterial taxa and their determined processes among interconnected aquatic habitats.

scholarly journals Geographic Patterns of Bacterioplankton among Lakes of the Middle and Lower Reaches of the Yangtze River Basin, China

2020 ◽  
Vol 86 (6) ◽  
Author(s):  
Chengrong Bai ◽  
Jian Cai ◽  
Lei Zhou ◽  
Xingyu Jiang ◽  
Yang Hu ◽  
...  
Keyword(s):  
Bacterial Communities ◽  
Yangtze River ◽  
Yangtze River Basin ◽  
Assembly Process ◽  
Wet Season ◽  
Rare Taxa ◽  
Biogeographic Patterns ◽  
Geographic Patterns ◽  
Lower Yangtze ◽  
Rare Bacteria

ABSTRACT The revolution of molecular techniques has revealed that the composition of natural bacterial communities normally includes a few abundant taxa and many rare taxa. Unraveling the mechanisms underlying the spatial assembly process of both abundant and rare bacterial taxa has become a central goal in microbial ecology. Here, we used high-throughput sequencing to explore geographic patterns and the relative importance of ecological processes in the assembly of abundant and rare bacterial subcommunities from 25 lakes across the middle and lower reaches of Yangtze River basin (MLYB), located in Southeast China, where most of the lakes are interconnected by river networks. We found similar biogeographic patterns of abundant and rare subcommunities which could significantly distinguish the community compositions of the two lake groups that were far from each other but which could not distinguish the community compositions of the nearby lakes. Both abundant and rare bacteria followed a strong distance-decay relationship. These findings suggest that the interconnectivity between lakes homogenizes the bacterial communities in local areas, and the abundant and rare taxa therein may be affected by the same ecological process. In addition, based on the measured environmental variables, the deterministic processes explain a small fraction of variation within both abundant and rare subcommunities, while both neutral and null models revealed a high stochasticity ratio for the spatial distribution patterns of both abundant and rare taxa. These findings indicate that the stochastic processes exhibited a greater influence on both abundant and rare bacterial subcommunity assemblies among interconnected lakes. IMPORTANCE The middle and lower Yangtze Plain is a typical floodplain in which many lakes connect with each other, especially in the wet season. More importantly, with the frequent change of regional water level in the wet season, there is a mutual hydrodynamic exchange among these lakes. The microbial biogeography among these interconnected lakes is still poorly understood. This study aims to unravel the mechanisms underlying the assembly process of abundant and rare bacteria among the interconnected lakes in the middle and lower Yangtze Plain. Our findings will provide a deeper understanding of the biogeographic patterns of rare and abundant bacterial taxa and their determined processes among interconnected aquatic habitats.

scholarly journals Multiple ecological processes jointly drive the soil microbial community assembly in subalpine coniferous forests

2018 ◽  
Author(s):  
Pengyu Zhao ◽  
Jiabing Bao ◽  
Xue Wang ◽  
Yi Liu ◽  
Cui Li ◽  
...  
Keyword(s):  
Microbial Community ◽  
Stochastic Processes ◽  
Community Assembly ◽  
Soil Microbial Community ◽  
Analytical Methods ◽  
Community Dynamics ◽  
Coniferous Forests ◽  
Ecological Processes ◽  
Soil Microbial ◽  
Microbial Community Assembly

The mechanisms underlying community dynamics, which govern the complicated biogeographical patterns of microbes, have long been a research hotspot in community ecology. However, the mixing of multiple ecological processes and the one-sidedness of analytical methods make it difficult to draw inferences about the community assembly mechanisms. In this study, we investigated the driving forces of the soil microbial community in subalpine coniferous forests of the Loess Plateau in Shanxi, China, by integrating multiple analytical methods. The results of the null model demonstrated that deterministic processes (especially interspecific relationships) were the main driving force of the soil microbial community assembly in this study area, relative to stochastic processes. Based on the results of the net relatedness index (NRI) and nearest taxon index (NTI), we inferred that historical and evolutionary factors, such as climate change and local diversification, may have similar effects on microbial community structure based on the climatic niche conservatism. Based on the results of a functional traits analysis, we found that the effects of ongoing ecological processes on the microbial community assembly varied among sites. Therefore, the functional structures seemed to be more related to ongoing ecological processes, whereas the phylogenetic structures seemed to be more related to historical and evolutionary factors, as well as the tradeoff between deterministic and stochastic processes. The functional and phylogenetic structures were mainly shaped by different ecological processes. By integrating multiple ecological processes, our results provide more details of the mechanisms driving the community assembly

scholarly journals The relative importance of antecedent soil moisture and precipitation in flood generation in the middle and lower Yangtze River basin

