scholarly journals Spreading of the semi-arid climate across South Africa

2021 ◽  
Author(s):  
Mark R. Jury
Keyword(s):  
South Africa ◽  
Coupled Model ◽  
Arid Climate ◽  
Shelf Zone ◽  
Potential Evaporation ◽  
Sea Breezes ◽  
Arid Conditions ◽  
Upper Level ◽  
Long Timescales ◽  
Semi Arid

Abstract The eastward shift of semi-arid climate across South Africa is studied using satellite assimilated cloud cover, vegetation temperature and potential evaporation 1981–2019, and 21st century coupled model projections. Semi-arid thresholds over the plateau have shifted hundreds of kilometers eastward in the Vaal River catchment for potential evaporation, cloud fraction, and vegetation temperature. Coastal cloudiness has also changed due to sea breezes modified by shelf zone sea temperatures. Processes underlying the spread of semi-arid conditions across South Africa are quantified. Desiccation is related to greater westerly airflow, as the atmospheric boundary layer over the Kalahari preferentially links with the upper-level circulation. Warm dry spells and climate change enhance the meridional temperature gradient and accelerate the sub-tropical jet at both short- and long timescales. According to observations and reanalysis, dry westerlies prevail during the afternoon and induce +0.2 °C/year trends in vegetation temperature over the Highveld during the study period. Coupled model projections show that semi-arid conditions expand eastward from Bloemhof (25.5°E) by 50,000 km2, altering future adaptation strategies.

XII.—On Salpingostoma dasu: A New Carboniferous Seed from East Lothian

1942 ◽  
Vol 60 (2) ◽  
pp. 427-464 ◽  
Author(s):  
W. T. Gordon
Keyword(s):  
Arid Climate ◽  
Fossil Plants ◽  
Lower Carboniferous ◽  
Positive Evidence ◽  
Arid Conditions ◽  
Lithological Character ◽  
Semi Arid

In a recent paper (Gordon, 1938) reasons were given for the belief that semi-arid conditions prevailed during Lower Carboniferous times in the neighbourhood of North Berwick, East Lothian. The evidence was opposed, in a measure, to that advanced by Mr George Barrow in the East Lothian Memoir (1910) to substantiate the same position. He had relied on the absence of fossils as part proof; but, in point of fact, fossil plants have been obtained in abundance from the actual bedded ashes of Oxroad Bay that he considered (a) to be unfossiliferous, and (b) to have been formed in a manner similar to beds on the Springbok Flats of the Transvaal. The plants that have now been obtained showed xerophytic features, and, consequently, a semi-arid climate was proved on positive evidence. Other positive evidence of a lithological character was also presented in confirmation (Gordon, 1938, pp. 352, 353).

scholarly journals Conservation Agriculture Practices Can Improve Earthworm Species Richness and Abundance in the Semi-Arid Climate of Eastern Cape, South Africa

Agriculture ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 576
Author(s):  
Sixolise Mcinga ◽  
Lindah Muzangwa ◽  
Kudzayi Janhi ◽  
Pearson Nyari Stephano Mnkeni
Keyword(s):  
South Africa ◽  
Species Richness ◽  
Conservation Agriculture ◽  
Residue Management ◽  
Arid Climate ◽  
Eastern Cape ◽  
Earthworm Species ◽  
No Till ◽  
Semi Arid ◽  
Residue Retention

Earthworms play a pivotal role in the regulation of soil health. Studies that explore the effects of conservation agriculture (CA) principles on earthworms under the semi-arid climate of the central Eastern Cape (EC) of South Africa (SA) are limited. Therefore, this study investigated the effects of tillage, crop rotations, and residue management on earthworms’ abundance and species richness. The study design followed a split-split plot with three replicates. The main plot was allocated to tillage treatment, which had conventional tillage (CT) and no-tillage (no-till) as factors. Crop rotation treatment was allocated to a subplot, and had maize (Zea mays)–fallow–maize (MFM), maize–fallow–soybean (Glycine max) (MFS), maize–wheat (Triticum aestivum)–maize (MWM), and maize–wheat–soybean (MWS). Residue management was in the sub-subplot with residue retention and residue removal. The study was carried out over four cropping seasons: summer 2015–2016, winter 2016, spring 2016, and summer 2016–2017. The results showed that the genera Amynthas and Lumbricus, both belonging to the anecic group, and Dendrobaena, belonging to the epigeic group, were present. Earthworm species diversity and density were highest under no-till than under CT. Residue retention improved earthworm density regardless of tillage management. Rotations that had fallow periods recorded lower earthworm numbers as compared to continuous cropping systems where wheat was grown in winter. The study concluded that maize–wheat–soybean (MWS) rotation with residue retention results in the highest earthworm abundance and species richness.

