| 1. |
- Castaño Soler, Carles, et al.
(författare)
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Soil microclimate changes affect soil fungal communities in a Mediterranean pine forest
- 2018
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Ingår i: New Phytologist. - : Wiley. - 0028-646X .- 1469-8137. ; 220, s. 1211-1221
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Tidskriftsartikel (refereegranskat)abstract
- Soil microclimate is a potentially important regulator of the composition of plant-associated fungal communities in climates with significant drought periods. Here, we investigated the spatio-temporal dynamics of soil fungal communities in a Mediterranean Pinus pinaster forest in relation to soil moisture and temperature. Fungal communities in 336 soil samples collected monthly over 1 year from 28 long-term experimental plots were assessed by PacBio sequencing of ITS2 amplicons. Total fungal biomass was estimated by analysing ergosterol. Community changes were analysed in the context of functional traits. Soil fungal biomass was lowest during summer and late winter and highest during autumn, concurrent with a greater relative abundance of mycorrhizal species. Intra-annual spatio-temporal changes in community composition correlated significantly with soil moisture and temperature. Mycorrhizal fungi were less affected by summer drought than free-living fungi. In particular, mycorrhizal species of the short-distance exploration type increased in relative abundance under dry conditions, whereas species of the long-distance exploration type were more abundant under wetter conditions. Our observations demonstrate a potential for compositional and functional shifts in fungal communities in response to changing climatic conditions. Free-living fungi and mycorrhizal species with extensive mycelia may be negatively affected by increasing drought periods in Mediterranean forest ecosystems.
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| 2. |
- Collado, Eduardo, et al.
(författare)
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Divergent above- and below-ground responses of fungal functional groups to forest thinning
- 2020
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Ingår i: Soil Biology and Biochemistry. - : Elsevier. - 0038-0717 .- 1879-3428. ; 150
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Tidskriftsartikel (refereegranskat)abstract
- Forest disturbances have a strong effect on soil fungal communities and associated ecosystem processes. However, little is known about the response of mycelial biomass to disturbances, and how fungi reallocate carbon into different fungal structures under environmental stressors. We investigated above- and below-ground fungal biomass shifts in response to different intensities of forest management in Mediterranean Pinus pinaster forests. Soil fungal biomass was estimated by ergosterol quantification and production of sporocarps was estimated from repeated field samplings during 5 years in 26 experimental plots. Abundance of mycorrhizal and saprotrophic fungi belowground was determined using Pacific Biosciences sequencing of fungal ITS2 amplicons. Thinning had a prolonged negative effect belowground, inter- and intra-annually, on total fungal biomass and on the biomass of ectomycorrhizal fungi, but not on saprotrophic fungi. Total and ectomycorrhizal mushroom yields were negatively correlated with the total and the ectomycorrhizal mycelial biomass, respectively. Thinning also correlated positively with the aboveground/belowground ratio of both total and ectomycorrhizal fungal biomass. We show potential short-term shifts in resource allocation of fungi from below-to above-ground structures under disturbances such as forest thinning. Ectomycorrhizal fungi may respond to disturbances by increasing reproduction rather than colonizing the surrounding soil.
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| 3. |
- Hagenbo, Andreas, 1987-, et al.
(författare)
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Carbon use efficiency of mycorrhizal fungal mycelium increases during the growing season but decreases with forest age across a Pinus sylvestris chronosequence
- 2019
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Ingår i: Journal of Ecology. - : Wiley. - 0022-0477 .- 1365-2745. ; 107:6, s. 2808-2822
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Tidskriftsartikel (refereegranskat)abstract
- In boreal forest soils, mycelium of mycorrhizal fungi is pivotal for regulating soil carbon (C) cycling and storage. The carbon use efficiency (CUE), a key parameter in C cycling models, can inform on the partitioning of C between microbial biomass, and potential soil storage, and respiration. Here, we test the dependency of mycorrhizal mycelial CUE on stand age and seasonality in managed boreal forest stands. Based on mycelial production and respiration estimates, derived from sequentially incubated ingrowth mesh bags, we estimated CUE on an ecosystem scale during a seasonal cycle and across a chronosequence of eight, 12- to 158-year-old, managed Pinus sylvestris forest stands characterized by decreasing pH and nitrogen (N) availability with increasing age. Mycelial respiration was related to total soil respiration, and by using eddy covariance flux measurements, primary production (GPP) was estimated in the 12- and 100-year-old forests, and related to mycelial respiration and CUE. As hypothesized, mycelial CUE decreased significantly with increasing forest age by c. 65%, supposedly related to a shift in mycorrhizal community composition and a metabolic adjustment reducing their own biomass N demand with declining soil N availability. Furthermore, mycelial CUE increased by a factor of five over the growing season; from 0.03 in May to 0.15 in November, and we propose that the seasonal change in CUE is regulated by a decrease in photosynthate production and temperature. The respiratory contribution of mycorrhizal mycelium ranged from 14% to 26% of total soil respiration, and was on average 17% across all sites and occasions. Synthesis. Carbon is retained more efficiently in mycorrhizal mycelium late in the growing season, when fungi have access to a more balanced C and nutrient supplies. Earlier in the growing season, at maximum host plant photosynthesis, when below-ground C availability is high in relation to N, the fungi respire excess C resulting in lower mycelial carbon use efficiency (CUE). Additionally, C is retained less efficiently in mycorrhizal fungal biomass in older forest stands characterized by more nutrient depleted soils than younger forest stands.
