Higher Vulnerability of Heterotrophic Soil Respiration to Temperature Drop in Fallows than in Meadows

2021 ◽  
Vol 7 (1) ◽  
pp. 57-67
Author(s):  
Dominika Chmolowska

The present study examines the difference between stability and climatic factors of soil microbial communities in two ecosystem types with similar plant biomass, while differing in plant diversity, successional stage and complexity. Observations of variation in stability can be applied to climate change investigations, a topic of current pivotal importance. We compared responses of soil basal respiration to short time perturbation in soils collected from six established (meadow) and six early successional (fallow) ecosystems by exposing them to thermal and water stress. Resistance and resilience indices were calculated to describe how much a system was affected by and recovered from perturbation. The soil’s physico-chemical properties and plant community composition were identified and used for correlation and regression analyses with the stability indices. There was a smaller relative change in soil respiration in meadows than in fallows as temperature decreased from 22 to 10°C. Resistance to coolness was correlated to higher soil pH, while resilience to plant species richness. The drying-rewetting experiment highlighted that the stability indices became non-linear when a data set had high variations. Soil microbial communities in a more complex and mature ecosystem type (meadow) were more stable under a moderate perturbation. This might have been supported by co-occurring factors, with soil pH being the most influential. The slightly acidic fallow soil might have a higher potential for carbon sequestration than neutral meadow soil.

2021 ◽  
Vol 97 (4) ◽  
Author(s):  
Lucas Dantas Lopes ◽  
Jingjie Hao ◽  
Daniel P Schachtman

ABSTRACT Soil pH is a major factor shaping bulk soil microbial communities. However, it is unclear whether the belowground microbial habitats shaped by plants (e.g. rhizosphere and root endosphere) are also affected by soil pH. We investigated this question by comparing the microbial communities associated with plants growing in neutral and strongly alkaline soils in the Sandhills, which is the largest sand dune complex in the northern hemisphere. Bulk soil, rhizosphere and root endosphere DNA were extracted from multiple plant species and analyzed using 16S rRNA amplicon sequencing. Results showed that rhizosphere, root endosphere and bulk soil microbiomes were different in the contrasting soil pH ranges. The strongest impact of plant species on the belowground microbiomes was in alkaline soils, suggesting a greater selective effect under alkali stress. Evaluation of soil chemical components showed that in addition to soil pH, cation exchange capacity also had a strong impact on shaping bulk soil microbial communities. This study extends our knowledge regarding the importance of pH to microbial ecology showing that root endosphere and rhizosphere microbial communities were also influenced by this soil component, and highlights the important role that plants play particularly in shaping the belowground microbiomes in alkaline soils.


2014 ◽  
Vol 80 (16) ◽  
pp. 4920-4929 ◽  
Author(s):  
Christian L. Lauber ◽  
Jessica L. Metcalf ◽  
Kyle Keepers ◽  
Gail Ackermann ◽  
David O. Carter ◽  
...  

ABSTRACTCarrion decomposition is an ecologically important natural phenomenon influenced by a complex set of factors, including temperature, moisture, and the activity of microorganisms, invertebrates, and scavengers. The role of soil microbes as decomposers in this process is essential but not well understood and represents a knowledge gap in carrion ecology. To better define the role and sources of microbes in carrion decomposition, lab-reared mice were decomposed on either (i) soil with an intact microbial community or (ii) soil that was sterilized. We characterized the microbial community (16S rRNA gene for bacteria and archaea, and the 18S rRNA gene for fungi and microbial eukaryotes) for three body sites along with the underlying soil (i.e., gravesoils) at time intervals coinciding with visible changes in carrion morphology. Our results indicate that mice placed on soil with intact microbial communities reach advanced stages of decomposition 2 to 3 times faster than those placed on sterile soil. Microbial communities associated with skin and gravesoils of carrion in stages of active and advanced decay were significantly different between soil types (sterile versus untreated), suggesting that substrates on which carrion decompose may partially determine the microbial decomposer community. However, the source of the decomposer community (soil- versus carcass-associated microbes) was not clear in our data set, suggesting that greater sequencing depth needs to be employed to identify the origin of the decomposer communities in carrion decomposition. Overall, our data show that soil microbial communities have a significant impact on the rate at which carrion decomposes and have important implications for understanding carrion ecology.


PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e6090 ◽  
Author(s):  
Craig R. Anderson ◽  
Michelle E. Peterson ◽  
Rebekah A. Frampton ◽  
Simon R. Bulman ◽  
Sandi Keenan ◽  
...  

Rapid and transient changes in pH frequently occur in soil, impacting dissolved organic matter (DOM) and other chemical attributes such as redox and oxygen conditions. Although we have detailed knowledge on microbial adaptation to long-term pH changes, little is known about the response of soil microbial communities to rapid pH change, nor how excess DOM might affect key aspects of microbial N processing. We used potassium hydroxide (KOH) to induce a range of soil pH changes likely to be observed after livestock urine or urea fertilizer application to soil. We also focus on nitrate reductive processes by incubating microcosms under anaerobic conditions for up to 48 h. Soil pH was elevated from 4.7 to 6.7, 8.3 or 8.8, and up to 240-fold higher DOM was mobilized by KOH compared to the controls. This increased microbial metabolism but there was no correlation between DOM concentrations and CO2respiration nor N-metabolism rates. Microbial communities became dominated byFirmicutesbacteria within 16 h, while few changes were observed in the fungal communities. Changes in N-biogeochemistry were rapid and denitrification enzyme activity (DEA) increased up to 25-fold with the highest rates occurring in microcosms at pH 8.3 that had been incubated for 24-hour prior to measuring DEA. Nitrous oxide reductase was inactive in the pH 4.7 controls but at pH 8.3 the reduction rates exceeded 3,000 ng N2–N g−1h−1in the presence of native DOM. Evidence for dissimilatory nitrate reduction to ammonium and/or organic matter mineralisation was observed with ammonium increasing to concentrations up to 10 times the original native soil concentrations while significant concentrations of nitrate were utilised. Pure isolates from the microcosms were dominated byBacillusspp. and exhibited varying nitrate reductive potential.


2021 ◽  
Author(s):  
Yi Zhang ◽  
Ying-Zhong Xie ◽  
Hong-Bin Ma ◽  
Juan Zhang ◽  
Le Jing ◽  
...  

Abstract Background: The study evaluates how rainfall change and temperature increase affect microbial communities in the desert grassland of Ningxia Autonomous Region, China to explore the soil microbial community and the relationships among the soil microbial community, chemical properties, soil respiration (SR) and plant biomass under the climate change. We established the field experiment with five levels of rainfall by rainout shelters and two levels of temperature by Open-Top Chamber (OTC). Results: The effect of temperature to soil microbial communities is not significant, but with the continuous increase of rainfall, the microbial community gradually increases. Soil microbial diversity negatively correlated with soil CO2 flux. The α-diversity of microbial communities positively correlated with above-living biomass (ALB) and soil temperature (ST), but negatively correlated with root biomass (RB). Conclusions: Both rainfall and temperature’s rising do not promote the soil community α-diversity, but it can promote soil microbial community β-diversity. Soil microbial communities show resistance to rainfall changing. Soil respiration (SR) will limit soil microbial diversity. Soil organic carbon (SOC), soil total nitrogen (STN), and soil total phosphorus (STP) will promote soil microbial abundance and diversity. ALB and ST will promote the soil α-diversity, but the effect of RB to soil microbial is opposite. These findings maybe provide a reliable theoretical basis for formulating a reasonable response strategy in desert steppe ecosystems.


2017 ◽  
Vol 14 (20) ◽  
pp. 4815-4827 ◽  
Author(s):  
Chuang Zhang ◽  
Xin-Yu Zhang ◽  
Hong-Tao Zou ◽  
Liang Kou ◽  
Yang Yang ◽  
...  

