The Earth Story

Kopjes of the Serengeti

Occasionally, in the middle of the flat plains of Africa’s Serengeti, sets of rocks like this stick out. This is a Kopje (pronounced Kopee) known as Simba Kopje, a piece of granitic rock that sticks out of the plains.

The plains are an area covered with nearly flat lying mudrocks and ash formed from volcanoes in the nearby African Rift Zone. These Kopjes are much older; these are pieces of the basement rocks that stick up through the overlying sediment.

To a geologist, the basement rock is the lowest rock type in a sequence. It is often granitic or close to it in composition and if you try to dig through it, you’ll just run into more granite until you reach the mantle. These rocks are metamorphosed granites formed hundreds of millions of years ago when Gondwana was being put together during the Precambrian.

Granites are hard to erode, but when they are eroded they will leave some topography. Some parts of the granite will be less fractured than others and will stick up above the surrounding terrain. If the environment changes from erosion to deposition, whatever topography sits on top of the granites will be preserved by the surrounding sediments.

These Kopjes are high points in the underlying granite. They were buried by sediments long after they were formed and are now being re-exposed. A variety of animals and plants make use of these outcrops where they stick above the plains for shelter. In fact, the name of this one, Simba Kopje, comes from the fact that it was inspiration for some of the scenes in the movie “The Lion King” where the lions are on high ground.

-JBB

Image credit: (Creative Commons): https://www.flickr.com/photos/plalbrecht/4938497781/

Read more: http://www.serengeti.org/kopjes_detail.html http://safari-ecology.blogspot.com/2012/03/how-do-kopjes-form.html http://www.geocaching.com/geocache/GC24XFP_serengeti-kopjes?guid=be9da067-bc93-4532-8948-afb413589e25 http://safari-ecology.blogspot.com/2011/08/kopjes.html http://www.naturalhighsafaris.com/faqs/article/the-serengeti-plains-formation

Namibia

A trip across ecosystems while climbing Kilimanjaro

AFRICA’S GREAT MIGRATION HURDLE

In the plight to conserve Africa’s wildlife, there are many different challenges. Though Africa’s grazing megafauna are well adapted to the diverse landscape of the continent, they are presently experiencing a relatively unheard-of threat – fences. In ecology, habitat fragmentation is broadly known as the unfavourable partitioning of wildlife habitat, which is often by man-made structures or development. Some species can survive in smaller patches of habitat, but migratory species can be severely impeded and wire fences contribute greatly to this issue. The African savannah has become a highway for many important megafaunal migrations, including the Great Migration, which consists of almost 2 million animals trekking gradually from the Serengeti to the Masai Mara in Kenya. The Masai Mara reserve is home to indigenous nomadic tribes that have, for a long time, been involved in the stewardship of the land and fauna in the Greater Mara region. However, economic turmoil in the country as well as urbanisation have recently led to a switch from the nomadic lifestyle to individuals claiming land for cattle rearing and farming. The rising conflicts between farmers in the region have resulted in the erection of wire fences in areas where wild animals roam.

A group of researchers from the Demark and Kenya teamed up to track the progression of fence erection over the past 31 years to determine the extent to which fencing has impacted the region both culturally and environmentally. They found that areas that were previously fenced and utilised as homesteads have expanded gradually over the years. The most startling result seen, however, was that fencing in the Greater Mara region increased sporadically from 2014 to 2016, with fences popping up in previously unoccupied regions between settlements and the reserve, threatening to encroach further toward protected areas. What does this mean for the animals that depend on the region for food and water? How will migration patterns be affected? According to the authors, the patterns of fencing seen here will dismantle the intricate system that has remained protected for thousands of years. Culturally, the shift in and abandonment of environmental stewardship will likely spell disaster for this highly specialised ecosystem. Large declines can already be seen in the numbers of migrating animals and further losses will see extensive secondary ecosystem effects. Some of the grazers prefer to feed in the outer regions of the reserve, where cattle generally forage as well. Farmers have therefore fenced off their grazing lands, cutting off access to a number of species. Large numbers of wildebeest also migrate between the Greater Mara and Loita plains. The Greater Mara serves as dry season refuge due to the high levels of rainfall and extended foraging periods but the region where the Loita herds graze has been so densely fenced that most wildebeest cannot access the area.

The situation appears dire if the trends in fence erection continue but the authors are hopeful that changes in conservation policies to drive community-based natural resource management may help to restore migratory patterns and provide a number of socio-economic benefits such as secured access to land, institutional support, employment and profits from ecotourism, to stewardship communities. Ultimately, more information is needed on the land use dynamics within the area and communities-based stewardship needs to be incentivised to ensure a long-lasting solution. However, action needs to be taken as soon as possible to restore the damage already inflicted on the ecosystem and to prevent further encroachment by educating and rewarding compliant farmers.

KR.

References:

Løvschal et al., 2017, Fencing bodes a rapid collapse of the unique Greater Mara ecosystem. Nature: Scientific reports. DOI: 10.1038/srep41450.

http://bit.ly/2CFDLIE

Image: http://bit.ly/2lILjlJ

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