Browsing by Author "Milton, S J"

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    Did the flora match the fauna? Acocks and historical changes in Karoo biota
    (2003) Dean, W R J; Milton, S J
    Years of observation in Karoo veld convinced JP Acocks that the perennial grasses that he occasionally encountered in barren Karoo landscapes were remnants of pre-colonial vegetation. He maintained that desertification, caused by overgrazing and alteration of drainage systems, had destroyed key grazing resources, reducing the carrying capacity of the vegetation for large herbivores. We attempt to test this notion by reconstructing the fauna for sample areas of the Karoo from farm names, plant common names and travellers records, and by examining the flora of these areas for evidence of co-evolution with large herbivores. We concluded that names of mapped features and farms that refer to animals do reflect the historical distribution of these animals. However, within Karoo sampling units of approximately 500 km2, we could find no close relationship between historical records of large herbivores and herbivore-adapted defence and dispersal traits of plants. This weak evidence for co-evolution might have been because many of the large herbivores were not permanent residents in the Karoo. Alternatively it might be an artefact caused by lack of abundance data for plant guilds. There is evidence that post-colonial land use of the Karoo has changed vegetation structure and productivity within the areas we sampled.
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    'Emerging ecosystems' - a washing-stone for ecologists, economists and sociologists?
    (2003) Milton, S J
    Two recent workshops have debated the relatively novel concept of the emerging ecosystem. Here I summarize the discussions that took place in the second of the two meetings, held in Brasilia in May this year, and examine its relevance for South Africa and in particular for the arid zone. [
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    Evidence for induced pseudo-vivipary in Pennisetum setaceum (Fountain grass) invading a dry river, arid Karoo, South Africa
    (2008) Milton, S J; Dean, W R J; Rahlao, S J
    We report the development of rootless plantlets in inflorescences of Pennisetum setaceum (Fountain grass) invasive in the Gamka River in the Karoo National Park, South Africa. The pseudo-vivipary appeared to have been induced by inundation of immature inflorescences when the river flooded. Plantlet production may facilitate the spread of this species in seasonally flooding rivers in arid regions. To the best of our knowledge this is the first record of induced pseudo-vivipary in this grass species.
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    Human response and adaptation to drought in the arid zone: lessons from southern Africa
    (2009) O'farrell, P J; Anderson, P M L; Milton, S J; Dean, W R J
    Human adaptation and response to drought is primarily through evasion or endurance. A review of historical agricultural practices in southern Africa demonstrates evidence of drought evasion response strategies in well-established transhumance routes, where herders move livestock on a seasonal basis in order to exploit resources subject to different climatic regimes. European settlers to the arid regions of South Africa quickly recognised the necessity of these evasion options to survive drought, and adopted the transhumance practices of indigenous farmers. Areas of geographically diverse resource bases became hotly contested by settlers and indigenous farmers. The success of evasion systems are shown to hinge on good social and institutional support structures. When movement is not an option, drought endurance is pursued by attempting to limit the damage to the natural resource base. This is through a number of means such as forage conservation, varying livestock types and numbers, water and soil conservation and taking up alternative livelihood options. State responses to drought over the last century reflect the general South African pattern of racially divided and unjust policies relating to resource access. Historically the state provided considerable support to white commercial farmers. This support was frequently contradictory in its aims and generally was inadequate to enable farmers to cope with drought. Since the advent of democracy in 1994, the state has intervened less, with some support extended to previously disadvantaged and poor communal farmers. Climate change predictions suggest an increase in drought, suggesting that the adoption of mitigating strategies should be a matter of urgency. To do this South Africa needs to build social and institutional capacity, strive for better economic and environmental sustainability, embed drought-coping mechanisms into land restitution policy to ensure the success of this programme, and acknowledge the diversity of the agricultural sector.
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    Scaling up from site-based research to a national research and monitoring network: lessons from Tierberg Karoo Research Centre and other design considerations
    (Academy of Science of South Africa, 2007) Dean, W R J; Milton, S J; O'Connor, T G; Mills, A J
    South Africa is in the process of setting up a national environmental observatory system (SAEON) to monitor and gain a predictive understanding of the effects of climate change and land use on biodiversity, carbon and nutrient fluxes, soils and sediments, primary and secondary productivity, hydrology and disturbance regimes. It is intended that the data should be archived, analysed and translated into information accessible to decision-makers. We present a case that illustrates the infrastructural needs and challenges for long-term research and then discuss optimal designs and collaborations required to detect change in many variables, land-use types and geographical areas of South Africa.