| 1. |
- Almeida, Juan Pablo, et al.
(författare)
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Phosphorus regulates ectomycorrhizal fungi biomass production in a Norway spruce forest
- 2023
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Ingår i: Biogeosciences. - : Copernicus Publications. - 1726-4170 .- 1726-4189. ; 20:7, s. 1443-1458
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Tidskriftsartikel (refereegranskat)abstract
- Ectomycorrhizal fungi (EMF) are important components of soil microbial communities, and EMF biomass can potentially increase carbon (C) stocks by accumulating in the soils as necromass and producing recalcitrant structures. EMF growth depends on the C allocated belowground by the host trees, and the nutrient limitation on tree growth is expected to influence this allocation. Therefore, studying EMF production and understanding the factors that regulates it in natural soils are important to understand C cycling in forests.Fungal mycelium collected from ingrowth mesh bags is commonly used to estimate EMF biomass, but these measurements might not reflect the total EMF production since turnover rates of the hyphae are not considered. Here we estimated EMF production and turnover in response to P fertilization (applied as superphosphate) in a Norway spruce forest where nitrogen (N) deposition has resulted in phosphorus (P) limitation of plant production by using a combination of mesh bags with different incubation periods and with Bayesian inferences. To test how localized patches of N and P influence EMF production and turnover we amended some bags with a nitrogen source (methylene urea) or P source (apatite). Additionally, the Bayesian model tested the effect of seasonality (time of mesh-bag harvesting) on EMF production and turnover.We found that turnover of EMF was not affected by P fertilization or mesh-bag amendment. P fertilization had a negative effect on EMF production in all the mesh-bag amendments, suggesting a reduced belowground C allocation to the EMF when P limitation is alleviated. Apatite amendment significantly increased EMF biomass production in comparison with the pure quartz bags in the control plots but not in the P-fertilized plots. This indicates that P-rich patches enhance EMF production in P-limited forests, but not when P is not limiting. Urea amendment had a generally positive effect on EMF production, but this was significantly reduced by P fertilization, suggesting that a decrease in EMF production due to the alleviated P limitation will affect N foraging. Seasonality had a significant effect on EMF production, and the differences registered between the treatments were higher during the warmer months and disappeared at the end of the growing season.Many studies highlight the importance of N for regulating belowground C allocation to EMF in northern coniferous forests, but here we show that the P status of the forest can be equally important for belowground carbon allocation to EMF production in areas with high N deposition.
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| 2. |
- Baskaran, Preetisri, et al.
(författare)
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Nitrogen dynamics of decomposing Scots pine needle litter depends on colonizing fungal species
- 2019
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Ingår i: FEMS Microbiology Ecology. - : Oxford University Press. - 0168-6496 .- 1574-6941. ; 95:6
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Tidskriftsartikel (refereegranskat)abstract
- In boreal ecosystems plant production is often limited by low availability of nitrogen. Nitrogen retention in below-ground organic pools plays an important role in restricting recirculation to plants and thereby hampers forest production. Saprotrophic fungi are commonly assigned to different decomposer strategies, but how these relate to nitrogen cycling remains to be understood. Decomposition of Scots pine needle litter was studied in axenic microcosms with the ligninolytic litter decomposing basidiomycete Gymnopus androsaceus or the stress tolerant ascomycete Chalara longipes. Changes in chemical composition were followed by 13C CP/MAS NMR spectroscopy and nitrogen dynamics was assessed by the addition of a 15N tracer. Decomposition by C. longipes resulted in nitrogen retention in non-hydrolysable organic matter, enriched in aromatic and alkylic compounds, whereas the ligninolytic G. androsaceus was able to access this pool, counteracting nitrogen retention. Our observations suggest that differences in decomposing strategies between fungal species play an important role in regulating nitrogen retention and release during litter decomposition, implying that fungal community composition may impact nitrogen cycling at the ecosystem level.
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| 3. |
- Boberg, Johanna, et al.
