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  • 1
    Language: English
    In: Science of the Total Environment, 01 September 2018, Vol.634, pp.305-315
    Description: The leaching of P from the upper 20 cm of forest topsoils influences nutrient (re-)cycling and the redistribution of available phosphate and organic P forms. However, the effective leaching of colloids and associated P forms from forest topsoils was so far sparsely investigated. We demonstrated through irrigation experiments with undisturbed mesocosm soil columns, that significant proportions of P leached from acidic forest topsoils were associated with natural colloids. These colloids had a maximum size of 400 nm. By means of Field-flow fractionation the leached soil colloids could be separated into three size fractions. The size and composition was comparable to colloids present in acidic forest streams known from literature. The composition of leached colloids of the three size classes was dominated by organic carbon. Furthermore, these colloids contained large concentrations of P which amounted between 12 and 91% of the totally leached P depending on the type of the forest soil. The fraction of other elements leached with colloids ranged between 1% and 25% (Fe: 1–25%; C : 3–17%; Al: 〈4%; Si, Ca, Mn: all 〈2%). The proportion of colloid–associated P decreased with increasing total P leaching. Leaching of total and colloid-associated P from the forest surface soil did not increase with increasing bulk soil P concentrations and were also not related to tree species. The present study highlighted that colloid-facilitated P leaching can be of higher relevance for the P leaching from forest surface soils than dissolved P and should not be neglected in soil water flux studies.
    Keywords: Colloids ; Forest Soil ; Leaching ; Mesocosm ; Nanoparticles ; Phosphorus ; Environmental Sciences ; Biology ; Public Health
    ISSN: 0048-9697
    E-ISSN: 1879-1026
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  • 2
    Language: English
    In: Journal of Plant Nutrition and Soil Science, June 2001, Vol.164(3), pp.253-258
    Description: The McIntyre and Phillip method yields the product of a gas‐diffusion coefficient (D) and the gas‐filled proportion of soil volume ε. Until now, ε had to be measured independently from soil cores in order to obtain D. To avoid soil sampling, we broke up chamber measurement results by means of an empirical relationship D= f(ε). In contrast to an exclusive use of such an empirical relationship, this approach is advantageous in that the site‐specific information concerning pore continuity is integrated into the result. Another modification involves the use of a non‐linear regression technique, which fits the unknown parameters of the mechanistic dilution function of the tracer gas to the measured values. In this way, the independent measurement of chamber clearance with a ruler could be replaced with an estimation based on the dilution function. We could then show, by means of a Monte Carlo simulation, that the exponential parameter of the dilution function contributes to the highest error of the diffusion coefficient estimation from the 6 input parameters. We then compared the results of the following methods at 6 sites. The methods included: (a) the approach described above, (b) the laboratory measurement on soil cores, and (c) the original McIntyre and Philip method. This method is a combination of in‐situ chamber measurement and laboratory measurement of the air‐filled soil fraction. We did not detect any significant differences in the means of our method (a) in any of the aforementioned cases, as well as in the laboratory measurement (b). Deviations between individual measurements could be attributed to differences in spatial integration. These deviations are a result of scale‐dependent spatial heterogeneity and thereby provide site‐specific information on soil structure. Ein modifizierter McIntyre‐and‐Phillip‐Ansatz zur in‐situ Bestimmung der Gasdiffusivität von Oberböden Die Methode von McIntyre und Phillip zur Bestimmung von Bodengasdiffusionskoeffizienten in‐situ liefert als eigentliches Messergebnis das Produkt aus Gasdiffusionskoeffizient (D) und luftgefülltem Bodenanteil (ε). Um den D zu erhalten, musste ε bisher an zusätzlich entnommenen Stechzylindern bestimmt werden. Wir extrahieren aus dem Ergebnis der Kammermessung den Diffusionskoeffizienten mit Hilfe eines empirischen Zusammenhangs D = f(ε). Da auch Informationen über die standortspezifische Porenkontinuität mit in die Schätzung des Diffusionskoeffizienten einfließen, ist dieses Vorgehen der rein empirischen Abschätzung von D aus ε überlegen. Eine weitere Modifikation liegt in der Verwendung eines nicht‐linearen Regressionsverfahrens zur Anpassung der unbekannten Parameter der mechanistischen Verdünnungsfunktion an die Messwerte. Damit konnte die bei rauen Waldbodenoberflächen problematische Bestimmung des lichten Kammervolumens durch Längenmessung überflüssig gemacht werden. Mit einer Monte‐Carlo‐Simulation konnten wir unter der Annahme normalverteilter Fehler zeigen, dass von den 6 Eingangsparametern der Steigungsparameter der Verdünnungskurve des Tracer‐Gases die größte Streuung der Ergebnisse bewirkt. Zur Prüfung der Methode wurden an 6 Waldstandorten verglichen: (a) der oben beschriebene Ansatz, (b) die Labormessung an Stechzylindern und (c) die ursprüngliche Methode, bei der die Kammermessung mit der Stechzylinderprobe zur Luftvolumenbestimmung kombiniert wird. In keinem Fall konnten wir signifikante Unterschiede im Mittelwert zwischen der von uns entwickelten Methode a) und der Labormessung b) finden. Ursache der zum Teil erheblichen Abweichungen der Einzelwerte ist wahrscheinlich die unterschiedliche räumliche Integration. Damit sind sie Ausdruck der skalenabhängigen räumlichen Heterogenität der Böden und enthalten somit standortspezifische Strukturinformationen.