2021 ◽  
Author(s):  
Sheng Ye ◽  
Jin Wang ◽  
Qihua Ran ◽  
Xiuxiu Chen ◽  
Lin Liu
Keyword(s):  
Soil Moisture ◽  
River Basin ◽  
Yangtze River ◽  
Yangtze River Basin ◽  
Dominant Factor ◽  
Economic Losses ◽  
Relative Importance ◽  
Antecedent Soil Moisture ◽  
Lower Yangtze ◽  
Flood Generation

Abstract. Floods have caused severe environmental and social economic losses worldwide in human history, and are projected to exacerbate due to climate change. Many floods are caused by heavy rainfall with highly saturated soil, however, the relative importance of rainfall and antecedent soil moisture and how it changes from place to place has not been fully understood. Here we examined annual floods from more than 200 hydrological stations in the middle and lower Yangtze River basin. Our results indicate that the dominant factor of flood generation shifts from rainfall to antecedent soil moisture with the increase of watershed area. The ratio of the relative importance of antecedent soil moisture and daily rainfall (SPR) is positively correlated with topographic wetness index and has a negative correlation with the magnitude of annual floods. This linkage between watershed characteristics that are easy to measure and the dominant flood generation mechanism provides a quantitative method for flood control and early warnings in ungauged watersheds in the middle and lower Yangtze River basin.

scholarly journals Multiple ecological processes jointly drive the soil microbial community assembly in subalpine coniferous forests

2018 ◽  
Author(s):  
Pengyu Zhao ◽  
Jiabing Bao ◽  
Xue Wang ◽  
Yi Liu ◽  
Cui Li ◽  
...  
Keyword(s):  
Microbial Community ◽  
Stochastic Processes ◽  
Community Assembly ◽  
Soil Microbial Community ◽  
Analytical Methods ◽  
Community Dynamics ◽  
Coniferous Forests ◽  
Ecological Processes ◽  
Soil Microbial ◽  
Microbial Community Assembly

The mechanisms underlying community dynamics, which govern the complicated biogeographical patterns of microbes, have long been a research hotspot in community ecology. However, the mixing of multiple ecological processes and the one-sidedness of analytical methods make it difficult to draw inferences about the community assembly mechanisms. In this study, we investigated the driving forces of the soil microbial community in subalpine coniferous forests of the Loess Plateau in Shanxi, China, by integrating multiple analytical methods. The results of the null model demonstrated that deterministic processes (especially interspecific relationships) were the main driving force of the soil microbial community assembly in this study area, relative to stochastic processes. Based on the results of the net relatedness index (NRI) and nearest taxon index (NTI), we inferred that historical and evolutionary factors, such as climate change and local diversification, may have similar effects on microbial community structure based on the climatic niche conservatism. Based on the results of a functional traits analysis, we found that the effects of ongoing ecological processes on the microbial community assembly varied among sites. Therefore, the functional structures seemed to be more related to ongoing ecological processes, whereas the phylogenetic structures seemed to be more related to historical and evolutionary factors, as well as the tradeoff between deterministic and stochastic processes. The functional and phylogenetic structures were mainly shaped by different ecological processes. By integrating multiple ecological processes, our results provide more details of the mechanisms driving the community assembly

scholarly journals Microbial Community Cohesion Mediates Community Turnover in Unperturbed Aquifers

mSystems ◽  
2018 ◽  
Vol 3 (4) ◽  
Author(s):  
Robert E. Danczak ◽  
Michael D. Johnston ◽  
Chris Kenah ◽  
Michael Slattery ◽  
Michael J. Wilkins
Keyword(s):  
Microbial Community ◽  
Stochastic Processes ◽  
Microbial Communities ◽  
Null Model ◽  
16S Rrna Gene Sequencing ◽  
Rrna Gene ◽  
Internal Dynamics ◽  
Ecological Processes ◽  
Stable Conditions ◽  
Community Complexity

