scholarly journals Simulating ectomycorrhiza in boreal forests: implementing ectomycorrhizal fungi model MYCOFON into CoupModel (V5)

2017 ◽  
Author(s):  
Hongxing He ◽  
Astrid Meyer ◽  
Per-Erik Jansson ◽  
Magnus Svensson ◽  
Tobias Rütting ◽  
...  
Keyword(s):  
Ectomycorrhizal Fungi ◽  
Mycorrhizal Fungi ◽  
N Uptake ◽  
Forest Growth ◽  
Soil Conditions ◽  
N Availability ◽  
Parameter Uncertainties ◽  
Ecosystem Models ◽  
N Fluxes ◽  
C And N

Abstract. Ectomycorrhizal fungi (ECM), the symbiosis between a host plant and mycorrhizal fungi, has been shown to considerably influence the C and N flux between soil, the rhizosphere and plant in boreal forest ecosystems. However, ECM is either neglected or presented as an implicit, non-dynamic term in most ecosystem models which can potentially reduce their predictive power. In order to investigate the necessity of an explicit consideration of ECM in ecosystem models, we implemented the previous developed MYCOFON model into a detail process-based soil-plant-atmosphere model, CoupModel. MYCOFON explicitly describes the C and N fluxes between ECM and roots. This new Coup-Mycofon model approach (ECM explicit) is compared to two simpler model approaches, of which one contains ECM implicitly as an non-dynamic N uptake function (ECM implicit) and the other represents a version where plant growth has a constant N availability (nonlim). Parameter uncertainties are quantified by using Bayesian calibration where the model outputs are constrained to current forest growth and soil conditions for four forest sites along a climate and N deposition gradient in Sweden over 100 year period. Our results show that the nonlim approach could not describe both the forest growth and soil C and N conditions properly. The ECM implicit/explicit approach is able to describe current conditions with acceptable uncertainty. The ECM explicit Coup-Mycofon model provide a more detailed description of internal ecosystems fluxes and feedbacks of C and N fluxes between plant, soil and ECM. Our modelling highlights the need of incorporating ECM in current ecosystem models. We also provide a key set of posterior fungal parameters which can be further investigated and evaluated in future ECM studies.

scholarly journals Simulating ectomycorrhiza in boreal forests: implementing ectomycorrhizal fungi model MYCOFON in CoupModel (v5)

2018 ◽  
Vol 11 (2) ◽  
pp. 725-751 ◽  
Author(s):  
Hongxing He ◽  
Astrid Meyer ◽  
Per-Erik Jansson ◽  
Magnus Svensson ◽  
Tobias Rütting ◽  
...  
Keyword(s):  
Ectomycorrhizal Fungi ◽  
N Uptake ◽  
Forest Growth ◽  
Organic N ◽  
Litter Production ◽  
Parameter Uncertainties ◽  
Ecosystem Models ◽  
Soil C ◽  
N Fluxes ◽  
C And N

Abstract. The symbiosis between plants and Ectomycorrhizal fungi (ECM) is shown to considerably influence the carbon (C) and nitrogen (N) fluxes between the soil, rhizosphere, and plants in boreal forest ecosystems. However, ECM are either neglected or presented as an implicit, undynamic term in most ecosystem models, which can potentially reduce the predictive power of models.In order to investigate the necessity of an explicit consideration of ECM in ecosystem models, we implement the previously developed MYCOFON model into a detailed process-based, soil–plant–atmosphere model, Coup-MYCOFON, which explicitly describes the C and N fluxes between ECM and roots. This new Coup-MYCOFON model approach (ECM explicit) is compared with two simpler model approaches: one containing ECM implicitly as a dynamic uptake of organic N considering the plant roots to represent the ECM (ECM implicit), and the other a static N approach in which plant growth is limited to a fixed N level (nonlim). Parameter uncertainties are quantified using Bayesian calibration in which the model outputs are constrained to current forest growth and soil C ∕ N ratio for four forest sites along a climate and N deposition gradient in Sweden and simulated over a 100-year period.The nonlim approach could not describe the soil C ∕ N ratio due to large overestimation of soil N sequestration but simulate the forest growth reasonably well. The ECM implicit and explicit approaches both describe the soil C ∕ N ratio well but slightly underestimate the forest growth. The implicit approach simulated lower litter production and soil respiration than the explicit approach. The ECM explicit Coup–MYCOFON model provides a more detailed description of internal ecosystem fluxes and feedbacks of C and N between plants, soil, and ECM. Our modeling highlights the need to incorporate ECM and organic N uptake into ecosystem models, and the nonlim approach is not recommended for future long-term soil C and N predictions. We also provide a key set of posterior fungal parameters that can be further investigated and evaluated in future ECM studies.

