| 1. |
- Arrazola Vasquez, Elsa Maria, et al.
(författare)
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Estimating energy costs of earthworm burrowing using calorimetry
- 2024
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Ingår i: European Journal of Soil Biology. - 1164-5563 .- 1778-3615. ; 121
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Tidskriftsartikel (refereegranskat)abstract
- Earthworm burrowing is essential for soil functioning in temperate climates. It is known that soil compaction hampers earthworm burrowing, but there is a lack of knowledge on how it affects the energy costs of earthworms. In the present study, we used respirometry and isothermal calorimetry to quantify earthworm respiration rates and heat dissipation in two endogeic species, Aporrectodea caliginosa and Aporrectodea tuberculata , in compacted and non -compacted soils. We put the measured respiration rates and heat dissipation in relation to the burrow volume and cast volume produced by the earthworms. We found that at higher compaction levels, respiration rates and dissipated heat increased for both studied species. The energy costs associated with burrowing were a significant fraction of the total energy costs. Our results indicate that energy costs per burrow volume increase due to compaction, and that the specific energy costs for burrowing (i.e., per gram earthworm) were lower for A. tuberculata than for A. caliginosa . Further studies are needed to confirm our results. We discuss the potential and current limitations of isothermal calorimetry as a method for direct quantification of energy costs of earthworms. There is a need for further studies that quantify how energy costs of burrowing are affected by various soil conditions, to better predict the implications of land use and soil management on soil processes and functions mediated by earthworm burrowing.
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| 2. |
- Bokhorst, Stef Frederik, et al.
(författare)
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Snow fungi as a food source form micro-arthropods
- 2014
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Ingår i: European Journal of Soil Biology. - : Elsevier BV. - 1164-5563 .- 1778-3615. ; 60, s. 77-80
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Tidskriftsartikel (refereegranskat)abstract
- Snow fungi are often visibly abundant on tundra and forest understory vegetation immediately after snow melt in Nordic regions. Fungal hyphae are a common food source for many terrestrial arthropods and snow fungi could therefore be a potentially important component of an as of yet unexplored winter food web. We compared the abundance of soil arthropods (Acari and Collembola) from paired patches with and without dense infections of snow fungi in the forest understory of a northern Swedish boreal forest after snow melt. Although we did not find increased abundance of these animals when snow fungi were present, Collembola and Acari were sustained on a diet of snow fungi for six months. The isotope signature of the snow fungi clearly differed from humus and other fungal types from literature values obtained from similar boreal forests, suggesting that these fungi may occupy a novel N niche during winter in northern boreal forests. Our study shows for the first time that snow fungi are a potential food source for micro-arthropods during winter and spring. Potentially, snow fungi may represent the basis of an unexplored sub-nivean winter food web but further work is required to assess their importance for community development and winter litter decomposition. (C) 2013 Elsevier Masson SAS. All rights reserved.
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| 3. |
- De Smedt, Pallieter, et al.
(författare)
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Desiccation resistance determines distribution of woodlice along forest edge-to-interior gradients
- 2018
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Ingår i: European journal of soil biology. - : Elsevier BV. - 1164-5563 .- 1778-3615. ; 85, s. 1-3
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Tidskriftsartikel (refereegranskat)abstract
- Forest edges show strong abiotic and biotic gradients potentially altering community composition and ecosystem processes such as nutrient cycling. While abiotic gradients are well studied, short-scale biotic gradients, like detritivore species composition and their associated trait distribution remains a poorly explored research-field. We sampled woodlice in 160 forest patches across Europe at varying distances from the forest edge and discovered that species desiccation resistance determines distribution along forest edge-to-interior gradients. Forest edges are warmer and dryer compared to interiors and favour drought-tolerant species, while abundance and activity of drought-sensitive species is reduced at the edge. Key ecological factors for litter-dwelling detritivores (i.e. humidity) act as environmental filter, because of species-specific differences in desiccation resistance. Future research should focus on quantifying the consequences of a changing detritivore community and their associated functional traits for nutrient cycling.
