Sunday, October 23, 2011

Bringing the sausage tree to Agahozo

The sausage tree is found in a variety of habitats, including the open
plains of Serengeti National Park, Tanzania.

The sausage tree is a prominent tree of the African landscape. It is native to sub-Saharan Africa and can be found in nearly every country in that range. But you hardly see them in Rwanda.

The tree gets its English name because its fruits resemble giant sausages.
This picture is from one of the only Kigelia trees I have seen in Rwanda.

Kigelia pinnata is found in the surrounding countries Democratic Republic of the Congo, Uganda, Tanzania, and Burundi in savannahs and woodlands from 1100-3000 above sea level (I have seen it in both Uganda and Tanzania). Despite having the elevation and (at least formerly having the) habitat, I have only seen a few individuals of this species in Rwanda, all near the shore of Lake Muhazi, but I would guess it can also be found in Akagera National Park.

A sausage tree in a much more wooded habitat than the picture above,
in this case in Lake Manyara National Park, Tanzania.

Most of Rwanda’s native trees outside the parks, especially the big ones, have been cut and replaced by non-native eucalyptus trees, grevillea trees, crops, and banana plants. I suspect that Rwanda's sausage trees were cut in the past. Many non-native ornamental trees, like filau (Asia) and jacaranda (Central America), are promoted, sold regularly, and planted throughout Rwanda as well. To me the lack of hornbills outside the parks in Rwanda is indicative of the lack of big native trees (hornbills nest in cavities in old, larger trees). You do see hornbills regularly in the countryside of Uganda because there are still many big native trees scattered among farms.

A young sausage tree outside Murchison Falls National Park, Uganda.

I scoured all the Kigali plant nurseries I could in search of sausage trees, but I could not find a single plant. As I mentioned, mostly exotic species are planted here as ornamental trees (Spathodea campanulata, the African tulip, a native, is also a popular choice). Interestingly enough, sausage trees are used as ornamental trees in other African countries and even in Australia. The sausage tree provides dense shade and has large attractive maroon flowers. Its flowers are also a great food source for bees, so it makes sense to plant when you have beekeeping operations (as ASYV does). But again, you don’t see sausage trees in Rwanda where everyone seems to opt for exotics.

The fruit (left) and seeds (right) of the sausage tree.

I decided to try to bring the sausage tree to our hillside. We need both shade and flowers for our bees at ASYV. I collected seeds from a rotting fruit and got a not-yet-ripe sausage fruit to save and harvest later. Kigelia seeds are known to be quite difficult to cultivate. I have found that to be the case unfortunately. I have tried five different methods, including the recommended method without much success. Out of over 100 seeds, I have only gotten four to sprout, all through keeping them moist in plastic bags.

Two Kigelia plants just after sprouting.

We have planted two of the sausage tree seedlings in our nature park. The Environment Club and the students of Agahozo-Shalom work each week to protect our recovering woodland from non-native invasive species. We have two more seedlings and are contemplating whether to plant them or keep them in the nursery until they get much bigger.

A member of the ASYV Environment Club plants a sausage tree seedling
in the Agahozo-Shalom Nature Park.

Bringing the sausage tree to this hillside is a small step in the native reforestation of Rwanda. It is up to just four plants at this location, but if they grow and eventually fruit, the sausage tree may again be a fixture of this African landscape. 

Just the beginning! In 4-5 years, this tree should provide shade and
reach up to 5 meters.

Works consulted:

  • Biggelaar, C. 1996. "Appendix: List of all tree (ibiti) and other plant sepcies cultivatedon the sample farms in the communes of Karama and Mabara." Farmer Experimentation and Innovation: A case study of knowledge generation processes in agroforestry systems in Rwanda. Food and Agriculture Organization. Accessed October 23, 2011 at
  • "Kigelia pinnata." AgroForestryTree Database. World Agroforestry Center. Accessed October 23, 2011 at

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