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SA now experiencing half-year summers

12 October 2020 | Story Leonie Bolleurs | Photo Supplied

Although several international studies have used temperature metrics to statistically classify their seasonal divisions, a study in which Adriaan van der Walt was involved, would be the first known publication in a South African context using temperature as classification metric.

Gone are the days when we as South Africans would experience a three-month spring season, easing into summer, and then cooling off for three months before we hit winter.

Adriaan van der Walt, Lecturer in the Department of Geography at the University of the Free State (UFS), focuses his research on biometeorology (a specialist discipline exploring the role and climate change in physical and human environments) as well as climatology and geographic information systems.

He recently published an article: ‘Statistical classification of South African seasonal divisions on the basis of daily temperature data’ in the South African Journal of Science.

In this study, which Van der Walt undertook with Jennifer Fitchett, a colleague from the University of the Witwatersrand, data on daily maximum and minimum temperatures was collected from 35 meteorological stations of the South African Weather Service, covering the period between 1980 and 2015.

They went to great lengths to ensure that they had a complete set of data before presenting it to demonstrate seasonal brackets.

First for South Africa

Their statistical seasonal brackets indicate that South Africans now experience longer summers (from October to March), autumn in April and May, winter from June to August, and spring in September.

Although considerable work has been done using rainfall to determine seasonality in Southern Africa, Van der Walt believes that these methods did not work well as there are too many inconsistencies in this approach, as identified by Roffe et al. (2019, South African Geographical Journal). To make matters more complicated – as a semi-arid region, and with desert conditions along the west coast – some regions do not have enough rainfall to use as a classifier.

Temperature, on the other hand, worked well in this study. “Temperature, by contrast, is a continuous variable, and in Southern Africa has sufficient seasonal variation to allow for successful classification,” says Van der Walt.

He continues: “Although several international studies used temperature metrics to statistically classify their seasonal divisions, this study would be the first known publication in a South African context using temperature as classification metric.”

Van der Walt says what we understand as seasons largely relates to phenology – the appearance of blossoms in spring, the colouration and fall of leaves in autumn, and the migration of birds as a few examples. “These phenological shifts are more sensitive to temperature than other climatic variables.”

Seasonal brackets

According to Van der Walt, they believe that a clearly defined and communicated method should be used in defining seasons, rather than just assigning months to seasons.

“One of the most important arguments of our work is that one needs to critically consider breaks in seasons, rather than arbitrarily placing months into seasons, and so we welcome any alternate approaches,” he says.

A number of sectors apply the temperature-based division to their benefit. “For example, in the tourism sector it is becoming increasingly important to align advertising with the season most climatically suitable for tourism,” says Van der Walt.

Temperature-based division is also used to develop adaptive strategies to monitor seasonal changes in temperature under climate change. However, Van der Walt points out that each sector will have its own way of defining seasons. “Seasonal boundaries should nevertheless be clearly communicated with the logic behind them,” he says.

News Archive

Research into surrogate milk important to wildlife conservation

2017-05-08

Prof Gary Osthoff from the UFS Department of
Microbial, Biochemical and Food Biotechnology,
will soon work on a milk formula for elephants.
Photo: Supplied

Research is being done at the University of the Free State (UFS) to analyse and synthetically imitate the unique milk of various wildlife species. This research is not only of scientific value, but also serves the conservation of South Africa’s wildlife species. At the forefront of this research is Prof Garry Osthoff from the Department of Microbial, Biochemical and Food Biotechnology.

Orphaned rhino calf pulled through with surrogate milk
“There is still a lot of research to be done. Naturally the research is of scientific importance, but with surrogate milk having the same composition as the mother’s milk of a specific species, orphaned calves or cubs of that species could be pulled through during a difficult time of weaning. Bearing in mind that exotic animals fetch thousands and even millions of rands at auctions, it goes without saying a game farmer will do everything possible to provide only the best nourishment to such an orphaned animal. In such a case, synthetically-manufactured milk would be the right choice,” says Prof Osthoff.

The fruits of his research were recently demonstrated in Germany when a rhino calf was left orphaned in the Leipzig Zoo. Prof Osthoff’s article: “Milk composition of a free-ranging white rhinoceros during late lactation” was used as a directive for applying surrogate milk for horse foals (which is already commercially available), since the composition of horse and rhino milk largely corresponds. The surrogate milk was used with great success and the rhino calf is flourishing. He mentions that such an orphan is often given the wrong nourishment with the best intentions, resulting in the starvation of the animal despite the amount of cow’s milk it devours.

With surrogate milk having the same
composition as the mother’s milk of a
specific species, orphaned calves or
cubs of that species could be pulled
through during the difficult time
of weaning.

Milk formula for baby elephants in the pipeline
With baby elephants left orphaned due to the increase in elephant poaching for their ivory, several attempts have been made to create a milk formula in order to feed these elephants. To date, many elephants have died in captivity from side effects such as diarrhoea as a result of the surrogate formula which they were fed.

Prof Osthoff recently received a consignment of frozen milk which he, together with researchers from Zimbabwe, will use to work on a milk formula for elephants. They are studying the milk in a full lactation period of two years. During lactation, the composition of the milk changes to such an extent that a single surrogate formula will not be sufficient. Four different formulas should probably be designed.

Prof Osthoff says that of the different species he has researched, elephants are the most interesting and deviate most from the known species.

Although his research to develop surrogate milk is adding much value to the wildlife industry, and although he finds this part of his work very exciting, his research focus is on food science and nutrition. “What is currently authentic in milk research is the study of the fat globules with content, the structure and composition of the casein micelle, and the prebiotic sugars. The knowledge which is gained helps to improve the processing, development of new food products, and development of food products for health purposes,” says Prof Osthoff.

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