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| 4. |
- Dimitrova Mårtensson, Linda-Maria
(författare)
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Earthworm populations and diversity under annual and perennial wheat in a North to South gradient in Western Europe
- 2023
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Ingår i: European Journal of Soil Biology. - 1164-5563 .- 1778-3615. ; 119
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Tidskriftsartikel (refereegranskat)abstract
- The challenge to sustain food security while halting the loss of biodiversity and soil quality might be achieved by a transformation in agriculture from high-input management of annual crops to a more nature-based solution introducing perennial cropping systems. This study analysed earthworm communities (numbers, biomass, ecological categories) and diversity over two years, from annual wheat and perennial intermediate wheatgrass (IWG, Thinopyrum intermedium, Kernza (R)) within the EU-Biodiversa project NAPERDIV from Southern to Northern Europe. Study sites in France, Belgium and Sweden represented diverse soil, climatic and plant growth conditions. In total, 16 species were identified with IWG in France having the highest (13) and annual wheat in Belgium and Sweden the lowest (7) species numbers. Improved biodiversity under perennial wheat was indicated by alpha-diversity indices (Simpson index, Shannon-Weaver index, Evenness). Earthworm abundance and biomass were generally significantly higher in IWG across the three sites (GLMM model). The overall mean earthworm number under IWG was 424.7 No. m(-2) compared to 164.7 No. m(-2) for annual wheat. Mean earthworm biomass under IWG was 83.7 g m(-2) relative to 45.9 g m(-2) under annual wheat, respectively. Remarkably, mean number of juvenile earthworms was several times higher on IWG sites relative to the annual comparatives. Moreover, endogeic and epigeic earthworms were supported on the IWG plots. Beta diversity (Sorensen coefficient) emphasised highest similarity between Belgium and Sweden and lowest between France and Sweden, indicating a possible South to North distribution within Western Europe. The Canonical Correspondence Analysis showed discrete clusters for study sites and species distribution (including the subtypes of Allolobophora chlorotica) in relation to soil parameters (pH, soil texture, TOC, TN, WHC, C-N ratio). The CCA additionally discriminated between annual and perennial plots in France. In summary, earthworm communities were more diverse under IWG and seemed to follow a South to North gradient.
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| 5. |
- Juhanson, Jaanis, et al.
(författare)
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Stable nitrogen-cycling capacity in relation to fertilization and intercropping in a sub-boreal grassland
- 2022
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Ingår i: European Journal of Soil Biology. - : Elsevier BV. - 1164-5563 .- 1778-3615. ; 113
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Tidskriftsartikel (refereegranskat)abstract
- Grasslands are important in sub-boreal climate agricultural systems and are managed with various combinations of N fertilization and plant species. Ammonia-oxidizing and denitrifying microorganisms are key players in determining the fate of nitrogen (N) and thereby also the yield in grassland systems and their impact on gaseous N losses and leaching. We established a three-year field study in southern Finland with fertilizer treatment as a main-plot factor, including organic and synthetic fertilizers and plant species and mixtures thereof as the sub-plot factor. We quantified six genes encoding key N-cycling enzymes by quantitative PCR to determine the abundance of the communities involved in N-transformation processes and also included previously published data on crop yield, soil properties and the overall bacterial community composition. With the exception of ammonia oxidizing bacteria (AOB), which were primarily affected by fertilization, the abundances of all other N-cycling communities changed over time with either an increase or decrease from summer to autumn. Differences in gene abundances between plant species treatments and in fertilizer by plant species interactions were detected mainly in the beginning of the cropping season during the first year. The nirS-type denitrifiers and nosZII nitrous oxide reducers responded more to changes in soil properties than their functional counterpart nirK and nosZI communities. Using structural equation modeling, we show that the overall microbial community composition and diversity played an important role in mediating the management effects on crop yield, genetic potential for N retention and N2O sink capacity. However, a trade-off between the genetic potential for N retention and N2O sink capacity was detected, indicating the challenges in managing grasslands in a sustainable way.
