Karl Josef Meiwes

Parameters for describing soil acidification and their relevance to the stability of forest ecosystems

Abstract A theoretical description of the soil processes involved in the buffering of protons has been used as the basis for a grouping of forest soil into various buffering ranges. Such a grouping provides a framework for studying the response of the system to acidification. This response is described in terms of the elasticity (resilience) of the system to the generation and buffering of protons. A number of soil, humus and root parameters are suggested as measures of the ‘elasticity’ of soils. The soil chemical parameters include the proportion of calcium in the exchange complex, the effective cation exchange capacity (CECe), H + Fe as fractions of the CECe and the molar ratios of base cations/acid cations in the solution phase. The Ca/Al ratio in both the humus layer (OH horizon) and the fine roots are suggested as other measures of the elasticity of the soil system. A number of recommendations to forest managers are provided concerning the application of major plant nutrients and lime to acid forest soils of Central Europe. Liming is discussed in relation to: (a) growing forest stands — to compensate for the incoming acidity and (b) application at the time of establishment as a part of the ameliorative measures to improve the chemical status of forest soils.

Effects of fertilization on the fluxes of chemical elements through different forest ecosystems

SummaryThe effects of N−K fertilization and of liming on the fluxes of chemical elements within forest ecosystems were followed in a beech and a spruce stand in the German Solling region.No effect on the chemistry of throughfall was obvious except for K (beech). N added in form of nitrate to the humus layer was transferred rapidly into the mineral soil and was nearly totally lost from the soil of the spruce stand while the beech stand took up considerable amounts of nitrate. No nitrification of the NH4−N added occurred within the humus layer of both stands. The input of K and NH4 caused a strong acidification push within the mineral soil due to the exchange of Al-ions and led to heavy losses mainly of Al and Mn with seepage water.Liming caused increased rates of NO3−N losses under both stands but was followed by a significant reduction of the output of Al, Mn and SO4 under the spruce stand as compared to the unfertilized stand. Only a slight reduction was found under beech.The ratio of Ca/Al in the soil solution was substantially raised after liming.

Distribution and cycling of sulphur in the vegetation of two forest ecosystems in an acid rain environment

SummaryIn the acid rain environment of northwest Germany the spruce ecosystem receives significantly higher amounts of atmospheric S input than the beech system. This leads to greater retention of sulphur by vegetation, litter and soil under spruce. However it does not cause any significant change in fluxes such as plant uptake, plant leaching and litter removal of sulphur. The higher amount of sulphur in the vegetation component of the spruce ecosystem is mainly due to a longer retention of foliage by spruce. N:S ratios of the spruce foliage decreased with age indicating that a significant quantity of sulphur in the foliage is accumulated as sulphate. This sulphate appears to be leached out of the leaf at senescence, and amounts to about 2 kg S ha−1 year−1.

Chemical composition of throughfall, soil water, leaves and leaf litter in a beech forest receiving long term application of ammonium sulphate

Nitrogen deposition in the range of 10–40 kg N ha-1 a-1 is common in large parts of Europe. Substancial amounts are deposited as NH4+ having fertilization and acidification effects in ecosystems. In a long term experiment the reactions of different compartments of a forest ecosystem were studied when the system became N saturated by continuously applying (NH4)2SO4. The experiment was conducted in a beech forest and the application of 10 kmolc N ha-1 a-1 lasted 11 yr from 1983 till 1993.The results revealed that despite the high soil acidity, the applied NH4+ was quickly oxidized to NO3- in the surface 10 cm soil layer and leached to deeper depths. The amount of NO3- leached from the surface soil increased during the initial three years and remained constant on a high level for the rest of the experimental period. Nitrification was associated with acidification of the soil solution, causing high concentrations of Al and Mn2+ in soil solutions. More than 50% of total Al in solution occurred in non-phytotoxic form (Al–SO4 complexes). Moreover, concentration of base cations and dissolved organic carbon increased. Concentrations of SO42- in soil solutions increased during the first few years approaching more or less constant values in the surface 40 cm depth, whereas in 40–100 cm depth it took about 10 yr to reach those levels of sulphate concentrations in soils, indicating its retention in the deeper soil layers. No significant change in the chemistry of throughfall water and leaves was observed, indicating to N-saturation of the trees.

