| 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. |
- Arnesson, Matilda, 1988, et al.
(författare)
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Residential vibration exposure from railway traffic in Sweden
- 2016
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Ingår i: Proceedings of the INTER-NOISE 2016 - 45th International Congress and Exposition on Noise Control Engineering: Towards a Quieter Future. ; , s. 2131-2137
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Konferensbidrag (refereegranskat)abstract
- Ground borne vibrations generated by train passages cause annoyance and sleep disturbance when the vibration velocity is too high in dwellings close to railway lines. In order to estimate how many people that are exposed to certain vibration velocities from railway traffic in Sweden, data almost 3 000 measurements of vibration have been used and classified according to geology at the receiving building and at the point on the railway line closest to the receiver. For 7 classes of geology the measurement results at the building foundation was used to estimate a simplified mathematical model, and by using 575 measurements of responses from foundation to indoor vibration velocity the weighted indoor levels could be predicted. Based on geological maps and a database of all properties close to railways the total number of exposed individuals in Sweden could be estimated. The results show that approximately 14 000 people are exposed to an rms-weighted maximum vibration velocity of 1.0 mm/s in their home in Sweden, which is about 65 percent higher than previous estimates.
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| 3. |
- Bahr, Adam, et al.
(författare)
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Growth of ectomycorrhizal fungal mycelium along a Norway spruce forest nitrogen deposition gradient and its effect on nitrogen leakage
- 2013
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Ingår i: Soil Biology and Biochemistry. - : Elsevier BV. - 0038-0717 .- 1879-3428. ; 59, s. 38-48
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Tidskriftsartikel (refereegranskat)abstract
- Almost all boreal and temperate forest tree species live in symbiosis with ectomycorrhizal fungi (EMF); the trees transfer carbon (C) to the fungi in exchange for nutrients and water. Several studies have shown that experimental application of inorganic nitrogen (N) represses production of EMF extramatrical mycelia (EMM), but studies along N deposition gradients are underrepresented. Other environmental variables than N may influence EMM production and in this study we included 29 thoroughly monitored Norway spruce stands from a large geographical region in Sweden in order to evaluate the importance of N deposition on EMM growth and N leaching in a broader context. It was concluded that N deposition was the most important factor controlling EMM production and that the amounts typically deposited in boreal and boreo-nemoral regions can be sufficient to reduce EMM growth. Other factors, such as phosphorus status and pH, were also correlated with EMM production and should be considered when predicting EMM growth and N leaching. We also showed that EMM production substantially contributed to the C sequestration (320 kg ha(-1) yr(-1)), suggesting that it should be included in C cycle modelling. Furthermore, EMF are probably important for the N retention capacity since high N leaching coincided with low EMM growth. However, it was not possible to differentiate between the effects of EMF and the direct effect of N deposition on N leaching in the present study.
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| 4. |
- 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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| 5. |
- Berglund, Linnea, et al.
(författare)
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Carbon and nitrogen transfer in leaf litter mixtures
- 2013
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Ingår i: Soil Biology and Biochemistry. - : Elsevier BV. - 0038-0717 .- 1879-3428. ; 57, s. 341-348
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Tidskriftsartikel (refereegranskat)abstract
- The decomposition rate of litter mixtures can differ from that expected on the basis of the decomposition rate of the individual components. This difference may be linked to nitrogen (N) transfer from high-N to low-N components. Transfer of N is probably also associated with transfer of C, but the extent and direction of this C transfer are unknown. This study examined transfer and loss in laboratory microcosms of C and N from two mixed litter species (Scots pine, Pinus sylvestris L and maize, Zea mays L), which have natural isotopic differences in C-13. Half the material was N-15-labelled and the plants were fertilised or unfertilised. Substantial bidirectional transfer of C and N occurred between the litters, with net transfer of C from pine to maize litter and net transfer of N from high-N to low-N litter. Mixtures of fertilised and unfertilised plant litter showed higher than expected C losses and net transfer of N. Mixtures with litters from the same fertilisation treatment had small or insignificant net transfer of N and their C losses did not differ from values estimated using the decomposition rates of the pure litters.
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| 6. |
- Björk, Robert G., 1974, et al.
(författare)
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Climate-related soil changes in tundra ecosystems at Latnjajaure, northern Sweden – an ITEX-IPY project
- 2010
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Ingår i: International Polar Year Oslo Science Conference.
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Konferensbidrag (refereegranskat)abstract
- During the 90'ies, the International Tundra Experiment (ITEX) was established as a leading project in arctic and alpine ecology, and has become a model for many later network establishments. The present study capitalizes on the early efforts of ITEX and aims at assessing ecosystem changes in the alpine areas of northern Sweden above timberline, i.e. the tundra, in relation to global change. By using the "old" ITEX plots established during the early years of the program we have measured ecosystem respiration (ER), the Normalized Difference Vegetation Index, and nitrogen (N) mineralization over the growing season. In addition, have soil samples been taken to quantify changes in the carbon (C) and N pool, including 13C and 15N. After 12 to 15 years of open top chamber (OTC) treatment no statistical effect was found on the soil temperature (10 cm soil depth), although the was an overall increase in all OTC by +0.2°C. However, the soil moisture decreased significantly by 3-14%, depending on plant community, in the OTCs compared to ambient conditions. Preliminary, there was a 20-37% non-significant higher mean ER in the OTC compared to the ambient plots over the growing season. Furthermore, the OTC treatment did not affect the growing season mineralization of inorganic N, or total C and N content of the soil. The stable isotope data showed both enrichment and depletion as a consequence of the OTC treatment, but no general pattern was discerned. Thus, this non-significant higher ER is most likely of plant origin than soil, as the plant standing biomass has increased in the OTCs. This study does not support the current consensus that tundra soils will alter their C and N dynamics in response to climate change.
