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Stone Contents (stone + content)

Distribution by Scientific Domains
Earth and Environmental Science100%

Selected Abstracts

Impact of stone content on water movement in water-repellent sand

EUROPEAN JOURNAL OF SOIL SCIENCE, Issue 3 2009
E. Urbanek
Summary Soils are commonly stony, especially in steep upland or heavily degraded sites. The hydrological effect of large stone contents has been previously investigated in wettable but not in water-repellent soils. For the latter, the focus has instead been on the impact of other soil characteristics (e.g. cracks and macropores) likely to promote water percolation. This paper investigates stone effects on water flow in water-repellent sand under laboratory conditions. Seventy-five experiments were performed on a water-repellent sand mixed with a range of quantities of different-sized wettable and water-repellent stones. The time taken for water to pass through each sand,stone mix, the percolated water volumes and numbers of dry and wet stones following each 60-minute experiment were recorded. At large stone contents (> 55% or > 65% by weight, depending on stone wettability), percolation occurred relatively quickly and in comparatively large quantities. At intermediate stone contents (45,65%) percolation response was variable and at stone contents < 45% for wettable and < 55% for water-repellent soils no water percolation occurred. We argue that with large stone contents flow pathways develop along sand,stone interfaces and a continuous preferential flow path can form provided there are sufficient stone-to-stone connections. The distribution and alignment of the stones, especially at intermediate stone contents, are important for promoting water movement. Water repellency determinations based only on the fine sediment component in stony soils could therefore be misleading as regards determining their hydrological response: the influence of the clastic component must also be considered. [source]

Application of ground-penetrating radar to determine the thickness of Pleistocene periglacial slope deposits

JOURNAL OF PLANT NUTRITION AND SOIL SCIENCE, Issue 6 2004
Daniela Sauer
Abstract Wide areas of the mountainous regions of Germany have rock covered by Pleistocene periglacial slope deposits (PPSD), formed by gelifluction during the cold periods of the ice ages in non-glaciated areas. The PPSD provide the parent material for soil development, and their physical characteristics affect several stabile soil properties. Because the PPSD play a significant ecological role, we studied the spatial distribution and properties of the PPSD in order to assess the distribution of the stabile soil properties. The high stone content of the PPSD greatly hinders augering and digging. Hence, we tested the use of ground-penetrating radar (GPR) as a potentially time-saving, non-destructive method to determine the thickness of the PPSD. In several study areas of the Rhenish Massif, GPR investigations of single soil profiles and soil transects along an exposed gas-pipeline ditch were carried out. The GPR images were compared to the actual thickness of the layers of the PPSD exposed in the profiles and the ditch. In the GPR images usually at least one distinct boundary could be identified, which occurs at the transition between the loose material and the hard rock, mostly ranging between 50 and 150,cm depth. In some cases, in which stone content changed abruptly between different layers of the PPSD, also the boundaries between these layers could be identified in the GPR image. On the other hand, in areas where remnants of the Mesozoic-Tertiary weathering mantle are preserved, the boundary between the saprolite and the overlying basal layer of the PPSD is ambiguous or not at all visible. Einsatz von Georadar zur Bestimmung der Mächtigkeit periglaziärer Lagen In den deutschen Mittelgebirgen sind die Gesteine weitflächig von periglaziären Lagen überzogen. Diese entstanden durch Gelifluktion während der Kaltzeiten in den unvergletscherten Bereichen. Sie stellen das Ausgangssubstrat der Bodenbildung dar und bestimmen eine Reihe stabiler Bodeneigenschaften. Die ökologische Bedeutung der periglaziären Lagen gab den Anlass, ihre Verbreitung und Eigenschaften zu erfassen, um daraus flächenhafte Aussagen über diese Eigenschaften abzuleiten. Da Bohrungen und Grabungen in den periglaziären Lagen häufig durch hohe Skelettgehalte erschwert werden, wurde untersucht, ob Georadar zur zeitsparenden, zerstörungsfreien Erfassung der Lagenmächtigkeiten eingesetzt werden kann. In verschiedenen Teilen des Rheinischen Schiefergebirges wurden Georadar-Messungen an Bodenprofilen sowie an Transekten entlang eines Gasleitungsgrabens durchgeführt, die jeweils mit den Mächtigkeiten der periglaziären Lagen verglichen wurden, die an der Graben- bzw. Profilwand aufgeschlossen waren. In den Radargrammen ist in der Regel mindestens eine deutliche Grenze zu erkennen. Diese tritt am Übergang vom Lockermaterial zum Festgestein auf, der in der Regel zwischen 50 und 150,cm Tiefe liegt. In einigen Fällen, in denen sich der Skelettgehalt an den Lagengrenzen abrupt stark verändert, sind auch Grenzen zwischen verschiedenen Lagen im Radargramm zu erkennen. Dagegen ist in Gebieten, in denen Reste der mesozoisch-tertiären Verwitterungsdecke im Untergrund anstehen, die Grenze zwischen der Basislage und dem Gestein im Radargramm nur diffus oder nicht ausgeprägt. [source]

