Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

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

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Suppression of resonances in kinked, superconducting, quantum wires
    Amsterdam : Elsevier
    Physica B: Physics of Condensed Matter 194-196 (1994), S. 1639-1640 
    Details
    ISSN: 0921-4526
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0921-4526(94)91319-6
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Density dependent interactions between VA mycorrhizal fungi and even-aged seedlings of two perennial Fabaceae species (1992)
    Springer
    Oecologia 91 (1992), S. 281-287 
    Details
    ISSN: 1432-1939
    Keywords: Vesicular-arbuscular mycorrhizas ; Densitydependence ; Plant population dynamics ; Resource depletion ; Phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The interaction of density and mycorrhizal effects on the growth, mineral nutrition and size distribution of seedlings of two perennial members of the Fabaceae was investigated in pot culture. Seedlings of Otholobium hirtum and Aspalathus linearis were grown at densities of 1, 4, 8 and 16 plants per 13-cm pot with or without vesicular-arbuscular (VA) mycorrhizal inoculum for 120 days. Plant mass, relative growth rates, height and leaf number all decreased with increasing plant density. This was ascribed to the decreasing availability of phosphorus per plant as density increased. O. hirtum was highly dependent on mycorrhizas for P uptake but both mycorrhizal and non-mycorrhizal A. linearis seedlings were able to extract soil P with equal ease. Plant size distribution as measured by the coefficient of variation (CV) of shoot mass was greater at higher densities. CVs of mycorrhizal O. hirtum plants were higher than those of non-mycorrhizal plants. CVs of the facultatively mycorrhizal A. linearis were similar for both mycorrhizal and non-mycorrhizal plants. Higher CVs are attributed to resource preemption by larger individuals. Individuals in populations with high CVs will probably survive stress which would result in the extinction of populations with low CVs. Mass of mycorrhizal plants of both species decreased more rapidly with increasing density than did non-mycorrhizal plant mass. It is concluded that the cost of being mycorrhizal increases as plant density increases, while the benefit decreases. The results suggest that mycorrhizas will influence density-dependent population processes of faculative and obligate mycorrhizal species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00317797
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Soil nitrogen mineralization in a coastal fynbos succession (1988)
    Springer
    Plant and soil 106 (1988), S. 295-298 
    Details
    ISSN: 1573-5036
    Keywords: fynbos ; fire ; mineralization ; nitrification ; succession
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Patterns of net nitrogen mineralization and nitrification in 0–7.5 cm deep mineral soils of different stages (seral ages 1, 6 and 20 years) of a post-fire coastal fynbos succession were assayed using laboratory andin situ incubations. No evidence of increasing allelopathic inhibition of nitrification with successional development was found as NO3−N was the predominant product at all seral stages and the NO3−N∶NH4−N ratio remained constant. Rather the results of field incubations of soils beneathProtea repens stands of different successional ages showed that increased mineralization and nitrification appeared to be associated with increased soil total N content rather than with successional age. Further, the incubation of soilsin situ during the dry summer months showed that NO3−N production appears to be closely related to temperature and soil moisture content, both of which are variables that vary throughout succession due to the changing structure of the vegetation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02371229
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Effect of defoliation on the arbuscular mycorrhizas of three perennial pasture and rangeland grasses (1998)
    Springer
    Plant and soil 202 (1998), S. 117-124 
    Details
    ISSN: 1573-5036
    Keywords: Digitaria eriantha ; external mycorrhizal hyphae ; Lolium perenne ; mycorrhizal fungal colonization ; Themeda triandra ; vital staining
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effect of different frequencies of defoliation on arbuscular mycorrhizal fungal (AMF) colonization and external hyphae production of three perennial grass species growing in pot culture in a non-sterile soil was investigated. Roots were assessed by acid fuschin staining and succinate dehydrogenase activity to obtain measurements of total and metabolically active AMF colonization. The grass species, Digitaria eriantha, Lolium perenne and Themeda triandra are of similar bunch morphology and responded to defoliation with massive root death. In Themeda defoliation was also associated with a decline in leaf growth rate, phosphorus accumulation in new leaf tissue, AMF colonization and external hyphae densities. In Digitaria and Lolium, AMF colonization declined but external hyphal densities were unaffected by defoliation frequency. In these two species phosphorus accumulation and leaf regrowth rates were also unchanged by defoliation. Only in Lolium did defoliation result in slightly more inactive AMF colonization. The results suggest that Lolium and Digitaria which are pasture species are better able to compensate for root loss following fairly frequent defoliation by maintaining an external AMF hyphal network. Themeda, a rangeland grass, which is more intolerant of grazing, has a lower capacity for sustaining its hyphal network when defoliated. Grazing is therefore likely to affect community dynamics because of variable effects of defoliation frequency on the mycorrhizal symbiosis of different plant species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004357027519
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Effects of grazing and cultivation on soil patterns and processes in the Paulshoek area of Namaqualand (1999)
    Springer
    Plant ecology 142 (1999), S. 179-187 
    Details
    ISSN: 1573-5052
    Keywords: Arid shrublands ; Mycorrhizas ; Soil resource patchiness
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Soils were sampled at three different sites within the Paulshoek area of the Leliefontein District in Namaqualand, South Africa. At one site the effect of heavy grazing on soil characteristics under shrubs and from open positions was compared to a more lightly grazed area. At this site a diverse shrub community was mostly replaced by a single species, Galenia africana, when overgrazed. In another area the effects of cultivation on soil properties was investigated. At the third site the effect of Galenia shrub size on soil properties was measured. Soils from the Paulshoek area of Namaqualand are generally infertile and very low in arbuscular mycorrhizal propagules. Patterns of nitrogen distribution at the landscape level are a result of nutrient enrichment associated with perennial shrubs. Arbuscular mycorrhizal infectivity, soil moisture and pH are also affected by shrubs. Only species capable of forming arbuscular mycorrhizas support populations of mycorrhizal propagules in their rhizosphere. Differences in plant available phosphorus under some shrubs indicate that processes associated with nutrient cycling are also affected by shrubs. Galenia tended to deplete soil moisture and increase soil pH more than other shrubs. Small stock production results in a depletion of soil nutrients at the landscape scale since larger areas of low nutrient soil develop when shrub density decreases following heavy grazing. Heavy grazing also affects soil properties indirectly through a change in shrub composition. Cultivation resulted in a decrease in soil nitrogen and organic matter, a loss which was still detectable after 20 years of fallow. Zones of nutrient enrichment and higher pH were found where Galenia established in the old field. When soil was sampled under different size Galenia shrubs a positive correlation was found between shrub diameter and nitrogen, available phosphorus and pH indicating that Galenia was capable of establishing patches in the soil with different properties rather than selecting such areas for establishment. Thus, Galenia is able to maintain soil patterns typical of Succulent Karoo although it also establishes conditions which probably ensure its success. Individual shrub species also affect soil differently with respect to some components such as mycorrhizas.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009826412617
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...