An overview:
The previous posting on Africa showed the photographic preparation for the trip. This posting is an introduction to the upcoming blogs which will feature the animal and plant wildlife in more detail. This photo safari was planned for thirty years. It has been postponed three times. At last, this was the opportunity to go. Botswana and Kenya are the two countries we visited in sub-Saharan Africa. The reasons to go there were their diversity of wildlife, ecosystems, and safety. The month of August was selected to be timely to see the greatest density of animals in the most clement season. It was also an opportunity to look for the similarities and differences of the comparable African and US locations. Here are thoughts, impressions and recounting of the two weeks of experience there.
The title sunset image is typical of the African sky. The beautiful sunset red comes from sand and minerals of the desert suspended in the air and refracted by the light. These same sands which are blown across the Atlantic Ocean color our Floridian sunsets too.
This lengthy monologue is only a rudimentary description of a very large subject. It is intended to help understand and appreciate the reasons for these features seen on this expedition and to summarize the complexities of the climate, geology, the flow of water on the land, the interdependency of species and some similarities to areas in the USA. The two major eco systems were marshlands and savanna. In Botswana the wetlands of the Okavango delta were the focal point. In Kenya the savanna of the Maasai Mara section of the Serengeti was of greatest interest. The Okavango delta ecosystem has some similarities to the wetlands found in the Southwest Florida Everglades National and State Park systems. The Maasai Mara is more like the grasslands of Montana where, 250 years ago, buffalo, antelope, elk, and wolf roamed in their own great migration.
Climate and Geology:
The Okavango delta is 19 degrees south of the Equator. The Florida Everglades are 19 degrees north of the equator. They receive approximately the same amount of energy from the sun. The marshlands of the Okavango delta and the Florida Everglades are both essentially inland dispersions of fresh water. The Okavango is a unique feature of the Kalahari Desert. This delta is deep in the interior of the land mass and the climate is continental. Unlike the Everglades, it does not have the moderating exposure to a neighboring ocean. It has a soil basis of sand that averages 200 feet deep. On top of that is a soil of a few inches depth with mixtures of soil brought by wind, flood, and a thin organic compost. The average elevation is 3100 ft. The delta has three biome types that include savanna, woodlands, and swamp. The Okavango River supply is derived from the confluence of the Cubango and Cuito rivers in Angola. The annual flow reaches the delta between March and June with maximum flow in July. Additionally, there is seasonal 18-inch rainfall in the Okavango from November to February which adds to water shed.
Floridian Everglades are at sea level and are founded on petrified sea bottom called sedimentary rock with a high calcium carbonate basis called limestone. The Florida Everglades topsoil is an average 17-foot-thick layer of marl (calcitic mud), peat and muck. The Everglades are subtropical wetlands whose freshwater system begins near Orlando in the Kissimmee River. The average annual rainfall is 60 inches. The Everglades have a maritime weather with tropical storms and moderation of climate. Climatically, there are no hurricanes in the Okavango and in the Everglades there is no drought.
In support of the science of plate tectonics. The Americas and Africa were one land mass 200 million years ago.
The concept of moving plates of the crust of the earth suggests that at a distant time in the past the assembly of the plates separated into the various land bodies. The shapes of the land mass fragments seen today can be manipulated as puzzle pieces into a larger land mass that fits together quite well. This particular assembly is called Pangea. If this is how the continents formed then there is a strong relationship between the eastern geology of the Americas and the western African geology. This fit is not entirely perfect, however, when considering the length of time for the division to transpire it is remarkably good. This has been supported by substantial evidence of rock formations that span the continents.The science is based on continental fit, matching rocks, fossils, corals, mountains, glacial striations, magnetic lineages and direct measurement of the movement.
