scholarly journals The Spatial Factor, Rather than Elevated CO2, Controls the Soil Bacterial Community in a Temperate Forest Ecosystem

2010 ◽  
Vol 76 (22) ◽  
pp. 7429-7436 ◽  
Author(s):  
Yuan Ge ◽  
Chengrong Chen ◽  
Zhihong Xu ◽  
Ram Oren ◽  
Ji-Zheng He

ABSTRACT The global atmospheric carbon dioxide (CO2) concentration is expected to increase continuously over the next century. However, little is known about the responses of soil bacterial communities to elevated CO2 in terrestrial ecosystems. This study aimed to partition the relative influences of CO2, nitrogen (N), and the spatial factor (different sampling plots) on soil bacterial communities at the free-air CO2 enrichment research site in Duke Forest, North Carolina, by two independent techniques: an entirely sequencing-based approach and denaturing gradient gel electrophoresis. Multivariate regression tree analysis demonstrated that the spatial factor could explain more than 70% of the variation in soil bacterial diversity and 20% of the variation in community structure, while CO2 or N treatment explains less than 3% of the variation. For the effects of soil environmental heterogeneity, the diversity estimates were distinguished mainly by the total soil N and C/N ratio. Bacterial diversity estimates were positively correlated with total soil N and negatively correlated with C/N ratio. There was no correlation between the overall bacterial community structures and the soil properties investigated. This study contributes to the information about the effects of elevated CO2 and soil fertility on soil bacterial communities and the environmental factors shaping the distribution patterns of bacterial community diversity and structure in temperate forest soils.


Author(s):  
Yinhong Hu ◽  
Weiwei Yu ◽  
Bowen Cui ◽  
Yuanyuan Chen ◽  
Hua Zheng ◽  
...  

Human disturbance and vegetation are known to affect soil microorganisms. However, the interacting effects of pavement and plant species on soil bacterial communities have received far less attention. In this study, we collected soil samples from pine (Pinus tabuliformis Carr.), ash (Fraxinus chinensis), and maple (Acer truncatum Bunge) stands that grew in impervious, pervious, and no pavement blocks to investigate the way pavement, tree species, and their interaction influence soil bacterial communities by modifying soil physicochemical properties. Soil bacterial community composition and diversity were evaluated by bacterial 16S amplicon sequencing. The results demonstrated that soil bacterial community composition and diversity did differ significantly across pavements, but not with tree species. The difference in soil bacterial community composition across pavements was greater in pine stands than ash and maple stands. Soil bacterial diversity and richness indices decreased beneath impervious pavement in pine stands, and only bacterial richness indices decreased markedly in ash stands, but neither showed a significant difference across pavements in maple stands. In addition, bacterial diversity did not differ dramatically between pervious pavement and no pavement soil. Taken together, these results suggest that pavement overwhelmed the effects of tree species on soil bacterial communities, and had a greater effect on soil bacterial communities in pine stands, followed by ash and maple stands. This study highlights the importance of anthropogenic disturbance, such as pavement, which affects soil microbial communities.



2020 ◽  
Author(s):  
Hao Qing Zhang ◽  
Xue Qiang Zhao ◽  
Yu Shi ◽  
Yuting Liang ◽  
Ren Fang Shen

