Soil is a limited resource often contaminated with heavy metals. Recently, several soil remediation processes have been developed, including an EDTA (ethylenediaminetetraacetic acid) chelating agent extraction that results in high removal efficiency of the contaminants. There is a limited knowledge on how this procedure affects soil microorganisms, including plant root endosymbiotic arbuscular mycorrhizal fungi. In this paper we present data on the mycorrhizal potential of soil after the remediation procedure, as well with the molecular characterization of arbuscular mycorrhizal fungal diversity before and after soil remediation, and before and after soil inoculation with commercial and indigenous (local) fungal inocula using an examination of 18S rRNA clone libraries. After the remediation treatment soils had very low mycorrhizal potential. Functional mycorrhizal symbiosis with plants was established either by commercial or local (grassland roots and rhizosphere soil) inoculum addition to the soil and remediated soil was successfully revitalized after the treatment. The use of the local inoculum resulted in a higher arbuscular mycorrhizal fungal diversity in the roots of plants growing in the remediated soil compared to the ones revitalized with the commercial inoculum.
COBISS.SI-ID: 8445305
Locally extreme environments are a powerful tool for the study of slow ecological and evolutionary processes, largely because they enable long-term insight into adaptation of the natural communities and their ecological networks. These systems allow the conceptual compression of both time and space, allowing the investigation of important questions at manageable spatiotemporal scales. Here a case study of mofettes as natural sites with constant geogenic CO2 exhalations and soil hypoxia acting on the biological communities is presented, with a review of a wide range of studies of other extreme environments enabling plant ecophysiological, and ecological studies of distinct groups of organisms from micro to macro scale. The paper also shows where the greatest advances in using discrete extreme environments with long-term and constant selective pressures in the context of global change ecology is likely to appear in the future.
COBISS.SI-ID: 8491129
The diversity and structure of soil microbial communities are crucial elements in understanding the ecological impacts of rapidly changing environments. One important group of soil microbes is the ubiquitous plant symbiotic arbuscular mycorrhizal (AM) fungi. Their diverse communities are shaped by complex interactions of their abiotic and biotic environments. Locally extreme ecosystems have proven to be useful for natural long-term experiments in the ecology and evolution of AM fungi, giving an insight into much-needed processes of adaptation and acclimation of natural communities to abiotic stress. Our data data show that when exposed to extreme long-term stress specific and temporary stable AM fungal communities form with a high abundance of specialised, stress-tolerant taxa. Moreover, in both natural- and human-impacted ecosystems there are several such cases. This chapter covers a wide range of extremes (abiotic stresses) in the pedosphere, from high to low temperatures, drought and floods, hypoxia, salinity, and soil pollution (e.g. with heavy metals). An overview of several specific stressed environments where AM fungal community ecology has been studied is presented. In some of these cases, locally extreme environments have already been used and could further serve as a powerful tool to study slow ecological and evolutionary processes that normally require long-term observations and experiments to study them
COBISS.SI-ID: 8831353
Efficiency and the preservation of soil functions are key requirements for sustainable remediation of contaminated soil. Microbial decomposition and conversion of substrates is a fundamental soil function. Pilot-scale EDTA-based soil washing recycled chelant generated no wastewater and removed 78% of Pb from acidic farmland soil with 860 mg/kg Pb and 60% of Pb from calcareous garden soil with 1030 mg/kg Pb. Remediation had an insignificant effect on microbial respiration in acidic soil induced by sequential additions of glucose, micro-cellulose, starch and alfa-alfa sprout powder (mimicking litter components, C-cycle). In contrast, remediation of calcareous soil reduced cumulative CO2 production after glucose (simple) and alfalfa (complex substrate) addition, by up to 40%. Remediation reduced the nitrification rate (denoting the N-cycle) in acidic soil by 30% and halved nitrification in calcareous soil. Remediation in both soils slightly or positively affected dehydrogenase and b-glucosidase activity (associated with C-cycle), and decreased urease activity (N-cycle). Generally, EDTA remediation modestly interfered with substrate utilisation in acidic soil. A more prominent effect of remediation on the functioning of calcareous soil could largely be attributed to the use of a higher EDTA dose (30 vs. 100 mmol/kg, respectively).
COBISS.SI-ID: 9026937
Climate change causes droughts, which in turn cause significant physiological stress for soil microorganisms. In this study, we investigated how the abundance of total bacterial, crenarchaeal and fungal communities and the abundance of N-cycling microbial guilds responded to a severe agricultural drought event in a long-term experiment of minimum tillage (MT) and conventional ploughing (CT) at two soil depths. Drought, defined as a reduction of soil water content and increased soil temperature, significantly decreased the abundance of all the studied microbial communities. The data showed linear relationships between all dependent variables and soil water content and soil temperature for the examined range of soil water content (WHC 13–76%) and examined range of average daily soil temperature at 5 cm depth (17–30 °C). Thus, we found that the abundance of most studied microbial communities decreased by about 2% when water content decreased by 1 mass % and by about 10% when temperature increases by 1 °C. When comparing communities at average soil water content and average soil temperature, MT had higher average abundances of total bacterial and crenarchaeal 16S rRNA and fungal ITS genes in the 0–10 cm soil layer than did CT (1.9, 2.9 and 2.5 times, respectively), as well as AOA and AOB amoA (3.9 and 1.7 times, respectively), nirK, nirS, nosZI and nosZII genes (2.0, 1.8, 1.8 and 2.3 times, respectively); while significant differences between MT and CT in the 10–20 cm soil layer were f ound only in the average abundance of crenarchaeal 16S rRNA and crenarchaeal amoA genes (3.5 and 2.7 times greater under MT than CT). Regardless of the weather conditions during our study, the abundances of all communities were greater under MT 0–10 than under CT 0–10. After three weeks of severe drought, the greatest decrease in the abundance of all communities, bacterial and archaeal N-cycling guilds as well as total prokaryotes and fungi, was observed under MT 0–10. However, after only a few rainfall events, all communities under both tillage systems reached their initial abundance, demonstrating a high resilience.
COBISS.SI-ID: 8956537