(författare)
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Nitrogen and Carbon Reallocation in Fungal Mycelia during Decomposition of Boreal Forest Litter
- 2014
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Ingår i: PLOS ONE. - : Public Library of Science. - 1932-6203. ; 9:3, s. e92897-
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Tidskriftsartikel (refereegranskat)abstract
- Boreal forests are characterized by spatially heterogeneous soils with low N availability. The decomposition of coniferous litter in these systems is primarily performed by basidiomycete fungi, which often form large mycelia with a well-developed capacity to reallocate resources spatially-an advantageous trait in heterogeneous environments. In axenic microcosm systems we tested whether fungi increase their biomass production by reallocating N between Pinus sylvestris (Scots pine) needles at different stages of decomposition. We estimated fungal biomass production by analysing the accumulation of the fungal cell wall compound chitin. Monospecific systems were compared with systems with interspecific interactions. We found that the fungi reallocated assimilated N and mycelial growth away from well-degraded litter towards fresh litter components. This redistribution was accompanied by reduced decomposition of older litter. Interconnection of substrates increased over-all fungal C use efficiency (i.e. the allocation of assimilated C to biomass rather than respiration), presumably by enabling fungal translocation of growth-limiting N to litter with higher C quality. Fungal connection between different substrates also restricted N-mineralization and production of dissolved organic N, suggesting that litter saprotrophs in boreal forest ecosystems primarily act to redistribute rather than release N. This spatial integration of different resource qualities was hindered by interspecific interactions, in which litters of contrasting quality were colonised by two different basidiomycete species. The experiments provide a detailed picture of how resource reallocation in two decomposer fungi leads to a more efficient utilisation of spatially separated resources under N-limitation. From an ecosystem point of view, such economic fungal behaviour could potentially contribute to organic matter accumulation in the litter layers of boreal forests.
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| 4. |
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| 5. |
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| 6. |
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| 7. |
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| 8. |
- Deckmyn, G., et al.
(författare)
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Simulating ectomycorrhizal fungi and their role in carbon and nitrogen cycling in forest ecosystems
- 2014
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Ingår i: Canadian Journal of Forest Research. - : Canadian Science Publishing. - 0045-5067 .- 1208-6037. ; 44:6, s. 535-553
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Forskningsöversikt (refereegranskat)abstract
- Although ectomycorrhizal fungi play an important role in forest ecosystem functioning, they are usually not included in forest growth or ecosystem models. Simulation is hampered by two main issues: a lack of understanding of the ecological functioning of the ectomycorrhizal fungi and a lack of adequate basic data for parameterization and validation. Concerning these issues, much progress has been made during the past few years, but this information has not found its way into the forest and soil models. In this paper, state-of-the-art insight into ectomycorrhizal functioning and basic values are described in a manner transparent to nonspecialists and modelers, together with the existing models and model strategies. As such, this paper can be the starting point and the motivator to include ectomycorrhizal fungi into existing soil and forest ecosystem models.
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| 9. |
- Ekblad, Alf, 1957-, et al.
(författare)
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Analysis of delta C-13 of CO2 distinguishes between microbial respiration of added C-4-sucrose and other soil respiration in a C-3-ecosystem
- 2000
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Ingår i: Plant and Soil. - 0032-079X .- 1573-5036. ; 219:1-2, s. 197-209
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Tidskriftsartikel (refereegranskat)abstract
- The main aim of this study was to test various hypotheses regarding the changes in δ13C of emitted CO2 that follow the addition of C4-sucrose to the soil of a C3-ecosystem. It forms part of an experimental series designed to assess whether or not the contributions from C3-respiration (root and microbial) and C4-respiration (microbial) to total soil respiration can be calculated from such changes. A series of five experiments, three on sieved (root-free) mor-layer material, and two in the field with intact mor-layer (and consequently with active roots), were performed. Both in the experiments on sieved mor-layer and the field experiments, we found a C4-sucrose-induced increase in C3-respiration that accounted for between 30% and 40% of the respiration increase 1 h after sucrose addition. When the course of C3-, C4- and total respiration was followed in sieved material over four days following addition of C4-sucrose, the initially increased respiration of C3-C was transient, passing within less than 24 h. In a separate pot experiment, neither ectomycorrhizal Pinus sylvestrisL. roots nor non-mycorrhizal roots of this species showed respiratory changes in response to exogenous sucrose. No shift in the δ13C of the evolved CO2 after adding C3-sucrose to sieved mor-layer material was found, confirming that the sucrose-induced increase in respiration of endogenous C was not an artefact of discrimination against 13C during respiration. Furthermore, we conclude that the C4-sucrose induced transient increase in C3-respiration is most likely the result of accelerated turnover of C in the microbial biomass. Thus, neither respiration of mycorrhizal roots, nor processes discriminating against δ13C were likely sources of error in the field. The estimated δ13C of evolved soil CO2 in three field experiments lay between −25.2‰ and −23.6‰. The study shows that we can distinguish between CO2 evolved from microbial mineralisation of added C4-sucrose, and CO2 evolved from endogenous carbon sources (roots and microbial respiration).
