| 1. |
- Abubaker, Jamal, et al.
(författare)
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Bacterial community structure and microbial activity in different soils amended with biogas residues and cattle slurry
- 2013
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Ingår i: Applied Soil Ecology. - : Elsevier BV. - 0929-1393 .- 1873-0272. ; 72, s. 171-180
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Tidskriftsartikel (refereegranskat)abstract
- Anaerobic digestion of organic materials generates residues of differing chemical composition compared to undigested animal manures, which may affect the soil microbial ecosystem differently when used as fertilizers. This study investigated the effects of two biogas residues (BR-A and BR-B) and cattle slurry (CS) applied at rates corresponding to 70 kg NH4+-N ha(-1) on bacterial community structure and microbial activity in three soils of different texture (a sandy, a clay and an organic clay soil). 16S rRNA genes were targeted in PCR reactions and bacterial community profiles visualized using terminal restriction fragment length polymorphism. General microbial activity was measured as basal respiration (B-resp), substrate-induced respiration (SIR), specific growth rate (mu(SIR)), metabolic quotient (qCO(2)) and nitrogen mineralization capacity (NMC). Non-metric multidimensional scaling analysis visualized shifts in bacterial community structure related to microbial functions. There were significant differences in bacterial community structure after 120 days of incubation (+20 degrees C at 70% of WHC) between non-amended (control) and amended soils, especially in the sandy soil, where CS caused a more pronounced shift than biogas residues. Terminal-restriction fragment (TRF) 307, the predominant peak in CS-amended sandy soil, was identified as possibly Bacillus or Streptococcus. TRF 226, the dominant peak in organic soil amended with BR-B, was classified as Rhodopseudomonas. B-resp significantly increased and SIR decreased in all amendments to organic soil compared with the control, potentially indicating decreased efficiency of heterotrophic microorganisms to convert organic carbon into microbial biomass. This was also reflected in an elevated qCO(2) in the organic soil. The mu(SIR) level was higher in the sandy soil amended with BR-A than with BR-B or CS, indicating a shift toward species capable of rapidly utilizing glucose. NMC was significantly elevated in the clay and organic soils amended with BR-A and BR-B and in the sandy soil amended with BR-B and CS. Thus, biogas residues and cattle slurry had different effects on the bacterial community structure and microbial activity in the three soils. However, the effects of biogas residues on microbial activities were comparable in magnitude to those of cattle slurry and the bacterial community structure was less affected. Therefore, we do not see any reason not to recommend using biogas residues as fertilizers based on the results presented. (C) 2013 Elsevier B.V. All rights reserved.
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| 2. |
- Campbell, Colin
(författare)
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The arbuscular mycorrhizal fungus Glomus hoi can capture and transfer nitrogen from organic patches to its associated host plant at low temperature
- 2011
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Ingår i: Applied Soil Ecology. - : Elsevier BV. - 0929-1393 .- 1873-0272. ; 48, s. 102-105
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Tidskriftsartikel (refereegranskat)abstract
- Arbuscular mycorrhizal fungi have been suggested to be of potential benefit in achieving sustainable agriculture systems. However, there is conflicting information on the degree to which arbuscular mycorrhizal fungi (AMF) can grow and function at soil temperatures typical of temperate regions. To resolve this conflict we grew Plantago lanceolata L inoculated with Glomus hoi (UY 110) in microcosm units maintained at 12/10 degrees C (day/night). The microcosms had two compartments, one planted and one not. The root-free compartment contained either an organic ((15)N:(13)C labelled milled shoot material) or a sand patch. When permitted access, G. hoi proliferated hyphae extensively in the organic patch material. Plant (15)N content was a simple function of length density of extra-radical mycelium (ERM) in the patch and c. 6% of host plant N was derived from the patch. These results indicate that G. hoi not only grew at these realistic soil temperatures, but also conferred a nutritional benefit to its host. (C) 2011 Elsevier B.V. All rights reserved.
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| 3. |
- Cederlund, Harald, et al.