Abstract. The nitrate to ammonium ratios in nitrogen (N) compounds in wet atmospheric deposits have increased over the recent past, which is a cause for some concern as the individual effects of nitrate and ammonium deposition on the biomass of different soil microbial communities and enzyme activities are still poorly defined. We established a field experiment and applied ammonium (NH4Cl) and nitrate (NaNO3) at monthly intervals over a period of 4 years. We collected soil samples from the ammonium and nitrate treatments and control plots in three different seasons, namely spring, summer, and fall, to evaluate the how the biomass of different soil microbial communities and enzyme activities responded to the ammonium (NH4Cl) and nitrate (NaNO3) applications. Our results showed that the total contents of phospholipid fatty acids (PLFAs) decreased by 24 and 11 % in the ammonium and nitrate treatments, respectively. The inhibitory effects of ammonium on Gram-positive bacteria (G+) and bacteria, fungi, actinomycetes, and arbuscular mycorrhizal fungi (AMF) PLFA contents ranged from 14 to 40 % across the three seasons. We also observed that the absolute activities of C, N, and P hydrolyses and oxidases were inhibited by ammonium and nitrate, but that nitrate had stronger inhibitory effects on the activities of acid phosphatase (AP) than ammonium. The activities of N-acquisition specific enzymes (enzyme activities normalized by total PLFA contents) were about 21 and 43 % lower in the ammonium and nitrate treatments than in the control, respectively. However, the activities of P-acquisition specific enzymes were about 19 % higher in the ammonium treatment than in the control. Using redundancy analysis (RDA), we found that the measured C, N, and P hydrolysis and polyphenol oxidase (PPO) activities were positively correlated with the soil pH and ammonium contents, but were negatively correlated with the nitrate contents. The PLFA biomarker contents were positively correlated with soil pH, soil organic carbon (SOC), and total N contents, but were negatively correlated with the ammonium contents. The soil enzyme activities varied seasonally, and were highest in March and lowest in October. In contrast, the contents of the microbial PLFA biomarkers were higher in October than in March and June. Ammonium may inhibit the contents of PLFA biomarkers more strongly than nitrate because of acidification. This study has provided useful information about the effects of ammonium and nitrate on soil microbial communities and enzyme activities.


2021 ◽  
Author(s):  
Chi Zhang ◽  
Chao Song ◽  
Donghui Wang ◽  
Wenkuan Qin ◽  
Biao Zhu ◽  
...  

Abstract Purpose: Changes in precipitation amount and land use are expected to greatly impact soil respiration (Rs) of grassland ecosystems. However, little is known about whether they can interactively impact Rs and how plant and soil microbial communities regulate the response of Rs. Methods: Here, we investigated the impacts of altered precipitation amount (–50%, ambient and +50%) and land-use regime (fencing, mowing and grazing) on Rs with a field experiment in the Inner Mongolian grassland.Results: We found that altered precipitation amount impacted Rs and its components across the 3-year study period, while land-use regime alone or its interaction with precipitation amount impacted them in certain years. In addition, changed soil microclimate, especially soil moisture, under altered precipitation amount and land-use regime can impact the components of Rs either directly or indirectly via influencing plant and soil microbial communities.Conclusions: Integrating changing precipitation amount and land-use regime within experiment can produce more accurate insights into grassland Rs, and chronically shifted plant and soil microbial communities under these changes may result in distinct long-term impacts on Rs.


2021 ◽  
Vol 12 ◽  
Author(s):  
Xingjia He ◽  
Hua Xie ◽  
Danmei Gao ◽  
M. Khashi U. Rahman ◽  
Xingang Zhou ◽  
...  

