Soil Microbial Community in Pesticide Bioremediation and a Case Study of Triveni Plant Complex

Impacts of the coexistence of polystyrene microplastics and pesticide imidacloprid on soil nitrogen transformations and microbial communities

Effect of repeated drying-rewetting cycles on soil extracellular enzyme activities and microbial community composition in arid and semi-arid ecosystems

Influences of litter diversity and soil moisture on soil microbial communities in decomposing mixed litter of alpine steppe species

Knowledge about the elevational patterns of soil microbial biomass and communities can facilitate accurate prediction of the responses of soil biogeochemical processes to climate change. However, previous studies that have considered intra‐ and inter‐annual variations have reported inconsistent results on the one hand, and they have paid little attention to the effect of soil layer on the other hand. We, therefore, conducted a 4‐year in situ soil core incubation experiment along a 2431‐m elevational gradient across the dry valley shrubland, valley‐montane ecotone forest, subalpine coniferous forest, alpine coniferous forest, and alpine meadow in an ecologically fragile alpine‐gorge region on the eastern edge of the Qinghai‐Tibetan Plateau. Soil microbial biomass and community composition in the organic and mineral layers were measured using the phospholipid fatty acids (PLFA) method at five critical periods each year. Our results indicated that soil microbial biomass in the organic layer was the highest in the subalpine coniferous forest, followed by the alpine meadow, alpine coniferous forest, and valley‐montane ecotone forest. In contrast, soil microbial biomass in the mineral layer was significantly higher in the alpine meadow than in the other sites. Soil microbial biomass exhibited differential seasonal fluctuations at different elevations, resulting in their elevational patterns being strongly intra‐annual and inter‐annual dependent. Our results revealed that elevation and seasonality significantly affected soil microbial communities. Seasonality had a more substantial effect than elevation on soil microbial communities during the first 3 years of incubation, whereas the relative importance of seasonal and elevational effects on microbial communities was reversed in the organic layer with incubation time. These results are mainly attributed to the magnitude and direction of effect of environmental variables on soil microbial biomass and communities vary with elevation, soil layer, and sampling time. Briefly, the elevational patterns and dominant factors of soil microbial biomass and communities have intense soil layer and temporal specificity, implying that differential responses of soil biochemical processes to climate change might be observed at different elevations.

Factors affecting soil microbial community structure in tomato cropping systems

oil microbes are important for many underground ecological processes and the change in their total biomass and community structure is regarded as a sensitive indicator for climate warming and human disturbances.Through open top chambers(OTCs) warming and clipping plus dung application,the effects of warming and grazing on soil microbial biomass and community structure were determined in an alpine meadow on the eastern Qinghai-Tibetan Plateau.The profiles of microbial phospholipid fatty acids(PLFAs) showed that soil microbial communities were dominated by bacteria in the growing seasons.An increase of 1.17 ℃ by OTCs warming soil at 10 cm depth resulted in a rise of 34.58% of total PLFAs,while the clipping plus dung application in spring caused a rise of 65.77%.Both experimental warming and grazing led to a significant change in soil microbial community structure.Compared to the control treatment,OTCs warming increased bacterial PLFAs by 8.80% and decresaed fungal PLFAs by 17.48%.The ratio of bacteria to fungi changed from 7.3 to 9.6.Grazing also markedly increased bacterial PLFAs by 8.40% and decreased fungal PLFAs by 14.04%.The ratio of bacteria to fungi increased to 9.2.The effects of OTCs warming and grazing on soil microbial biomass and community structure were found more notable than those of OTCs warming or grazing alone.Our results suggest that climatic warming and human disturbances might cause significant changes in soil microbial communities in a short period of time,which could have important effects on carbon budget and nutrient cycling in the alpine meadow ecosystem in the eastern Qinghai-Tibetan Plateau.

The responses of soil microbes to climatic and anthropological factors in the Tibetan grasslands

Summary Resource control over abundance, structure and functional diversity of soil microbial communities is a key determinant of soil processes and related ecosystem functioning. Copiotrophic organisms tend to be found in environments which are rich in nutrients, particularly carbon, in contrast to oligotrophs, which survive in much lower carbon concentrations. We hypothesized that microbial biomass, activity and community structure in nutrient‐poor soils of an Amazonian rain forest are limited by multiple elements in interaction. We tested this hypothesis with a fertilization experiment by adding C (as cellulose), N (as urea) and P (as phosphate) in all possible combinations to a total of 40 plots of an undisturbed tropical forest in French Guiana. After 2 years of fertilization, we measured a 47% higher biomass, a 21% increase in substrate‐induced respiration rate and a 5‐fold higher rate of decomposition of cellulose paper discs of soil microbial communities that grew in P‐fertilized plots compared to plots without P fertilization. These responses were amplified with a simultaneous C fertilization suggesting P and C colimitation of soil micro‐organisms at our study site. Moreover, P fertilization modified microbial community structure (PLFAs) to a more copiotrophic bacterial community indicated by a significant decrease in the Gram‐positive : Gram‐negative ratio. The Fungi : Bacteria ratio increased in N fertilized plots, suggesting that fungi are relatively more limited by N than bacteria. Changes in microbial community structure did not affect rates of general processes such as glucose mineralization and cellulose paper decomposition. In contrast, community level physiological profiles under P fertilization combined with either C or N fertilization or both differed strongly from all other treatments, indicating functionally different microbial communities. While P appears to be the most critical from the three major elements we manipulated, the strongest effects were observed in combination with either supplementary C or N addition in support of multiple element control on soil microbial functioning and community structure. We conclude that the soil microbial community in the studied tropical rain forest and the processes it drives is finely tuned by the relative availability in C, N and P. Any shifts in the relative abundance of these key elements may affect spatial and temporal heterogeneity in microbial community structure, their associated functions and the dynamics of C and nutrients in tropical ecosystems.

