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  • 1
    Language: English
    In: Plant and Soil, Sept, 1999, Vol.209(2), p.115
    Description: Byline: Heinz Rennenberg (1) Keywords: allocation; beech; cysteine; Fagus sylvatica; glutathione; Laccaria laccata; methionine; mycorrhization; oak; phloem; Quercus robur; sulfate; sulfur; uptake; xylem; xylem loading Abstract: Sulfur nutrition of plants is largely determined by sulfate uptake of the roots, the allocation of sulfate to the sites of sulfate reduction and assimilation, the reduction of sulfate to sulfide and its assimilation into reduced sulfur-containing amino acids and peptides, and the allocation of reduced sulfur to growing tissues that are unable to fulfill their own demand for reduced sulfur in growth and development. Association of the roots of pedunculate oak (Quercus robur L.) and beech (Fagus sylvatica L.) trees with ectomycorrhizal fungi seems to interact with these processes of sulfur nutrition in different ways, but the result of these interactions is dependent on both the plant and the fungal partners. Mycorrhizal colonisation of the roots can alter the response of sulfate uptake to sulfate availability in the soil and enhances xylem loading and, hence, xylem transport of sulfate to the leaves. As a consequence, sulfate reduction in the leaves may increase. Simultaneously, sulfate reduction in the roots seems to be stimulated by ectomycorrhizal association. Increased sulfate reduction in the leaves of mycorrhizal trees can result in enhanced phloem transport of reduced sulfur from the leaves to the roots. Different from herbaceous plants, enhanced phloem allocation of reduced sulfur does not negatively affect sulfate uptake by the roots of trees. These interactions between mycorrhizal association and the processes involved in sulfur nutrition are required to provide sufficient amounts of reduced sulfur for increased protein synthesis that is used for the enhanced growth of trees frequently observed in response to ectomycorrhizal association. Author Affiliation: (1) Institut fur Forstbotanik und Baumphysiologie, Professur fur Baumphysiologie, Albert-Ludwigs-Universitat Freiburg, Am Flughafen 17, D-79085, Freiburg i.Br., Germany Article History: Registration Date: 28/09/2004
    ISSN: 0032-079X
    Source: Cengage Learning, Inc.
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  • 2
    Language: English
    In: Plant and Soil, 2013, Vol.364(1), pp.287-301
    Description: Background and aims: Nitrous oxide (N sub(2)O) and methane (CH sub(4)) can be emitted from surfaces of riparian plants. Data on the emission of these greenhouse gases by upland trees are scarce. We quantified CH sub(4) and N sub(2)O emissions from stems of Fagus sylvatica, an upland tree, and Alnus glutinosa, a riparian tree. Methods: The gas fluxes were investigated in mesocosms under non-flooded control conditions and during a flooding period using static chamber systems and gas chromatographic analyses. Results: Despite differences in the presence of an aerenchyma system, both tree species emitted N sub(2)O and CH sub(4) from the stems. Flooding caused a dramatic transient increase of N sub(2)O stem emissions by factors of 740 (A. glutinosa) and even 14,230 (F. sylvatica). Stem emissions of CH sub(4) were low and even deposition was determined (F. sylvatica controls). The results suggest that CH sub(4) was transported mainly through the aerenchyma, whereas N sub(2)O transport occurred in the xylem sap. Conclusions: For the first time it has been demonstrated that upland trees such as F. sylvatica clearly significantly emit N sub(2)O from their stems despite lacking an aerenchyma. If this result is confirmed in adult trees, upland forests may constitute a new and significant source of atmospheric N sub(2)O.
    Keywords: Methane ; Nitrous oxide ; Soil and stem emission ; Alnus glutinosa ; Fagus sylvatica ; Flooding
    ISSN: 0032-079X
    E-ISSN: 1573-5036
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  • 3
    Language: English
    In: Plant and Soil, 2013, Vol.368(1), pp.519-534
    Description: Background and aims: Litter decomposition is regulated by e.g. substrate quality and environmental factors, particularly water availability. The partitioning of nutrients released from litter between vegetation and soil microorganisms may, therefore, be affected by changing climate. This study aimed to elucidate the impact of litter type and drought on the fate of litter-derived N in beech seedlings and soil microbes. Methods: We quantified super(15)N recovery rates in plant and soil N pools by adding super(15)N-labelled leaf and/or root litter under controlled conditions. Results: Root litter was favoured over leaf litter for N acquisition by beech seedlings and soil microorganisms. Drought reduced super(15)N recovery from litter in seedlings thereby affecting root N nutrition. super(15)N accumulated in seedlings in different sinks depending on litter type. Conclusions: Root turnover appears to influence (a) N availability in the soil for plants and soil microbes and (b) N acquisition and retention despite a presumably extremely dynamic turnover of microbial biomass. Compared to soil microorganisms, beech seedlings represent a very minor short-term N sink, despite a potentially high N residence time. Furthermore, soil microbes constitute a significant N pool that can be released in the long term and, thus, may become available for N nutrition of plants.