Zum Einfluß von Weichlaubhölzern auf Vegetation und Auflagehumus von Fichtenforsten — Untersuchungen in einem zwei Jahrzehnte alten Birken-Ebereschen-Vorwald im Hoch-Solling

ZusammenfassungIn einem Birken-Ebereschen-Vorwald auf Mittlerem Buntsandstein im Hoch-Solling wurden die Vegetation, die Bestandesstruktur und die Humusauflage untersucht. Das Ergebnis einer ca. 20jährigen, weitgehend ungestörten Entwicklung nach Fichtenwindwurf und Holzräumung wird im Hinblick auf den Einfluß von Weichlaubhölzern auf mit reiner Fichte bestockte Waldstandorte analysiert und diskutiert. Im Vergleich zum benachbarten Restbestand des heute ca. 100jährigen Fichtenaltholzes weist der Birken-Ebereschen-Vorwald eine mechrschichtige Gehölzstruktur und eine höhere Artenvielfalt auf. Wesentliche Veränderungen konnten im Inventar und in der Häufigkeit der Arten in der Krautschicht ermittelt werden. Während unter Fichte die Drahtschmiele(Avenella flexuosa) dominiert, hat sich im Vorwald deren Deckungsanteil deutlich zugunsten von Rotem Straußgras(Agrostis tenuis) verringert. Die im Vorwald gegenüber dem Fichtenaltbestand häufigeren Arten weisen nicht nur auf den im Mittel höheren Lichtgenuß am Boden des Birken-Ebereschen-Vorwaldes hin, sondern auch auf eine höhere Nitrifizierungsrate im Oberboden und frische bis wechselfeuchte Standortsverhältnisse. Humusformen und -qualitäten im Vorwald und Fichtenaltholz weichen deutlich voneinander ab. Die Untersuchungsergebnisse geben Hinweise auf die unter den Aspekten eines naturnahen Waldbaus positiven Einflüsse einer vorübergehenden Weichlaubholzbestockung auf Auflagehumus und Bodenvegetation von Nadelholzforsten.SummaryVegetation, stand structure, and organic soil layer of a birch-rowan forest on sand-stone in the upper Solling (NW-Germany) were studied at a site where 20 years ago the spruce stand had been thrown by storm and cleared afterwards. The result of a largely undisturbed softwoods stand development lasting approximately 20 years is analysed and discussed in order to find out about the influence of softwoods on the vegetation, structure and organic layer of stands with Norway spruce. Compared with the neighbouring remnant of the now approximately 100-year-old spruce stand, the birch-rowan forest is more diverse in terms of stand structure and number of species. Significant changes were found in composition and dominance of species in the herb and moss layer. High cover values ofAvenella flexuosa in the spruce stand were displaced withAgrostis tenuis in the birch-rowan forest. The species which are more frequent in the birch-rowan forest than in the spruce stand indicate the relatively higher light intensity on the forest floor, a higher nitrification rate in the upper soil and moist site conditions or temporarily stagnating wetness. Qualities of the organic layers in the spruce stand and the birch-rowan forest differ significantly. In view of near-natural silviculture the results show positive effects of a temporary softwood stand on the organic soil layer and vegetation of coniferous stands.

The influence of softwood broadleaves on vegetation and the soil organic layer in Norway spruce stands - investigations in a two-decade old birch-rowan forest in the upper Solling area, Lower Saxony, NW Germany.

ZusammenfassungIn einem Birken-Ebereschen-Vorwald auf Mittlerem Buntsandstein im Hoch-Solling wurden die Vegetation, die Bestandesstruktur und die Humusauflage untersucht. Das Ergebnis einer ca. 20jährigen, weitgehend ungestörten Entwicklung nach Fichtenwindwurf und Holzräumung wird im Hinblick auf den Einfluß von Weichlaubhölzern auf mit reiner Fichte bestockte Waldstandorte analysiert und diskutiert. Im Vergleich zum benachbarten Restbestand des heute ca. 100jährigen Fichtenaltholzes weist der Birken-Ebereschen-Vorwald eine mechrschichtige Gehölzstruktur und eine höhere Artenvielfalt auf. Wesentliche Veränderungen konnten im Inventar und in der Häufigkeit der Arten in der Krautschicht ermittelt werden. Während unter Fichte die Drahtschmiele(Avenella flexuosa) dominiert, hat sich im Vorwald deren Deckungsanteil deutlich zugunsten von Rotem Straußgras(Agrostis tenuis) verringert. Die im Vorwald gegenüber dem Fichtenaltbestand häufigeren Arten weisen nicht nur auf den im Mittel höheren Lichtgenuß am Boden des Birken-Ebereschen-Vorwaldes hin, sondern auch auf eine höhere Nitrifizierungsrate im Oberboden und frische bis wechselfeuchte Standortsverhältnisse. Humusformen und -qualitäten im Vorwald und Fichtenaltholz weichen deutlich voneinander ab. Die Untersuchungsergebnisse geben Hinweise auf die unter den Aspekten eines naturnahen Waldbaus positiven Einflüsse einer vorübergehenden Weichlaubholzbestockung auf Auflagehumus und Bodenvegetation von Nadelholzforsten.SummaryVegetation, stand structure, and organic soil layer of a birch-rowan forest on sand-stone in the upper Solling (NW-Germany) were studied at a site where 20 years ago the spruce stand had been thrown by storm and cleared afterwards. The result of a largely undisturbed softwoods stand development lasting approximately 20 years is analysed and discussed in order to find out about the influence of softwoods on the vegetation, structure and organic layer of stands with Norway spruce. Compared with the neighbouring remnant of the now approximately 100-year-old spruce stand, the birch-rowan forest is more diverse in terms of stand structure and number of species. Significant changes were found in composition and dominance of species in the herb and moss layer. High cover values ofAvenella flexuosa in the spruce stand were displaced withAgrostis tenuis in the birch-rowan forest. The species which are more frequent in the birch-rowan forest than in the spruce stand indicate the relatively higher light intensity on the forest floor, a higher nitrification rate in the upper soil and moist site conditions or temporarily stagnating wetness. Qualities of the organic layers in the spruce stand and the birch-rowan forest differ significantly. In view of near-natural silviculture the results show positive effects of a temporary softwood stand on the organic soil layer and vegetation of coniferous stands.