The application of biochar stimulates the activities of microorganisms that affect soil quality and plant growth. However, studies on the impacts of biochar mainly focus on a monoculture, its effects on interspecific interactions are rarely reported. Here, we investigated the impacts of biochar on tomato/potato–onion intercropped (TO) in a pot experiment. Tomato monoculture (T) and TO were treated with no, 0.3, 0.6, and 1.2% biochar concentrations in a pot experiment. Microbial communities from tomato rhizosphere soil were analyzed by quantitative PCR and Illumina MiSeq. The results showed that compared with the tomato monoculture, 0.6%TO and 1.2%TO significantly increased tomato yield in 2018. TO and 1.2%TO significantly increased plant height and dry weight in 2018 and 2019. Biochar treatments increased soil pH, decreased NO3--N and bulk density, and increased the absorption of N, P, and K by tomato. Bacterial and fungal abundances increased with an increase in biochar concentration, while Bacillus spp. and Pseudomonas spp. abundances showed an “increase-decrease-increase” trend. Biochar had a little effect on bacterial diversities but significantly lowered fungal diversities. TO, 0.6%TO, and 1.2%TO increased the potentially beneficial organisms (e.g., Pseudeurotium and Solirubrobacter) and lowered the potentially pathogenic organisms (e.g., Kribbella and Ilyonectria). Different concentrations of biochar affected the bacterial and fungal community structures. Redundancy analysis indicated that the bacterial community was strongly correlated with soil pH, NO3--N, and EC, while the fungal community was closely related to soil NO3--N and moisture. The network analysis showed that biochar and intercropping affected the symbiosis pattern of the microorganisms and increased the proportion of positive interactions and nitrifying microorganisms (Nitrospirae) in the microbial community. Overall, our results indicated that monoculture and intercropping with biochar improved soil physicochemical states and plant nutrient absorption, and regulated soil microbial communities, these were the main factors to promote tomato growth and increase tomato productivity.


2017 ◽  
Author(s):  
Chuang Zhang ◽  
Xin-Yu Zhang ◽  
Hong-Tao Zou ◽  
Liang Kou ◽  
Yang Yang ◽  
...  

Abstract. The ratios of nitrate to ammonium in wet atmosphere nitrogen (N) deposition compounds were increasing recently. However, the individual effects of nitrate and ammonium deposition on soil microbial communities biomass and enzyme activities are still unclear. We conducted a four-year N addition field experiment to evaluate the responses of soil microbial communities biomass and enzyme activities to ammonium (NH4Cl) and nitrate (NaNO3) additions. Our results showed that (1) the inhibitory effects of ammonium additions on total mass of phospholipid fatty acid (PLFA) were stronger than those of nitrate additions. Both decreased total PLFA mass about 24 % and 11 %, respectively. The inhibitory effects of ammonium additions on gram positive bacteria (G+) and bacteria, fungi, actinomycetes (A), and arbuscular mycorrhizal fungi (AMF) PLFA mass ranged from 14 %–40 %. (2) Both ammonium and nitrate additions inhibited absolute activities of C, N, and P hydrolyses and oxidases, and nitrate additions had stronger inhibition effects on the acid phosphatase (AP) than ammonium additions. Both ammonium and nitrate additions decreased N-acquisition specific enzyme activities (enzyme activities normalized by total PLFA mass) about 21 % or 43 %, respectively. However, ammonium additions increased P-acquisition specific enzyme activities about 19 % comparing to control. (3) Redundancy analysis (RDA) showed that the measured C, N, and P hydrolyses and polyphenol oxidase (PPO) activities were positively correlated with soil pH and ammonium contents, but negatively with nitrate contents; the mass of PLFA biomarkers were positively correlated with soil pH, soil organic carbon (SOC), and total N contents, but negatively with ammonium contents. (4) The soil enzyme activities varied seasonally in the order of March > June > October. On the contrary, microbial PLFA mass was higher in October than in March and June. Our results concluded that inhibition of mass of PLFA biomarkers and enzyme activities might be contributed to acidification caused by ammonium addition. Soil absolute enzyme activities were inhibited indirectly by acidification and nitrification, but specific enzyme activities normalized by PLFA were directly affected by N additions. It was meaningful to separate the effects of ammonium and nitrate additions on soil microbial communities and enzyme activities.


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