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| 4. |
- Hagenbo, Andreas, et al.
(författare)
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Changes in turnover rather than production regulate biomass of ectomycorrhizal fungal mycelium across a Pinus sylvestris chronosequence
- 2017
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Ingår i: New Phytologist. - : John Wiley & Sons. - 0028-646X .- 1469-8137. ; 214:1, s. 424-431
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Tidskriftsartikel (refereegranskat)abstract
- In boreal forest soils, ectomycorrhizal fungi are fundamentally important for carbon (C) dynamics and nutrient cycling. Although their extraradical mycelium (ERM) is pivotal for processes such as soil organic matter build-up and nitrogen cycling, very little is known about its dynamics and regulation.In this study, we quantified ERM production and turnover, and examined how these two processes together regulated standing ERM biomass in seven sites forming a chronosequence of 12- to 100-yr-old managed Pinus sylvestris forests. This was done by determining ERM biomass, using ergosterol as a proxy, in sequentially harvested in-growth mesh bags and by applying mathematical models.Although ERM production declined with increasing forest age from 1.2 to 0.5 kg ha(-1) d(-1) , the standing biomass increased from 50 to 112 kg ha(-1) . This was explained by a drastic decline in mycelial turnover from seven times to one time per year with increasing forest age, corresponding to mean residence times from 25 d up to 1 yr.Our results demonstrate that ERM turnover is the main factor regulating biomass across differently aged forest stands. Explicit inclusion of ERM parameters in forest ecosystem C models may significantly improve their capacity to predict responses of mycorrhiza-mediated processes to management and environmental changes.
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| 5. |
- Hagenbo, Andreas
(författare)
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Ectomycorrhizal Fungal Mycelial Dynamics and its Role in Forest Soil Carbon Cycling
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Most boreal tree species rely on root-associated ectomycorrhizal fungi for nutrient acquisition, in exchange the trees allocate part of their photosynthetically fixed carbon (C) to these fungi. This has a feedback on soil C dynamics as mycorrhizal fungi are important in regulating soil C cycling and storage. However, mycorrhizal fungi are often not included in C dynamics models, as mechanistic understanding of their contribution to mycorrhiza-mediated processes are largely lacking. The aim of the work described in this thesis was to address this knowledge gap by studying the contribution of mycorrhizal fungi in regulating soil C fluxes. This was done by quantifying C fluxes associated with the extraradical mycelium (ERM) of mycorrhizal fungi, and examining how the ERM contributes to variations in soil C cycling along a nemoboreal chronosequence of managed Pinus sylvestris forests. Production and turnover of ERM was quantified by determining ERM biomass in sequentially harvested ingrowth mesh bags and by mathematical modelling. Respiration of ERM was measured as CO2 efflux from mesh bags, and carbon use efficiency (CUE) was calculated from ERM production and respiration rates. We assessed soil fungal communities along the chronosequence and investigated correlations between taxonomic composition and enzyme activities. The ERM standing biomass increased despite decreased production along the chronosequence. This contradiction was explained by a drastic decline in biomass turnover, from seven times to one time per year. The CUE decreased with forest age, but increased tenfold from summer (0.019) to autumn (0.200). This seasonal increase in CUE was associated with a decline in gross photosynthetic production, suggesting that variation in photosynthetic C supply regulates seasonal variations in CUE. Relative abundance of ectomycorrhizal taxa increased with forest age, and was dominated by Atheliaceae species in young forests, and by Cortinarius and Russula species in mature forests. Enzyme activities were related to community composition, and seem to be important for maintaining forest productivity, by facilitating organic nutrient mobilisation. This thesis is a first step in parameterizing mycorrhizal mycelial C fluxes to enable explicit inclusion of ERM parameters in forest ecosystem C models.