Comparison of ecosystems:
Water and Land:
About 98% of the water that goes into the Okavango delta is eventually lost through evaporation and transpiration. Transpiration results when water moves through the plant and evaporates from leaves and flowers. Despite the subtropical sun generating intense evaporation, the delta’s water is fresh, not salty. I was surprised by this because non circulating ponds of water in the middle parts of the islands have very high chemical and salt concentrations. This chemical concentration occurs in thousands of islands. The reason the water is fresh is that trees on the edges of the islands create a barrier of natural filters between the inner part of the islands and the floodplain. The second reason is a process of transpiration caused by trees. Water flows into the delta and carries with it silica and soluble minerals like sodium carbonate. As the water is lost from the trees, the silica and salts remain to build islands. The center of the islands concentrates the accumulated salt and as a result the vegetation dies from dehydration leaving a central bare white mineral spot. Termites facilitate island formation when they build nests of organic material, fungus, soil and water. These mounds of soil and nutrients promote tree and other plant growth. When the seasonal water rises the termites build skyward forming islands. Eventually the nest is abandoned to form a new colony. The mound then collapses from animal invasion and erosion. Termites are the keystone species of the Okavango. Without them the delta would be like the desert. Water would be lost, and life would be less dense and less diverse.The Okavango has no palm trees and pines are also nearly absent.
The vegetation in Florida also plays an important role. The ocean barrier to salt invasion are mangroves which are salt tolerant. These mangroves are key to prevention of back flow of the salty ocean and hold the soil preventing erosion. Some fresh water flow does reach the ocean creating a relative partial positive pressure. The soils of the Everglades are rich in nitrates and farmers increase the nitrogen of a large portion of the Everglades. This has resulted in an overgrowth of a complex of bacteria species which feeds on the nitrates and deplete the nutrient value of the topsoil. The Everglades have no Acacia trees and lots of mosquitos.
The Kenyan savanna is climatically and geologically very different from the Okavango savanna. Kenya is at the Equator. It is a mile high in altitude and the soil is volcanic in origin. It is more like the area around Denver CO. It is surrounded by hills and mountains and has two rivers flowing through it. The major river flow is the Mara. The other is the Talek. It is part of the Mara-Serengeti ecosystem spanning Tanzania and Kenya and has been geologically very active with ancient and recent rock formations. It is in the Great Rift Valley. It is in this valley that the million-year-old petrified remains of very early hominoids have been found.
The plants and animals are widely different in speciation in these three areas but they have similar behavior. This may be the result of adaptation to similar geologic and weather conditions. The apex predators of all locations are big cats. All have eagles, egrets, large carnivorous reptiles and cats and lots of grass.
Human impact:
The effect of the behavior of large numbers of modern people on the Florida ecosystem is dramatically different from the African locations. The Everglades water flow is highly engineered and not necessarily for the best. Southward flow of the Florida delta is interfered by highways and farms to the point that it does not meet the sea as it original did. The Okavango delta also does not meet the sea. In Africa the observed locations have relatively low populations and have been benignly neglected or protected from hunting, industrialization, mining or drilling and farming so that the plants and animals have survived basically unchanged for centuries or even millennia.
Romancing Wild Africa:
We went to see the animal life of Africa and did not go to see the cities, towns, or villages. We did not have much contact with the people of the areas we visited. Africa is a huge, populous, resource rich continent with a history that dates to the origin of most species. There is great wealth and great poverty. Too many people have nothing. They live an impoverished stone age existence in the space age. I acknowledge that many of these are desperately poor and politically persecuted to enslavement and/or death. The NGOs, like CARE, work to help many but must be careful to manage their limited resources. They also try not to support the migrant people in camps to a better level than the local people. The native residents also live by subsistence on gardening, raising a few cattle, contract farm working, tourism, and crafts. Some also engage in a variety of illegal endeavors such as poaching and grazing their animals on park land. You can read the newspapers for details of other antisocial behaviors such as intertribal warfare, abduction, extortion, theft, civil insurrection etc. Desperate people do desperate things.
The wilderness of the savanna of Africa is nothing like anything in eastern US. There is no sense of luxury to the plants or the soil. Much of the topsoil is sand deposited by wind and water. The stark beige color varies little by the source of volcanic mineralization. The organic content is not a rich loam of plant breakdown. It is thin and the organic content is from the sparse droppings from animals or the occasional bush or more rarely from a tree. Animal droppings are recycled by the life on the planes and provide an episodic line of trees from incompletely digested seeds. The brilliant emerald green plants, startling blue sky and the breathtaking color of twilight is such a relief from the monotony.
Next:
We will look in greater detail at the findings of this two-week photo expedition in the following blogs. They will focus more on species than locations.
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#Africa #Okavango #Botswana #Kenya #Everglades #transpiration #Maasai Mara #salt #tectonics #transpiration #evaporation #Tanzania #marsh land #savanna
Everglades Ark 