Conversion of 15N-ammonium in forest soils

Stams, A.J.M.; Schipholt, I.J. Lutke; Marnette, E.C.L.; Beemsterboer, B.; Woittiez, J. R. W.

doi:10.1007/bf00010752

“…Organic nitrogen is the predominant form of N in most temperate forest soils [30,31]. In one calcareous and two acid forest soils the proportion of organic N was more than 95% of the total [30].…”

Section: Forms Of Organic Nitrogen Available In Forest Soilsmentioning

confidence: 99%

Physiology of organic nitrogen acquisition by ectomycorrhizal fungi and ectomycorrhizas

Chalot¹

1998

FEMS Microbiology Reviews

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Ectomycorrhizal fungi are symbiotically associated microorganisms which ecological importance has been repeatedly demonstrated. There has been a considerable amount of research aimed at assessing the ability of ectomycorrhizal fungi and ectomycorrhizas to utilize organic nitrogen sources. The fate of soil proteins, peptides and amino acids has been studied from a number of perspectives. Exocellular hydrolytic enzymes have been detected and characterized in a number of ectomycorrhizal and ericoid fungi. Studies on amino acid transport through the plasma membrane have demonstrated the ability of ectomycorrhizal fungi to take up the products of proteolytic activities. Investigations on intracellular metabolism of amino acids have allowed the identification of the metabolic pathways involved. Possible intracellular compartmentation of amino acids will be examined by immunocytochemistry. Further translocation of amino acids in symbiotic tissues has been established by experiments using isotopic tracers, although the exact nature of the nitrogenous compounds transferred at the symbiotic interface remained unclear. One of the main future challenges in the physiology of organic nitrogen acquisition is to determine the nature, the regulation and the location of N-compound transporters at the soil-fungus and fungus-plant interfaces. The molecular approach which is just emerging in this particular research area will greatly improve our knowledge. Future research should also address the extent of competition between different ectomycorrhizal species and between different microbial populations for organic nitrogen.

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“…Organic nitrogen is the predominant form of N in most temperate forest soils [30, 31]. In one calcareous and two acid forest soils the proportion of organic N was more than 95% of the total [30].…”

Section: Extracellular Degradation Of Organic Nitrogen Compoundsmentioning

confidence: 99%

Physiology of organic nitrogen acquisition by ectomycorrhizal fungi and ectomycorrhizas

Chalot¹,

Brun²

1998

FEMS Microbiology Reviews

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Ectomycorrhizal fungi are symbiotically associated microorganisms which ecological importance has been repeatedly demonstrated. There has been a considerable amount of research aimed at assessing the ability of ectomycorrhizal fungi and ectomycorrhizas to utilize organic nitrogen sources. The fate of soil proteins, peptides and amino acids has been studied from a number of perspectives. Exocellular hydrolytic enzymes have been detected and characterized in a number of ectomycorrhizal and ericoid fungi. Studies on amino acid transport through the plasma membrane have demonstrated the ability of ectomycorrhizal fungi to take up the products of proteolytic activities. Investigations on intracellular metabolism of amino acids have allowed the identification of the metabolic pathways involved. Possible intracellular compartmentation of amino acids will be examined by immunocytochemistry. Further translocation of amino acids in symbiotic tissues has been established by experiments using isotopic tracers, although the exact nature of the nitrogenous compounds transferred at the symbiotic interface remained unclear. One of the main future challenges in the physiology of organic nitrogen acquisition is to determine the nature, the regulation and the location of N-compound transporters at the soil-fungus and fungus-plant interfaces. The molecular approach which is just emerging in this particular research area will greatly improve our knowledge. Future research should also address the extent of competition between different ectomycorrhizal species and between different microbial populations for organic nitrogen.