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| 6. |
- Hagenbo, Andreas, et al.
(författare)
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Ectomycorrhizal necromass turnover is one-third of biomass turnover in hemiboreal Pinus sylvestris forests
- 2024
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Ingår i: Plants, People, Planet. - : John Wiley & Sons. - 2572-2611. ; 6:4, s. 951-964
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Tidskriftsartikel (refereegranskat)abstract
- Societal Impact Statement:Efficient mitigation of climate change requires predictive models of forest ecosystems as sinks for atmospheric carbon. Mycorrhizal fungi are drivers of soil carbon storage in boreal forests, yet they are typically excluded from ecosystem models, because of a lack of information about their growth and turnover. Closing this knowledge gap could help us better predict future responses to climate change and guide policy decisions for sustainable management of forest ecosystems. This study provides new estimates of the production and turnover of mycorrhizal mycelial biomass and necromass. This information can facilitate the integration of mycorrhizal fungi into new predictive models of boreal forest soils.Summary:In boreal forests, turnover of biomass and necromass of ectomycorrhizal extraradical mycelia (ERM) are important for mediating long-term carbon storage. However, ectomycorrhizal fungi are usually not considered in ecosystem models, because data for parameterization of ERM dynamics is lacking.Here, we estimated the production and turnover of ERM biomass and necromass across a hemiboreal Pinus sylvestris chronosequence aged 12 to 100 years. Biomass and necromass were quantified in sequentially harvested in-growth bags, and incubated in the soil for 1-24 month, and Bayesian calibration of mathematical models was applied to arrive at parametric estimates of ERM production and turnover rates of biomass and necromass.Steady states were predicted to be nearly reached after 160 and 390 growing season days, respectively, for biomass and necromass. The related turnover rates varied with 95% credible intervals of 1.7-6.5 and 0.3-2.5 times yr-1, with mode values of 2.9 and 0.9 times yr-1, corresponding to mean residence times of 62 and 205 growing season days.Our results highlight that turnover of necromass is one-third of biomass. This together with the variability in the estimates can be used to parameterize ecosystem models, to explicitly include ERM dynamics and its impact on mycorrhizal-derived soil carbon accumulation in boreal forests.
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| 7. |
- Hagenbo, Andreas, et al.
(författare)
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Fungal community shifts underpin declining mycelial production and turnover across a Pinus sylvestris chronosequence
- 2018
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Ingår i: Journal of Ecology. - : Wiley. - 0022-0477 .- 1365-2745. ; 106, s. 490-501
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Tidskriftsartikel (refereegranskat)abstract
- 1. Fungi play critical roles in ecosystem processes such as decomposition and nutrient cycling, but have also been highlighted as significant contributors to organic matter build-up in boreal forest soils. Ectomycorrhizal (ECM) mycelial biomass and necromass dynamics have recently been highlighted as essential for regulating build-up of soil organic matter. Understanding the extent to which shifts in mycelial community or growth trait composition cause changes in mycelial production and turnover over ecological gradients would aid a mechanistic understanding of these important processes at an ecosystem scale.2. Here, we test the hypotheses that shifting species and mycelial trait (exploration type) composition within the mycelial community underpin changes in biomass turnover with increasing forest age. We quantified mycelial turnover and assessed fungal community composition in a chronosequence of eight, 12- to 158-year-old, managed Pinus sylvestris forests. Turnover was estimated by determining mycelial biomass (ergosterol) in a sequence of ingrowth mesh bags and applying mathematical models. Fungal communities in the bags were identified using Pacific Biosciences sequencing of fungal ITS2 amplicons. To evaluate the accuracy of this method to represent all ECM fungi, community composition in bags was followed over time and compared with communities in soil.3. Mycelial communities changed with stand age, but we found no evidence that there were concurrent shifts in mycelial exploration types. Forest age and turnover were significantly correlated with ECM mycelial community composition and collectively explained 39.4% of total variation. The similarity between fungal communities in mesh bags and in soil was strongly forest age dependent, with communities in mesh bags diverging from soil communities in stands older than 60 years. However, in all stands, when bag incubation time exceeded 75 days, communities became more similar to soil communities.4. Synthesis. Our results support the idea that shifts in fungal community composition underpin the forest age-related decrease in mycelial turnover; however, since ingrowth mesh bags exclude some mycorrhizal species in older forests, it remains a possibility that turnover estimates were not reflecting the entire community. While we found no evidence that mycelial exploration types of fungi changed systematically with forest age, we suggest that other traits that relate to biomass turnover and necromass degradation require further study, as they may explain the extent to which ectomycorrhizal fungi regulate and contribute to soil organic matter accumulation.
