Kenya contains a wide variety of environments and habitats within its boundaries. At Mpala, we observed savannah and woodland environments that were very green following good amounts of rainfall. We are not in Mpala anymore! Students observed the stark differences between the vegetation in the semi-desert surrounding TBI Ileret and that of Mpala in Laikipia. Even the acacia trees have different shapes. The canopies have wide, flat tops and they slowly decrease in width towards the base, providing as much shade for the roots as possible to prevent evaporation.
We set out to explore this new environment at Sibiloi National Park. With far less annual rainfall, the vegetation in this area is all specially adapted to surviving with little water, retaining whatever it can, and having fairly dramatic methods of protection (such as thorns, spines, or toxins). Luckily for us, several different plant species were flowering, and we observed all sorts of different pollinators visiting the blooms. It was particularly rewarding to visit this park with Dr. Dino J. Martins, a leading expert in the field of entomology and biodiversity.
Some of these plants are highly specialized to this environment. Such as the desert rose – a plant firmly rooted in the rocky ground. It grows incredibly slowly, conserving energy. We estimated the age of a particularly large desert rose tree. Turns out it is likely about 1000 years old!
Students discovered ancient Nile oyster beds among the rocks during our Sibiloi park hike. This area was once underwater!
Indigofera spinosa is a spiny plant that can survive in extremely hot and dry environments. It is abundant in this semi-desert environment, providing a food source for livestock. These plants are some of the most abundant in the areas around Ileret. Because they are a main food source for livestock, they are perfect subjects for studies human impact on vegetation by pastoralism.
TBI students in 2015 began collecting data on the heights of Indigofera spinosa plants located inside the TBI Ileret compound (a fenced area without grazing animals) and outside of the fence (areas frequently grazed by livestock). Students replicated this study this semester, collecting another dataset. It turns out that a significant pattern is emerging – showing differences in the sizes of Indigofera spinosa plants in areas with and without grazing.
Data like these are essential to understanding human impact on the environment – a highly relevant issue for a sensitive arid environment and pastoralist communities who so heavily depend on its stability. Does grazing help control the coverage of indigofera spinosa, thus making way for a larger diversity of plants to co-exist? Or does grazing effectively spread indigofera spinosa plant seeds, encouraging more growth in previously grazed areas? How much grazing is too much? If the plants are grazed too heavily, will the soil underneath them recover and host other plant life? These are all important questions that can be answered with the methodologies that we have learned over the past few weeks in vegetation ecology.
After completing this lab exercise, the students and I went to visit some of the local pastoralist families that live close to the TBI compound. These types of experiences are important for us to understand a little bit about the life of pastoralist peoples in this arid environment. The biggest cultural group that surrounds TBI Ileret is the Dassenitch. The main livelihood of the Dassenitch is pastoralism. We visited two nomadic homesteads that house both people and livestock – called bomas.
On our visit we spoke with families who kept several different types of livestock: sheep, goat, donkeys, and cattle. These bomas are simple structures made mostly of natural, local materials (such as branches), as well as some other commercial materials (plastic, corrugated tin, etc.). The simplicity of these structures is intentional, as these pastoralists move around the landscape often, according to changes in the rainy and dry seasons. There is no sense in building a brick and mortar home, only to leave it three months later. Life for the Dassenitch depends on the health of livestock, which is related to the seasons and the health of surrounding vegetation.
We ended our ecology module with lessons about freshwater ecology. Lake Turkana is a slightly Alkaline lake (but its safe to swim in).
There are all kinds of species that have evolved around the lake. In class we discussed some of the implications about declining lake levels due to dams for irrigation in the Omo river (in Ethiopia) and climate change. What will happen to the environment and communities of people surrounding the lake? There is no straight-forward answer. We do know that human activities and declining lake levels are impacting keystone species. A keystone animal is a species that contributes more than its own body mass to an environment. For example, hippos feed on vegetation around the lake margins and their dung adds nutrients to the system. This keeps some vegetation in check, while ensuring there are enough nutrients for more vegetation to grow. All sorts of aquatic organisms feed on this vegetation, moving all the way up the food chain. So, changes in hippo populations can have drastic impacts on the entire ecosystem. Hippos and Nile crocodiles are keystone species for the Lake Turkana.
The health of the Lake Turkana ecosystem is of dire importance to its surrounding animal and human communities. Fishing contributes a huge proportion of the economy surrounding Lake Turkana. Fisheries operate on local and global commercial scales. Fish, such as Nile Perch and Tilapia, are dried and smoked and sent all over Kenya and other countries in Africa. Some of this fish is even sent across continents to Europe and North America. Check the prices of Nile Perch (if you can find it) back home – it’s pricey stuff when it’s exported internationally. The TBI students often have the treat of these fresh fish for dinner at least once or twice a week – we are spoiled!
A sound scientific understanding of the ecology of Lake Turkana and its surrounding areas is pertinent to the health of wildlife, but also of the economy. Future generations of scientists need to investigate the impacts of human activities (dams, irrigation, agricultural and human waste, etc.), climate change, and declining lake levels on Lake Turkana ecological systems. Maybe some of our students will have the opportunity to do such science.
But in the meantime, the students enjoyed a refreshing swim in the lake.
Stay tuned for an update on our next module…Paleontology!