    Keywords: Litter types ; Root litter ; Leaf litter ; Decomposition ; Microbial biomass ; Plant N metabolism ; Soil N pools ; N recovery
    ISSN: 0032-079X
    E-ISSN: 1573-5036
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  • 4
    Language: English
    In: Plant and Soil, 2010, Vol.332(1), pp.387-403
    Description: The root/shoot-ratio is a simple parameter to describe the systemic response of plants to alterations of their nutritional status, as indicated by the C/N-balance of leaves. The ‘functional equilibrium hypothesis’ holds that leaf growth is limited by the supply of nitrogen from the roots, whereas root growth depends on the carbon supply from leaves. The nature of the systemic control that balances root and shoot growth is not fully understood. Previous experiments have shown that root growth of transformed tobacco plants, which lack functional root nitrate reductase, was severely impeded, when plants were grown on NO 3 − as the sole N-source. In these experiments, the root/shoot-ratio was correlated with the Glutamate/Glutamine-ratio of roots. In the present study we tested the hypothesis that high internal Glu contents (in relation to Gln) inhibit root growth. Wild type and transformed tobacco plants were given access to both NH 4 and NO 3 , and were cultivated at ambient and elevated p CO 2 in order to vary carbon availability. The uptake and assimilation of NH 4 + by the root was significantly higher in transformed than in wild type tobacco, in particular at elevated p CO 2 . Consequently, the Glu/Gln-ratio in the root of transformants was significantly lower than in NO 3 − -grown plants, and was, in the present study, not different from the wild type. However, we failed to observe a correlation between plant architecture and the Glu/Gln-ratio of roots, suggesting that signals arising from the immediate products of nitrate reduction (nitrite) are involved in the systemic control of root growth. Furthermore the synthesis of root-derived signals, which affect N-turnover, starch re-mobilization and the growth of leaves, appears to be associated with root nitrate reduction. This enzymatic step seems to be indispensable for the systemic control of biomass partitioning, and plays a crucial role for the integration of carbon and nitrogen metabolism at the whole plant level.
    Keywords: Systemic control ; C/N-balance ; Root: shoot ratio ; Nitrate reduction ; Ammonium assimilation ; Glutamate signalling
    ISSN: 0032-079X
    E-ISSN: 1573-5036
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  • 5
    Language: English
    In: Plant and Soil, 2013, Vol.369(1), pp.657-668
    Description: Aims: Our aims were to characterize the fate of leaf-litter-derived nitrogen in the plant-soil-microbe system of a temperate beech forest of Southern Germany and to identify its importance for N nutrition of beech seedlings. Methods: super(15)N-labelled leaf litter was traced in situ into abiotic and biotic N pools in mineral soil as well as into beech seedlings and mycorrhizal root tips over three growing seasons. Results: There was a rapid transfer of super(15)N into the mineral soil already 21 days after tracer application with soil microbial biomass initially representing the dominant litter-N sink. However, super(15)N recovery in non-extractable soil N pools strongly increased over time and subsequently became the dominant super(15)N sink. Recovery in plant biomass accounted for only 0.025 % of super(15)N excess after 876 days. After three growing seasons, super(15)N excess recovery was characterized by the following sequence: non-extractable soil N〉〉extractable soil N including microbial biomass〉〉plant biomass〉ectomycorrhizal root tips. Conclusions: After quick vertical dislocation and cycling through microbial N pools, there was a rapid stabilization of leaf-litter-derived N in non-extractable N pools of the mineral soil. Very low super(15)N recovery in beech seedlings suggests a high importance of other N sources such as root litter for N nutrition of beech understorey.