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| 10. |
- Ekblad, Alf, 1957-, et al.
(författare)
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C-13-discrimination during microbial respiration of added C-3-, C-4- and C-13-labelled sugars to a C-3-forest soil
- 2002
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Ingår i: Oecologia. - : Springer Science and Business Media LLC. - 0029-8549 .- 1432-1939. ; 131:2, s. 245-249
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Tidskriftsartikel (refereegranskat)abstract
- We tested whether 13C-discrimination during microbial respiration, or during CO2 sampling in the field, can explain changes observed in the δ13C of emitted CO2 that follow the addition of C4-sucrose, as a microbial substrate, to the soil of a C3-ecosystem. We approached this problem by adding C3-glucose (δ13C=–23.4‰), C4-sucrose (–10.8‰) or 13C-labelled glucose (103.7‰) to the intact mor layer, the upper organic soil (–26.5‰, bulk soil organic matter), of a boreal Pinus sylvestris L. forest. If 13C-discrimination is significant, it should generate illusory differences in the calculated contributions from the added C and endogenous C3-C to total soil respiration, when C4-sucrose or 13C-labelled glucose is added. Further, if discrimination occurs, we should also be able to detect a shift in the δ13C of respired CO2 after the addition of C3-glucose. The addition of the three sugar solutions gave similar increases in soil respiration (up to a doubling 1 h after the additions), while the addition of water gave no increase in respiration. There was no change in δ13C of the emitted CO2 after additions of H2O or C3-glucose. In contrast, the addition of C4-sucrose and 13C-labelled glucose gave δ13C values of evolved CO2 that were 4.5‰ and 30.3‰ higher than the pre-sugar values, respectively. The calculated respiration rates of the added carbon sources, C4-C or 13C-labelled C, were very similar. Also, we found very similar sugar-induced increases in respiration of endogenous C3-C in the plots supplied with C4-sucrose and 13C-labelled glucose, accounting for about 50% of the total increase in respiration 1 h after addition. Our results confirm that any microbial 13C-discrimination during respiration is minor.
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| 11. |
- Ekblad, Alf, 1957-, et al.
(författare)
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Day-to-day variation in nitrogenase activity of alnus-incana explained by weather variables : a multivariate time-series analysis
- 1994
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Ingår i: Plant, Cell and Environment. - : Wiley. - 0140-7791 .- 1365-3040. ; 17:3, s. 319-325
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Tidskriftsartikel (refereegranskat)abstract
- A modelling system is described that indicates the extent to which day-to-day variations in nitrogenase activity in young Alnus incana (L.) Moench, grown in defined conditions in the field, may be affected by weather conditions both during and prior to the day of measurement. Nitrogenase activity (acetylene reduction activity, ARA) was measured weekly on intact field-grown grey alder (A. incana) plants, 0.15–0.42 m tall at planting, nodulated with Frankia. The measurements were done at noon on two groups of plants in 1987 and on two other groups in 1988. Each group was made up of five or six plants. Seven weather variables: daily sunshine hours, daily mean, maximum and minimum air temperature, daily mean and 1300 h relative humidity, and daily rainfall were used. The relation between log(ARA/leaf area) and the weather variables were analysed using a PLS model (partial least squares projection to latent structures). The advantage of PLS is that it can handle x-variables that are correlated. Data from 1987 were chosen as a training set. Multivariate PLS time series analysis was made by adding, in a stepwise manner, the weather data up to 5 d before the day of measurement. This procedure gave six models with n * 7 x-variables (n= 1–6). With the models from the time series analysis of 1987 data, true predictions of ARA per leaf area were made from weather data 1988 (test set 1) and from ‘early-season’ weather data from 1987 and 1988 (test set 2). The variation in ARA/leaf area could be predicted from the weather conditions. The predictions of the two test sets improved when the weather conditions one and two days before the day of measurements were added to the model. The further addition of weather data from 3 to 5 d before the day of measurement did not improve the model. The good predictions of ARA/leaf area show that the alders responded to the variable weather conditions in the same way in 1988 as in 1987, despite the ten-fold difference in size (leaf area) at the end of the growing season. Among the weather variables, air temperature and the daily sunshine hours were positively correlated to ARA, while relative air humidity and rainfall were negatively correlated to ARA. The daily minimum temperature and rainfall appeared to have least impact on ARA. By use of PLS, we could extract information out of a data set containing highly correlated x-variables, information that is non-accessible with conventional statistical tools such as multiple regression. When making measurements of nitrogenase activities under field conditions, we propose that attention should be paid to the weather conditions on the days preceding the day of measurement. The day-to-day variation in nitrogenase activity is discussed with reference to known effects of stress factors under controlled conditions.
