scholarly journals Tree rows in temperate agroforestry croplands alter the composition of soil bacterial communities

PLoS ONE ◽  
2021 ◽  
Vol 16 (2) ◽  
pp. e0246919
Author(s):  
Lukas Beule ◽  
Petr Karlovsky

Background Tree-based intercropping (agroforestry) has been advocated to reduce adverse environmental impacts of conventional arable cropping. Modern agroforestry systems in the temperate zone are alley-cropping systems that combine rows of fast-growing trees with rows of arable crops. Soil microbial communities in these systems have been investigated intensively; however, molecular studies with high taxonomical resolution are scarce. Methods Here, we assessed the effect of temperate agroforestry on the abundance, diversity and composition of soil bacterial communities at three paired poplar-based alley cropping and conventional monoculture cropland systems using real-time PCR and Illumina sequencing of bacterial 16S rRNA genes. Two of the three systems grew summer barley (Hordeum vulgare); one system grew maize (Zea mays) in the sampling year. To capture the spatial heterogeneity induced by the tree rows, soil samples in the agroforestry systems were collected along transects spanning from the centre of the tree rows to the centre of the agroforestry crop rows. Results Tree rows of temperate agroforestry systems increased the abundance of soil bacteria while their alpha diversity remained largely unaffected. The composition of the bacterial communities in tree rows differed from those in arable land (crop rows of the agroforestry systems and conventional monoculture croplands). Several bacterial groups in soil showed strong association with either tree rows or arable land, revealing that the introduction of trees into arable land through agroforestry is accompanied by the introduction of a tree row-associated microbiome. Conclusion The presence of tree row-associated bacteria in agroforestry increases the overall microbial diversity of the system. We speculate that the increase in biodiversity is accompanied by functional diversification. Differences in plant-derived nutrients (root exudates and tree litter) and management practices (fertilization and tillage) likely account for the differences between bacterial communities of tree rows and arable land in agroforestry systems.

2004 ◽  
Vol 70 (9) ◽  
pp. 5057-5065 ◽  
Author(s):  
Evelyn Hackl ◽  
Sophie Zechmeister-Boltenstern ◽  
Levente Bodrossy ◽  
Angela Sessitsch

ABSTRACT The diversity and composition of soil bacterial communities were compared among six Austrian natural forests, including oak-hornbeam, spruce-fir-beech, and Austrian pine forests, using terminal restriction fragment length polymorphism (T-RFLP, or TRF) analysis and sequence analysis of 16S rRNA genes. The forests studied differ greatly in soil chemical characteristics, microbial biomass, and nutrient turnover rates. The aim of this study was to relate these differences to the composition of the bacterial communities inhabiting the individual forest soils. Both TRF profiling and clone sequence analysis revealed that the bacterial communities in soils under Austrian pine forests, representing azonal forest types, were distinct from those in soils under zonal oak-hornbeam and spruce-fir-beech forests, which were more similar in community composition. Clones derived from an Austrian pine forest soil were mostly affiliated with high-G+C gram-positive bacteria (49%), followed by members of the α-Proteobacteria (20%) and the Holophaga/Acidobacterium group (12%). Clones in libraries from oak-hornbeam and spruce-fir-beech forest soils were mainly related to the Holophaga/Acidobacterium group (28 and 35%), followed by members of the Verrucomicrobia (24%) and the α-Proteobacteria (27%), respectively. The soil bacterial communities in forests with distinct vegetational and soil chemical properties appeared to be well differentiated based on 16S rRNA gene phylogeny. In particular, the outstanding position of the Austrian pine forests, which are determined by specific soil conditions, was reflected in the bacterial community composition.


2006 ◽  
Vol 72 (3) ◽  
pp. 1852-1857 ◽  
Author(s):  
Michelle Sait ◽  
Kathryn E. R. Davis ◽  
Peter H. Janssen

ABSTRACT The pH strongly influenced the development of colonies by members of subdivision 1 of the phylum Acidobacteria on solid laboratory media. Significantly more colonies of this group formed at pH 5.5 than at pH 7.0. At pH 5.5, 7 to 8% of colonies that formed on plates that were incubated for 4 months were formed by subdivision 1 acidobacteria. These colonies were formed by bacteria that spanned almost the entire phylogenetic breadth of the subdivision, and there was considerable congruence between the diversity of this group as determined by the cultivation-based method and by surveying 16S rRNA genes in the same soil. Members of subdivision 1 acidobacteria therefore appear to be readily culturable. An analysis of published libraries of 16S rRNAs or 16S rRNA genes showed a very strong correlation between the abundance of subdivision 1 acidobacteria in soil bacterial communities and the soil pH. Subdivision 1 acidobacteria were most abundant in libraries from soils with pHs of <6, but rare or absent in libraries from soils with pHs of >6.5. This, together with the selective cultivation of members of the group on lower-pH media, indicates that growth of many members of subdivision 1 acidobacteria is favored by slightly to moderately acidic growth conditions.