scholarly journals Arbuscular Mycorrhizal Community in Roots and Nitrogen Uptake Patterns of Understory Trees Beneath Ectomycorrhizal and Non-ectomycorrhizal Overstory Trees

2021 ◽  
Vol 11 ◽  
Author(s):  
Chikae Tatsumi ◽  
Fujio Hyodo ◽  
Takeshi Taniguchi ◽  
Weiyu Shi ◽  
Keisuke Koba ◽  
...  
Keyword(s):  
Community Composition ◽  
Mycorrhizal Fungi ◽  
N Uptake ◽  
Arbuscular Mycorrhizal ◽  
Nitrate Content ◽  
N Availability ◽  
Fungal Community Composition ◽  
Mycorrhizal Association ◽  
Understory Trees ◽  
Overstory Trees

Nitrogen (N) is an essential plant nutrient, and plants can take up N from several sources, including via mycorrhizal fungal associations. The N uptake patterns of understory plants may vary beneath different types of overstory trees, especially through the difference in their type of mycorrhizal association (arbuscular mycorrhizal, AM; or ectomycorrhizal, ECM), because soil mycorrhizal community and N availability differ beneath AM (non-ECM) and ECM overstory trees (e.g., relatively low nitrate content beneath ECM overstory trees). To test this hypothesis, we examined six co-existing AM-symbiotic understory tree species common beneath both AM-symbiotic black locust (non-ECM) and ECM-symbiotic oak trees of dryland forests in China. We measured AM fungal community composition of roots and natural abundance stable isotopic composition of N (δ15N) in plant leaves, roots, and soils. The root mycorrhizal community composition of understory trees did not significantly differ between beneath non-ECM and ECM overstory trees, although some OTUs more frequently appeared beneath non-ECM trees. Understory trees beneath non-ECM overstory trees had similar δ15N values in leaves and soil nitrate, suggesting that they took up most of their nitrogen as nitrate. Beneath ECM overstory trees, understory trees had consistently lower leaf than root δ15N, suggesting they depended on mycorrhizal fungi for N acquisition since mycorrhizal fungi transfer isotopically light N to host plants. Additionally, leaf N concentrations in the understory trees were lower beneath ECM than the non-ECM overstory trees. Our results show that, without large differences in root mycorrhizal community, the N uptake patterns of understory trees vary between beneath different overstory trees.

Nitrogen uptake and growth in vitro by Hebeloma crustuliniforme and other Pacific Northwest mycorrhizal fungi

1984 ◽  
Vol 62 (4) ◽  
pp. 647-652 ◽  
Author(s):  
Willis R. Littke ◽  
Caroline S. Bledsoe ◽  
Robert L. Edmonds
Keyword(s):  
Pacific Northwest ◽  
Ectomycorrhizal Fungi ◽  
Mycorrhizal Fungi ◽  
Radial Growth ◽  
N Uptake ◽  
Ammonium Uptake ◽  
Biomass Growth ◽  
N Source ◽  
Uptake Rates ◽  
Hebeloma Crustuliniforme

Since little is known about the nitrogen (N) physiology of ectomycorrhizal fungi, this study was initiated to study both radial and biomass growth and N uptake of Hebeloma crustuliniforme and other Pacific Northwest ectomycorrhizal fungi. Hebeloma crustuliniforme utilized either nitrate or ammonium as the N source in buffered liquid media, but biomass growth was greatest with ammonium. Without buffers, biomass growth on ammonium-based media was reduced, apparently owing to low pH. These results emphasize the strong interrelationship between N source and pH of the media. A pronounced pH optimum for biomass growth of H. crustuliniforme occurred at pH 5.0. Ammonium uptake rates were five to nine times greater than nitrate uptake rates over a range of N concentrations (40–600 μM). Radial growth rates of a range of mycorrhizal fungi were greater on high-N than on low-N media. For those few species that grew faster on low-N medium, their growth habit was more diffuse and dry weight production was decreased, indicating that radial growth had occurred at the expense of biomass production.