    Keywords: Nitrogen cycling ; Beech ; 15N-labelled leaf litter ; 15N tracing ; Microbial biomass ; Ectomycorrhiza
    ISSN: 0032-079X
    E-ISSN: 1573-5036
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  • 6
    Language: English
    In: Plant and Soil, May, 2002, Vol.242(1), p.291
    Description: Byline: Stefan Seegmuller (1), Heinz Rennenberg (1) Keywords: glutamine; glutathione; GSH; Laccaria laccata; oak; Quercus robur; roots; uptake; xylem loading Abstract: Uptake and xylem loading of organic sulfur and nitrogen were analyzed in detached mycorrhizal (Laccaria laccata L.) roots of pedunculate oak (Quercus robur L.) seedlings using radiolabeled reduced glutathione (GSH) and glutamine (Gln) for transport analyses. The experiments showed for the first time that GSH is taken up by plant roots from the nutrient solution and is partially allocated to the shoot. Apparently, GSH produced during mineralization processes in the soil can be used by plant roots as a sulfur source. GSH uptake into the roots showed biphasic kinetics within the concentration range studied (0--500 uM) with maximum transport velocities (v .sub.max) and substrate affinities (K .sub.m) that were similar to the kinetics of Gln uptake. GSH uptake kinetics were also in the same range as previously reported for sulfate uptake by mycorrhizal roots of pedunculate oak. It may therefore be assumed that GSH and sulfate uptake can be of comparable significance for sulfur nutrition, provided both sulfur sources are available at similar concentrations at the sites of uptake. Xylem loading of GSH and Gln showed monophasic transport kinetics with v .sub.max significantly lower than observed for the two respective uptake systems and, as indicated by the K .sub.m-values, a substrate affinity between the high and the low affinity uptake systems. The possible nature of the transport systems for GSH and Gln is discussed. Author Affiliation: (1) Institut fur Forstbotanik und Baumphysiologie, Professur fur Baumphysiologie, Albert-Ludwigs-Universitat, Freiburg Georges-Kohler-Allee 053/054, D-79110, Freiburg i.Br., Germany Article History: Registration Date: 13/10/2004
    ISSN: 0032-079X
    Source: Cengage Learning, Inc.
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  • 7
    Language: English
    In: Plant and Soil, 1999, Vol.215(2), pp.115-122
    Description: Sulfur nutrition of plants is largely determined by sulfate uptake of the roots, the allocation of sulfate to the sites of sulfate reduction and assimilation, the reduction of sulfate to sulfide and its assimilation into reduced sulfur-containing amino acids and peptides, and the allocation of reduced sulfur to growing tissues that are unable to fulfill their own demand for reduced sulfur in growth and development. Association of the roots of pedunculate oak (Quercus robur L.) and beech (Fagus sylvatica L.) trees with ectomycorrhizal fungi seems to interact with these processes of sulfur nutrition in different ways, but the result of these interactions is dependent on both the plant and the fungal partners. Mycorrhizal colonisation of the roots can alter the response of sulfate uptake to sulfate availability in the soil and enhances xylem loading and, hence, xylem transport of sulfate to the leaves. As a consequence, sulfate reduction in the leaves may increase. Simultaneously, sulfate reduction in the roots seems to be stimulated by ectomycorrhizal association. Increased sulfate reduction in the leaves of mycorrhizal trees can result in enhanced phloem transport of reduced sulfur from the leaves to the roots. Different from herbaceous plants, enhanced phloem allocation of reduced sulfur does not negatively affect sulfate uptake by the roots of trees. These interactions between mycorrhizal association and the processes involved in sulfur nutrition are required to provide sufficient amounts of reduced sulfur for increased protein synthesis that is used for the enhanced growth of trees frequently observed in response to ectomycorrhizal association.
    Keywords: allocation ; beech ; cysteine ; Fagus sylvatica ; glutathione ; Laccaria laccata ; methionine ; mycorrhization ; oak ; phloem ; Quercus robur ; sulfate ; sulfur ; uptake ; xylem ; xylem loading
    ISSN: 0032-079X
    E-ISSN: 1573-5036
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  • 8
    Language: English
    In: Plant and Soil, 2002, Vol.240(1), pp.23-32
    Description: Differences in ammonium net uptake by the roots of beech ( Fagus sylvatica L.) and spruce ( Picea abies (L.) Karst) trees between day and night were examined during the growing seasons in 1995 and 1996 using the depletion technique. In addition, diurnal courses of ammonium net uptake of both species were analysed in five sets of uptake experiments in May and September 1997 and were related (1) to the content of carbohydrates, organic acids and total soluble non protein N (TSNN) in the fine roots, and (2) to xylem flow densities and soil temperature. During the growing seasons 1995 and 1996, ammonium net uptake of beech was significantly lower during the night than during the day at 5 of 8 dates of measurement. On average, uptake rates during the night amounted to 50% of the uptake rates during the day. In spruce, the mean values of ammonium net uptake rates determined were similar between day and night during both growing seasons. In beech, the assessment of diurnal courses showed highest ammonium uptake rates during noon and in the afternoon and minima at midnight. In May 1997, comparable, but less pronounced diurnal patterns of ammonium uptake were observed in spruce, whereas in September 1997, ammonium uptake by spruce was constant during the day. Since no distinct differences in carbohydrate and organic acid contents in fine roots were observed during the diurnal courses and since the addition of sucrose into the artificial soil solutions root tips were exposed to did not alter ammonium uptake, depression of uptake by C- and/or energy limitation during night could be excluded. The TSNN contents in the fine roots of beech (May and September 1997) and spruce (May 1997) showed a diurnal pattern inverse to ammonium uptake. It is concluded that the enrichment of TSNN compounds during night that is apparently caused by a reduction of xylem transport is responsible for the down-regulation of ammonium net-uptake.