Forests ◽  
2019 ◽  
Vol 10 (4) ◽  
pp. 299 ◽  
Author(s):  
Pengxiang Gao ◽  
Xiaofeng Zheng ◽  
Lai Wang ◽  
Bin Liu ◽  
Shuoxin Zhang

Agroforestry (tree-based intercropping) is regarded as a promising practice in sustainable agricultural management. However, the impacts of converting cropland to an agroforestry system on microbial communities remain poorly understood. In this study, we assessed the soil bacterial communities in conventional wheat monoculture systems and a chronosequence (5–14 years) walnut-wheat agroforestry system through the high-throughput sequencing of 16S rRNA genes to investigate the effect of agroforestry age on soil bacterial communities and the correlation between soil properties and bacterial communities in the agroecosystem. Our results demonstrate that establishing and developing walnut tree-based agroforestry increased soil bacterial diversity and changed bacterial community structure. Firmicutes, Proteobacteria, Actinobacteria and Acidobacteria were the dominant soil bacterial phyla and Bacillus was the dominant genus. Crop monoculture systems were characterized by the Bacillus (Firmicutes)-dominated microbial community. The relative abundance of Bacillus decreased with agroforestry age; however, subgroups of Proteobacteria and Actinobacteria increased. Of the selected soil physicochemical properties, soil pH and bulk density were significantly correlated with bacterial alpha diversity, and soil pH and organic carbon were the principal drivers in shaping the soil microbial structure as revealed by redundancy analysis (RDA).


2019 ◽  
Author(s):  
Myrto Tsiknia ◽  
Stilianos Fodelianakis ◽  
Nikolaos P. Nikolaidis ◽  
Nikolaos V. Paranychianakis

AbstractThere is a renewed interest in recent years on the ecological processes (stochastic vs selective) driving the assembly of microbial communities. Such information could potentially improve our understanding on ecosystem functioning and resilience to disturbances, ecosystem response to environmental shifts, and adoption of sustainable soil management practices. Herein, employing a suite of existing methodologies, we show that stochastic processes have an important role on the assembly of soil bacterial communities at a Mediterranean watershed. Moreover, we document that the relative contribution of assembly processes varies over the years. The observed intensification of stochastic processes was accompanied by a decrease in the contribution of variable selection in favor of homogeneous selection and dispersal and this trend was only marginally affected by land use (natural vs agricultural lands) or soil depth. Our study also revealed a high inter-annual turnover of soil microbial communities that was likely stimulated by the weak environmental selection and the prevailing environmental conditions (drying-wetting cycles) in Mediterranean landscapes, implying potential impacts on ecosystem functioning and our ability to predict soil response to environmental shifts. Using nitrogen mineralization rate (NMR) as a representative function we document highly variable NMR over the sampling years, land uses and soil depths and lack of significant associations with the monitored environmental variables and individual taxa. In summary, our study provides novel insights on the organization and functioning of microbial communities at Mediterranean ecosystems and sets directions towards a more advanced understanding of the relationships among environmental factors, microbial community structure, and ecosystem functioning that could contribute to sustainable management of these severely degraded ecosystems.


Agronomy ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1526
Author(s):  
Xiaoqin Yang ◽  
Yang Wang ◽  
Luying Sun ◽  
Xiaoning Qi ◽  
Fengbin Song ◽  
...  