ABSTRACT Microbial ecological processes are frequently studied in the presence of perturbations rather than in undisturbed environments, despite the relatively stable conditions dominating many microbial habitats. To examine processes influencing microbial community structuring in the absence of strong external perturbations, three unperturbed aquifers in Ohio (Greene, Licking, and Athens) were sampled over 2 years and analyzed using geochemical measurements, 16S rRNA gene sequencing, and ecological modeling. Redox conditions ranging from highly reducing to more oxidizing distinguished aquifer geochemistry across the three locations. Distinct microbial communities were present in each aquifer, and overall community structure was related to geochemistry, although community composition was more similar between the Athens and Licking locations. The ecological processes acting upon microbial assemblages within aquifers were varied; geochemical changes affected the Athens location, while time or some unknown factor affected Greene County. Stochastic processes, however, dominated the Licking aquifer, suggesting a decoupling between environmental fluctuations and community development. Although physicochemical differences might be expected to drive variable selection, dispersal limitation (inability to mix) explained differences between Athens and Licking. Finally, community complexity as measured by “cohesion” indicated that less-interconnected communities experienced higher turnover and were more likely to be affected by stochastic processes. Conversely, more-interconnected communities experienced lower turnover and susceptibility to homogenizing selection. Based upon these data, we support the hypothesis that unperturbed environments house dynamic microbial communities due to external and internal forces. IMPORTANCE Many microbial ecology studies have examined community structuring processes in dynamic or perturbed situations, while stable environments have been investigated to a lesser extent. Researchers have predicted that environmental communities never truly reach a steady state but rather exist in states of constant flux due to internal, rather than external, dynamics. The research presented here utilized a combined null model approach to examine the deterministic and stochastic processes responsible for observed community differences in unperturbed, groundwater ecosystems. Additionally, internal dynamics were investigated by relating a recently published measure of community complexity (cohesion) to ecological structuring processes. The data presented here suggest that communities that are more cohesive, and therefore more complex, are more likely affected by homogenizing selection, while less-complex communities are more susceptible to dispersal. By understanding the relationship between internal dynamics and community structuring processes, insight about microbial population development in natural systems can be obtained.

scholarly journals Link between East Asian summer monsoon and sedimentation in river-mouth sandbars since the early Holocene preserved in the Yangtze River subaqueous delta front

2020 ◽  
Vol 95 ◽  
pp. 84-96
Author(s):  
Gang Xu ◽  
Jian Liu ◽  
Marcello Gugliotta ◽  
Yoshiki Saito ◽  
Lilei Chen ◽  
...  
Keyword(s):  
Yangtze River ◽  
Late Holocene ◽  
Asian Summer Monsoon ◽  
Yangtze River Basin ◽  
River Mouth ◽  
Early Holocene ◽  
The Yangtze River ◽  
Delta Front ◽  
The Yangtze River Basin ◽  
Asian Summer

AbstractThis paper presents geochemical and grain-size records since the early Holocene in core ECS0702 with a fine chronology frame obtained from the Yangtze River subaqueous delta front. Since ~9500 cal yr BP, the proxy records of chemical weathering from the Yangtze River basin generally exhibit a Holocene optimum in the early Holocene, a weak East Asian summer monsoon (EASM) period during the middle Holocene, and a relatively strong EASM period in the late Holocene. The ~8.2 and ~4.4 cal ka BP cooling events are recorded in core ECS0702. The flooding events reconstructed by the grain-size parameters since the early Holocene suggest that the floods mainly occurred during strong EASM periods and the Yangtze River mouth sandbar caused by the floods mainly formed in the early and late Holocene. The Yangtze River-mouth sandbars since the early Holocene shifted from north to south, affected by tidal currents and the Coriolis force, and more importantly, controlled by the EASM. Our results are of great significance for enriching both the record of Holocene climate change in the Yangtze River basin and knowledge about the formation and evolution progress of the deltas located in monsoon regions.

