**7.** *Terminalia arjuna* **as a keystone species in Cauvery riverine ecosystem**

Distributed throughout moist deciduous places of southern India, frequenting the banks of the water courses. Identified by thick grey smooth bark, exfoliating in large thin irregular sheets and buttressed trunk. It thrives best on loose moist, fertile alluvial loams and light deep sandy soils, often overlying more or less imprevious rock. The soil should have ample water supplies but should normally be well-drained. The soil under this tree becomes rich in calcium as the leaves are rich in this element. *Terminalia arjuna* species is deciduous, dominant canopy species and a representative riparian elements in riparian forests in lower reaches of Cauvery river. It can live grows to approximately 30m-45 in height, with a diameter at breast height (DBH) ranging from 300 cm – 600 cm. The *Terminalia arjuna* species is well adapted in the riparian zone by developing the buttressed type of root system to withstand the flood events.

as to provide a competitive advantage for adventitive forbs and grasses with higher nutrient

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requirements than their native counter parts.

**Figure 3.** Species *Terminalia arjuna* growing along the banks of River Cauvery

**Figure 4.** Species *T. arjuna* with its interlocking root system

*Terminalia arjuna* scattered along the lower of stretch of riparian forest is identified as a Keystone species. These scattered trees will acts as keystone structures as it supports wide array of species groups (e.g. arthropods, birds or mammals) for food resource and as shelter or nesting site (Munzbergova and Ward 2002; Plieninger *et al*., 2003; Tews *et al*., 2004).
