DIVERSITY ANALYSIS OF ANGIOSPERMS IN RIPARIAN SYSTEM ALONG THUPPANAD RIVER, SOUTHERN WESTERN GHATS, KERALA, INDIA

Thuppanad river is a major tributary of Thutha river that drains into Bharathappuzha, the second largest river in Kerala and is draining out from north of Palghat gap of southern Western Ghats. The present inquiry summarizes the angiosperm diversity along the riparian system of Thuppanad river along with its phytogeographical affinities, percentage endemism, morphological adaptations and biological invasion. The evaluation of the angiosperm diversity revealed the presence of 270 species belonging to 70 families with higher elemental contribution by Euphorbiaceae followed by Fabaceae, Asteraceae, Rubiaceae and Acanthaceae. The riparian flora of this river basin embodies seven characteristic riparian taxa together with fifty six wetland species. Of the taxa recorded, twelve species show an extended distribution in Palakkad district of the state of Kerala. The analysis on endemism revealed that thirty four taxa are endemic to Western Ghats and at the same time, broad scale phytogeographical affinities of the riverine flora extend to African, Australian, Holarctic, Indo-Pacific and South American floristic kingdoms. The altitudinal profiling of the vegetation along the riverine belts revealed higher degree of variation in floristic elements and in the low land belts, human intervention and pollution has resulted in the gradual shift of vegetation elements into alien and invasive ones. The invading taxa in conjunction with anthropogenic disturbances pose serious threats to riparian vegetation of this area. This pioneer study on the riparian elements of this river basin indicated the need for implementing site-specific conservation plan for ecosystem management as this vegetation acts as a buffer zone between the river and cultivable lands.