Abstract Background: Ammonium (NH4+) and nitrate (NO3−) are two major inorganic nitrogen (N) forms available for plant growth. Soil microbes affect the availability and transformation of these N forms in the rhizosphere, and this affects the N-use efficiency of plants. However, little is known about the responses of the rhizosphere bacterial community structure to NH4+ and NO3−. Here, a rhizobox containing a root zone (root growing area) and various soil compartments (0–0.5 cm, 0.5–1 cm, 1–2 cm, 2–4 cm, and 4–9 cm from the root zone) was designed to investigate the spatial distribution of bacterial diversity, community structure, and co-occurrence patterns along a distance from maize (Zea mays L.) roots with the addition of 15N-labeled NH4+ or NO3− in an acidic red soil.Results: Addition of NH4+ and NO3− reduced soil bacterial diversity in the maize root zone. The structures of soil bacterial communities differed between NH4+ and NO3− in the root zone and 0.5 cm away from the root zone. Soil pH was the major driver of bacterial community assembly during plant uptake of N. Maize roots recruited potentially beneficial acidophilic bacteria (e.g. Acidibacter, Burkholderia, and Catenulispora) under NH4+ treatment, and recruited growth-promoting bacteria that prefer higher pH (e.g. Sphingomonas, Sphingobium, Azospirillum, and Novosphingobium) under NO3− treatment. In the N-fertilization treatments, the soil bacterial networks were more complex in the root zone and its adjacent 0.5–1 cm zone than in other soil compartments. The soil bacterial networks were more complex under NH4+ treatment than under NO3−. More bacterial taxa in the networks responded positively and negatively to soil residual NH4+ than to NO3− in all zones in the rhizobox.Conclusions: The combined effects of the N form and the rhizosphere influenced the spatial patterns and co-occurrence network of soil bacterial communities at different distances from the maize root zone, mainly because of changes in soil pH during the uptake of NH4+ and NO3− by maize roots. Regulating microbial communities by adjusting soil pH through NH4+ and NO3− supply may be an environmentally friendly option for promoting soil microbial functions in intensively managed agro-ecosystems.



2009 ◽  
Vol 75 (15) ◽  
pp. 5111-5120 ◽  
Author(s):  
Christian L. Lauber ◽  
Micah Hamady ◽  
Rob Knight ◽  
Noah Fierer

ABSTRACT Soils harbor enormously diverse bacterial populations, and soil bacterial communities can vary greatly in composition across space. However, our understanding of the specific changes in soil bacterial community structure that occur across larger spatial scales is limited because most previous work has focused on either surveying a relatively small number of soils in detail or analyzing a larger number of soils with techniques that provide little detail about the phylogenetic structure of the bacterial communities. Here we used a bar-coded pyrosequencing technique to characterize bacterial communities in 88 soils from across North and South America, obtaining an average of 1,501 sequences per soil. We found that overall bacterial community composition, as measured by pairwise UniFrac distances, was significantly correlated with differences in soil pH (r = 0.79), largely driven by changes in the relative abundances of Acidobacteria, Actinobacteria, and Bacteroidetes across the range of soil pHs. In addition, soil pH explains a significant portion of the variability associated with observed changes in the phylogenetic structure within each dominant lineage. The overall phylogenetic diversity of the bacterial communities was also correlated with soil pH (R2 = 0.50), with peak diversity in soils with near-neutral pHs. Together, these results suggest that the structure of soil bacterial communities is predictable, to some degree, across larger spatial scales, and the effect of soil pH on bacterial community composition is evident at even relatively coarse levels of taxonomic resolution.



2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Mayank Krishna ◽  
Shruti Gupta ◽  
Manuel Delgado – Baquerizo ◽  
Elly Morriën ◽  
Satish Chandra Garkoti ◽  
...  

Abstract This study investigated the potential role of a nitrogen-fixing early-coloniser Alnus Nepalensis D. Don (alder) in driving the changes in soil bacterial communities during secondary succession. We found that bacterial diversity was positively associated with alder growth during course of ecosystem development. Alder development elicited multiple changes in bacterial community composition and ecological networks. For example, the initial dominance of actinobacteria within bacterial community transitioned to the dominance of proteobacteria with stand development. Ecological networks approximating species associations tend to stabilize with alder growth. Janthinobacterium lividum, Candidatus Xiphinematobacter and Rhodoplanes were indicator species of different growth stages of alder. While the growth stages of alder has a major independent contribution to the bacterial diversity, its influence on the community composition was explained conjointly by the changes in soil properties with alder. Alder growth increased trace mineral element concentrations in the soil and explained 63% of variance in the Shannon-diversity. We also found positive association of alder with late-successional Quercus leucotrichophora (Oak). Together, the changes in soil bacterial community shaped by early-coloniser alder and its positive association with late-successional oak suggests a crucial role played by alder in ecosystem recovery of degraded habitats.



