| 1. |
- Bengtsson, Jan, et al.
(författare)
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Springtail diversity in South Africa
- 2011
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Ingår i: South African Journal of Science. - : Academy of Science of South Africa. - 0038-2353 .- 0370-8462 .- 1996-7489. ; 107, s. 75-81
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Annan publikation (refereegranskat)abstract
- Despite their significance in soil ecosystems and their use for investigations of soil ecosystem functioning and in bioindication elsewhere, springtails (Collembola) have not been well investigated in South Africa. Early recognition of their role in soil systems and sporadic systematic work has essentially characterised knowledge of the southern African fauna for some time. The situation is now changing as a consequence of systematic and ecological work on springtails. To date this research has focused mostly on the Cape Floristic Region and has revealed a much more diverse springtail fauna than previously known (136 identifiable species and an estimated 300 species for the Cape Floristic Region in total), including radiations in genera such as the isotomid Cryptopygus. Quantitative ecological work has shown that alpha diversity can be estimated readily and that the group may be useful for demonstrating land use impacts on soil biodiversity. Moreover, this ecological work has revealed that some disturbed sites, such as those dominated by Galenia africana, may be dominated by invasive springtail species. Investigation of the soil fauna involved in decomposition in Renosterveld and Fynbos has also revealed that biological decomposition has likely been underestimated in these vegetation types, and that the role of fire as the presumed predominant source of nutrient return to the soil may have to be re-examined. Ongoing research on the springtails will provide the information necessary for understanding and conserving soils: one of southern Africa's major natural assets.
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| 3. |
- Boelhouwers, J., Meiklejohn, I.
(författare)
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Quaternary periglacial geomorphology of southern Africa : review and synthesis
- 2002
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Ingår i: South African Journal of Science. - 0038-2353 .- 1996-7489. ; 98:1/2, s. 47-55
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Tidskriftsartikel (refereegranskat)abstract
- The literature on southern African Quaternary periglacial andglacial studies is qualitative in nature with an apparent lack ofscientific rigour. Landforms attributed to being of periglacial andglacial origin exist through a broad belt of high relief from theWestern Cape mountains along the Great Escarpment to theLesotho highlands. Present-day frost action is limited to thesurficial action of needle-ice and segregation ice resulting fromdiurnal to mild seasonal freeze–thaw cycles. Environmentalcontrols on current frost action are still poorly understood forthe Lesotho highlands, where frost-induced processes are animportant factor in accelerating land degradation. Relict periglaciallandforms are most reliably identified in the form of large patternedground, widespread solifluction mantles and blockstreams. Theseobservations are supported by adjunct information, which togetherindicate somewhat drier conditions than present. Erosional forms,such as nivation hollows, cirques, and cryoplanation terraces, lackpositive evidence and imply wetter conditions than at present.Interpretations suggesting rock glaciers, glacial cirques andformer ice wedges at low relative altitudes are highly anomalouswith respect to the other periglacial records and proxy data for theregion. The limitations of the current research literature suggestthat future emphasis should be directed towards sedimentaryrecords by means of clay mineral, soil micro-structural andchemical analysis and dating to improve the reliability and accuracyof the interpretations and their temporal framework
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| 5. |
- Boelhouwers, Jan
(författare)
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Quaternary slope development in the Lesotho Highlands: Review and alternative model
- 2003
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Ingår i: South African Journal of Science. - 0038-2353 .- 1996-7489. ; 99:1/2, s. 44-46
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Tidskriftsartikel (refereegranskat)abstract
- Discusses the quaternary slope development in the Lesotho highlands. Nature and spatial distribution of quaternary slope deposits; Asymmetry in the quaternary sedimentary record of Lesotho highlands; Existence of perigalcial slope dynamics; Paleoenvironmental implications.
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| 7. |
- Dahlgren, Hanna, et al.
(författare)
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Solar flares detected by the new narrowband VLF receiver at SANAE IV
- 2011
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Ingår i: South African Journal of Science. - : Academy of Science of South Africa. - 0038-2353 .- 1996-7489. ; 107:9-10, s. 39-46
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Tidskriftsartikel (refereegranskat)abstract
- A narrowband receiver was installed at the SANAE IV base in Antarctica to monitor specific very low frequency (VLF) radio signals from transmitters around the world. VLF waves propagating through the Earth-Ionosphere Waveguide are excellent probes of the varying properties of the lower region of the ionosphere. This paper describes the set-up of the narrowband system and demonstrates its capabilities with data from a set of solar flares on 08 February and 12 February 2010.
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