Geography – Okavango Delta and Maasai Mara Savanna

UNDERSTANDING THE TWO ECOLOGICAL SYSTEMS BY COMPARING THEM FROM THE GROUND UP.

To help understand what is happening in this system it may be made easier by look at its parts. There may be some errors in this method but at least this is a reasonable hypothetical start. Let’s begin with the idea that every detail is important and that everything is interconnected. Also, if a part of the system is lost the entire system is compromised. See the map at the end of this posting.

The featured image shows one of thousands of termite colony mounds

The Okavango and Mara locations are very different not only in location and elevation but also in geology. Two soil samples were taken from typical road side areas in the savannah-like landscapes away from human traffic areas. Under the microscope you can see that the individual sand grains are transparent, something which is not obvious when looking at the sand with the unaided eye. The sand of the Delta (Fig. A1 & 2 is made up mostly of silicon dioxide (SiO2). It is completely glassy. It is not soluble and has no mineral content. Volcanic pumice Fig B1 & 2 is a complex particle aggregate of ash feldspar. It is an incomplete glass with other minerals at the particles’ surfaces. The Mara soil has a much higher metabolizable mineral content which makes the soil more fertile than the Delta.

Fig A1. Sand particle sample from Okavango Delta. (20X) Completely translucent. Illuminated with transmitted plane light. This is nearly pure silica.

Fig. A2. Sand particle sample from Okavango Delta. (20X)
Completely translucent. Illuminated with transmitted *polarized* light.

Fig.B1
Sand particle sample from Mara.
Note the surface’s complex micro-porosity. Illuminated in dark field with direct lighting. This amorphous, opaque particle is definitely volcanic in origin. (20X)

Fig. B2.
Sand particle sample from Mara. (20X) Completely opaque. The red color is iron oxide. Illuminated in dark field with direct lighting.

–—+—-

OKOVANGO DELTA

The Delta is flat but it is cyclically flooded and the colors are green and tan. The islands of the Delta were built by the humblest of creatures. The termites as architects, engineers and builders have created a landscape of unbelievable variety. They harvest the dead plants and with the sand of the Kalahari desert and they build massive, nearly indestructible castles reaching meters into the sky. The nest height is determined by the water level. The higher the water level, the taller the nest will be. When the population reaches a critical mass, a new colony is initiated. With erosion by water, wind, and the burrowing of animals the mounds collapse and islands grow. As a result of centuries of this cycle the islands provide a collective of soil used by the large mammals, birds and fish. The aquatic plants are supplemented by grasses, brush, bushes, and trees. These form savannas in the Delta for non-migrating herds of grazing land animals and the creatures which accompany them. They also encourage aquatic animals like fish, birds, reptiles, and mammals which are supported by the aquatic environment.

Termite mound on savannah island of the Okavango Delta

Pampa Grass (*Niscanthus junceus*) Assists in forming islands by trapping sand and with decaying plants supports rooted water plants such as water lillies.

Blue Water Lilly (*Nymphea* *nouchali*). These also assist in the formation of islands and support protective areas for aquatic animals.

Marshland in the Okavango Delta with grazing zebras. The trees in the background are on the island that emerged from the work of the termites and plants.

Impala roaming through of the woodlands of the Okavango Delta. This land is based on the foundation of sand deposited by wind and water sediment which is fixed and enriched by termites and plants.

These zebras are grazing on a very large island in the Okavango Delta. It appears like a classic savannah landscape.

Tree covered island succumbing to salt accumulation in the Okavango. The islands dehydrate and accumulate salt at the periphery. When high water returns and infiltrates the interior of the island the salt enters the soil. Plants, weakened by drought, are further dehydrated and die.

The water levels rise and fall because of the flow of several rivers that end in the Delta. The water never reaches the sea; hence the Delta. Water is lost by evaporation and transpiration. The animals have a reliable supply of water and plants. They do not migrate.

—-+—-

MAASAI MARA

The Kenyan savannah is so starkly different from the Okavango Delta they seem worlds apart. The Serengeti plane colors are tan and beige. The Mara land is flat and dry. In contrast to the Delta, the Maasai Mara is the result of volcanism and rain. Dominating the landscape is the ancient volcano of Mt. Kenya along with the range of uplands that are a result of the enormous energy expended in tectonic plate collision and the spread of the great Rift Valley. It stands as a plateau at an elevation of about 1,480 to 2,280 meters. The volcanoes of the area have created a mineral rich soil which when watered by the seasonal rain provides an opportunity for lush grass to grow. There are few trees growing on the savanna of the Mara making it seem like a great lake of soil dressed in golden grass. The Mara also has riverine forests. The seasonal rains are predictably distributed regionally causing the rotation of the animal migration. The people of the Maasai tribe move their domesticated herds in synchrony with the wildlife, plants and rainfall.

Mara river cutting through the savannah. The river is a limited but reliable source of water. Seasonal rain is the major water resource however it is variable and recently very deminished.

The massive savannah of the Serengeti plane supports an animal migration that may be the greatest seasonal movement of animals on earth. The grass is lush and green.

Mount Kenya off in the distance as part of the Great Rift Valley. No migratory animals here.

This map* of the central eastern sextant of the continent of Africa shows the relative position of the two areas of our grand safari.

These two systems are much more complex than this simple description. This only becomes apparent after returning from there, collecting and organizing observations, and reflecting on the diversity and life forms and cycles. This leads to many more questions such as: Where did the glassy sand come from? Why do the two areas share so many identical species? Why are there so few cactus or pine species? How would you summarize the comparison of these two areas? Perhaps these questions can stimulate discussion in our comment section.

* Modified from African Safari Planning Map, 3rd ed. African Adventure Company 2018

#Kenya #Botswana #termite #savannah #sand #Kalahari #desert #map #Africa #great rift valley #Serengeti #Mara #Okavango #woods #marsh #zebra #impalla #great migration

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