Forests ◽  
2019 ◽  
Vol 11 (1) ◽  
pp. 51 ◽  
Author(s):  
Jiangmei Qiu ◽  
Jianhua Cao ◽  
Gaoyong Lan ◽  
Yueming Liang ◽  
Hua Wang ◽  
...  

Land use patterns can change the structure of soil bacterial communities. However, there are few studies on the effects of land use patterns coupled with soil depth on soil bacterial communities in the karst graben basin of Yunnan province, China. Consequently, to reveal the structure of the soil bacterial community at different soil depths across land use changes in the graben basins of the Yunnan plateau, the relationship between soil bacterial communities and soil physicochemical properties was investigated for a given area containing woodland, shrubland, and grassland in Yunnan province by using next-generation sequencing technologies coupled with soil physicochemical analysis. Our results indicated that the total phosphorus (TP), available potassium (AK), exchangeable magnesium (E-Mg), and electrical conductivity (EC) in the grassland were significantly higher than those in the woodland and shrubland, yet the total nitrogen (TN) and soil organic carbon (SOC) in the woodland were higher than those in the shrubland and grassland. Proteobacteria, Verrucomicrobia, and Acidobacteria were the dominant bacteria, and their relative abundances were different in the three land use types. SOC, TN, and AK were the most important factors affecting soil bacterial communities. Land use exerts strong effects on the soil bacterial community structure in the soil’s surface layer, and the effects of land use attenuation decrease with soil depth. The nutrient content of the soil surface layer was higher than that of the deep layer, which was more suitable for the survival and reproduction of bacteria in the surface layer.



2017 ◽  
Vol 63 (5) ◽  
pp. 392-401 ◽  
Author(s):  
Wei Sun ◽  
Xun Qian ◽  
Jie Gu ◽  
Xiao-Juan Wang ◽  
Yang Li ◽  
...  

Three different organic-phosphorus-mineralizing bacteria (OPMB) strains were inoculated to soil planted with soybean (Glycine max), and their effects on soybean growth and indigenous bacterial community diversity were investigated. Inoculation with Pseudomonas fluorescens Z4-1 and Brevibacillus agri L7-1 increased organic phosphorus degradation by 22% and 30%, respectively, compared with the control at the mature stage. Strains P. fluorescens Z4-1 and B. agri L7-1 significantly improved the soil alkaline phosphatase activity, average well color development, and the soybean root activity. Terminal restriction fragment length polymorphism analysis demonstrated that P. fluorescens Z4-1 and B. agri L7-1 could persist in the soil at relative abundances of 2.0%–6.4% throughout soybean growth. Thus, P. fluorescens Z4-1 and B. agri L7-1 could potentially be used in organic-phosphorus-mineralizing biofertilizers. OPMB inoculation altered the genetic structure of the soil bacterial communities but had no apparent influence on the carbon source utilization profiles of the soil bacterial communities. Principal components analysis showed that the changes in the carbon source utilization profiles of bacterial community depended mainly on the plant growth stages rather than inoculation with OPMB. The results help to understand the evolution of the soil bacterial community after OPMB inoculation.



2020 ◽  
Author(s):  
Regina B. Bledsoe ◽  
Carol Goodwillie ◽  
Ariane L. Peralta

