Effects of excess nitrogen and phosphorus starvation on the extramatrical mycelium of ectomycorrhizas of <i>Pinus sylvestris</i> L.

Wallander, Håkan; Nylund, Jan‐Erik

doi:10.1111/j.1469-8137.1992.tb01798.x

Cited by 216 publications

(133 citation statements)

References 22 publications

Supporting

Mentioning

118

Contrasting

Unclassified

Order By: Relevance

“…Wallander and Nylund (1992) reported that S. bovinus was more sensitive to N additions than was Laccaria bicolor when both were grown on Pinus sylvestris in a semi-hydroponic medium. In a microcosm experiment conducted by Arnebrant (1994), two isolates of P. involutus, one isolate of S. bovinus, and two additional unidentified species of ECM fungi were exposed to increasing N availability.…”

Section: Elevated Comentioning

confidence: 99%

Mycorrhizal fungi have a potential role in soil carbon storage under elevated CO₂ and nitrogen deposition

2000

View full text Add to dashboard Cite

In this review, we discuss the potential for mycorrhizal fungi to act as a source or sink for carbon (C) under elevated CO # and nitrogen deposition. Mycorrhizal tissue has been estimated to comprise a significant fraction of soil organic matter and below-ground biomass in a range of systems. The current body of literature indicates that in many systems exposed to elevated CO # , mycorrhizal fungi might sequester increased amounts of C in living, dead and residual hyphal biomass in the soil. Through this process, the fungi might serve as a negative feedback on the rise in atmospheric CO # levels caused by fossil fuel burning and deforestation. By contrast, a few preliminary studies suggest that N deposition might increase turnover rates of fungal tissue and negate CO # effects on hyphal biomass. If these latter responses are consistent among ecosystems, C storage in hyphae might decline in habitats surrounding agricultural and urban areas. When N additions occur without CO # enrichment, effects on mycorrhizal growth are inconsistent. We note that analyses of hyphal decomposition under elevated CO # and N additions are extremely sparse but are critical in our understanding of the impact of global change on the cycling of mycorrhizal C. Finally, shifts in the community composition of arbuscular and ectomycorrhizal fungi with increasing CO # or N availability are frequently documented. Since mycorrhizal groups vary in growth rate and tissue quality, these changes in species assemblages could produce unforeseeable impacts on the productivity, survivorship, or decomposition of mycorrhizal biomass.

show abstract

Section: Elevated Comentioning

confidence: 99%

Mycorrhizal fungi have a potential role in soil carbon storage under elevated CO₂ and nitrogen deposition

2000

View full text Add to dashboard Cite

show abstract

“…In natural forest ecosystems, no data are available for uptake rates of specific root sections or hyphae (George & Marschner, 1996), though laboratory experiments assessing fungal biomass showed that production of extramatrical mycelium decreases with increasing N concentration (Wallander & Nylund, 1992). Since the Ho$ glwald site is exposed to high loads of N, it is unlikely that the rhizomorphs make a considerable contribution to nutrient uptake.…”

Section: mentioning

confidence: 99%

Field and laboratory experiments on net uptake of nitrate and ammonium by the roots of spruce (Picea abies) and beech (Fagus sylvatica) trees

et al. 1998

View full text Add to dashboard Cite

During the vegetation periods 1994 and 1995, net uptake of nitrate and ammonium by roots of adult spruce (Picea abies (L.) Karst) and beech (Fagus sylvatica L.) trees was studied at a field site exposed to high loads of N (' Ho$ glwald ', Germany). In addition, uptake experiments were carried out under controlled conditions with young spruce and beech trees grown at normal N supply.In the field, nitrate was not taken up by the roots of spruce trees in appreciable amounts. This was also true for beech except during September 1995. Apparently, beech trees was capable of taking up nitrate, but the environmental condition prevailing at the field site usually prevented net uptake. Net uptake of ammonium in both tree species showed a seasonal course, with maximum rates in mid summer. Rates of ammonium uptake by both species correlated with soil temperature at the field site.Laboratory experiments on the influence of root temperature on uptake of nitrate indicated that uptake rates at temperatures found in the field were low compared with the uptake capacity at optimum temperature. At temperatures of 10 and 15 mC, frequently found in the soil at the field site, net uptake of nitrate by spruce and beech amounted to c. 16 % and 11 %, respectively, of maximum uptake at 25 mC. By contrast, net uptake of ammonium at 10 mC reached 73 % and 31 % of the maximum uptake for spruce and beech trees, respectively. Independent of temperature, rates of nitrate uptake were considerably lower than those of ammonium. In young spruce and beech trees, net uptake of nitrate was significantly inhibited by ammonium at nitrate : ammonium ratios found in the soil solution at the forest site. Preincubation of roots of both species, with amino acids present in the phloem of adult trees at the field site, led to an increase in the amino acid pool in the roots. For spruce trees a correlation between inhibition of uptake of nitrate and enrichment of the roots with the amino compounds Glu, γ-amino butyric acid (Gaba), Gln, and Asn was observed. In beech trees, enrichment of Asp and Gln in the roots correlated with a decrease in net uptake of nitrate. The results of laboratory experiments on the effects of temperature, the nitrate to ammonium ratio in the nutrient solution, and amino acid enrichment in the roots are discussed with special emphasis on the patterns of net uptake of ammonium and nitrate observed in the field.Key words : Nitrate uptake, ammonium uptake, soil temperature, nitrate to ammonium ratio, amino acids. In forest ecosystems, nitrate and ammonium are the most abundant N compounds available to the roots * To whom correspondence should be addressed. E-mail : here!sun2.ruf.uni-freiburg.de of trees. Total amounts of nitrate and ammonium, and the ratio of nitrate to ammonia depend on quality and quantity of N input and on the balance of ammonification, nitrification, immobilization and denitrification processes in the soil (Haynes & Goh,

