Kooperativer Bibliotheksverbund

Berlin Brandenburg

and
and

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
Type of Medium
Language
Year
  • 1
    Language: English
    In: Plant and Soil, 2011, Vol.340(1), pp.59-72
    Description: Over the last few decades, due to increase in grazing intensity, animal trampling has led to soil structure deterioration in Inner Mongolia, China. We investigated two different steppe ecosystems: Leymus chinensis (LCh, characterized by relatively higher precipitation) and Stipa grandis (SG) and two grazing intensities: ungrazed since 1979 (UG79) and grazed (continuously grazed, CG, at the Stipa grandis site and winter grazed, WG, at Leymus chinensis ). Soil mechanical and hydraulic properties of semiarid steppe soils from each site and treatment were determined for soil aggregates and disturbed and bulk soil samples from different depths (4–8, 18–22, 30–34 and 56–60 cm for disturbed and bulk samples and 0–15 cm for the aggregates). Grazing causes a significant increase in tensile strength of aggregates and in the precompression stress of the bulk soil as well as a decrease in air and saturated hydraulic conductivity, irrespective of the vegetation type. Furthermore, exclusion from grazing led to more pronounced recovery of soil strength and pore continuity and hydraulic conductivity at the LCh site but it also depended on the moisture conditions of the sites. Under wetter conditions as well as after repeated freezing and thawing the soil strength declined.
    Keywords: Grazing ; Precompression stress ; Aggregate tensile strength ; Repellency index ; Steppe
    ISSN: 0032-079X
    E-ISSN: 1573-5036
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    Language: English
    In: Plant and Soil, 2011, Vol.340(1), pp.89-102
    Description: Long-term monitoring of soil properties reveals site-specific ecosystem shifts in soil processes due to land use and climate changes. This paper aims to study the effects of physical landscape changes associated with grazing on soil thermal and moisture regime at the plot scale in a semiarid Leymus chinensis steppe of Inner Mongolia, China. The investigated sites were subjected to three grazing intensities: ungrazed since 1979 (UG79), moderately grazed only in winter time (WG), and heavily grazed (HG). At each plot, we recorded the soil moisture and temperature over a 6-year period that spanned between June 2004 and September 2009 and experienced a large range in precipitation (162 to 362 mm). Based on these monitoring data, we divided a year into four hydric periods: (1) growing period (late April to August); (2) transitional period from summer to winter (September–October); (3) winter time (November–first March); and (4) transitional period from winter to summer (March–April). In general, soil moisture in grazed sites was lower than in the ungrazed site, particularly for the 30–50 cm soil layer. Seasonal fluctuation of the soil moisture, due to variable precipitation and atmospheric demands, was most significant in the topsoil (0–10 cm) and was less pronounced in deeper soil. Regardless of hydric seasons, soil moisture was significantly influenced by grazing intensity, whereas soil temperature was slightly influenced. With increasing grazing intensity, soil water storage decreased remarkably. Consequently, grazing reduced plant available water and therefore grassland productivity, which are linked to a great extent with the trampling-induced soil structure change and soil moisture regime.
    Keywords: Long-term monitoring ; Grazing intensity ; Soil moisture ; Soil temperature ; Plant available water ; Semiarid steppe
    ISSN: 0032-079X
    E-ISSN: 1573-5036
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 3
    Language: English
    In: Soil Science Society of America journal, 2011, Vol.75(2), pp.426-433
    Description: In Inner Mongolia, animal trampling is one of the main factors causing soil degradation manifested by altered mechanical strength or changes in water and gas fluxes. Soil samples were collected at two depths (4–8 and 18–22 cm) on the Stipa grandis steppe ecosystem in Inner Mongolia from two treatments characterized by different grazing intensities: ungrazed since 1979 (UG) and continuously grazed (CG). The following mechanical soil properties were determined under static and repeated loading conditions: precompression stress, P c; coefficient of cyclic compressibility, c n, and compression index, C c Air conductivity measurements were used to quantify the changes in soil functions due to application of repeated loading. The CG site showed significantly higher precompression stress values (111 kPa) than the UG site (64 kPa) at the first soil depth. The highest c n values were found in the topsoil of the UG site, while the CG site had significantly lower c n values. Repeated loading caused higher soil deformation compared to the static loading test. It was also found that the strain of soil samples from the UG site was higher than the CG site. We found a good fit between c n and precompression stress. The C c values of the cyclically loaded samples were significantly lower at the CG site than the statically loaded ones. The air conductivity of the UG site remained constant for a wider stress range of repeatedly applied stress compared with the CG site, which reflects higher stability of the soil pore network at the UG site. ; p. 426-433.