Fate of atmospheric nitrogen depositions in two Italian temperate mountain forests assessed by isotopic analysis

2020 ◽  
Author(s):  
Luca Da Ros ◽  
Maurizio Ventura ◽  
Mirco Rodeghiero ◽  
Damiano Gianelle ◽  
Giustino Tonon
Keyword(s):  
Forest Canopy ◽  
N Uptake ◽  
Isotopic Signature ◽  
N Deposition ◽  
Forest Growth ◽  
N Availability ◽  
N Addition ◽  
Total N ◽  
Sequestration Potential ◽  
Soil And Water

<p><strong>Abstract.</strong> Forests ability to store carbon is strongly connected with the amount of nitrogen (N) that forest ecosystems can retain; N is indeed considered the most limiting nutrient for terrestrial ecosystem's net primary productivity. Since the industrial revolution, human activities have more than doubled the rate of N input into the nitrogen cycle and this could alleviate N limitation thus stimulating plant growth. However, it has been suggested that when N availability exceeds biotic demand and abiotic sinks, additional N can trigger a negative cascade effect: nutrient imbalance, reduced productivity, increased losses of N, eutrophication and acidification of soil and water, leading toward forest decline and net greenhouse gases emissions. The consequences of increased N deposition on forest depend in large share on the fate of N in the ecosystem, which can be simulated and quantified by a fertilization at a known isotopic signature. Nevertheless, most of the tracer experiments performed so far added the fertilizer directly to the forest floor, neglecting the potential role of N uptake by the forest canopy. In the Italian Alps, we are conducting an experiment where both types of N additions (above and below the canopy layer) are performed in two different forest stands, to understand if canopy fertilization better simulates ecological consequences of increased atmospheric N deposition. These field-scale manipulation experiments are willing to test two different hypotheses: i) the N uptake by trees in the above-canopy N addition experimental sites is higher than under-canopy N addition ii) forest growth rate varies with the type of treatment. To describe the fate of the applied N, stable isotope techniques have been adopted: the forest sites, fertilized with NH<sub>4</sub>NO<sub>3</sub> at a known isotopic signature, are sampled for all the ecosystem components (plant, soil and water) periodically to determine the total N content and its isotopic signature. The δ<sup>15</sup>N values permit to calculate the recovery of N-fertilizer in tree tissues, soil and leaching-water, allowing us to understand how N allocation varies under these two fertilization strategies and how this affects C sequestration potential. Results regarding the short-term effects over the first 6 years of data collection will be presented.</p>

scholarly journals Simulating ectomycorrhizal fungi and their role in carbon and nitrogen cycling in forest ecosystems

2014 ◽  
Vol 44 (6) ◽  
pp. 535-553 ◽  
Author(s):  
G. Deckmyn ◽  
A. Meyer ◽  
M.M. Smits ◽  
A. Ekblad ◽  
T. Grebenc ◽  
...  
Keyword(s):  
Ectomycorrhizal Fungi ◽  
Forest Ecosystem ◽  
State Of The Art ◽  
Forest Growth ◽  
Ecosystem Models ◽  
Carbon And Nitrogen ◽  
The Past ◽  
Starting Point ◽  
Insight Into ◽  
Ecological Functioning

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.

scholarly journals Review and analysis of strengths and weaknesses of agro-ecosystem models for simulating C and N fluxes

2017 ◽  
Vol 598 ◽  
pp. 445-470 ◽  
Author(s):  
Lorenzo Brilli ◽  
Luca Bechini ◽  
Marco Bindi ◽  
Marco Carozzi ◽  
Daniele Cavalli ◽  
...  
Keyword(s):  
Ecosystem Models ◽  
N Fluxes ◽  
C And N

Alternative methods for terminating green manures in organic grain systems

2021 ◽  
pp. 1-9
Author(s):  
Margaret Pickoff ◽  
Ellen B. Mallory ◽  
Thomas Molloy
Keyword(s):  
Grain Yield ◽  
Soil Cover ◽  
Spring Barley ◽  
N Uptake ◽  
Red Clover ◽  
Alternative Methods ◽  
Soil Conditions ◽  
N Availability ◽  
Green Manures ◽  
Late Fall

Abstract Legume green manures (GM) are a vital source of nitrogen (N) for many organic grain systems. A common practice among organic growers is to undersow clover into a small grain, harvest the grain crop and terminate the clover stand in late fall by moldboard plowing in preparation for a cash crop the following spring. While fall plowing offers excellent clover kill, growers increasingly seek an alternative termination method that reduces tillage intensity and bare winter soil. This study, performed at two sites in Maine, evaluates three clover termination methods for kill efficacy, winter soil cover, spring soil conditions and N uptake and grain yield and protein of a subsequent test crop of hard red spring wheat (Triticum aestivum L., var. Glenn). Red clover (Trifolium pratense L.) was intercropped with spring barley (Hordeum vulgare L.) and terminated in late fall by moldboard plowing (PL), skim plowing (SK) or undercutting (UC). A control treatment received no clover and was fall plowed. An additional treatment, winterkilled field peas (WK), was evaluated at one site. SK, UC and WK increased soil cover relative to PL, though UC resulted in low clover kill efficacy in a wet spring and is in need of improved design. Grain yield was higher following red clover compared to the no-clover control at one site, but was unaffected by termination method. At one site, grain crude protein was higher following PL than the other treatments, indicating the possibility for more favorable timing of N availability associated with PL.