scholarly journals Carbon Storage Change Analysis and Emission Reduction Suggestions under Land Use Transition: A Case Study of Henan Province, China

2021 ◽  
Vol 18 (4) ◽  
pp. 1844
Author(s):  
Dongyang Xiao ◽  
Haipeng Niu ◽  
Jin Guo ◽  
Suxia Zhao ◽  
Liangxin Fan
Keyword(s):  
Land Use ◽  
River Basin ◽  
Yangtze River ◽  
Carbon Emission ◽  
Yellow River ◽  
Yangtze River Basin ◽  
Yellow River Basin ◽  
River Basins ◽  
Henan Province ◽  
Huai River

The significant spatial heterogeneity among river basin ecosystems makes it difficult for local governments to carry out comprehensive governance for different river basins in a special administrative region spanning multi-river basins. However, there are few studies on the construction of a comprehensive governance mechanism for multi-river basins at the provincial level. To fill this gap, this paper took Henan Province of China, which straddles four river basins, as the study region. The chord diagram, overlay analysis, and carbon emission models were applied to the remote sensing data of land use to analyze the temporal and spatial patterns of carbon storage caused by land-use changes in Henan Province from 1990 to 2018 to reflect the heterogeneity of the contribution of the four basins to human activities and economic development. The results revealed that food security land in the four basins decreased, while production and living land increased. Ecological conservation land was increased over time in the Yangtze River Basin. In addition, the conversion from food security land to production and living land was the common characteristic for the four basins. Carbon emission in Henan increased from 134.46 million tons in 1990 to 553.58 million tons in 2018, while its carbon absorption was relatively stable (1.67–1.69 million tons between 1990 and 2018). The carbon emitted in the Huai River Basin was the main contributor to Henan Province’s total carbon emission. The carbon absorption in Yellow River Basin and Yangtze River Basin had an obvious spatial agglomeration effect. Finally, considering the current need of land spatial planning in China and the goal of carbon neutrality by 2060 set by the Chinese government, we suggested that carbon sequestration capacity should be further strengthened in Yellow River Basin and Yangtze River Basin based on their respective ecological resource advantages. For future development in Hai River Basin and Huai River Basin, coordinating the spatial allocation of urban scale and urban green space to build an ecological city is a key direction to embark upon.

scholarly journals Spatiotemporal Pattern of Pine Wilt Disease in the Yangtze River Basin

Forests ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 731
Author(s):  
Zhuoqing Hao ◽  
Jixia Huang ◽  
Yantao Zhou ◽  
Guofei Fang
Keyword(s):  
River Basin ◽  
Yangtze River ◽  
Yangtze River Basin ◽  
Pine Wilt Disease ◽  
Wilt Disease ◽  
Spatiotemporal Pattern ◽  
Pinewood Nematode ◽  
The Yangtze River ◽  
Pine Wilt ◽  
The Yangtze River Basin

The Yangtze River Basin is among the river basins with the strongest strategic support and developmental power in China. As an invasive species, the pinewood nematode (PWN) Bursaphelenchus xylophilus has introduced a serious obstacle to the high-quality development of the economic and ecological synchronization of the Yangtze River Basin. This study analyses the occurrence and spread of pine wilt disease (PWD) with the aim of effectively managing and controlling the spread of PWD in the Yangtze River Basin. In this study, statistical data of PWD-affected areas in the Yangtze River Basin are used to analyse the occurrence and spread of PWD in the study area using spatiotemporal visualization analysis and spatiotemporal scanning statistics technology. From 2000 to 2018, PWD in the study area showed an “increasing-decreasing-increasing” trend, and PWD increased explosively in 2018. The spatial spread of PWD showed a “jumping propagation-multi-point outbreak-point to surface spread” pattern, moving west along the river. Important clusters were concentrated in the Jiangsu-Zhejiang area from 2000 to 2015, forming a cluster including Jiangsu and Zhejiang. Then, from 2015–2018, important clusters were concentrated in Chongqing. According to the spatiotemporal scanning results, PWD showed high aggregation in the four regions of Zhejiang, Chongqing, Hubei, and Jiangxi from 2000 to 2018. In the future, management systems for the prevention and treatment of PWD, including ecological restoration programs, will require more attention.

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