A GRASS-ALFALFA MIXTURE COMPARED WITH CEREAL GRAINS FOR FODDER PRODUCTION UNDER SEMI-ARID CONDITIONS

1961 ◽  
Vol 41 (4) ◽  
pp. 799-804 ◽  
Author(s):  
M. R. Kilcher ◽  
D. H. Heinrichs
Keyword(s):  
Arid Climate ◽  
Cereal Grains ◽  
Cereal Crop ◽  
Perennial Crop ◽  
Forage Crops ◽  
Arid Conditions ◽  
Fodder Production ◽  
Semi Arid

From 1952 to 1960 at Swift Current, Saskatchewan, the performance of a grass-alfalfa mixture was compared to that of oats and of wheat on dryland, principally from the standpoint of hay production. Average annual hay yields over the 9-year period were similar, but within single years large differences in yield occurred between crops. In seasons with favourable precipitation the perennial forage mixture gave higher hay yields, while the cereals gave the highest yields during very dry seasons.Small yields from the perennial crop were associated with low rainfall in May. It was concluded that perennial forage crops should be the main source of winter feed in a semi-arid climate, if used in conjunction with a cereal crop for insurance.

XII.—On Salpingostoma dasu: A New Carboniferous Seed from East Lothian

1942 ◽  
Vol 50 (2) ◽  
pp. 427-464
Author(s):  
W. T. Gordon
Keyword(s):  
Arid Climate ◽  
Fossil Plants ◽  
Lower Carboniferous ◽  
Positive Evidence ◽  
Arid Conditions ◽  
Lithological Character ◽  
Semi Arid

In a recent paper (Gordon, 1938) reasons were given for the belief that semi-arid conditions prevailed during Lower Carboniferous times in the neighbourhood of North Berwick, East Lothian. The evidence was opposed, in a measure, to that advanced by Mr George Barrow in the East Lothian Memoir (1910) to substantiate the same position. He had relied on the absence of fossils as part proof; but, in point of fact, fossil plants have been obtained in abundance from the actual bedded ashes of Oxroad Bay that he considered (a) to be unfossiliferous, and (b) to have been formed in a manner similar to beds on the Springbok Flats of the Transvaal. The plants that have now been obtained showed xerophytic features, and, consequently, a semi-arid climate was proved on positive evidence. Other positive evidence of a lithological character was also presented in confirmation (Gordon, 1938, pp. 352, 353).

scholarly journals Observations on the survival capacity of 118 plant taxa on a green roof in a semi-arid climate: 12 year update

2021 ◽  
Vol 8 (1) ◽  
pp. 19-40
Author(s):  
Amy Schneider ◽  
◽  
Michelle Landis ◽  
Jennifer Bousselot ◽  
◽  
...  
Keyword(s):  
Overall Survival ◽  
Green Roof ◽  
Survival Rates ◽  
Green Roofs ◽  
Arid Climate ◽  
Botanic Gardens ◽  
Growth Type ◽  
Arid Conditions ◽  
Survival Capacity ◽  
Semi Arid

The Green Roof at Denver Botanic Gardens was built in the fall of 2007. Since installation, data on the green roof have been collected on 118 plant taxa 43 of which have survived for over 10 years. Plants were grouped based on their metabolic and growth type: succulents, creeping forbs, upright forbs, graminoid, and shrubs. Overall, shrubs and succulents have displayed the highest survival rates, showing the greatest potential for use on green roofs in semi-arid conditions. Graminoids survived about half the time and creeping and upright forbs had the lowest overall survival in semi-arid Colorado. Species survivability rates were calculated based on the number of plants of that species originally installed on the green roof.

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