| 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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| 2. |
- 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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| 3. |
- Koen, Etienne J., et al.
(författare)
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Mid-latitude ionospheric signature of a weak solar flare in winter
- 2013
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Ingår i: South African Journal of Science. - : Academy of Science of South Africa. - 0038-2353 .- 1996-7489. ; 109:1-2, s. 83-87
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Tidskriftsartikel (refereegranskat)abstract
- Measurements of the amplitude and phase of very low frequency transmitter signals were used to evaluate the effects on the ionosphere of a moderate intensity solar flare that occurred on 13 December 2007. These measurements were compared to modelled results from the Long Wave Propagation Capability code. The ionospheric effects were found to be delayed by ∼1 min with respect to the 0.1-0.8 nm solar X-ray flux.
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| 4. |
- Lombard, Marlize, et al.
(författare)
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Bridging disciplines to better elucidate the evolution of early Homo sapiens in southern Africa
- 2013
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Ingår i: South African Journal of Science. - : Academy of Science of South Africa. - 0038-2353 .- 1996-7489. ; 109:11-12
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Tidskriftsartikel (refereegranskat)abstract
- Elucidating the history of Homo sapiens has been a passion shared by many researchers spanning several decades. There are now overwhelming lines of evidence from genetic, archaeological, palaeoanthropological and, to some extent, palaeoenvironmental research, that place Africa as the region of origin of our species. The different fields of study use diverse types of data, and methods are subject to variances introduced by mutation rates, time estimates and/or sampling biases. All of these approaches have their respective shortcomings and error ranges and are accompanied by intense debate. Yet, it is timeous to review the most recent and salient highlights that the different approaches are contributing towards explaining our deep history and ancestry. It is, after all, one history, and consequently, there ought to be several convergent patterns between data sets. Our focus is to present an updated regional synthesis from each discipline for a specific window in time within the southern African context, namely between similar to 160 ka and 85 ka, and to speculate about possible connections between data sets for this period. Even though our focus is specific in time and space, it is not intended to consider southern Africa in isolation from the rest of Africa or to suggest a singular 'origins' locale for modern Homo sapiens. We hope that this integrated approach will stimulate discussions to include broader time periods within Africa and between continents.
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