Impact of stone content on water movement in water-repellent sand

EUROPEAN JOURNAL OF SOIL SCIENCE, Issue 3 2009
E. Urbanek
Summary Soils are commonly stony, especially in steep upland or heavily degraded sites. The hydrological effect of large stone contents has been previously investigated in wettable but not in water-repellent soils. For the latter, the focus has instead been on the impact of other soil characteristics (e.g. cracks and macropores) likely to promote water percolation. This paper investigates stone effects on water flow in water-repellent sand under laboratory conditions. Seventy-five experiments were performed on a water-repellent sand mixed with a range of quantities of different-sized wettable and water-repellent stones. The time taken for water to pass through each sand,stone mix, the percolated water volumes and numbers of dry and wet stones following each 60-minute experiment were recorded. At large stone contents (> 55% or > 65% by weight, depending on stone wettability), percolation occurred relatively quickly and in comparatively large quantities. At intermediate stone contents (45,65%) percolation response was variable and at stone contents < 45% for wettable and < 55% for water-repellent soils no water percolation occurred. We argue that with large stone contents flow pathways develop along sand,stone interfaces and a continuous preferential flow path can form provided there are sufficient stone-to-stone connections. The distribution and alignment of the stones, especially at intermediate stone contents, are important for promoting water movement. Water repellency determinations based only on the fine sediment component in stony soils could therefore be misleading as regards determining their hydrological response: the influence of the clastic component must also be considered. [source]

Soil nutrient supply and biomass production in a mixed forest on a skeleton-rich soil and an adjacent beech forest

JOURNAL OF PLANT NUTRITION AND SOIL SCIENCE, Issue 6 2002
Dirk Hölscher
Abstract In the natural forest communities of Central Europe, beech (Fagus sylvatica L.) predominates in the tree layer over a wide range of soil conditions. An exception with respect to the dominance of beech are skeleton-rich soils such as screes where up to 10 broad-leaved trees co-exist. In such a Tilia-Fagus-Fraxinus-Acer-Ulmus forest and an adjacent mono-specific beech forest we compared (1) soil nutrient pools and net nitrogen mineralization rates, (2) leaf nutrient levels, and (3) leaf litter production and stem increment rates in order to evaluate the relationship between soil conditions and tree species composition. In the mixed forest only a small quantity of fine earth was present (35 g l,1) which was distributed in patches between basalt stones; whereas a significantly higher (P < 0.05) soil quantity (182 g l,1) was found in the beech forest. In the soil patches of the mixed forest C and N concentrations and also concentrations of exchangeable nutrients (K, Ca, Mg) were significantly higher than in the beech forest. Net N mineralization rates on soil dry weight basis in the mixed forest exceeded those in the beech forest by a factor of 2.6. Due to differences in fine earth and stone contents, the volume related soil K pool and the N mineralization rate were lower in the mixed forest (52 kg N ha,1 yr,1, 0,10 cm depth) than in the beech forest (105 kg N ha,1 yr,1). The leaf N and K concentrations of the beech trees did not differ significantly between the stands, which suggests that plant nutrition was not impaired. In the mixed forest leaf litter fall (11,%) and the increment rate of stem basal area (52,%) were lower than in the beech forest. Thus, compared with the adjacent beech forest, the mixed forest stand was characterized by a low volume of patchy distributed nutrient-rich soil, a lower volume related K pool and N mineralization rate, and low rates of stem increment. Together with other factors such as water availability these patterns may contribute to an explanation of the diverse tree species composition on Central European screes. Bodennährstoffangebot und Biomasseproduktion in einem Mischwald auf einem stark skeletthaltigen Standort und in einem benachbarten Buchenwald In den natürlichen Waldgesellschaften Mitteleuropas dominiert die Buche (Fagus sylvatica L.) über ein weites Spektrum an bodenchemischen Standortsbedingungen. Eine Ausnahme in Bezug auf die Buchendominaz bilden stark skeletthaltige Standorte, wie etwa Blockhalden, wo bis zu 10 Laubbaumarten gemeinsam vorkommen. In solch einem Tilia-Fagus-Fraxinus-Acer-Ulmus -Wald und einem benachbarten Buchenreinbestand haben wir (1) die Bodennährstoffvorräte und Stickstoffmineralisationsraten, (2) den Blattnährstoffstatus und (3) die Blattproduktion und die Stammzuwachsraten vergleichend untersucht, um die Beziehung zwischen den Bodenbedingungen und der Baumartenzusammensetzung zu charakterisieren. In dem Mischwald fanden wir nur eine geringe Menge an Feinboden (35 g l,1), die sich in Taschen zwischen den Basaltsteinen befand, wohingegen ein signifikant (P < 0.05) höherer Gehalt an Feinboden (182 g l,1) in dem Buchenwald vorhanden war. In den Bodentaschen des Mischwaldes waren die C- und N-Konzentrationen und auch die Konzentrationen an austauschbar gebundenem K, Ca und Mg signifikant höher als im Buchenwald. Die Netto-N-Mineralisation pro Gewichtseinheit im Mischwald überstieg diejenige im Buchenwald um den Faktor 2,6. Wegen der unterschiedlichen Anteile an Feinboden und Skelett waren der volumenbezogene K-Vorrat und die volumenbezogene N-Mineralisationsrate im Mischwald (52 kg N ha,1 yr,1, 0,10 cm Tiefe) geringer als im Buchenwald (105 kg N ha,1 yr,1). Die Blattnährstoffgehalte von Buchen unterschieden sich zwischen den beiden Beständen nicht signifikant, was darauf hinweist, dass die Pflanzenernährung nicht beeinträchtigt war. Der herbstliche Blattstreufall (11,%) und die Zuwachsraten der Stammquerflächen (52,%) waren im Mischwald geringer als im Buchenwald. Im Vergleich mit dem benachbarten Buchenwald wies der Mischwald somit einen geringen Gehalt an sehr ungleichmäßig verteiltem, nährstoffreichen Boden, geringere volumenbezogene K-Vorräte und N-Mineralisationsraten und geringe Stammzuwächse auf. Gemeinsam mit anderen Faktoren, wie etwa der Wasserverfügbarkeit, können diese Muster zu einer Erklärung der Baumartenvielfalt auf mitteleuropäischen Blockstandorten beitragen. [source]