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| 12. |
- Ekblad, Alf, 1957-, et al.
(författare)
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Deforestation releases old carbon
- 2019
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Ingår i: Nature Geoscience. - : Nature Publishing Group. - 1752-0894 .- 1752-0908. ; 12:7, s. 499-500
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Tidskriftsartikel (refereegranskat)abstract
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| 13. |
- Ekblad, Alf, 1957-, et al.
(författare)
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Determination of chitin in fungi and mycorrhizal roots by an improved HPLC analysis of glucosamine
- 1996
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Ingår i: Plant and Soil. - 0032-079X .- 1573-5036. ; 178:1, s. 29-35
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Tidskriftsartikel (refereegranskat)abstract
- A method to measure chitin content in fungi and ectomycorrhizal roots with high-performance liquid chromatography (HPLC) was developed. Measurements of fluorescence of 9-fluorenylmethylchloroformate (FMOC-CI) derivatives of glucosamine were made on acid hydrolysates of pure chitin, chitin-root mixtures and fungal-root mixtures. The method was applied on 5 isolates of ectomycorrhizal fungi, and ectomycorrhizal and non-mycorrhizal Pinus sylvestris roots. Interference from amino acids was removed by pre-treatment of samples with 0.2 N NaOH. This pre-treatment did not reduce the recovery of chitin, nor did plant material affect the recovery of chitin. The HPLC method was compared with a colorimetric chitin-method by measurements on root-fungal mixtures, with known fungal content. The HPLC method gave estimates of fungal biomass which were equal to the expected while the colorimetric method showed values significantly (p<0.001) lower than the expected. The present chitin method offers a sensitive and specific tool for the quantification of chitin in fungi and in ectomycorrhizal roots.
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| 14. |
- Ekblad, Alf, 1957-, et al.
(författare)
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Fungal biomass in roots and extramatrical mycelium in relation to macronutrients and plant biomass of ectomycorrhizal Pinus sylvestris and Alnus incana
- 1995
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Ingår i: New Phytologist. - : Wiley. - 0028-646X .- 1469-8137. ; 131:4, s. 443-451
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Tidskriftsartikel (refereegranskat)abstract
- SummaryWe studied the effects of macronutrients on the production and distribution of fungal biomass and plant biomass in ectomycorrhizal (Paxillus involutus (Fr.) Fr.) or non-mycorrhiza] Pinus sylvestris L, and Alnus incana (L.) Moench. Fungal biomass was measured as ergosterol content in roots and extramatrical mycelium, Alnus infants was nodulated with Frankia. All six macronutrients were varied according to a two-level fractional factorial design, The plants were grown in pots during two growing periods in a growth chamber. Levels of N, P and sometimes K and interactions between them, had highly significant effects, whereas Ca. Mg and S had no significant effects. The production of extramatrical mycelial biomass peaked when P was low and other nutrients were high. This investment in extramatrical mycelium resulted in a 660%, higher biomass in mycorrhizal compared with non-mycorrhizal P. sylvestris at this nutrient regime. The proportion of fungal biomass in roots was stable in P. sylvestris hut more variable in A. incana. Alnus incana grew less when mycorrhizal then when non-mycorrhizal. The growth responses to mycorrhiza and to the different nutrient treatments were evident at the end of the first growing period. Non-mycorrhizal P. sylvestris did not respond to P limitation by a production of proportionally more roots. This might be a reflection of an obligate dependency on mycorrhiza for effective P uptake. By contrast, the root/shoot ratio in both mycorrhizal and non-mycorrhiza] P. sylvestris decreased strongly in response to increased N. The opposite root/shoot response was found in Alnus incana, and the ratio decreased strongly in response to increased P and increased in response to increased N.
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| 15. |
- Ekblad, Alf, 1957-, et al.