    Keywords: Gas Diffusion Coefficient ; In‐Situ Measurement ; Closed Chamber ; Volume Estimation ; Non‐Linear Regression ; Analytical Solution
    ISSN: 1436-8730
    E-ISSN: 1522-2624
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  • 3
    Language: English
    In: Forest Ecology and Management, 2002, Vol.159(1), pp.15-25
    Description: In middle-European silviculture, oak species are largely used for restoration of wind-thrown spruce stands on dense or badly aerated soils. However, vitality of mature oak stands have decreased in the last decade. Symptoms of fine root degeneration as well as soil structure deficiencies in the upper layer have been observed. This study tested the working hypothesis that deficiencies in soil gas permeability reduce fine root formation and thereby reduce stress tolerance of trees. Topsoil gas diffusivity, root density and oak vitality were assessed for 36 oak stands with pedunculate oak (Quercus robur L.) and sessile oak (Quercus petraea [Matt.] Liebl.). The relationship between topsoil gas diffusivity, soil respiration and soil CO sub(2) concentration were also investigated. Evidence that root density decreases significantly with decreasing soil gas permeability was found, which is representative for oak stands at southwest Germany. Heavily damaged oak stands have been found only at sites suffering from soil aeration deficiencies. Although, we observed decreased soil respiration in compacted soils, CO sub(2) concentration in soil was up to three times higher on these sites. High soil CO sub(2) concentrations indicate insufficient soil aeration rather than high biological activity. Insufficient soil aeration is apparently an important factor causing oak decline. It cannot be, therefore, concluded from the oak's ability to open up dense subsoils that they can be used for the restoration of stands with compacted topsoils.
    Keywords: Oak Decline ; Soil Aeration ; Fine Roots ; Gas-Diffusion Coefficient ; Soil Air Carbon Dioxide ; Soil Respiration ; Forestry ; Biology
    ISSN: 0378-1127
    E-ISSN: 1872-7042
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  • 4
    Language: English
    In: Plant and Soil, 2000, Vol.224(2), pp.195-205
    Description: The external mycelium forms the major part of the absorbing surface of mycorrhized tree roots. Because the macro pore space of acid forest soils is selectively depleted of mobile nutrient cations, it is ecologically important, whether soil hyphae grow into the soil aggregates or not. Seedlings of Norway Spruce ( Picea abies (L.) Karst.) with defined mycorrhiza were grown in unsterilized soil cores taken from the A and B-horizon of a limed and an unlimed cambisol on triassic sandstone in the Northern Black Forest, Germany. Water-tension treatments were 10, 30, 160 and 900 hPa. On ground and polished vertical cuts stained with acridine orange, we identified and measured the location of hyphae and characterized their micropedological environment using an image analyzing system. Mean length density varied between 17 m/cm 3 and 100 m/cm 3 and was independent of aeration parameters. The percentage of hyphae completely embedded in the soil matrix varied between 30% and 8% and decreased significantly with increasing CO 2 concentration in the soil air. Of the hyphae in the soil matrix, 70% were located in a 50 μm shell around the macro pores. Pair correlation functions show, that the majority of soil hyphae occur in clusters with diameters below 100 μm. Between 60% and 80% of randomly chosen circles with 250 μm diameters were completely devoid of hyphae. The inefficient opening up of the intra-aggregate space by soil hyphae is explained by the very slow oxygen diffusion between air-filled macro pores and the intra-aggregate space and mechanical restrictions for hyphae growth.