    Keywords: Kastanozems ; Animals ; Topsoil ; Grazing ; Soil Pore System ; Ecosystems ; Deformation ; Soil Mechanical Properties ; Soil Sampling ; Soil Depth ; Steppes ; Soil Degradation ; Trampling Damage ; Air ; Compressibility
    ISSN: 0361-5995
    E-ISSN: 14350661
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 4
    Language: English
    In: Journal of hydrology, 2013, Vol.486, pp.175-186
    Description: Soil research done over the past decades has proven that water repellent soils are widespread in all climates. Water repellency enhances the leaching of contaminants in the unsaturated zone by introducing preferential flow. In order to predict soil water fluxes in the unsaturated zone the accurate knowledge of the soil hydraulic properties (SHP) is mandatory. In this study the effect of water repellency on both imbibition and drainage SHP was studied. Inflow/outflow experiments were conducted in the laboratory for two soils and two artificially created hydrophobic mixtures. In the inflow/outflow experiments the pressure head at the bottom of the soil column was increased/decreased and the estimated SHP functions were obtained by means of inverse modeling. Inflow/outflow experiments were also conducted using ethanol instead of water in order to estimate the effect of liquid wetting properties on the estimated characteristic curves of the materials under study. The results showed that the water retention functions and the unsaturated hydraulic conductivity functions estimated from the dynamic experiments are strongly dependent on the degree of water repellency and the wetting/drying process. ; p. 175-186.
    Keywords: Drying ; Drainage ; Prediction ; Unsaturated Hydraulic Conductivity ; Preferential Flow ; Imbibition ; Models ; Soil Water ; Water Repellent Soils ; Ethanol ; Hydrophobicity ; Leaching ; Climate
    ISSN: 0022-1694
    Source: AGRIS (Food and Agriculture Organization of the United Nations)
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 5
    Language: English
    In: Journal of Hydrology, 12 April 2013, Vol.486, pp.175-186
    Description: ► Flow experiments were performed with ethanol and water on water repellent soils. ► Effective soil hydraulic properties obtained by inverse modeling. ► Water repellency contributes to an enhanced retention curve hysteresis. Soil research done over the past decades has proven that water repellent soils are widespread in all climates. Water repellency enhances the leaching of contaminants in the unsaturated zone by introducing preferential flow. In order to predict soil water fluxes in the unsaturated zone the accurate knowledge of the soil hydraulic properties (SHP) is mandatory. In this study the effect of water repellency on both imbibition and drainage SHP was studied. Inflow/outflow experiments were conducted in the laboratory for two soils and two artificially created hydrophobic mixtures. In the inflow/outflow experiments the pressure head at the bottom of the soil column was increased/decreased and the estimated SHP functions were obtained by means of inverse modeling. Inflow/outflow experiments were also conducted using ethanol instead of water in order to estimate the effect of liquid wetting properties on the estimated characteristic curves of the materials under study. The results showed that the water retention functions and the unsaturated hydraulic conductivity functions estimated from the dynamic experiments are strongly dependent on the degree of water repellency and the wetting/drying process.
    Keywords: Water Repellency ; Hydrophobicity ; Soil Hydraulic Properties ; Inverse Modeling ; Ethanol ; Geography
    ISSN: 0022-1694
    E-ISSN: 1879-2707
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 6
    Language: English
    In: Soil & Tillage Research, January 2011, Vol.111(2), pp.180-189
    Description: ▶ Water and gas flux in soil depend on grazing and vegetation type. ▶ Exclusion from grazing improves soil structure and functions. ▶ Anisotropy of soil functions changes with matric potential. Intensive overgrazing, practiced for the last decades in Inner Mongolia, has led to serious grassland degradation and deterioration of soil structure. As a consequence, the soil gas and water fluxes and therefore soil functions were affected by grazing. We investigated two steppe ecosystems characterized by two plant communities: (SG) and (LCh) and different grazing intensities: ungrazed since 1979 (UG79), continuously grazed (CG, at the SG site) and winter grazed (WG, at the LCh site). The undisturbed soil samples, for determination of saturated ( ) and unsaturated ( ) hydraulic conductivities and air conductivities ( ), were collected in vertical and horizontal direction from two soil horizons. The coefficients of anisotropy were calculated as ratios of the values obtained for the samples taken in horizontal direction to the values of the vertical samples. The results indicated a good recovery of soil structure at the sites ungrazed for more than 30 years. Furthermore, the recovery was more pronounced at the LCh site compared with the SG site. The results suggested that grazing causes significant changes in anisotropy of soil functions related to rearrangement of aggregates and creation of a platy soil structure. The results of the coefficients of anisotropy of hydraulic conductivity showed that they depend on the matric potential for both treatments.