Conservative agricultural practices have been adopted to improve soil quality and maintain crop productivity. An efficient intercropping of maize with mushroom has been developed in Northeast China. The objective of this study was to evaluate and compare the effects of planting patterns on the diversity and structure of the soil bacterial communities at a 0–20 cm depth in the black soil zone of Northeast China. The experiment consisted of monoculture of maize and mushroom, and intercropping in a split-plot arrangement. The characteristics of soil microbial communities were performed by 16S rRNA gene amplicom sequencing. The results showed that intercropping increased soil bacterial richness and diversity compared with maize monoculture. The relative abundances of Acidobacteria, Chloroflexi, Saccharibacteria and Planctomycetes were significantly higher, whereas Proteobacteria and Firmicutes were lower in intercropping than maize monoculture. Redundancy analysis suggested that pH, NO3−-N and NH4+-N contents had a notable effect on the structure of the bacterial communities. Moreover, intercropping significantly increased the relative abundance of carbohydrate metabolism pathway functional groups. Overall, these findings demonstrated that intercropping of maize with mushroom strongly impacts the physical and chemical properties of soil as well as the diversity and structure of the soil bacterial communities, suggesting this is a sustainable agricultural management practice in Northeast China.


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.


Agronomy ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 878 ◽  
Author(s):  
Zoltán Mayer ◽  
Zita Sasvári ◽  
Viktor Szentpéteri ◽  
Beatrix Pethőné Rétháti ◽  
Balázs Vajna ◽  
...  

Soil microbial communities are involved in the maintenance of productivity and health of agricultural systems; therefore an adequate understanding of soil biodiversity plays a key role in ensuring sustainable use of soil. In the present study, we evaluated the influence of different cropping systems on the biodiversity of the soil bacterial communities, based on a 54-year field experiment established in Martonvásár, Hungary. Terminal restriction fragment length polymorphism (T-RFLP) fingerprinting technique was used to assess soil bacterial diversity and community structure in maize monoculture and three different crop rotations (maize–alfalfa, maize–wheat and the maize–barley–peas–wheat Norfolk type). No differences in richness and diversity were detected between maize monoculture and crop rotations except for the most intense rotation system (Norfolk-type). Although the principal component analysis did not reveal a clear separation between maize monoculture and the other rotation systems, the pairwise tests of analysis of similarity (ANOSIM) revealed that there are significant differences in the composition of bacterial communities between the maize monoculture and maize–alfalfa rotation as well as between wheat–maize and Norfolk-type rotation.


Diversity ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 217 ◽  
Author(s):  
Adenike Eunice Amoo ◽  
Olubukola Oluranti Babalola

Soil microbial communities are an important part of ecosystems that possess the capability to improve ecosystem services; however, several aspects of the ecology of forest soil bacterial communities are still unknown. Here, we investigated the impact of land-use change on soil bacterial communities and the soil characteristics. High-throughput sequencing was used to ascertain the bacterial diversity and canonical correspondence analysis was used to determine relationships between the bacterial communities and environmental variables. Our results show spatial heterogeneity in the distribution of the microbial communities and significant relationships between the microbes and soil characteristics (axis 1 of the canonical correspondence analysis (CCA) plot explained 64.55% of the total variance while axis 2 described 24.49%). Knowledge of this is essential as it has direct consequences for the functioning of the soil ecosystem.


SOIL ◽  
2021 ◽  
Vol 7 (2) ◽  
pp. 611-637
Author(s):  
Capucine Baubin ◽  
Arielle M. Farrell ◽  
Adam Št'ovíček ◽  
Lusine Ghazaryan ◽  
Itamar Giladi ◽  
...  

Abstract. Ecosystem engineers (EEs) are present in every environment and are known to strongly influence ecological processes and thus shape the distribution of species and resources. In this study, we assessed the direct and indirect effect of two EEs (perennial shrubs and ant nests), individually and combined, on the composition and function of arid soil bacterial communities. To that end, topsoil samples were collected in the Negev desert highlands during the dry season from four patch types: (1) barren soil; (2) under shrubs; (3) near ant nests; or (4) near ant nests situated under shrubs. The bacterial community composition and potential functionality were evaluated in the soil samples (14 replicates per patch type) using 16S rRNA gene amplicon sequencing together with physico-chemical measures of the soil. We have found that the EEs affected the community composition differently. Barren patches supported a soil microbiome, dominated by Rubrobacter and Proteobacteria, while in EE patches Deinococcus-Thermus dominated. The presence of the EEs similarly enhanced the abundance of phototrophic, nitrogen cycle, and stress-related genes. In addition, the soil characteristics were altered only when both EEs were combined. Our results suggest that arid landscapes foster unique communities selected by patches created by each EE(s), solo or in combination. Although the communities' composition differs, they support similar potential functions that may have a role in surviving the harsh arid conditions. The combined effect of the EEs on soil microbial communities is a good example of the hard-to-predict non-additive features of arid ecosystems that merit further research.


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