Ficus racemosa and Elephant Ecology

uluulublog

8 years ago

ABOVE: Elephants feeding on Ficus racemosa fig fruits along the banks of the Kinabatangan river in Sabah. Elephants love the figs but find the leaves distasteful. Illustration by Karen Phillipps

The Tabin River in the Tabin Wildlife Reserve in Sabah. *Ficus racemosa* trees are one of the most common trees that grow along the river bank which is criss-crossed by numerous elephant trails. The tree on the left is *Ficus racemosa*. Further upriver another *Ficus racemosa* tree has fallen across the river. Note the large brown object behind the fallen trunk.

Beyond the fallen Ficus racemosa fig tree, two elephants are having a bath in the river. The leaves of the Ficus racemosa are easily accessible but the elephants are not interested in eating them because of toxins in the leaves. Without these toxins Ficus racemosa would have been eliminated from Borneo’s river banks by elephants long ago.

Go back a few hundred years to an era when Borneo was covered in unending forest. Apart from small tree fall and landslide gaps the only open areas in Borneo where pioneer plants such as this *Etlingera* ginger could grow were the banks of Borneo’s numerous rivers.

The key to understanding pioneer plant ecology in Borneo is to understand the process of river formation. Rivers are constantly eroding the soil from one bank and depositing it on the river bank opposite. This “creative destruction” is constantly felling tall forest trees on the outer curve where the river flows fastest and providing a constantly replenished ribbon of bare soil for river deposited seeds on the opposite bank.

These ribbons of pioneer growth along rivers are the favoured habitat of both Ficus racemosa and of the grasses favoured by grazing elephants. If you want to find a herd of elephants along the Kinabatangan river, head for the patches of pioneer grasses growing on newly deposited banks of river silt.

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