    Keywords: Soil Functions ; Hydraulic Conductivity ; Air Conductivity ; Anisotropy ; Agriculture
    ISSN: 0167-1987
    E-ISSN: 1879-3444
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 7
    Language: English
    In: Plant and Soil, 2011, Vol.340(1), pp.35-58
    Description: Semiarid steppe ecosystems account for large terrestrial areas and are considered as large carbon (C) sinks. However, fundamental information on topsoil sensitivity to grazing is lacking across different spatial scales including the effects of topography. Our interdisciplinary approach considering soil chemical, physical, and vegetation properties included investigations on pit scale (square-metre scale), plot scale (hectare scale), and the scale of a landscape section (several hectares). Five different sites, representing a grazing intensity gradient, ranging from a long-term grazing exclosure to a heavily grazed site were used. On the pit scale, data about aggregate size distribution, quantity of different soil organic carbon (SOC) pools, SOC mineralisation, hydraulic conductivity and shear strength was available for topsoil samples from representative soil profiles. Spatial variability of topographical parameters, topsoil texture, bulk density, SOC, water repellency, and vegetation cover was analysed on the basis of regular, orthogonal grids in differently grazed treatments by using two different grid sizes on the plot scale and landscape section. On the pit scale, intensive grazing clearly decreased soil aggregation and the amount of fresh, litter-like particulate organic matter (POM). The weak aggregation in combination with animal trampling led to an enhanced mineralisation of SOC, higher topsoil bulk densities, lower infiltration rates, and subsequently to a higher risk of soil erosion. On the plot scale, the effects of soil structure disruption due to grazing are enhanced by the degradation of vegetation patches and resulted in a texture-controlled wettability of the soil surface. In contrast, topsoils of grazing exclosures were characterised by advantageous mechanical topsoil characteristics and SOC-controlled wettability due to higher POM contents. A combined geostatistical and General Linear Model approach identified topography as the fundamental factor creating the spatial distribution of texture fractions and related soil parameters on the scale of a landscape section. Grazing strongly interfered with the topography-controlled particle relocation processes in the landscape and showed strongest effects on the aboveground biomass production and biomass-related soil properties like SOC stocks. We conclude that interdisciplinary multi-scale analyses are essential (i) to differentiate between topography- and grazing-controlled spatial patterns of topsoil and vegetation properties, and (ii) to identify the main grazing-sensitive processes on small scales that are interacting with the spatial distribution and relocation processes on larger scales.
    Keywords: Steppe soils ; Soil organic matter fractions ; Organic carbon mineralisation ; Wind erosion ; Texture ; Vegetation cover ; Shear strength ; Hydraulic conductivity ; Water repellency ; Anisotropy
    ISSN: 0032-079X
    E-ISSN: 1573-5036
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 8
    In: European Journal of Soil Science, May 2014, Vol.65(3), pp.369-376
    Description: Long‐term capillary rise experiments (0 to about 89 000 hour) were performed at 19°C on homogenized and heat‐treated podsolic forest top‐ and subsoil samples. These were packed into columns, the bases of which were then partially immersed, at constant depth, in water reservoirs to simulate a constant water table. Selected columns were equipped with tensiometer and probes. Other columns were removed at prescribed times and divided into 2‐cm horizontal segments whose volumetric water contents were determined. The degree of saturation was then estimated by comparison with the capillary rise in duplicate arrangements of samples immersed in ethanol. It was found that the heat treatments conferred increased water repellency () on the soil, which increased with temperature (significantly so at greater than 60°C). This had a profound effect on the capillary rise characteristics and development of water content in the soil behind the wetting front, indicating an effective, albeit slow, reduction in effective . This has implications for hydraulic modelling of soils with significant and demonstrates that sub‐surface exerts a significant influence on capillary rise from a water table and suggests that commonly used indicators of surface using droplet tests may not be useful for such modelling purposes.