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| 7. |
- Björk, Robert G., 1974, et al.
(författare)
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Extramatrical mycelia production and turnover in two drained Norway spruce forests
- 2010
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Ingår i: 1st COST meeting ‘Belowground carbon in Europeanforest’, Birmensdorf, Switzerland, 26–28 January 2010..
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Root systems form important associations with fungi, so called mycorrhiza, which in spruce forests are dominated by ectomycorrhiza. Ectomycorrhizal fungi is functionally important in water and nutrient capture, and therefore probably have major influence on the overall ecosystem functioning. In addition to transferring water and nutrient to its host plant the fungus receive photosynthetic C. The extramatrical mycelium (EMM) is thereby an important sink for carbon in boreal forests, but estimation of the actual EMM production is rare. The objective was to quantify the annual and seasonal production and turnover of EMM in two drained coniferous soils. The study was conducted in two Norway spruce stands at Skogaryd Research Forest, southwest Sweden. One of the sites was a mineral soil (“the mineral site”), with high organic content, and affor-ested in 1962. The other site was a peat soil of minerotrophic origin (“the peat site”), drained in the 1870s and afforested in 1951. In-growth tubes (10-20 cm long) were used to estimate EMM production and turnover through sequential harvesting during 2007-2009. Preliminary results show a higher EMM production at the mineral site than at the peat site. At the peat site the annual EMM production varied largely between years, 0.1-10.1 gdw m-2 (no annual data are currently available for the mineral site). Interestingly, a significant EMM production from December to 15th of June at the mineral site was found, most likely occurring during late May-early June. How-ever, the major EMM production (21-53 mg m-2 d-1) occurred mid-August to mid-September at both sites. It was not possible to calculate an EMM turnover the first two years due to the large spatial vari-ability. Our study suggests that high EMM production coincides with fine root production, and can equal one-fourth of belowground production. However, the large spatial variability in EMM production accentuates the need to increase within sub-site replication.
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| 8. |
- Björk, Robert G., 1974, et al.
(författare)
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Long-term warming effects on carbon and nitrogen dynamics in tundra soils
- 2012
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Ingår i: 20th Anniversary ITEX Workshop, El Paso, USA, 17–21 January 2012.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- During IPY 2008 we used the ITEX experiment in Latnjajaure (northern Sweden), established during the early years of the program, to investigate long-term warming effects on ecosystem respiration (ER), carbon (C) and nitrogen (N) pool (including d13C and d15N), soil organic C (SOC) chemical composition, and N mineralization among plant communities. After 12 to 15 years of open top chamber (OTC) treatment no statistical effect was found on the soil temperature (10 cm soil depth), although the was an overall increase in all OTC by +0.2°C. However, the soil moisture decreased significantly by 3-14%, depending on plant community, in the OTCs compared to ambient conditions. Preliminary, there was a 19-61% non-significant increase in annual growing season ER in the OTC compared to the ambient plots over the growing season. The were distinct differences in the SOM functional composition among plant communities with c 10% more O-alkyls stored in tussock tundra than in dry meadow. The OTCs did not consistently alter the SOM composition among the vegetation types but clearly showed a trend for reduced aliphatic and O-alkyl C in the OTCs suggesting increased decomposition (or reduced inputs) of these compounds. Thus, the non-significantly higher ER may in some communities be of plant origin linked to greater plant biomass in the OTCs, and in other (e.g. tussock tundra) from increased decomposition rates. In conclusion, this study showed that 12-15 years of OTC treatment had a modest effects impact C and N dynamics in tundra soils specific to distinct plant communities.
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| 9. |
- Björk, Robert G., 1974, et al.
(författare)
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Root biomass distribution and morphology in Norway spruce forests on drained organic soils: root system variation in d13C and d15N
- 2010
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Ingår i: 1st COST meeting ‘Belowground carbon in Europeanforest’, Birmensdorf, Switzerland, 26–28 January 2010..
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Little is known about the distribution and morphology of fine roots in organic soils. Organic soils are typical features of northern Europe, covering over 250 000 km2, and in the recent century, 1/3 of the pristine peatlands have been drained for forestry and large areas of peatlands used for agriculture have been afforested. The aim of the present study was to investigate how fine root distribution, mor-phology, and 13C/15N differed between two fertile drained and forested organic soils. The study was conducted in two Norway spruce stands at the Skogaryd Research Forest, in south-west Sweden. One of the sites was a mineral soil (“the mineral site”) with high organic content that had been under agricultural use since the 15th century, and was afforested in 1962. The other site was a peat soil of minerotrophic origin (“the peat site”) that was used for extensive grazing from the 1800s to the 1870s, used for crop production after the drainage in the 1870s and afforested in 1951. Root biomass and necromass were estimated using soil cores, to a depth of 40 cm. Washed roots were scanned and sorted into five diameter classes, and analysed for 13C and 15N. There was a distinct difference in fine root morphology between the two sites, with longer and thinner roots at the peat site. Despite this, no significant differences in total root biomass or biomass-to-necromass ratio between the sites were found. At the peat site, the fine roots were en-riched in 15N by 1-1.5‰ compared to the mineral site, and had consistently lower C/N within the root classes. The mineral site, which is the less fertile of the sites, produced shorter and thicker roots, and more extensive extramatrical mycelia. Thus, one possibility is that the trees at the mineral site invest more in their mycorrhizal symbiont instead of exploring the soil environment themselves.
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| 10. |
- 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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