    Keywords: aeration ; external mycelium ; macro pores ; micromorphology ; mycorrhiza
    ISSN: 0032-079X
    E-ISSN: 1573-5036
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  • 5
    Language: German
    In: Zeitschrift für Pflanzenernährung und Bodenkunde, 1993, Vol.156(4), pp.307-310
    Description: Es wird ein vertikal hochauflösendes, auf Partialdruckdifferenzen beruhendes Sammelsystem für Bodenluft beschrieben. In verschiedenen Tiefen wird das gasgefüllte Porenkontinuum des Bodens an ein He‐gefülltes Sammelgefäß angeschlossen, das als diffusive Senke wirkt. Die trennbare Verbindung zwischen dem Gasraum des Bodens in Form einer künstlichen Makropore und dem Probengefäß erfolgt über eine Kanüle, auf die das mit einem Septum verschlossene Probengefäß aufgesetzt wird. Inertes Helium als vorgelegtes Austauschgas bewirkt eine rasche Füllung des Probengefäßes mit der Bodengleichgewichtsatmosphäre. Aufgrund der diffusiven Gleichgewichtseinstellung besitzt das Bodenluftaliquot im Probengefäß einen genauen, das heißt durch die Position der künstlichen Makropore definierten Tiefenbezug. Soil gas sampling avoiding mass‐flow A soil atmosphere sampling device based upon partial pressure gradients is presented. In different soil depths, the air filled pore volume is connected with a He‐filled sampling vessel, which acts as a diffusive sink. A separable connection between the aerated soil space (represented by an artificial macropore) and the sampling vessel is achieved by a cannula upon which the vessel, closed by a septum seal, is placed. Inert He as counter gas causes the sampling vessel to fill rapidly with the equilibrium soil atmosphere. As only diffusive transport accounts for sampling, the atmosphere aliquot in the vessel can spatially be attributed exactly to the localisation of the artificial macropore.
    ISSN: 0044-3263
    E-ISSN: 1522-2624
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  • 6
    Language: English
    In: Hydrological Processes, 15 June 2000, Vol.14(8), pp.1439-1448
    Description: The stable isotope oxygen‐18 is often used as a natural tracer in stream‐flow separation studies in forested catchments. Knowledge about the O content of throughfall and soil water is needed. The present study was conducted in order to assess the effect of vegetation structure on the stable isotope O composition of rainwater input during its passage through the canopy and into the unsaturated zone. The research area was a small (0\1 km) forested catchment in the mountainous ‘Black Forest’ region of southern Germany. During the 3‐month periods (September to December 1995 and April to July 1996) several structural units were instrumented according to tree species (beech and spruce) and canopy density. Overall throughfall was enriched compared with open rainfall by +0\38‰ and +0\36‰ for spruce and beech, respectively. Considerable differences existed in the results of the crown centre and the crown periphery sites. Throughfall in the crown centre showed a higher degree of enrichment, with a mean value of +0\30‰ for beech and +0\37‰ for spruce. Enrichment and depletion were observed in the lower canopy density locations. Mean results of the crown periphery were similar to those of open precipitation (+0\15‰ for beech and −0\01‰ for spruce). Soil water was sampled at five different depths (0, 15, 60, 120 and 180 cm). The signals of individual rainfall events could be traced down to a depth of 60 cm. The soil water in the upper layers followed the seasonal trend in the precipitation input. At a depth of 180 cm, soil water had a very constant δO value. The O composition of the soil water at various depths at different locations showed a similar behaviour. No detectable differences could be found between the structural units in the different layers, except at 180 cm depth. This might be attributed to downslope directed flow at that depth. Copyright © 2000 John Wiley & Sons, Ltd.
    Keywords: Forest Heterogeneity ; Oxygen‐18 ; Throughfall ; Soil Water ; Enrichment
    ISSN: 0885-6087
    E-ISSN: 1099-1085
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  • 7
    Language: English
    In: Zeitschrift für Pflanzenernährung und Bodenkunde, 04/1998, Vol.161(2), pp.179-185
    Keywords: Soils ; Hydrogeology ; Accuracy ; Correlation ; Dielectric Constant ; Electrical Methods ; Experimental Studies ; Forest Soils ; Frequency Domain Analysis ; Geophysical Methods ; In Situ ; Laboratory Studies ; Moisture ; Soils ; Thermal Analysis ; Thermogravimetric Analysis ; Time Domain Reflectometry;
    ISSN: Zeitschrift für Pflanzenernährung und Bodenkunde
    E-ISSN: 00443263
    Source: Wiley (via CrossRef)
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  • 8
    Article
    Article
    Language: German
    In: Fresenius' Zeitschrift für analytische Chemie, 1958, Vol.161(6), pp.439-440
    ISSN: 0016-1152
    E-ISSN: 1618-2650
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  • 9
    Article
    Article
    Language: German
    In: Fresenius' Zeitschrift für analytische Chemie, 1958, Vol.162(1), pp.62-64
    ISSN: 0016-1152
    E-ISSN: 1618-2650
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  • 10
    Article
    Article
    Language: German
    In: Fresenius' Zeitschrift für analytische Chemie, 1959, Vol.165(6), pp.452-453
    ISSN: 0016-1152
    E-ISSN: 1618-2650
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