(författare)
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Is growth of soil microorganisms in boreal forests limited by carbon or nitrogen availability?
- 2002
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Ingår i: Plant and Soil. - 0032-079X .- 1573-5036. ; 242:1, s. 115-122
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Tidskriftsartikel (refereegranskat)abstract
- To study whether the biomass of soil microorganisms in a boreal Pinus sylvestris-Vaccinium vitis-idaea forest was limited by the availability of carbon or nitrogen, we applied sucrose from sugar cane, a C4 plant, to the organic mor-layer of the C3–C dominated soil. We can distinguish between microbial mineralization of the added sucrose and respiration of endogenous carbon (root and microbial) by using the C4-sucrose as a tracer, exploiting the difference in natural abundance of 13C between the added C4-sucrose (δ13C −10.8‰) and the endogenous C3–carbon (δ13C −26.6 ‰). In addition to sucrose, NH4Cl (340 kg N ha−1) was added factorially to the mor-layer. We followed the microbial activity for nine days after the treatments, by in situ sampling of CO2 evolved from the soil and mass spectrometric analyses of δ13C in the CO2. We found that microbial biomass was limited by the availability of carbon, rather than nitrogen availability, since there was a 50% increase in soil respiration in situ between 1 h and 5 days after adding the sucrose. However, no further increase was observed unless nitrogen was also added. Analyses of the δ13C ratios of the evolved CO2 showed that increases in respiration observed between 1 h and 9 days after the additions could be accounted for by an increase in mineralization of the added C4–C.
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| 16. |
- Ekblad, Alf, 1957-, et al.
(författare)
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Natural abundance of C-13 in CO2 respired from forest soils reveals speed of link between tree photosynthesis and root respiration
- 2001
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Ingår i: Oecologia. - : Springer Science and Business Media LLC. - 0029-8549 .- 1432-1939. ; 127:3, s. 305-308
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Tidskriftsartikel (refereegranskat)abstract
- Soil respiration from a boreal mixed coniferous forest showed large seasonal variation in natural abundance of 13C, ranging from –21.6‰ to –26.5‰. We tested if weather conditions could explain this variation in δ13C of respired CO2, and found that the air relative humidity 1–4 days before the days of CO2 sampling best explained the variation. This suggested that high δ13C values were caused by effects of air humidity on isotope fractionation during photosynthesis and that it took 1–4 days for the C from canopy photosynthesis of 20–25 m trees to become available for root/rhizosphere respiration. We calculated that these new photoassimilates could account for at least 65% of total soil respiration.
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| 17. |
- Ekblad, Alf, 1957-, et al.
(författare)
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Nitrogen fixation by Alnus incana and nitrogen transfer from A-incana to Pinus sylvestris influenced by macronutrients and ectomycorrhiza
- 1995
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Ingår i: New Phytologist. - : Wiley. - 0028-646X .- 1469-8137. ; 131:4, s. 453-459
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Tidskriftsartikel (refereegranskat)abstract
- The aims of this study were to evaluate the effect of macronutrients on nitrogen fixation in mycorrhizal and non-mycorrhizal grey alder (Alnus incana (L.) Moench), and to evaluate the effect of ectomycorrhizal mycelium on the transfer of symbolically fixed nitrogen from grey alder to Scots pine (Pinus sylvestris L). One alder and one pine were grown together in pots with root systems separated by a 20μm mesh nylon filter which allowed hyphae but not roots to penetrate. Half the plants of both species were inoculated with Paxillus involutus (Ft.) Ft. and all alders were inoculated with Frankia. Nutrient solutions were added with macronutrient (N, K, P, Ca, Mg and S) concentrations varied according to a two-level fractional factorial design. The plants were harvested after two growing periods in a growth chamber. Nitrogen fixation by alder and transfer of symbiotically fixed N from alder to pine was measured by 15N-dilution. Fixed N (mg) correlated with nodule biomass in both mycorrhizal and non-mycorrhizal alders. On average, specific nodule activity over the two periods was 510 mg N fixed R' nodule d. wt. This was not affected by mycorrhizal infection or by the different nutrient treatments. By contrast there was a strong nutrient effect on the proportion of N derived from fixation. These results indicate that the regulation of nitrogen fixation was via nodule growth rather than via nodule specific activity. Nitrogen had a strong negative effect and P a positive effect on the percentage of N derived from fixation (%Ndfa). However, the effect of N depended on the level of P. This N × P interaction resulted in a %Ndfa when N was high, of 5-10%, at low P and 45–48%, at high P. The highest value of 90% Ndfa was found at the combination of low N and high P. Potassium had a small but statistically significant effect on the %Ndfa but Ca, Mg and S had no significant effects. No mycorrhizal effect was found on the %Ndfa in alder. By contrast, the %Ndfa and biomass were lower in mycorrhizal than in non-mycorrhizal alders. The proportion of fixed N in pine, transferred from alder, was greatest (9%) when the pine was nitrogen starved and mycorrhizal and the alder was fixing maximally (low N and high P). However, the amount of fixed N transferred to pine was not statistically different from zero.
