The previous two posts in this series address my own magnetic draw to the African bush, and the tireless work of the National Park Ranger service against poaching. This final post will discuss the work which I undertook in South Africa as a scientist, and the results revealed.
African savannahs are shaped by the forces of nature which surround them, the burning sun, the periodic rains, the raging bushfires and the relentless chomping of the largest grazing herds on the planet. Ecologists, who study these systems, are interested in understanding how these mechanisms work to create and maintain these ecosystems, in a context of scientific discovery, but also in an attempt to manage our own impact on these environments.
Whilst we know how grazing and fire influence vegetative regrowth, it is less clear how these pressures influence other organisms who form a vital part of these environments. When faced with the bulldozing impact of an elephant, it is often easy to forget the role of infinitely smaller insects. Seemingly inconspicuous ants have a huge role in these systems, by modifying soils through nest construction, exerting a huge pressure as predators on other insect populations, and on plant populations as seed harvesters and herbivores. Unlocking the secrets of a savannah’s functioning cannot be done without an understanding of the key role of these insects.
Given their inescapable link with the landscape, it is of interest to see how these habitats change under different management regimes. A sad truth is that certain areas of Africa have lost large swathes of herbivores as a result of our over poaching, leaving the grasslands to regress and the encroachment of the surrounding trees. How does this shift in herbivore populations impact on equally important ants?
To examine this change, my research team have been collecting ants in the Kruger National Park for over ten years, in 3 areas reflecting different grazing pressures: a zone of open access, a zone fenced with a high electric wire preventing elephant and giraffe, and a zone of complete exclusion. As the vegetation changed following the exclusion, so too did the ant species collected. Generalist heat tolerant species such as Monomorium junodi, were replaced by species more closely associated with the closing canopy, such as Cataulacus sp.
Such a change is to be expected given the close link of ants with their surrounding vegetation. But other scientists have shown that a removal of certain elements of a natural system such as herbivore grazing can have further reaching consequences. Palmer and his team revealed that ants which protected trees from other insect predators modified their behaviour when elephant damage to these trees was removed, which in turn made these trees more vulnerable to disease. Removing herbivores will thus lead to changes in the ant community, which can in turn have an irreversible impact on the future of the savannah systems.
Future research must not aim to expose the deeper functioning of other ant species. Almost one hundred different species of ant were captured during our sampling campaign, and the inner workings of their ecology are largely unknown. It is impossible to predict our impact on an environment without a broader understanding of the role of the numerous elements of ecosystems on their functioning.
Whilst we know how grazing and fire influence vegetative regrowth, it is less clear how these pressures influence other organisms who form a vital part of these environments. When faced with the bulldozing impact of an elephant, it is often easy to forget the role of infinitely smaller insects. Seemingly inconspicuous ants have a huge role in these systems, by modifying soils through nest construction, exerting a huge pressure as predators on other insect populations, and on plant populations as seed harvesters and herbivores. Unlocking the secrets of a savannah’s functioning cannot be done without an understanding of the key role of these insects.
Given their inescapable link with the landscape, it is of interest to see how these habitats change under different management regimes. A sad truth is that certain areas of Africa have lost large swathes of herbivores as a result of our over poaching, leaving the grasslands to regress and the encroachment of the surrounding trees. How does this shift in herbivore populations impact on equally important ants?
To examine this change, my research team have been collecting ants in the Kruger National Park for over ten years, in 3 areas reflecting different grazing pressures: a zone of open access, a zone fenced with a high electric wire preventing elephant and giraffe, and a zone of complete exclusion. As the vegetation changed following the exclusion, so too did the ant species collected. Generalist heat tolerant species such as Monomorium junodi, were replaced by species more closely associated with the closing canopy, such as Cataulacus sp.
Such a change is to be expected given the close link of ants with their surrounding vegetation. But other scientists have shown that a removal of certain elements of a natural system such as herbivore grazing can have further reaching consequences. Palmer and his team revealed that ants which protected trees from other insect predators modified their behaviour when elephant damage to these trees was removed, which in turn made these trees more vulnerable to disease. Removing herbivores will thus lead to changes in the ant community, which can in turn have an irreversible impact on the future of the savannah systems.
Future research must not aim to expose the deeper functioning of other ant species. Almost one hundred different species of ant were captured during our sampling campaign, and the inner workings of their ecology are largely unknown. It is impossible to predict our impact on an environment without a broader understanding of the role of the numerous elements of ecosystems on their functioning.
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