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12 October 2020 | Story Leonie Bolleurs | Photo Supplied
Adriaan van der Walt
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

Mushrooms, from gourmet food for humans to fodder for animals
2016-12-19

Description: Mushroom research photo 2 Tags: Mushroom research photo 2 

From the UFS Department of Microbial Biochemical and
Food Biotechnology are, from left: Prof Bennie Viljoen,
researcher,
MSc student Christie van der Berg,
and PhD student Christopher Rothman
Photo: Anja Aucamp

Mushrooms have so many medicinal applications that humans have a substance in hand to promote long healthy lives. And it is not only humans who benefit from these macrofungi growing mostly in dark spaces.

“The substrate applied for growing the mushrooms can be used as animal fodder. Keeping all the medicinal values intact, these are transferred to feed goats as a supplement to their daily diet,” said Prof Bennie Viljoen, researcher in the Department of Microbial, Biochemical and Food Biotechnology at the UFS.

Curiosity and a humble start
“The entire mushroom project started two years ago as a sideline of curiosity to grow edible gourmet mushrooms for my own consumption. I was also intrigued by a friend who ate these mushrooms in their dried form to support his immune system, claiming he never gets sick. The sideline quickly changed when we discovered the interesting world of mushrooms and postgraduate students became involved.

“Since these humble beginnings we have rapidly expanded with the financial help of the Technology Transfer Office to a small enterprise with zero waste,” said Prof Viljoen. The research group also has many collaborators in the industry with full support from a nutraceutical company, an animal feed company and a mushroom growers’ association.

Prof Viljoen and his team’s mushroom research has various aspects.

Growing the tastiest edible mushrooms possible
“We are growing gourmet mushrooms on agricultural waste under controlled environmental conditions to achieve the tastiest edible mushrooms possible. This group of mushrooms is comprised of the King, Pink, Golden, Grey, Blue and Brown Oysters. Other than the research results we have obtained, this part is mainly governed by the postgraduate students running it as a business with the intention to share in the profit from excess mushrooms because they lack research bursaries. The mushrooms are sold to restaurants and food markets at weekends,” said Prof Viljoen.

Description: Mushroom research photo 1 Tags: Mushroom research photo 1 

Photo: Anja Aucamp

Natural alternative for the treatment of various ailments
“The second entity of research encompasses the growth and application of medicinal mushrooms. Throughout history, mushrooms have been used as a natural alternative for the treatment of various ailments. Nowadays, macrofungi are known to be a source of bioactive compounds of medicinal value. These include prevention or alleviation of heart disease, inhibition of platelet aggregation, reduction of blood glucose levels, reduction of blood cholesterol and the prevention or alleviation of infections caused by bacterial, viral, fungal and parasitic pathogens. All of these properties can be enjoyed by capsulation of liquid concentrates or dried powdered mushrooms, as we recently confirmed by trial efforts which are defined as mushroom nutriceuticals,” he said.

Their research focuses on six different medicinal genera, each with specific medicinal attributes:
1.    Maitake: the most dominant property exhibited by this specific mushroom is the reduction of blood pressure as well as cholesterol. Other medicinal properties include anticancer, antidiabetic and immunomodulating while it may also improve the health of HIV patients.
2.    The Turkey Tail mushroom is known for its activity against various tumours and viruses as well as its antioxidant properties.
3.    Shiitake mushrooms have antioxidant properties and are capable of lowering blood serum cholesterol (BSC). The mushroom produces a water-soluble polysaccharide, lentinan, considered to be responsible for anticancer, antimicrobial and antitumour properties.
4.    The Grey Oyster mushroom has medicinal properties such as anticholesterol, antidiabetic, antimicrobial, antioxidant, antitumour and immunomodulatory properties.
5.    Recently there has been an increased interest in the Lion’s Mane mushroom which contains nerve growth factors (NGF) and may be applied as a possible treatment of Alzheimer’s disease as this compound seems to have the ability to re-grow and rebuild myelin by stimulating neurons.
6.    Reishi mushrooms are considered to be the mushrooms with the most medicinal properties due to their enhancing health effects such as treatment of cancer, as well as increasing longevity, resistance and recovery from diseases.


Description: Mushroom research photo 3 Tags: Mushroom research photo 3


Valuable entity for the agricultural sector
Another research focus is the bio-mushroom application phenome, to break down trees growing as encroaching plants. This research is potentially very valuable for the agricultural sector in the areas where Acacia is an encroaching problem. With this process, waste products are upgraded to a usable state. “It is therefore, possible to convert woody biomass with a low digestibility and limited availability of nutrients into high-quality animal fodder. By carefully selecting the right combination of fungus species to ferment agro-wastes, a whole host of advantages could become inherently part of the substrate. Mushrooms could become a biotechnological tool used to ‘inject’ the substrate that will be fed to animals with nutrition and/or medicine as the need and situation dictates,” said Prof Viljoen.

 

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