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| 18. |
- Ekblad, Alf, 1957-, et al.
(författare)
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The production and turnover of extramatrical mycelium of ectomycorrhizal fungi in forest soils : role in carbon cycling
- 2013
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Ingår i: Plant and Soil. - : Springer Science and Business Media LLC. - 0032-079X .- 1573-5036. ; 366:1-2, s. 1-27
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Forskningsöversikt (refereegranskat)abstract
- There is growing evidence of the importance of extramatrical mycelium (EMM) of mycorrhizal fungi in carbon (C) cycling in ecosystems. However, our understanding has until recently been mainly based on laboratory experiments, and knowledge of such basic parameters as variations in mycelial production, standing biomass and turnover as well as the regulatory mechanisms behind such variations in forest soils is limited. Presently, the production of EMM by ectomycorrhizal (EM) fungi has been estimated at similar to 140 different forest sites to be up to several hundreds of kg per ha per year, but the published data are biased towards Picea abies in Scandinavia. Little is known about the standing biomass and turnover of EMM in other systems, and its influence on the C stored or lost from soils. Here, focussing on ectomycorrhizas, we discuss the factors that regulate the production and turnover of EMM and its role in soil C dynamics, identifying important gaps in this knowledge. C availability seems to be the key factor determining EMM production and possibly its standing biomass in forests but direct effects of mineral nutrient availability on the EMM can be important. There is great uncertainty about the rate of turnover of EMM. There is increasing evidence that residues of EM fungi play a major role in the formation of stable N and C in SOM, which highlights the need to include mycorrhizal effects in models of global soil C stores.
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| 19. |
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| 20. |
- Eriksson, Ulrika, 1972-, et al.
(författare)
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Comparison of PFASs contamination in the freshwater and terrestrial environments by analysis of eggs from osprey (Pandion haliaetus), tawny owl (Strix aluco), and common kestrel (Falco tinnunculus)
- 2016
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Ingår i: Environmental Research. - San Diego, USA : Academic Press. - 0013-9351 .- 1096-0953. ; 149, s. 40-47
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Tidskriftsartikel (refereegranskat)abstract
- The level of PFAS (per- and polyfluorinated alkyl substances) contamination in freshwater and terrestrial Swedish environments in 2013/2014 was assessed by analyzing a range of perfluorinated alkyl acids, fluorotelomer acids, sulfonamides, sulfonamidoethanols and polyfluoralkyl phosphate diesters (diPAPs) in predator bird eggs. Stable isotopes ((13)C and (15)N) were analyzed to elucidate the dietary source. The tawny owl (Strix aluco, n=10) and common kestrel (Falco tinnunculus, n=40), two terrestrial species, and the osprey (Pandion haliaetus, n=30), a freshwater specie were included. In addition, a temporal trend (1997-2001, 2008-2009, 2013) in osprey was studied as well. The PFAS profile was dominated by perfluorooctane sulfonic acid (PFOS) in eggs from osprey and tawny owl, while for common kestrel perfluorinated carboxylic acids (∑PFCA) exceeded the level of PFOS. PFOS concentration in osprey eggs remained at the same level between 1997 and 2001 and 2013. For the long-chained PFCAs, there were a significant increase in concentrations in osprey eggs between 1997 and 2001 and 2008-2009. The levels of PFOS and PFCAs were about 10 and five times higher, respectively, in osprey compared to tawny owl and common kestrel. Evidence of direct exposure from PFCA precursor compounds to birds in both freshwater and terrestrial environment was observed. Low levels of diPAPs were detected in a few samples of osprey (<0.02-2.4ng/g) and common kestrel (<0.02-0.16ng/g) eggs, and 6:2 FTSA was detected in a majority of the osprey eggs (<6.3-52ng/g). One saturated telomer acid (7:3 FTCA), which is a transformation marker from precursor exposure, was detected in all species (<0.24-2.7ng/g). The (15)N data showed higher levels in osprey eggs compared to tawny owl and common kestrel, indicating that they feed on a 2-3 times higher trophic level. We conclude that ospreys are continuously exposed to PFAS at levels where adverse toxic effects have been observed in birds.
