• The arjuna tree (Terminalia arjuna) may be best known for its medicinal properties and its importance to the charismatic grizzled giant squirrel, but it plays a special role in the river-forests of Karnataka’s Cauvery Wildlife Sanctuary too.
  • A higher number of trees specific to riverine habitats thrive under the canopies of old arjuna trees.
  • The soil under these trees’ enormous canopies is also more moist and higher in organic carbon.
  • This makes a case to recognize it as a keystone species — one that plays a crucial role in the landscape — and conserve large, old trees.

Please tell us more about it

  • The arjuna is a large, buttressed tree that usually grows along river banks.
  • With its interlocking roots and large canopy, does the tree influence the composition of plant communities under it?
  • To find out, scientists at Bangalore University noted the plant species growing under the canopy of arjuna trees, as well as in areas without the trees.
  • This revealed a higher species diversity (44 species; some like the mahua tree Madhuca latifolia grew only under the canopy of arjuna trees) under these trees, while similar riverine areas without arjuna trees housed only 26 species.
  • Areas devoid of the trees also had more species that were not native to riverine stretches.
  • Soil in areas under the canopy of the tree had higher organic carbon and moisture contents, probably due to the presence of the large canopy.
  • Put together, these factors prove that the arjuna is a crucial tree in the landscape.
  • Interestingly, the proposed Mekedatu project — that aims to provide drinking water to Bengaluru — could result in the submergence of numerous old arjuna trees.
  • Given that the regeneration of the species is very low (there are very few young arjuna trees or its saplings in the area), this could be a cause for worry, he warned.