show abstract

“…Nevertheless, because the extraradical mycelium is the main ECM fungal component in terms of nutrient mobilization and supply to the host plant for several species (Read, 1984 ;Read, Francis & Finlay, 1985 ;Read, 1992 ;Rousseau, Sylvia & Fox, 1994 ;Bending & Read, 1995) more detailed field investigations are required. Laboratory experiments indicate a negative correlation between increasing N availability and development of the extraradical mycelium : Wallander & Nylund (1992) investigated the effect of excess N alone and in combination with P and Mg starvation in a semi-hydroponic cultivation system with Pinus sylvestris seedlings infected with Laccaria bicolor, Hebeloma crustuliniforme and Suillus bovinus. Whereas the mycelial biomass increased rapidly at concentrations of 0n7-1n4 m NH % + the production of extraradical mycelium by all species ceased in the presence of high N concentrations (14n3 m NH % + ).…”

Section:        mentioning

confidence: 99%

Nitrogen deposition and ectomycorrhizas

1998

View full text Add to dashboard Cite

As a result of increasing anthropogenic nitrogen deposition, N availability in many forest ecosystems, which are normally N-limited, has been enhanced. We discuss the impacts of this increased N availability on the ectomycorrhizal (ECM) symbiosis which is generally regarded as an adaptation to nutrient limited conditions. Nitrogen deposition can influence fruit-body formation by ECM fungi, the production and distribution of the extraradical mycelium in the soil and the formation of ectomycorrhizas.Available data from long-term N deposition studies indicate that the most prominent effects might be discernible above-ground (i.e. on the formation of fruit bodies). ' Generalist ' species, forming a symbiosis with a wide range of tree species, seem to be less affected by increased N availability than ' specialist ' species, especially those living in symbiosis with conifers. However, the importance of below-ground investigations to determine the impacts of N deposition on the ECM symbiosis must not be underestimated. Culture experiments show an optimum N concentration for the formation of extraradical mycelium and mycorrhizas. Often, negative effects only become visible at comparatively high N concentrations, but the use of a few easily cultivated species of ECM fungi, which are adapted to higher N concentrations, undermines our ability to generalize.So far, N deposition experiments in the field have only shown minor changes in the below-ground mycorrhizal population, as estimated from the investigation of mycorrhizal root tips. However, effects on the ECM mycelium, which is the main fungal component in terms of nutrient uptake, cannot be excluded and need further consideration.Because the photoassimilate supply from the plant to the fungal partner is crucial for the maintenance of the ECM symbiosis, we discuss the possible physiological implications of increasing N inputs on the allocation of C to the fungus. Together with ultrastructural changes, physiological effects might precede obvious visible changes and might therefore be useful early indicators of negative impacts of increasing N inputs on the ECM symbiosis.

show abstract

Effects of excess nitrogen and phosphorus starvation on the extramatrical mycelium of ectomycorrhizas of Pinus sylvestris L.

Cited by 216 publications

References 22 publications

Mycorrhizal fungi have a potential role in soil carbon storage under elevated CO₂ and nitrogen deposition

Mycorrhizal fungi have a potential role in soil carbon storage under elevated CO₂ and nitrogen deposition

Field and laboratory experiments on net uptake of nitrate and ammonium by the roots of spruce (Picea abies) and beech (Fagus sylvatica) trees

Nitrogen deposition and ectomycorrhizas

Contact Info

Product

Resources

About

Effects of excess nitrogen and phosphorus starvation on the extramatrical mycelium of ectomycorrhizas of Pinus sylvestris L.

Cited by 216 publications

References 22 publications

Mycorrhizal fungi have a potential role in soil carbon storage under elevated CO2 and nitrogen deposition

Mycorrhizal fungi have a potential role in soil carbon storage under elevated CO2 and nitrogen deposition

Field and laboratory experiments on net uptake of nitrate and ammonium by the roots of spruce (Picea abies) and beech (Fagus sylvatica) trees

Nitrogen deposition and ectomycorrhizas

Contact Info

Product

Resources

About

Mycorrhizal fungi have a potential role in soil carbon storage under elevated CO₂ and nitrogen deposition

Mycorrhizal fungi have a potential role in soil carbon storage under elevated CO₂ and nitrogen deposition