Effects of Long-Term Application of Ammonium Sulphate on Nitrogen Fluxes in a Beech Ecosystem at Solling, Germany

To study the effects of elevated inputs of acidity and nitrogen (N), 1000 mmol m−2 a−1 of ammonium sulphate (NH4NO3) equivalent to an input of potential acidity of 2000 mmol m−2 a−1 was applied annually for 11 yr between 1983 and 1993 in a beech forest at Soiling, Germany. Most of the applied NH 4 + was nitrified in the litter layer and in the upper mineral soil. N in soil leachate quickly responded to the elevated input, but most of the applied N was stored in the soil or left the ecosystem via pathways other than soil output. Leaching of N from the soil increased until the last year of N addition. After the last N application, N fluxes decreased rapidly to low values. The buffering of acidity produced by the nitrification of the applied NH 4 + was caused mainly by three different processes: (i) sulphur (S) retention, (ii) release of aluminium, (iii) release of base cations. Retention of S took place mostly in the subsoil. 72% of the S input was recovered in output after 14 years of the experiment. Due to the increased fluxes of mobile anions with soil solution, outputs of cations increased drastically.

Langzeitwirkungen von Kalkung und Düngung auf den chemischen Zustand im Oberboden, die Humusformen und die Bodenvegetation in einem Fichtenforst

ZusammenfassungIn einem 1949 in Lutter am Barenberg in Norddeutschland angelegten Düngeversuch wurden die Humusformen, die Zusammensetzung der Vegetation und die Chemischen Eigenschaften des oberen Mineralbodens untersucht. In dem heute 109jährigen Fichtenbestand waren bis zu 2,9 t Ca/ha, 210 kg P/ha und 150 kg N/ha ausgebracht worden. Auf den mit Kalk und Phosphordünger behandelten Parzellen konnte eine Verschiebung der Humusformen von Rohhumus, rohhumusartigen und feinhumusarmen Moder zu feinhumusreichem, mullartigem Moder und F-Mull nachgewiesen werden. Im Auflagehumus lagen die pH-Werte (KCl) zwischen 2,6 und 2,9. Die Varianten mit 2,9 t Ca/ha hatten gegenüber der Kontrolle noch signifikant höhere pH-Werte. Bei diesen Varianten war in den oberen 17 cm des Mineralbodens der Äquivalentanteil der austauschbaren H-Ionen signifikant niedriger als in der Kontrolle. Bei den übrigen Kationen gab es keine Unterschiede. Die Krautvegetation war durch die Kalkung und Düngung nicht so verändert, daß sich dies auch in den Zeigerwerten für Stickstoff und Bodenfeuchte ausdrückte.SummaryType of humus layer, ground vegetation, and chemical properties of the upper mineral-soil horizons were studied in a 40-years-old fertilization and liming experiment at Lutter am Barenberg in Northern Germany. In the today 109-years-old stand of Norway spruce up to 2.9 t Ca/ha, 210 kg P/ha and 150 kg N/ha had been applied. With liming and fertilization (P), raw humus and moder changed to moder and mull. In the top organic layer, pH-values (KCl) ranged from 2.6 to 2.9. In the treatment with 2.9 t Ca/ha, pH-values of the top organic layer were significantly different from those on the other plots, and in the upper 17 cm of the mineral soil the equivalent fractions of exchangeable H-ions were significantly lower. Liming and fertilization did not change the composition of the ground vegetation to such an extent, that the indicator values for nitrogen and soil moisture were different.