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| 8. |
- Hagenbo, Andreas, 1987-, et al.
(författare)
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Production and turnover of mycorrhizal soil mycelium relate to variation in drought conditions in Mediterranean Pinus pinaster, Pinus sylvestris and Quercus ilex forests
- 2021
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Ingår i: New Phytologist. - : Wiley-Blackwell Publishing Inc.. - 0028-646X .- 1469-8137. ; 230:4, s. 1609-1622
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Tidskriftsartikel (refereegranskat)abstract
- In forests, ectomycorrhizal mycelium is pivotal for driving soil carbon and nutrient cycles, but how ectomycorrhizal mycelial dynamics vary in ecosystems with drought periods is unknown. We quantified production and turnover of mycorrhizal mycelium in Mediterranean Pinus pinaster, Pinus sylvestris and Quercus ilex forests and related the estimates to standardized precipitation index (SPI), to study how mycelial dynamics relates to tree species and drought-moisture conditions.Production and turnover of mycelium was estimated between July-February, by quantifying the fungal biomass (ergosterol) in ingrowth mesh bags and using statistical modelling. SPI for time scales of 1 to 3 months, was calculated from precipitation records and precipitation data over the study period.Forests dominated by Pinus trees displayed higher biomass but were seasonally more variable, as opposed to Q. ilex forests where the mycelial biomass remained lower and stable over the season. Production and turnover respectively varied between 1.4-5.9 kg ha-1 day-1 and 7.2-9.9 times year-1 over the different forest types and were positively correlated with 2- and 3-month SPI over the study period.Our results demonstrate that mycorrhizal mycelial biomass vary with season and tree species and we speculate that production and turnover are related to physiology and plant-host performance during drought.
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| 9. |
- Kyaschenko, Julia, et al.
(författare)
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Shift in fungal communities and associated enzyme activities along an age gradient of managed Pinus sylvestris stands
- 2017
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Ingår i: ISME Journal. - : Springer Science and Business Media LLC. - 1751-7362 .- 1751-7370. ; 11, s. 863-874
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Tidskriftsartikel (refereegranskat)abstract
- Forestry reshapes ecosystems with respect to tree age structure, soil properties and vegetation composition. These changes are likely to be paralleled by shifts in microbial community composition with potential feedbacks on ecosystem functioning. Here, we assessed fungal communities across a chronosequence of managed Pinus sylvestris stands and investigated correlations between taxonomic composition and extracellular enzyme activities. Not surprisingly, clear-cutting had a negative effect on ectomycorrhizal fungal abundance and diversity. In contrast, clear-cutting favoured proliferation of saprotrophic fungi correlated with enzymes involved in holocellulose decomposition. During stand development, the re-establishing ectomycorrhizal fungal community shifted in composition from dominance by Atheliaceae in younger stands to Cortinarius and Russula species in older stands. Late successional ectomycorrhizal taxa correlated with enzymes involved in mobilisation of nutrients from organic matter, indicating intensified nutrient limitation. Our results suggest that maintenance of functional diversity in the ectomycorrhizal fungal community may sustain long-term forest production by retaining a capacity for symbiosis-driven recycling of organic nutrient pools.
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| 10. |
- Kyaschenko, Julia, et al.
(författare)
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Soil fertility in boreal forest relates to root-driven nitrogen retention and carbon sequestration in the mor layer
- 2019
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Ingår i: New Phytologist. - : Blackwell Science Ltd.. - 0028-646X .- 1469-8137. ; 221:3, s. 1492-1502
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Tidskriftsartikel (refereegranskat)abstract
- Boreal forest soils retain significant amounts of carbon (C) and nitrogen (N) in purely organic layers, but the regulation of organic matter turnover and the relative importance of leaf litter and root‐derived inputs are not well understood.We combined bomb 14C dating of organic matter with stable isotope profiling for Bayesian parameterization of an organic matter sequestration model. C and N dynamics were assessed across annual depth layers (cohorts), together representing 256 yr of organic matter accumulation. Results were related to ecosystem fertility (soil inorganic N, pH and litter C : N).Root‐derived C was estimated to decompose two to 10 times more slowly than leaf litter, but more rapidly in fertile plots. The amounts of C and N per cohort declined during the initial 20 yr of decomposition, but, in older material, the amount of N per cohort increased, indicating N retention driven by root‐derived C.The dynamics of root‐derived inputs were more important than leaf litter dynamics in regulating the variation in organic matter accumulation along a forest fertility gradient. N retention in the rooting zone combined with impeded mining for N in less fertile ecosystems provides evidence for a positive feedback between ecosystem fertility and organic matter turnover.
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