(författare)
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Soil carbon quality and nitrogen fertilization structure bacterial communities with predictable responses of major bacterial phyla
- 2014
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Ingår i: Applied Soil Ecology. - : Elsevier BV. - 0929-1393 .- 1873-0272. ; 84, s. 62-68
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Tidskriftsartikel (refereegranskat)abstract
- Agricultural practices affect the soil ecosystem in multiple ways and the soil microbial communities represent an integrated and dynamic measure of soil status. Our aim was to test whether the soil bacterial community and the relative abundance of major bacterial phyla responded predictably to long-term organic amendments representing different carbon qualities (peat and straw) in combination with nitrogen fertilization levels and if certain bacterial groups were indicative of specific treatments. We hypothesized that the long-term treatments had created distinctly different ecological niches for soil bacteria, suitable for either fast-growing copiotrophic bacteria, or slow-growing oligotrophic bacteria. Based on terminal-restriction fragment length polymorphism of the 16S rRNA genes from the total soil bacterial community and taxa-specific quantitative real-time PCR of seven different groups, all treatments significantly affected the community structure, but nitrogen fertilization was the most important driver for changes in the relative abundances of the studied taxa. According to an indicator species analysis, the changes were largely explained by the decline in the relative abundances of Acidobacteria, Gemmatimonadetes and Verrucomicrobia with nitrogen fertilization. Conditions more favourable for copiotrophic life strategies were indicated in these plots by the decreased metabolic quotient, i.e. the ratio between basal respiration rate and soil biomass. Apart from the Alphaproteobacteria that were significantly associated with peat, no taxa were indicative of organic amendment in general. However, several significant indicators of both peat and straw were identified among the terminal restriction fragments suggesting that changes induced by the organic amendments were mainly manifested at a lower taxonomical level. Our findings strengthen the proposition that certain higher bacterial taxa adapt in an ecologically coherent way in response to changes induced by fertilization. (C) 2014 Elsevier B.V. All rights reserved.
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| 4. |
- Jensen, Erik Steen
(författare)
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Effects of digestate from anaerobically digested cattle slurry and plant materials on soil microbial community and emission of CO2 and N2O
- 2013
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Ingår i: Applied Soil Ecology. - : Elsevier BV. - 0929-1393 .- 1873-0272. ; 63, s. 36-44
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Tidskriftsartikel (refereegranskat)abstract
- Anaerobic digestion of animal manure and crop residues may be employed to produce biogas as a climate-neutral source of energy and to recycle plant nutrients as fertilizers. However, especially organic farmers are concerned that fertilizing with the digestates may impact the soil microbiota and fertility because they contain more mineral nitrogen (N) and less organic carbon (C) than the non-digested input materials (e.g. raw animal slurry or fresh plant residues). Hence, an incubation study was performed where (1) water, (2) raw cattle slurry, (3) anaerobically digested cattle slurry/maize, (4) anaerobically digested cattle slurry/grass-clover, or (5) fresh grass-clover was applied to soil at arable realistic rates. Experimental unites were sequentially sampled destructively after 1, 3 and 9 days of incubation and the soil assayed for content of mineral N, available organic C, emission of CO2 and N2O, microbial phospholipid fatty acids (biomass and community composition) and catabolic response profiling (fiinctional diversity). Fertilizing with the anaerobically digested materials increased the soil concentration of NO3- ca. 30-40% compared to when raw cattle slurry was applied. Grass-clover contributed with four times more readily degradable organic C than the other materials, causing an increased microbial biomass which depleted the soil for mineral N and probably also O-2. Consequently, grass-clover also caused a 10 times increase in emissions of CO2 and N2O greenhouse gasses compared to any of the other treatments during the 9 days. Regarding microbial community composition, grass-clover induced the largest changes in microbial diversity measures compared to the controls, where raw cattle slurry and the two anaerobically digested materials (cattle slurry/maize, cattle slurry/grass-clover) only induced minor and transient changes. (C) 2012 Elsevier B.V. All rights reserved.
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| 5. |
- Kardol, Paul
(författare)
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Climate change effects on soil microarthropod abundance and community structure
- 2011
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Ingår i: Applied Soil Ecology. - : Elsevier BV. - 0929-1393 .- 1873-0272. ; 47, s. 37-44
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Tidskriftsartikel (refereegranskat)abstract
- Our data demonstrate how simultaneously acting climate change factors can affect the structure of soil microarthropod communities in old-field ecosystems. Overall, changes in soil moisture content, either as direct effect of changes in precipitation or as indirect effect of warming or elevated [CO2], had a larger impact on microarthropod communities than did the direct effects of the warming and elevated [CO2] treatments. Moisture-induced shifts in soil microarthropod abundance and community composition may have important impacts on ecosystem functions, such as decomposition, under future climatic change. (c) 2010 Elsevier B.V. All rights reserved.
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| 6. |
- Krab, Eveline J., et al.