    Keywords: carbohydrates ; N compounds ; organic acids ; regulation ; xylem flow
    ISSN: 0032-079X
    E-ISSN: 1573-5036
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  • 9
    Language: English
    In: Plant and Soil, March, 1996, Vol.180(2), p.197
    Description: Byline: Paul Weber (2), Heinz Rennenberg (2) Keywords: dynamic chamber; gas exchange; nitrogen dioxide; nitric oxide; wheat canopy monolith Abstract: The fluxes of NO and NO.sub.2 between wheat canopy monoliths and the atmosphere were investigated with the dynamic chamber technique. For this purpose monoliths were dug out at different plant growth stages from a field site, transported to the institute, and placed in an environmental growth chamber. The wheat canopy monoliths were exposed over a period of four days to the average ratios of atmospheric NO.sub.2 and NO measured at the field site, i.e. NO.sub.2 concentration of about 18 mL L.sup.-1 plus NO concentration lower than 0.5 nL L.sup.-1. Under these conditions NO emission into the atmosphere and NO.sub.2 deposition into canopy monoliths was observed. Both fluxes showed diurnal variation with maximum rates during the light and minimum rates during darkness. NO.sub.2 fluxes correlated with soil temperature as well as with light intensity. NO fluxes correlated with soil temperature but not with light intensity. From the investigation performed the diurnal variation of the NO and NO.sub.2 compensation points, the maximum rates of NO and NO.sub.2 emission, and the total resistances of NO and NO.sub.2 fluxes were calculated. Under the assumption that the measured data are representative for the whole vegetation period, annual fluxes of NO and NO.sub.2 were estimated. Annual NO emission into the atmosphere amounted to 87 mg N m.sup.-2 y.sup.-1 (0.87 kg ha.sup.-1 y.sup.-1), annual NO.sub.2 deposition into canopy monoliths amounted to 1273 mg N m.sup.-2 y.sup.-1 (12.73 kg ha.sup.-1 y.sup.-1). Apparently, the uptake of atmospheric nitrogen by the wheat field from NO.sub.2 deposition is about 15 times higher than the loss of nitrogen from NO emission. It can therefore be assumed that even in rural areas wheat fields are a considerable sink for atmospheric nitrogen. The annual sink strength estimated in the present study is ca. 12 kg N ha.sup.-1 y.sup.-1. The possible origin of the NO emitted and the fate of atmospheric NO.sub.2 taken up by the wheat canopy monoliths are discussed. Author Affiliation: (2) Fraunhofer-Institut fur Atmospharische Umweltforschung, Kreuzeckbahn str. 19, D-82467, Garmisch-Partenkirchen, Germany (3) Institut fur Forstbotanik und Baumphysiologie, Professur fur Baumphysiologie, Albert-Ludwigs-Universitat Freiburg, Am Flughafen 1.7, D-79085, Freiburg i. Br., Germany Article History: Registration Date: 07/04/2004 Received Date: 11/08/1995 Accepted Date: 18/12/1995 Article note: Preliminary results of this paper were presented at the Joint Workshop COST 611/Working Party 3 and EUROTRAC in Delft, The Netherlands (Ludwig et al., 1991).
    Keywords: Wheat ; Nitric Oxide
    ISSN: 0032-079X
    Source: Cengage Learning, Inc.
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  • 10
    Language: English
    In: Plant and Soil, 2017, Vol.418(1), pp.89-114
    Description: Background For 15+ years, a beech (Fagus sylvatica L.) dominated forest on calcareous soil was studied on two opposing slopes with contrasting microclimate in Tuttlingen, Swabian Alb, Germany. The cool-humid NE aspect of these slopes represents the majority of beech forests under current climate, the warmer and drier SW aspect represents beech forests under future climate conditions. The field studies were supplemented by investigations under controlled conditions. Scope The research program aimed to provide a comprehensive understanding of plant-soil-microbe water, carbon and nitrogen feedbacks in a changing climate and a holistic view of the sensitivity of beech to climate change. Conclusions The results of comparative and experimental studies underpin the high vulnerability of adult beech and its natural regeneration on calcareous soil to both direct climate change effects on plant physiology and indirect effects mediated by soil biogeochemical cycles. Mechanisms contributing to this vulnerability at the ecosystem and organismic level indicate a high significance of competitive interactions of beech with other vegetation components and soil microbial communities. Obvious forest management practices such as selective felling did not necessarily counteract negative effects of climate change.
    Keywords: Climate extremes ; Competition ; Forest management strategies ; Girdling ; Rhizodeposition and mycorrhiza ; Thinning
    ISSN: 0032-079X
    E-ISSN: 1573-5036
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