Functional trait variation and community-weighted means of tree traits can alter soil microbial biomass and community composition

Changes in soil microbial biomass and community composition in coastal wetlands affected by restoration projects in a Chinese delta

This study investigated the influence of corn straw application on soil microbial communities and the relationship between such communities and soil properties in black soil. The crop used in this study was maize (Zea mays L.). The five treatments consisted of applying a gradient (50, 100, 150, and 200%) of shattered corn straw residue to the soil. Soil samples were taken from May through September during the 2012 maize growing season. The microbial community structure was determined using phospholipid fatty acid (PLFA) analysis. Our results revealed that the application of corn straw influenced the soil properties and increased the soil organic carbon and total nitrogen. Applying corn straw to fields also influenced the variation in soil microbial biomass and community composition, which is consistent with the variations found in soil total nitrogen (TN) and soil respiration (SR). However, the soil carbon-to-nitrogen ratio had no effect on soil microbial communities. The abundance of PLFAs, TN, and SR was higher in C1.5 than those in other treatments, suggesting that the soil properties and soil microbial community composition were affected positively by the application of corn straw to black soil. A Principal Component Analysis indicated that soil microbial communities were different in the straw decomposition processes. Moreover, the soil microbial communities from C1.5 were significantly different from those of CK (p < 0.05). We also found a high ratio of fungal-to-bacterial PLFAs in black soil and significant variations in the ratio of monounsaturated-to-branched fatty acids with different straw treatments that correlated with SR (p < 0.05). These results indicated that the application of corn straw positively influences soil properties and soil microbial communities and that these properties affect these communities. The individual PLFA signatures were sensitive indicators that reflected the changes in the soil environment condition.

Soil removal and stockpiling prior to mining activities have adverse effects on soil health, which raises concerns about the suitability of stockpiled soils as a reclamation substrate. Due to the fundamental roles microbes play in ecosystem function and services, they can be used as indicators of soil health and quality. We analyzed the prokaryotic microbial communities in a chronosequence of 0.5–28-year-old stockpiles at increasing depths (0–300 cm), in two oil-extraction locations in northern Alberta. Our results indicate that the microbial communities of the seven stockpiles examined were more similar to each other than to the undisturbed soils used as reference, which might indicate that stockpiling shifts the microbial community composition outside the range of natural variability. Furthermore, while microbial communities in younger and older stockpiles were dissimilar to the reference soils, the communities of intermediate-age stockpiles were more similar to those in the reference soils. We interpret these divergences in similarity to indicate that initial disturbance leads to a shift in the microbial community, which then recovers following several years of storage, but eventually, long-term storage leads to a secondary divergence from the range of natural variability. Additionally, the bacterial diversity decreased significantly with increasing stockpile depth, which could be attributed to the harsh conditions of the deeper stockpile layers and the scarcity of nutrients. Our findings provide important insights into the impact of soil stockpiling on microbial communities and complement those of earlier studies highlighting the importance of stockpile depth and storage time as predictors of variability of soil microbial diversity and community composition. Furthermore, due to the crucial functions played by microbes in soils, our conclusions should serve for reclamation agencies to modify the stockpiling protocols in order to mitigate the impact of stockpiling on soil microbial communities.

Dynamic changes of soil microbial community in Pinus sylvestris var. mongolica plantations in the Mu Us Sandy Land

Forest management often results in changes in soil microbial communities. To understand how forest management can change microbial communities, we studied soil microbial abundance and community structure in a natural Chamaecyparis (NCP) forest, a disturbed Chamaecyparis (DCP) forest, a secondary (regenerated) Chamaecyparis (SCP) forest and a secondary (reforested) Cryptomeria (SCD) forest. We analyzed soil microbial abundance by measuring phospholipid fatty acids (PLFAs) and microbial community structure by denaturing gradient gel electrophoresis (DGGE) in the studied forest soils. The content of the soil PLFA fungal biomarker decreased from NCP to SCP, DCP and SCD forest soils, associated with the degree of disturbance of forest management. The ratio of soil Gram positive–to-negative bacteria and the stress index (16:1ω7t to 16:1ω7c) increased from NCP to SCP and DCP soils; thus, disturbed forests except for SCD showed increased soil microbial stress. Principal component analysis of soil microbial groups by PLFAs separated the four forest soils into three clusters: NCP, DCP and SCP, and SCD soil. The DGGE analysis showed no difference in the microbial community structure for NCP, DCP and SCP soils, but the community structure differed between SCD and the three other forest soils. In cloud montane forests, disturbance due to forest management had only a slight influence on the soil microbial community, whereas reforestation with different species largely changed the soil microbial community structure.

Deyeuxia angustifolia Kom. encroachment changes soil physicochemical properties and microbial community in the alpine tundra under climate change