(författare)
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Northern peatland Collembola communities unaffected by three summers of simulated extreme precipitation
- 2014
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Ingår i: Agriculture, Ecosystems & Environment. Applied Soil Ecology. - : Elsevier BV. - 0929-1393 .- 1873-0272. ; 79, s. 70-76
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Tidskriftsartikel (refereegranskat)abstract
- Extreme climate events are observed and predicted to increase in frequency and duration in high-latitudeecosystems as a result of global climate change. This includes extreme precipitation events, which maydirectly impact on belowground food webs and ecosystem functioning by their physical impacts and byaltering local soil moisture conditions.We assessed responses of the Collembola community in a northern Sphagnum fuscum-dominatedombrotrophic peatland to three years of experimentally increased occurrence of extreme precipitationevents. Annual summer precipitation was doubled (an increase of 200 mm) by 16 simulated extremerain events within the three months growing season, where on each occasion 12.5 mm of rain was addedwithin a few minutes. Despite this high frequency and intensity of the rain events, no shifts in Collemboladensity, relative species abundances and community weighted means of three relevant traits (moisturepreference, vertical distribution and body size) were observed. This strongly suggests that the peatlandCollembola community is unaffected by the physical impacts of extreme precipitation and the short-termvariability in moisture conditions. The lack of response is most likely reinforced by the fact that extremeprecipitation events do not seem to alter longer-term soil moisture conditions in the peat layers inhabitedby soil fauna.This study adds evidence to the observation that the biotic components of northern ombrotrophicpeatlands are hardly responsive to an increase in extreme summer precipitation events. Given the importance of these ecosystems for the global C balance, these findings significantly contribute to the currentknowledge of the ecological impact of future climate scenarios. (C) 2014 Elsevier B.V. All rights reserved.
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| 7. |
- Lagerlöf, Jan, et al.
(författare)
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Land-use intensification and agroforestry in the Kenyan highland: Impacts on soil microbial community composition and functional capacity
- 2014
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Ingår i: Applied Soil Ecology. - : Elsevier BV. - 0929-1393 .- 1873-0272. ; 82, s. 93-99
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Tidskriftsartikel (refereegranskat)abstract
- This study investigates microbial communities in soil from sites under different land use in Kenya. We sampled natural forest, forest plantations, agricultural fields of agroforestry farms, agricultural fields with traditional farming and eroded soil on the slopes of Mount Elgon, Kenya. We hypothesised that microbial decomposition capacity, biomass and diversity (1) decreases with intensified cultivation; and (2) can be restored by soil and land management in agroforestry. Functional capacity of soil microbial communities was estimated by degradation of 31 substrates on Biolog EcoPlates (TM). Microbial community composition and biomass were characterised by phospholipid fatty acid (PLFA) and microbial C and N analyses. All 31 substrates were metabolised in all studied soil types, i.e. functional diversity did not differ. However, both the substrate utilisation rates and the microbial biomass decreased with intensification of land use, and the biomass was positively correlated with organic matter content. Multivariate analysis of PLFA and Biolog EcoPlate (TM) data showed clear differences between land uses, also indicated by different relative abundance of PLFA markers for certain microorganism groups. In conclusion, our results show that vegetation and land use control the substrate utilisation capacity and microbial community composition and that functional capacity of depleted soils can be restored by active soil management, e. g. forest plantation. However, although 20-30 years of agroforestry farming practises did result in improved soil microbiological and chemical conditions of agricultural soil as compared to traditional agricultural fields, the change was not statistically significant. (C) 2014 Elsevier B. V. All rights reserved.
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| 8. |
- Malmström, Anna, et al.