    Keywords: Soil Moisture – Analysis;
    ISSN: 1351-0754
    E-ISSN: 1365-2389
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 9
    Language: English
    In: European Journal of Soil Science, Feb, 2012, Vol.63(1), p.22(10)
    Description: To authenticate to the full-text of this article, please visit this link: http://dx.doi.org/10.1111/j.1365-2389.2011.01418.x Byline: M. Wiesmeier (a), M. Steffens (a), C. W. Mueller (a), A. Kolbl (a), A. Reszkowska (b), S. Peth (b), R. Horn (b), I. Kogel-Knabner (a) Abstract: Spatial inaccessibility of soil organic carbon (SOC) for microbial decay within soil aggregates is an important stabilization mechanism. However, little is known about the stability of aggregates in semiarid grasslands and their sensitivity to intensive grazing. In this study, a combined approach using soil chemical and physical analytical methods was applied to investigate the effect of grazing and grazing exclusion on the amount and stability of soil aggregates and the associated physical protection of SOC. Topsoils from continuously grazed (CG) and ungrazed sites where grazing was excluded from 1979 onwards (UG79) were sampled for two steppe types in Inner Mongolia, northern China. All samples were analysed for basic soil properties and separated into free and aggregate-occluded light fractions (fLF, oLF) and mineral-associated fractions. Tensile strength of soil aggregates was measured by crushing tests. Undisturbed as well as artificially compacted samples, where aggregates were destroyed mechanically by compression, were incubated and the mineralization of SOC was measured. For undisturbed samples, the cumulative release of CO.sub.2-C was greater for CG compared with UG79 for both steppe types. A considerably greater amount of oLF was found in UG79 than in CG soils, but the stabilities of 10-20-mm aggregates were less for ungrazed sites. Compacted samples showed only a slightly larger carbon release with CG but a considerably enhanced mineralization with UG79. We assume that the continuous trampling of grazing animals together with a smaller input of organic matter leads to the formation of mechanically compacted stable 'clods', which do not provide an effective physical protection for SOC in the grazed plots. In UG79 sites, a greater input of organic matter acting as binding agents in combination with an exclusion of animal trampling enhances the formation of soil aggregates. Thus, grazing exclusion promotes the physical protection of SOC by increasing soil aggregation and is hence a management option to enhance the C sequestration potential of degraded steppe soils. Author Affiliation: (a)Lehrstuhl fur Bodenkunde, Department fur Okologie und Okosystemmanagement, Wissenschaftszentrum Weihenstephan fur Ernahrung, Landnutzung und Umwelt, Technische Universitat Munchen, D-85350 Freising-Weihenstephan, Germany (b)Institute of Plant Nutrition and Soil Science, Christian-Albrechts-University zu Kiel, Hermann-Rodewald-Str. 2, D-24118 Kiel, Germany Article History: Received 23 March 2010; revised version accepted 21 November 2011 Article note: M. Wiesmeier. E-mail: wiesmeier@wzw.tum.de
    Keywords: Steppes ; Soil Structure ; Soil Carbon ; Soils ; Soil Microbiology
    ISSN: 1351-0754
    Source: Cengage Learning, Inc.
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 10
    Language: Polish
    In: Annales Academiae Medicae Stetinensis, 2011, Vol.57(3), pp.70-6
    Description: Wegener's granulomatosis is a disease of unknown etiology associated with the presence of serum antibodies against proteinase 3 in most cases. It is characterized by formation of inflammatory infiltrates presenting as granulomas with fibrinoid necrosis, as well as by ulceration and inflammation of small and medium-sized vessels with the involvement of upper and lower airways and kidneys. The process may also occur in other less typical locations, such as the gastrointestinal tract, heart, and nervous system. There are some reports on the location of lesions in the breast. We report a case of a 57-year-old female with Wegener's granulomatosis. In this patient, lesions in the skin, kidneys, upper airways, and lungs were accompanied by a breast tumor revealing the distinctive pattern of an inflammatory granuloma. The disease began in December 2002. The patient experienced painful and swollen joints, fever, mucous-purulent-bloody nasal discharge, and subcutaneous nodules with a tendency to ulceration. Histologically, the nodules had a texture typical for inflammatory granuloma. Renal symptoms included mild proteinuria, abnormalities in the sediment (fresh and leached erythrocytes), and slightly elevated serum creatinine. HRCT of the lungs revealed bilateral pulmonary nodules. The presence of antineutrophil cytoplasmic antibodies in serum with the cytoplasmic fluorescence pattern (c-ANCA/PR-3) was confirmed. The disease progressed with perforation of the nasal septum and extensive destructive changes within the bony structures of the paranasal sinuses. The patient underwent thoracic surgery in 2008 due to an inflammatory tumor in the upper lobe of the right lung. Two years later a tumor in the right breast was detected. Histopathology of the lung and breast tumors showed high similarity of both processes corresponding to lesions typical for Wegener's granulomatosis. The patient was treated with prednisone, methylprednisolone, methotrexate, cyclophosphamide, and azathioprine. This case provides evidence that Wegener's granulomatosis is a systemic disease with a wide spectrum of organ involvement which should be taken into account during differential diagnosis of breast tumors.
    Keywords: Breast Diseases -- Diagnosis ; Granulomatosis With Polyangiitis -- Diagnosis ; Lung Diseases -- Diagnosis
    ISSN: 1427-440X
    Source: MEDLINE/PubMed (U.S. National Library of Medicine)
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. Further information can be found on the KOBV privacy pages