ABSTRACTIn nutrient-limited conditions, plants rely on rhizosphere microbial members to facilitate nutrient acquisition, and in return plants provide carbon resources to these root-associated microorganisms. However, atmospheric nutrient deposition can affect plant-microbe relationships by changing soil bacterial composition and by reducing cooperation between microbial taxa and plants. To examine how long-term nutrient addition shapes rhizosphere community composition, we compared traits associated with bacterial (fast growing copiotrophs, slow growing oligotrophs) and plant (C3 forb, C4 grass) communities residing in a nutrient poor wetland ecosystem. Results revealed that oligotrophic taxa dominated soil bacterial communities and that fertilization increased the presence of oligotrophs in bulk and rhizosphere communities. Additionally, bacterial species diversity was greatest in fertilized soils, particularly in bulk soils. Nutrient enrichment (fertilized vs. unfertilized) and plant association (bulk vs. rhizosphere) determined bacterial community composition; bacterial community structure associated with plant functional group (grass vs. forb) was similar within treatments but differed between fertilization treatments. The core forb microbiome consisted of 602 unique taxa, and the core grass microbiome consisted of 372 unique taxa. Forb rhizospheres were enriched in potentially disease suppressive bacterial taxa and grass rhizospheres were enriched in bacterial taxa associated with complex carbon decomposition. Results from this study demonstrate that fertilization serves as a strong environmental filter on the soil microbiome, which leads to distinct rhizosphere communities and can shift plant effects on the rhizosphere microbiome. These taxonomic shifts within plant rhizospheres could have implications for plant health and ecosystem functions associated with carbon and nitrogen cycling.ImportanceOver the last century, humans have substantially altered nitrogen and phosphorus cycling. Use of synthetic fertilizer and burning of fossil fuels and biomass have increased nitrogen and phosphorous deposition, which results in unintended fertilization of historically low-nutrient ecosystems. With increased nutrient availability, plant biodiversity is expected to decline and bacterial communities are anticipated to increase in abundance of copiotrophic taxa. Here, we address how bacterial communities associated with different plant functional types (forb, grass) shift due to long-term nutrient enrichment. Unlike other studies, results revealed an increase in bacterial diversity, particularly, of oligotrophic bacteria in fertilized plots. We observed that nutrient addition strongly determines forb and grass rhizosphere composition, which could indicate different metabolic preferences in the bacterial communities. This study highlights how long-term fertilization of oligotroph-dominated wetlands could alter the metabolism of rhizosphere bacterial communities in unexpected ways.



PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e6147 ◽  
Author(s):  
Shu-Hong Wu ◽  
Bing-Hong Huang ◽  
Jian Gao ◽  
Siqi Wang ◽  
Pei-Chun Liao

Grassland afforestation dramatically affects the abiotic, biotic, and ecological function properties of the original ecosystems. Interference from afforestation might disrupt the stasis of soil physicochemical properties and the dynamic balance of microbiota. Some studies have suggested low sensitivity of soil properties and bacterial community to afforestation, but the apparent lack of a significant relationship is probably due to the confounding effects of the generalist habitat and rare bacterial communities. In this study, soil chemical and prokaryotic properties in a 30-year-old Mongolia pine (Pinus sylvestris var. mongolica Litv.) afforested region and adjacent grassland in Inner Mongolia were classified and quantified. Our results indicate that the high richness of rare microbes accounts for the alpha-diversity of the soil microbiome. Few OTUs of generalist (core bacteria) and habitat-specialist bacteria are present. However, the high abundance of this small number of OTUs governs the beta-diversity of the grassland and afforested land bacterial communities. Afforestation has changed the soil chemical properties, thus indirectly affecting the soil bacterial composition rather than richness. The contents of soil P, Ca2+, and Fe3+ account for differentially abundant OTUs such as Planctomycetes and subsequent changes in the ecologically functional potential of soil bacterial communities due to grassland afforestation. We conclude that grassland afforestation has changed the chemical properties and composition of the soil and ecological functions of the soil bacterial community and that these effects of afforestation on the microbiome have been modulated by changes in soil chemical properties.



2020 ◽  
Author(s):  
Juanjuan Fu ◽  
Yilan Luo ◽  
Pengyue Sun ◽  
Jinzhu Gao ◽  
Donghao Zhao ◽  
...  