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| 21. |
- Franklin, Oskar, et al.
(författare)
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Pine forest floor carbon accumulation in response to N and PK additions : Bomb C-14 modelling and respiration studies
- 2003
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Ingår i: Ecosystems (New York. Print). - : Springer Science and Business Media LLC. - 1432-9840 .- 1435-0629. ; 6:7, s. 644-658
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Tidskriftsartikel (refereegranskat)abstract
- The addition of nitrogen via deposition alters the carbon balance of temperate forest ecosystems by affecting both production and decomposition rates. The effects of 20 years of nitrogen (N) and phosphorus and potassium (PK) additions were studied in a 40-year-old pine stand in northern Sweden. Carbon fluxes of the forest floor were reconstructed using a combination of data on soil 14C, tree growth, and litter decomposition. N-only additions caused an increase in needle litterfall, whereas both N and PK additions reduced long-term decomposition rates. Soil respiration measurements showed a 40% reduction in soil respiration for treated compared to control plots. The average age of forest floor carbon was 17 years. Predictions of future soil carbon storage indicate an increase of around 100% in the next 100 years for the N plots and 200% for the NPK plots. As much as 70% of the increase in soil carbon was attributed to the decreased decomposition rate, whereas only 20% was attributable to increased litter production. A reduction in decomposition was observed at a rate of N addition of 30 kg C ha−1 y−1, which is not an uncommon rate of N deposition in central Europe. A model based on the continuous-quality decomposition theory was applied to interpret decomposer and substrate parameters. The most likely explanations for the decreased decomposition rate were a fertilizer-induced increase in decomposer efficiency (production-to-assimilation ratio), a more rapid rate of decrease in litter quality, and a decrease in decomposer basic growth rate.
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| 22. |
- Ganguly, M., et al.
(författare)
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Variation of δ15N in Indian coal, lignite and peat
- 2023
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Ingår i: Chemie der Erde. - : Elsevier. - 0009-2819 .- 1611-5864. ; 83:4
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Tidskriftsartikel (refereegranskat)abstract
- Nitrogen (N) stable isotope ratio (δ15N) in coal organic matter (OM) provides information on the N source and dominant mechanisms affecting isotopic fractionation during coalification. However, published data on δ15N distribution in coal is rare. The present study is one of the first reports on the δ15N composition of peat, lignite, sub-bituminous and anthracite coals in India and one of the first attempts to understand the processes influencing δ15N composition at different stages of coalification from peat to anthracite. Peats were collected from the western coast of North Andaman Islands and Lake Loktak in Manipur. Plant samples were collected from the peat sampling locations. Cenozoic lignites were collected from Panandhro, Matanomadh, Umarsar and Tadkeshwar mines in Gujarat and Neyveli in Tamil Nadu. Cenozoic sub-bituminous and Permian anthracite coals were collected from Assam and Sikkim, respectively. Variation of δ15N in plants is attributed to the differences in rainfall, plant type and N sources. Lower δ15N values in peats (mean 1.19) compared to the plant samples (mean 2.77) indicate a nonlinear response of δ15N to the relative enrichment or loss of N during peat formation in Lake Loktak and decomposition of OM under anaerobic conditions leading to selective preservation of 14N in the Andaman Islands. The δ15N composition of the studied peat (−1.4–1.6), lignite (−1.4–1.8) and coals (−2.8–5.0) retains their OM source signature. Overall higher δ15N values of Cenozoic lignites compared to the Cenozoic sub-bituminous coal reflects regional differences in climate. Higher δ15N (1.3–5.0) values in Gondwana anthracites reflects the tectonic influence of Himalayan orogeny.
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| 23. |
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| 24. |
- Gkarmiri, Konstantia, et al.
