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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

Multi-disciplinary research approach at UFS

2005-10-25

UFS follows multi-disciplinary research approach with opening of new centre

“A new way of doing business in necessary in the research and teaching of agriculture and natural sciences in South Africa. We must move away from departmentalised research infrastructures and a multi-disciplinary approach to research involving several disciplines must be adapted,” said Prof Herman van Schalkwyk, Dean: Faculty of Natural and Agricultural Sciences at the University of the Free State (UFS).

Prof van Schalkwyk delivered the keynote address during the launch of the Centre for Plant Health Management (CePHMa) at the Main Campus in Bloemfontein today (21 October 2005). CePHMa is an initiative of the UFS Department of Plant Sciences.

According to Prof van Schalkwyk a tertiary institution must practice multi-disciplinary research to be a world-class research institution. “It is difficult for researchers to admit that they do not know a lot about each other’s area of speciality. It is therefore necessary for researchers to make a paradigm shift and to focus on inter-disciplinary co-operation. To do this, we must encourage them to work together and to find a common language to communicate ideas en establish symbiotic relationships,” said Prof Van Schalkwyk.

“We tend to think that research is better and faster if it is specialised. This is not true. The new generation of scientists are young and they are trained to form a concept of the total system and not to focus on a specific area of speciality. At the UFS we encourage this approach to research. This was one of the main reasons for the establishment of CePHMa,” said Prof Van Schalkwyk.
CePHMa is the only centre of its kind in Africa and is established to extend the expertise in plant health management in South Africa and in Africa, to train experts in plant health and to conduct multi-disciplinary research about the health of agricultural crops.

“CePHMa is a virtual centre comprising of ten disciplines applicable to crop production and crop protection,” said Prof Wijnand Swart, Chairperson of CePHMa during the opening ceremony.

“The UFS is the leading institution in Africa in terms of news crop development and manages three research programmes that concentrate on new crops, i.e. the New Crop Pathology Programme, the New Crop Development Programme and the Insects on New Crops Programme. Other applied research programmes that are unique to the UFS are genetic resistance to rust diseases of small grain crops and sustainable integrated disease management of field crops,” said Prof Swart.

“Because the expected growth in population will be 80% in 2020 in sub-Saharan Africa, the future demands of food produce in Africa will be influenced. Therefore research will in future be focused on ways to improve food security by employing agricultural systems that are economically viable and environmentally sound,” said Prof Swart.

“Thorough knowledge of the concept of holistic plant health management is crucial to meet the challenge and it is therefore imperative that innovative crop protection and crop production strategies, with particular emphasis on plant health, be adopted. This is why the Department of Plant Sciences initiated the establishment of CePHMA,” he said.

According to Prof Swart there is a shortage of expertise in plant health management. “The UFS has shown the potential to address the demand of the sub-continent of Africa regarding expertise training and CePHMa is the leader in southern Africa to provide in this need,” he said.

The appropriateness and quality of training in plant health management is reflected in the fact that students from Ethiopia, Eritrea, Malawi, Uganda, Zambia, Ghana, Tanzania, Cameroon, Angola, Mozambique and Lesotho have already been trained or are in the process of being trained in at the UFS.

Scientists from CePHMa have forged partnerships with numerous national and international institutions including the Agricultural Research Council (ARC), various community trusts, seed, pesticide and agricultural chemical companies, in addition to overseas universities.

Media release
Issued by: Lacea Loader
Media Representative
Tel: (051) 401-2584
Cell: 083 645 2454
E-mail: loaderl.stg@mail.uovs.ac.za
21 October 2005

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