scholarly journals Nitrogen Uptake, Not Transfer of Carbon and Nitrogen by CMN, Explains the Effect of AMF on the Competitive Interactions Between Flaveria bidentis and Native Species

2021 ◽  
Vol 9 ◽  
Author(s):  
Xue Chen ◽  
Qiao Li ◽  
Liting Wang ◽  
Yanliang Meng ◽  
Shaona Jiao ◽  
...  
Keyword(s):  
Mycorrhizal Fungi ◽  
Native Species ◽  
N Uptake ◽  
Competitive Interactions ◽  
Competitive Growth ◽  
Native Plant ◽  
Eclipta Prostrata ◽  
C And N ◽  
The Common ◽  
Flaveria Bidentis

Rhizophagus intraradices, one of the common arbuscular mycorrhizal fungi (AMF) grown in the roots of Flaveria bidentis, facilitates the invasion of this exotic plant species into China. However, it is still unknown whether nutrient transfer through the common mycorrhizal networks (CMN) between this exotic species and the native species enhances the competitive growth of F. bidentis over the native species. To elucidate this question and the related mechanism, an isotopic labeling technique was used to test the transfer of carbon (C) and nitrogen (N) by CMN. Native species like Setaria viridis and Eclipta prostrata were selected to compete with F. bidentis in a polyvinyl chloride (PVC) box. Two competitive groups (F. bidentis-S. viridis and F. bidentis- E. prostrata), three treatments (monoculture of F. bidentis, the mixture of F. bidentis and the native plant, and the monoculture of the native plant), and two levels of AMF (presence or absence) were assigned. Results showed that the corrected index of relative competition intensity (CRCI) of F. bidentis in the presence of AMF < 0 suggests that the competition facilitated the growth of F. bidentis with either S. viridis or E. prostrata. The reason was that the inoculation of R. intra radices significantly increased the C and N contents of F. bidentis in the mixtures. However, the effects of R. intra radices on the two native species were different: negative effect on the growth of S. viridis and positive effect on the growth of E. prostrata. The change of N content in S. viridis or E. prostrata was consistent with the variation of the biomass, suggesting that the N uptake explains the effects of R. intraradices on the competitive interactions between F. bidentis and the two native species. Moreover, the transfer of C and N via AMF hyphal links did occur between F. bidentis and the native species. However, the transfer of C and N by the CMN was not positively related to the competitive growth of F. bidentis.

Effects of shading on photosynthesis, plant organic nitrogen uptake, and root fungal colonization in a subarctic mire ecosystem

Botany ◽  
2009 ◽  
Vol 87 (5) ◽  
pp. 463-474 ◽  
Author(s):  
Maria Olsrud ◽  
Anders Michelsen
Keyword(s):  
Mycorrhizal Fungi ◽  
N Uptake ◽  
High Irradiance ◽  
Dwarf Shrub ◽  
Organic N ◽  
Mountain Birch ◽  
Fungal Colonization ◽  
Hair Roots ◽  
C And N ◽  
Birch Forests

Arctic dwarf shrub ecosystems are predicted to be exposed to lower light intensity in a changing climate where mountain birch forests are expanding. We investigated how shading at 0%, 65%, and 97% affects photosynthesis, organic N uptake, C and N allocation patterns in plants, and root fungal colonization in an ericoid dwarf shrub ecosystem. The ecosystem was labeled by injection of [2-13C,15N]glycine into the soil, and the uptake of 15N and 13C in roots and leaves 24 h later was analysed. Fungal colonization in hair roots was determined visually. Hair root 13C:15N ratios showed that dwarf shrub ecosystems are capable of taking up organic N as intact glycine both under high irradiance levels and under shaded conditions when photosynthesis is strongly reduced. The allocation of 15N to green leaves of Rubus chamaemorus L. increased with shading, whereas the allocation of 13C to leaves of both deciduous and evergreen plant species decreased. Species dominance was correlated with uptake of 13C, i.e., the most productive species also took up the highest amount of glycine. The ecosystem exhibited a tendency towards lower colonization by ericoid mycorrhizal fungi and dark septate endophytes in hair roots when shaded. Thus, shading has implications for processes central to both C and N cycling in subarctic ecosystems. This should be considered in projections of ecosystem responses to climate change and expanding mountain birch forests.

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