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“…This shift in approach to the study of nitrogen mineralization has been made possible by technological advances (faster colorimetric analysis of inorganic-N by Flow Injection Analysis and the ready availability and relatively cheap price of isotopes and mass spectrometers) and has benefited greatly from new techniques (for example, fumigation methods for microbial biomass, carbon, nitrogen and phosphorus; see review by Parkinson & Coleman, 1991 For many years it was thought that nitrification was negligible in soils of low pH; there are now numerous reports of nitrification in forest soils of pH less than 5 (e.g. Williams, 1972;Remade, 1977;Van Miegrot & Cole, 1985;Adams & Attiwill, 19866;Van Breemen, De Visser & Van Grinsven 1986;Becquer et al, 1990;Stams et al, 1990). Together with the observations of nitrification in acidic heathland, grassland and woodland soils, these results have prompted studies which have demonstrated :…”

Section: Phosphorus Cycling and Availability In Forest Soilsmentioning

confidence: 99%

“…(i) That heterotrophic nitrification is a significant process (Schimel, Firestone & Killham, 1984, Adams 1986Stroo, Klein & Alexander, 1986 Stams et al, 1990;Stams et al, 1991).…”

Section: Phosphorus Cycling and Availability In Forest Soilsmentioning

confidence: 99%

Nutrient cycling in forests

Attiwill

¹

,

Adams

²

1993

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SUMMARY Studies of nutrient cycling in forests span more than 100 yr. In earlier years, most attention was given to the measurement of the pools of nutrients in plants and soil and of the return of nutrients from plant to soil in litterfall. The past 20 yr or so have seen a major concentration on the processes of nutrient cycling, with particular emphasis on those processes by which the supply of nutrients to the growing forest is sustained. In the more highly productive forests, up to 10 tonnes of litter of low nutritional quality is deposited annually on the forest floor. The decomposition of this litter, the mineralization of the nutrients it holds, and the uptake of nutrients by tree roots in the carbon‐rich environment which results are the themes of this review. Studies of decomposition of litter in forests have been dominated by the role of nitrogen as a limiting factor, a domination which reflects the preponderance of studies of temperate forests in the Northern Hemisphere. For many forests of the world growing on soils of considerable age, it seems more probable that growth and nutrient cycling are limited by phosphorus (or some other element). There is increasing evidence for a number of forests that phosphorus is immobilized in the first stages of decomposition to a significantly greater extent than is nitrogen. Advances in research will depend, as with studies of soil organic matter, in denning and developing analytical techniques for studying biologically active forms of potentially limiting nutrients, rather than total elemental concentrations. The availability of phosphorus in forests is sustained by phosphorus cycling. More than 50% of the total phosphorus in the surface soils is in organic forms and much of the more labile phosphorus is in the form of diesters. Phosphorus availability is determined by competition between biological and geochemical sinks, and it is clear that the sinks in the rhizosphere (plant roots, microorganisms, soil mineral and organic components) are extensively modified by active processes (e.g. production of exudates, nutrient storage in a variety of organic or polymeric forms and nutrient transport away from sites of uptake). There is abundant evidence that roots of many species exude compounds which have the ability to solubilize sources of phosphorus of otherwise low availability. The significance of root exudates (for example, phosphatases, organic acids) in the functioning of perennial ecosystems has yet to be quantified and there are conflicting reports as to the effects of simple organic acids on phosphorus availability. The distribution of phosphorus sinks and their relative competitiveness and their modification are topics of fundamental importance for future research. In contrast to the mineralization of phosphorus, our knowledge of transformations and availability of nitrogen in forest soils is well‐developed. Net nitrogen mineralization rates approximate rates of nitrogen return in litterfall but the contribution of nitrification is variable. Nitrification is ...

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Conversion of 15N-ammonium in forest soils

Cited by 14 publications

References 12 publications

Physiology of organic nitrogen acquisition by ectomycorrhizal fungi and ectomycorrhizas

Physiology of organic nitrogen acquisition by ectomycorrhizal fungi and ectomycorrhizas

Physiology of organic nitrogen acquisition by ectomycorrhizal fungi and ectomycorrhizas

Nutrient cycling in forests

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