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| 6. |
- Lagerlöf, Jan
(författare)
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Trophic interactions among soil arthropods in contrasting land-use systems in Kenya, studied with stable isotopes
- 2017
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Ingår i: European Journal of Soil Biology. - : Elsevier BV. - 1164-5563 .- 1778-3615. ; 79, s. 31-39
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Tidskriftsartikel (refereegranskat)abstract
- Understanding how land use intensification changes organism communities and trophic interactions in soil is important for development of sustainable agriculture and forestry.We analysed the food web of soil arthropods with help of natural C-13/C-12 and N-15/N-14 ratios (delta C-13 and delta N-15) in two habitats in the Kenyan Highland - a natural forest and an agricultural site on former forest land. Aims of the study: (1) to describe the structure and feeding relationships in the two systems for major soil arthropod groups, (2) to find differences in feeding strategies within major arthropod groups, (3) to determine if soil arthropod groups have the same trophic positions in forest and agricultural soil, (4) to evaluate if delta C-13 and delta N-15 can be explained by additional reasons, e.g. the physiology and C:N ratios of organisms.This is one of few studies of the trophic structure of soil arthropod communities in tropical ecosystems. It confirms that the structure is similar to comparable systems in the temperate zones. There was a large variation in delta N-15 among families of Oribatida, Mesostigmata and Collembola (the most common groups) indicating great variety in feeding ecology. Collembola and Diplopoda had comparatively high delta N-15, indicating a contribution of animals to the diet. Although lower abundance and diversity of arthropods in the agricultural soil, the trophic positions of particular taxa, indicated as delta N-15 level, were similar to the forest. The delta C-13 values were negatively correlated to the C:N ratio, therefore increasing values of delta C-13 with trophic level could not be demonstrated. (C) 2017 Elsevier Masson SAS. All rights reserved.
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| 7. |
- Larsbo, Mats, et al.
(författare)
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Quantifying earthworm soil ingestion from changes in vertical bulk density profiles
- 2024
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Ingår i: European journal of soil biology. - : Elsevier. - 1164-5563 .- 1778-3615. ; 120
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Tidskriftsartikel (refereegranskat)abstract
- Soil mixing by earthworms can have a large impact on the fate of nutrients and pollutants and on the soil's ability to sequester carbon. Nevertheless, methods to quantify earthworm ingestion and egestion under field conditions are largely lacking. Soils of the Fennoscandian tundra offer a special possibility for such quantifications, as these soils commonly lack burrowing macrofauna and exhibit a well-defined O horizon with low bulk density on top of a mineral soil with higher density. Since ingestion-egestion mixes the two soil layers, the temporal changes in the bulk density profile of such soils may be useful for estimating field ingestion rates. In this study, we applied a model for earthworm burrowing through soil ingestion to observed changes in soil densities occurring in a mesocosm experiment carried out in the arctic during four summers with intact soil. The earthworms present in the mesocosms were Aporrectodea trapezoides, Aporrectodea tuberculata, Aporrectodea rosea, Lumbricus rubellus and Lumbricus Terrestris (fourth season only). We show that changes in soil density profiles can indeed be used to infer earthworm ingestion rates that are realistic in comparison to literature values. Although uncertainties in parameter values were sometimes large, the results from this study suggest that soil turnover rates and endogeic earthworm soil ingestion rates in tundra heath and meadow soils may be as high as those reported for temperate conditions. Such large ingestion rates can explain observed large morphological changes in arctic soils where dispersing earthworms have resulted in complete inmixing of the organic layer into the mineral soil. Our approach is applicable to soil profiles with marked vertical differences in bulk density such as the soils of the Fennoscandian tundra where earthworms are currently dispersing into new areas and to layered repacked soil samples that are incubated in the field.
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| 8. |
- Liu, Yuhuai, et al.
