Goats, Grazing and Seed-pods: learning in Turkana

The Spring 2015 Origins Field School students are now settled in at the Turkana Basin Institute and have been busy with the Ecology Module for the past few days. One of our first lessons has been looking at the vegetation. In this arid region, plants are essential for animals, including livestock, which is what supports the livelihood of pastoralists. As livestock graze on plants, they shape the vegetation community and plants respond in different ways. One of the most important species for goats, sheep and camels in this region is the short, spiny plant called Indigofera spinosa.

Studying the vegetation at TBI

As TBI was built, an exclosure was created to keep goats out, and this serves as a controlled experiment to look at the effect of grazing by goats and other animals on the vegetation. These kinds of ecological experiments generate useful long-term data for scientists and help us understand better the kinds of restoration ecology that may need to be undertaken as well as the carrying capacity of the land and how it might be changing.

Dylan and Mike counting pods on Indigofera

The students compared the heights of plants and the number of pods they produced between the fenced in area (no goats, sheep or camels) and the openly grazed habitats adjacent to TBI.

Plants are taller on average when not heavily grazed

And much shorted where grazed as Jayde and Anna discover

‘Many hands make light work’ and this was true of the students – who as a class were able to measure 200 different plants spread over a large area so as to get a good picture of what what happening in the landscape.

The difference in the height of plants: inside TBI on the left, and outside (grazed) on the right.

As you can see from the data gathered by the students, there is a significant difference in the height of plants – this suggests how important these wild plants are for supporting livestock.

Students also counted the pods on the plants in the two different areas.

Kate and Page (foreground) and Sam and Aileen, counting pods

As with the height of plants – we found there were differences in pod production. This is important information, as the Indigofera is often leafless, but does hold on to its pods – which are extremely rich in nutrients and proteins. So basically the pods of these plants are among the most important component for livestock in these drylands.

Differences in pod numbers (ungrazed on left, grazed on the right)

The students learned about the importance of wild plants as forage for livestock and how having lots of replicates in ecology is essential for measuring the differences in a phenomenon as there is a lot of variation that needs to be taken into account when collecting data in nature. As we worked, herds of goats and sheep were feeding on the Indigofera plants nearby:

Goats grazing on Indigofera

Later in the evening we explored the river and learnt about the distinctive riverine vegetation along the Turkwel River (as well as enjoying the cooler weather and splashing about in the water!)