Schwefel in Waldböden Nordwest-Deutschlands und seine vegetationsabhängige Akkumulation

SummaryAmounts of total sulfur and sulfate (NaHCO3-extractable) were determined in soil samples from 19 representative profiles under forest vegetation in the areas of pleistocene and of the triassic middle range mountains in Germany. The mean total sulfur contents in surface and subsurface samples were 278 and 136 μg S/g soil respectively. The total amount of sulfate and its fraction in the total sulfur was low in the surface samples. The subsurface soil samples of pH>5 contained very little sulfate. The difference between total sulfur and NaHCO3-extractable sulfate described as nonsulfate fraction was mainly constituted by the fraction of organic sulfur. The mean C:N:S ratio (sulfur as nonsulfate) for samples with carbon content more than 2% was 225∶10∶1.14. Compared with the parent material there was an accumulation of S in the acid brown earths developed from loess. Comparison of the sites with beech and spruce vegetation showed that the amount of nonsulfate-sulfur was of the same magnitude in both sites, but the amount of sulfate was higher in the spruce area. Similar differences between a beech and a spruce site were also observed for soils developed from weathered sandstone. The high amounts of sulfate under spruce are probably the result of higher inputs in the area due to the ‘filtering action’ of the spruce trees on emitted SO2.

Normative calculation of minerals in North German loess soils using the modified CIPW norm

The quantitative mineralogical composition which determines considerably the acid buffering capacity of soils can either be analyzed directly (modal) using mineralogical methods or can be calculated (normative) from the chemical total analysis of the soil considering previous knowledge of its qualitative mineralogical composition. In this study the normative mineralogical composition of loess-derived soils in Northern Germany is compared with their modal mineralogical composition determined by X-ray diffractometry and infrared spectroscopy. The CIPW norm (acronym for Cross, Iddings, Pirsson and Washington; Cross et al., 1902) has been used to calculate the mineralogical composition. For the application to soils the CIPW norm had to be modified with respect to pedogenic minerals. The differences between the normative (n) mineral contents and the respective modal (m) data [(n-m) × m−1 × 100] are for quartz −10% ± 4% (mean ± standard deviation), for orthoclase −8% ± 24%, for albite 26% ± 17%, for illite/mica −9% ± 24%, for calcite 14% ± 2%, and for dolomite 11% ± 19%. The chemical composition of illite/mica has been defined horizon-specific. The differences between normative and modal data are in the range of the error of mineralogical methods such as X-ray and optical techniques. Therefore the modified CIPW norm proves to be useful to estimate quantitatively the mineralogical composition of loess-derived soils. Normative Mineralberechnung in norddeutschen Lossboden nach der modifizierten CIPW-Norm Die mineralogische Zusammensetzung von Boden, die masgeblich das Saurepuffervermogen bestimmt, kann entweder direkt mittels mineralogischer Verfahren (modal) analysiert oder aus der chemischen Gesamtanalyse von Bodenproben (normativ) berechnet werden. Fur letzteren Weg ist Vorwissen uber die qualitative mineralogische Zusammensetzung erforderlich. In der vorliegenden Arbeit werden mittels rontgenographischer und infrarotspektroskopischer Verfahren ermittelte (modale) Daten mit dem normativ berechneten Mineralbestand von Lossboden aus Norddeutschland verglichen. Die normative Berechnung erfolgte mit der CIPW-Norm (Akronym fur Cross, Iddings, Pirsson and Washington; Cross et al., 1902), die fur diese Anwendung auf Boden bezuglich pedogener Minerale modifiziert wurde. Die Abweichungen der normativen (n) mineralogischen Zusammensetzung gegenuber der modal (m) bestimmten [(n-m) × m−1 × 100] liegen fur Quarz bei −10% ± 4% (Mittelwert ± Standardabweichung), fur Orthoklas bei −8% ± 24%, fur Albit bei 26% ± 17% und fur Illit/Glimmer bei −9% ± 24%. Bei Illit/Glimmer wurde von einer horizontspezifischen Stochiometrie ausgegangen. Bei den Carbonaten betragt die Abweichung fur Calcit 14% ± 2% und fur Dolomit 11% ± 19%. Die Abweichungen zwischen modalem und normativem Mineralbestand liegen im Fehlerbereich von modalen Mineralanalysen, die mittels rontgenographischer und optischer Verfahren durchgefuhrt werden. Die Anwendung der modifizierten CIPW-Norm kann daher als ein geeignetes Verfahren zur Schatzung des quantitativen Mineralbestandes in Lossboden betrachtet werden.