(författare)
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Effects of root exudate stoichiometry on CO2 emission from paddy soil
- 2020
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Ingår i: European Journal of Soil Biology. - : Elsevier BV. - 1164-5563 .- 1778-3615. ; 101
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Tidskriftsartikel (refereegranskat)abstract
- Root exudates are a labile source of carbon (C) for microorganisms that can lead to increased CO2 emission. Root exudates can vary in C:N stoichiometric ratio and their impact on microbially driven soil organic matter (SOM) turnover in paddy soils still remains unclear. The objective was to explore the underlying mechanisms involved in SOM decomposition due to root exudate (artificial) addition with three different C:N ratios (10, 20, and 40) during 45 days incubation. Different root exudates C:N ratios were obtained by adding mineral N and exudate components (glucose, oxalic acid, and glutamate) to paddy soil. N-only addition decreased dissolved organic C to limit CO2 emissions, which is an indicative of C sequestration. Conversely, simulated C:N stoichiometric ratios of root exudates significantly increased both microbial activity and metabolism without altering the microbial biomass C:N ratio. However, soil available dissolved organic C to NH4+ ratio decreased by exudates addition. The stoichiometric ratio of key C and N compound degrading enzymes activities increased only with C:N = 10 and remained unchanged with exudates C:N = 20 and 40. The qCO2 values increased with decreasing N-containing compounds in root exudates (i.e. highest CO2 emission was observed under C:N = 40 exudates addition). The results suggest that increasing exudates C:N ratio intensify CO2 emission due to high microbial N demand. Overall result show that root exudates C:N ratio and soil available N co-regulate on CO2 emission, which was controlled by microbial and potential extracellular enzyme activities.
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| 9. |
- Nikolausz, Marcell, et al.
(författare)
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Diurnal redox fluctuation and microbial activity in the rhizosphere of wetland plants
- 2008
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Ingår i: European journal of soil biology. - : Elsevier BV. - 1164-5563 .- 1778-3615. ; 44:3, s. 324-333
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Tidskriftsartikel (refereegranskat)abstract
- Wetland plants release oxygen through the aerenchyma system to the roots, providing oxic habitats in the rhizosphere. The consumption of the oxygen during the night establishes a diurnal fluctuation of the redox conditions (-320 mV to +300 mV) that explains the coexistence of aerobic and anaerobic microorganisms in the rhizosphere. The redox fluctuation and its effect on the activity of rhizosphere microorganisms were investigated by RNA-based fingerprinting techniques in a laboratory scale reactor planted with Juncus effusus. The denaturing gradient gel electrophoresis (DGGE) patterns of 16S rRNA obtained with "universal" primers were very similar regardless of the time of sampling, indicating that the overall ribosome level of the predominantly active members did not change significantly. The amoA transcript DGGE patterns showed moderate diurnal dynamics with specific bands observed either in day or night samples. However, the majority of amoA genes were continuously expressed, indicating that the activity of functional genes may only partly be a measure sensitive enough for tracing the physiological activity on a short time scale. The results indicate that loose regulation of functional genes can be the main strategy for accommodation to fluctuating environmental conditions. The spatial separation of microbial activities as a result of diurnal fluctuating oxygen availability probably contributes to niche differentiation in the rhizosphere but this is difficult to track it at transcriptome level. © 2008 Elsevier Masson SAS. All rights reserved.
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| 10. |
- Oksinska, Malgorzata P., et al.
(författare)
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Colonization of wheat seedlings (Triticum aestivum L.) by strains of Pseudomonas spp. with respect to their nutrient utilization profiles
- 2011
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Ingår i: European journal of soil biology. - : Elsevier BV. - 1164-5563 .- 1778-3615. ; 47:6, s. 364-373
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Tidskriftsartikel (refereegranskat)abstract
- Nutrients that leach out from roots constitute a major source of food for root-colonizing bacteria. The role of specific nutrients in this interaction is unclear. The aim of the present study was to examine whether colonization ability could be attributed to specific nutrient utilization profiles. Twenty fluorescent pseudomonads were tested for colonization ability of 48-h-old wheat seedlings. Analyses of RFLPs of amplified 165 rRNA gene and of BIOLOG GN2 data demonstrated that colonization ability did not associate with any particular RFLP or metabolic group. The best colonizers PPS96, PSR2, PSR21, good colonizer PSR6 and four of ineffective colonizers were identified through 16S sequence analysis as Pseudomonas reactans. The best and good colonizers distinguished themselves from the less efficient colonizers by specifically utilizing: p-hydroxyphenylacetic acid, bromosuccinic acid, benzoic acid, methyl pyruvate. N-acetyl-D-glucosamine, D-trehalose and adonitol. However, there was no specific sole nutrient utilization profile that predicted excellent root colonization ability of wheat, since the best colonizers did not have identical profiles. This work indicates that strains of P. reactans are present in the rhizosphere of oil seed rape and wheat and that some of them are effective colonizers of wheat roots.
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