Abstract Background: The shade represents one of the major environmental limitations for turfgrass growth. Shade influences plant growth and alters plant metabolism, yet little is known about how shade affects the structure of rhizosphere soil microbial communities and the role of soil microorganisms in plant shade responses. In this study, a glasshouse experiment was conducted to examine the impact of shade on the growth and photosynthetic capacity of two contrasting shade-tolerant turfgrasses, shade-tolerant dwarf lilyturf (Ophiopogon japonicus, OJ) and shade-intolerant perennial turf-type ryegrass (Lolium perenne, LP). We also examined soil-plant feedback effects on shade tolerance in the two turfgrass genotypes. The composition of the soil bacterial community was assayed using high-throughput sequencing. Results: OJ maintained higher photosynthetic capacity and root growth than LP under shade stress, thus OJ was found to be more shade-tolerant than LP. Shade-intolerant LP responded better to both shade and soil microbes than shade-tolerant OJ. The shade and live soil decreased LP growth, but increased biomass allocation to shoots in the live soil. The plant shade response index of LP is higher in live soil than sterile soil, driven by weakened soil-plant feedback under shade stress. In contrast, there was no difference in these values for OJ under similar shade and soil treatments. Shade stress had little impact on the diversity of the OJ and the LP bacterial communities, but instead impacted their composition. The OJ soil bacterial communities were mostly composed of Proteobacteria and Acidobacteria. Further pairwise fitting analysis showed that a positive correlation of shade-tolerance in two turfgrasses and their bacterial community compositions. Several soil properties (NO3--N, NH4+-N, AK) showed a tight coupling with several major bacterial communities under shade stress. Moreover, OJ shared core bacterial taxa known to promote plant growth and confer tolerance to shade stress, which suggests common principles underpinning OJ-microbe interactions. Conclusion: Soil microorganisms mediate plant responses to shade stress via plant-soil feedback and shade-induced change in the rhizosphere soil bacterial community structure for OJ and LP plants. These findings emphasize the importance of understanding plant-soil interactions and their role in the mechanisms underlying shade tolerance in shade-tolerant turfgrasses.



Agronomy ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 14 ◽  
Author(s):  
Yadong Yang ◽  
Peixin Wang ◽  
Zhaohai Zeng

Fertilization plays important roles in improving soil fertility and in increasing crop yield. Soil microbial communities are sensitive indicators of soil quality and health, which could be affected by fertilization strategy. However, our knowledge on how organic–inorganic fertilizers application affects soil bacterial communities remains largely poorly understood. In this study, we investigated the long-term effects of different organic–inorganic fertilization strategies: without fertilizer (CK), fertilizers NPK (CF), fertilizers NPK, plus 30% organic manure (CFM1), and fertilizers NPK plus 60% organic manure (CFM2) on soil bacterial communities in paddy fields. Results showed that the bacterial 16S ribosomal DNA (rDNA) gene abundances in treatments CF, CFM1, and CFM2 were 1.44, 1.54, and 1.28 times higher than that in CK and the ACE index in treatment CFM1 was 9.0% greater than that in treatment CFM2, respectively. Fertilization strategy significantly changed the relative abundance of Nitrospirae, Gemmatimonadetes, and unclassified bacteria at the phylum level and bacteria belonging to order Nitrospira, candidate bacterium SBR2076, unclassified bacteria, Syntrophobacterales, and Solibacterales at the order level, respectively. High organic–inorganic fertilizer application rates inhibited the growth of Nitrospirae by 20–35%, and stimulated the growth of Gemmatimonadetes by 14–77%, relative to the rest of the treatments, respectively. Hierarchical cluster and principal coordinate analysis (PCoA) showed that the fertilization strategy affected the bacterial community structures, and the organic–inorganic fertilized treatments possessed similar bacterial community structures. Furthermore, soil pH, total nitrogen (TN), and soil organic carbon (SOC) were the main driving factors altering the bacterial communities. Our results suggested that combined organic–inorganic fertilizers application increased soil nutrient contents and bacterial abundances, and this could be an optimized fertilization strategy in regulating soil bacterial communities for rice production.



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