(författare)
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Do burned areas recover from inside? An experiment with soil fauna in a heterogeneous landscape
- 2012
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Ingår i: Applied Soil Ecology. - : Elsevier BV. - 0929-1393 .- 1873-0272. ; 59, s. 73-86
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Tidskriftsartikel (refereegranskat)abstract
- The post-fire soil faunal communities are formed both by animals having survived the fire and by colonizers from the surrounding landscape. The relative impact of these processes is largely affected by fire intensity. However, with the same fire intensity, the severity of the fire and, thus, the survival of soil animals could vary depending on environmental heterogeneity. We hypothesized that much fewer soil animals would survive the same fire intensity on shallow, dry soils than on deep, moist soils. To clarify the impact of soil depth and moisture on animal survival after fire, we conducted a burning experiment in the laboratory. Soil samples containing indigenous populations of soil fauna were taken along two transects from the top, slope and foot of two respective rocky outcrops within a mixed coniferous forest in Central Sweden. Half of the samples were burnt and half were left unburnt. Burning depth varied between 24 mm (soils from the top of the gradient) to 12 mm (slope and foot soils) indicating a difference in flammability. The proportion of animals surviving fire seemed to be fairly independent of burning depth (42 to 62% survival rate). Contribution of eggs which survived fire in the soil to the overall animal abundance restoration was negligible (1–3%). A multi-trophic approach resulted in different sensitivity estimates to artificial burning of various parameters. Abundance and biomass of all fauna groups studied was more sensitive to fire than species richness. Collembolans and macrofauna predators were the groups most tolerant to fire, while oribatid mites and macrofaunal detritivores showed higher mortality after the fire treatment. Despite a more pronounced alteration of the components of soil food-web by burning in the lowland Sphagnum plots, they may be important as refugia, especially for more slowly moving soil-dwelling macro- and microarthropods
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| 9. |
- Malmström, Anna
(författare)
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Life-history traits predict recovery patterns in Collembola species after fire: A 10 year study
- 2012
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Ingår i: Applied Soil Ecology. - : Elsevier BV. - 0929-1393 .- 1873-0272. ; 56, s. 35-42
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Tidskriftsartikel (refereegranskat)abstract
- Fire is the most dominant natural large scale disturbance regime in many of the world's ecosystems, including boreal forests. Fires usually destroy vegetation and litter and, if the fires are severe enough, parts of the humus layer. Soil animals that are using those resources are therefore expected to be sensitive to fire. Collembola are a species rich group of soil animals that shows a broad variability in life-history traits. In this study I use a fire experiment with burnt clear-cut, unburnt clear-cut and unburnt forest to examine the recovery of the collembolan community at species level during 10 years after a fire of moderate severity. I also investigate if there are certain life-history traits that are advantageous for recovery after fire. Neither total abundances nor species composition had recovered at burnt plots compared to unburnt plots 10 years after fire. A few species had recovered during the study period and the recovering species shared common traits, i.e. they were mainly surface living and sexually reproducing species with traits for fast active dispersal. Community weighted trait means showed that for the whole community life-history traits varied between treatments only the first years after fire. (C) 2012 Elsevier B.V. All rights reserved.
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| 10. |
- Oksinska, M. P., et al.
(författare)
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Resistance to oxidation products of caffeic acid is important for efficient colonization of wheat seedlings by Pseudomonas proteolytica strain PSR114
- 2013
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Ingår i: Applied Soil Ecology. - : Elsevier BV. - 0929-1393 .- 1873-0272. ; 66, s. 71-80
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Tidskriftsartikel (refereegranskat)abstract
- The interrelationships between plants and rhizosphere bacteria are strongly dependent on the quality and quantity of root exudates. The ability to colonize roots is crucial for pseudomonads to function as biological control agents of root- and soil-borne pathogenic microbes. The multiplication of rhizosphere bacteria is restricted in the presence of simple phenolic compounds, which are components of the resistance mechanisms of plants to pathogens. Caffeic acid is a phenolic compound, which is commonly found in wheat tissues. It is prone to oxidation into o-quinones, which are toxic to microorganisms. The aim of the present study was to determine whether the ability of microorganisms to resist caffeic acid and its oxidation products could play a role in the early colonization of wheat seedlings. Among the fluorescent pseudomonads that we have studied, strain PSR114 is one of the most efficient colonizers of wheat seedlings during the first 48 h after seed germination, and it is particularly resistant to products resulting from the spontaneous oxidation of caffeic acid. This strain was isolated from the rhizosphere of oilseed rape and identified as being closely related to Pseudomonas proteolytica through the analysis of 16S rRNA and rpoB gene sequences. At pH 7.0, this strain grew intensively in the presence of 1.50 mg mL−1 of caffeic acid. Its multiplication was partially reduced in the presence of oxidized caffeic acid at concentrations above 0.21 mg mL−1, and completely inhibited at concentrations above 0.38 mg mL−1. A Tn5 transposon mutant of PSR114 had lower level of resistance to the oxidation products of caffeic acid, as well as reduced capacity to colonize wheat seedlings when compared to the wild type strain. This work demonstrates that resistance to oxidation products of caffeic acid can be important for successful bacterial colonization of wheat seedlings.
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