Browsing by Author "Bekker, S. J."

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    Ecophysiology, vigour, berry and wine characteristics of grapevines growing on and off heuweltjies
    (South African Society for Enology and Viticulture, 2016) Bekker, S. J.; Hoffman, J. E.; Jacobs, S. M.; Strever, A. E.; Van Zyl, J. L.
    Heuweltjies are unique landscape features putatively created by the termite Microhodotermes viator through their burrowing and nest-building activities. They have been closely examined in the natural veld of the Western Cape in the recent past and are the focus of many ecological studies, but their effect in cultivated landscapes (e.g. vineyards and orchards) has remained unexplored. This study addresses the vigour and physiology of vines growing on and off heuweltjies, as well as the wine emanating from these vines. This study was conducted on Cabernet Sauvignon and Shiraz in two climatic regions of the Western Cape, namely Stellenbosch (Mediterranean climate) and Robertson (semi-arid climate) respectively, to better understand how differences in heuweltjie characteristics correspond to differences in rainfall and temperature. Through the use of ANOVAs and Fisher’s LSD post hoc tests to indicate statistical significance, it was apparent that the soil on and off heuweltjies differed significantly in respect of several physical and chemical properties. Consequently, soil water content was more favourable on heuweltjies, especially in the Stellenbosch area, where only supplementary irrigation was applied. Heuweltjies induce substantial changes in grapevine vigour and grape composition. Differences in grapevine physiology between heuweltjie and non-heuweltjie plots were subtle, but vine vigour was severely altered on the heuweltjieassociated vines, exhibiting excessive vegetative growth in Stellenbosch and leading to variations in berry and wine characteristics on and off the heuweltjies. The opposite was observed in the semi-arid climate of Robertson. The presence of heuweltjies in vineyards presents an opportunity to produce and market wines with a difference in respect of their characteristics and unique origin.
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    Die invloed van sosio-ekologiese veranderlikes op die aard en omvang van die probleemdierkwessie in Suid-Oos Kaapland
    (Stellenbosch : Stellenbosch University, 1994-03) Bekker, S. J.; Bigalke, R. C.; Van Hensbergen, H. J.; Stellenbosch University. Faculty of Arts and Social Sciences. Dept. of Geography and Environmental Studies.
    ENGLISH ABSTRACT: The entire problem animal issue was investigated in the Southwestern Cape over a period of four years. One of the primary objectives of the study was to quantify and qualif.y the problem scientifically and to develop the necessary techniques to pursue this objective. A necropsy procedure was developed to facilitate a distinction between three main categories of mortality (predation, pseudopredation and other causes). This procedure was also integrated in an expert system to facilitate decisionmaking. The natural food availability of perceived problem animals in the study area (on private and state land in winter and summer) was also investigated through extensive small mammal surveys and a number of flood censusing operations. Stomach contents analyses were also carried out to quantify and qualify the diet of perceived problem animals, with specific emphasis on the contribution of small stock. The correlation between predation and natural food availability was also investigated. Farmers in the study area were exposed to a semi-structured interview to determine their attitudes towards perceived problem animals. A personality. factor analysis was also carried out on all the farmers and the correlation between their personalities and attitudes towards perceived problem animals was investigated. Farmer's perceptions of their own efficiency regarding agricultural practices as well as their perception of the extent of predation, was compared with an objective evaluation of the actual situation by the author. Need-stress diagrams were also constructed to illustrate the negative impact of perceived levels of competence and predation on behavioural change. The implications of the findings for extension are also discussed.