(författare)
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Identifying the Active Microbiome Associated with Roots and Rhizosphere Soil of Oilseed Rape
- 2017
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Ingår i: Applied and Environmental Microbiology. - : American Society for Microbiology. - 0099-2240 .- 1098-5336. ; 83:22
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Tidskriftsartikel (refereegranskat)abstract
- RNA stable isotope probing and high-throughput sequencing were used to characterize the active microbiomes of bacteria and fungi colonizing the roots and rhizosphere soil of oilseed rape to identify taxa assimilating plant-derived carbon following (13)CO2 labeling. Root- and rhizosphere soil-associated communities of both bacteria and fungi differed from each other, and there were highly significant differences between their DNA- and RNA-based community profiles. Verrucomicrobia, Proteobacteria, Planctomycetes, Acidobacteria, Gemmatimonadetes, Actinobacteria, and Chloroflexi were the most active bacterial phyla in the rhizosphere soil. Bacteroidetes were more active in roots. The most abundant bacterial genera were well represented in both the (13)C- and (12)C-RNA fractions, while the fungal taxa were more differentiated. Streptomyces, Rhizobium, and Flavobacterium were dominant in roots, whereas Rhodoplanes and Sphingomonas (Kaistobacter) were dominant in rhizosphere soil. "Candidatus Nitrososphaera" was enriched in (13)C in rhizosphere soil. Olpidium and Dendryphion were abundant in the (12)C-RNA fraction of roots; Clonostachys was abundant in both roots and rhizosphere soil and heavily (13)C enriched. Cryptococcus was dominant in rhizosphere soil and less abundant, but was (13)C enriched in roots. The patterns of colonization and C acquisition revealed in this study assist in identifying microbial taxa that may be superior competitors for plant-derived carbon in the rhizosphere of Brassica napusIMPORTANCE This microbiome study characterizes the active bacteria and fungi colonizing the roots and rhizosphere soil of Brassica napus using high-throughput sequencing and RNA-stable isotope probing. It identifies taxa assimilating plant-derived carbon following (13)CO2 labeling and compares these with other less active groups not incorporating a plant assimilate. Brassica napus is an economically and globally important oilseed crop, cultivated for edible oil, biofuel production, and phytoextraction of heavy metals; however, it is susceptible to several diseases. The identification of the fungal and bacterial species successfully competing for plant-derived carbon, enabling them to colonize the roots and rhizosphere soil of this plant, should enable the identification of microorganisms that can be evaluated in more detailed functional studies and ultimately be used to improve plant health and productivity in sustainable agriculture.
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| 25. |
- Goswami, Linee, 1985-, et al.
(författare)
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Vermi-converted Tea Industry Coal Ash efficiently substitutes chemical fertilization for growth and yield of cabbage (Brassica oleracea var. capitata) in an alluvial soil : A field-based study on soil quality, nutrient translocation, and metal-risk remediation
- 2024
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Ingår i: Science of the Total Environment. - : Elsevier. - 0048-9697 .- 1879-1026. ; 907
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Tidskriftsartikel (refereegranskat)abstract
- Although coal ashes (CA) can be converted into an eco-friendly product through vermicomposting, the utility of vermiconverted CA in agriculture still needs to be explored. Therefore, the feasibility of vermicomposted tea industry coal ash (VCA) as an alternative nutrient source for cabbage (Brassica oleracea, var. Capitata) production was evaluated through an on-field experiment in alluvial soil. Two types of vermicomposts were prepared using Eisenia fetida (VCAE) and Lampito mauritii (VCAL) and were applied in different combinations with chemical fertilizers. The results revealed a significant increase in nutrient availability (nitrogen, phosphorus, and potassium) in the soil treated with VCA, alongside a concurrent build-up of soil organic carbon stocks, activation of microbial growth, and enhanced soil enzyme activity. Additionally, VCA application substantially reduced toxic metals in the soil, thereby improving soil health and promoting the uptake of essential nutrients (nitrogen, phosphorus, potassium, iron, manganese, copper, and zinc) in cabbage. Correspondingly, VCA application reduced the bioaccumulation of potentially toxic metals (chromium, lead, and cadmium) from coal ash, ensuring safer food production. Notably, a 25 % substitution of chemical fertilizers with VCA and farmyard manure (FYM) led to a two-fold increase in the growth and productivity of cabbage. The economic assessment also indicated that large-scale and sustainable recycling of toxic tea industry coal ash in agriculture is feasible. Hence, by integrating VCA-based nutrient management into agricultural practices, developing nations can take significant strides toward achieving circular economy objectives while addressing environmental challenges associated with CA disposal.
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