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

Kunnamkumarath Jisha and Maya Chandrasekharan Nair. Post Graduate and Research Department of Botany, Govt. Victoria College, Palakkad, Kerala, India – 678001. ...................................................................................................................... Manuscript Info Abstract ......................... ........................................................................ Manuscript History

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.

Introduction:-
Riparian systems are the three-dimensional ecotones of interaction including terrestrial and aquatic ecosystems that extend down into the groundwater, up above the canopy, outward across the floodplain, up the near-slopes that drain to the water, laterally into the terrestrial ecosystem and along the water course (Illhardt et al., 2000). They form complex assemblage of organisms and their environment existing adjacent to and near flowing water (Lowrance et al., 1985). As ecotones, they encompass sharp gradients of environmental factors, ecological processes and plant communities. Riparian ecosystem provides a corridor for the movement of biota and serves many important roles for humans (Kemper, 1999).

ISSN: 2320-5407
Int. J. Adv. Res. 6(9), 531-539 532 The biotic communities living in the riparian areas, their interaction with immediate environment and their role in functioning of the river basin as a whole have gained more focus in the past two decades (Naiman and Decamps 1993;1997). However, there is a lacuna in the riparian floristic research in India except few ecological studies (Singh and Joshua 1989., Bachan, 2003;Sreedharan, 2005;Sunil et al., 2010;Nandhakumar et al., 2012;Vyas et al., 2012., Paul, 2013., Vincy et al., 2014., Bhaskar and Karthik 2015., Sankhwal et al., 2015. As per these reports, the Western Ghats river ecotones comprise an amalgamation of evergreen, semi evergreen, deciduous, riparian, wetland and mangrove components with high species diversity and endemism. Moreover, the vegetation in the riparian area has characteristics of both aquatic and upland habitats. Plants of the riparian forest have numerous morphological and physiological adaptations which suit them for life in high-energy and wet environments (Barker et al., 2002;Merritt et al., 2010).
Thuppanad river, one of the major tributary of Thutha river originates from Kalladikkode hills, along the northern lip of Palghat gap of Southern Western Ghats. Human interventions to the river basins of Kerala, has numerous impacts on land, water and biota. Although the riverine vegetation along this river is regarded as biologically rich, it is currently threatened and no exhaustive floristic information is available. The present documentation provides a synoptic account of the riparian phanerogamic flora of Thuppanad river, Kerala, with emphasis on phytogeographical affinities and endemism.

Study area
Thuppanad river originates from Kalladikkode hills at an elevation of 1099 m above mean sea level. Its watershed extend from 10 o 53' to 10 o 55' North Latitude and 76 o 25' to 76 o 35' East Longitude and the river draining has a length of 25km with an area of 158km 2 . The study area experiences a humid tropical climate and an average rainfall of 2135mm. Though during monsoon, the river become full and floods the nearby low lying areas, there is acute shortage of water in summer. The temperature of this area ranges from 20 0 C to 45 0 C and this rain fed river turns into a dry bed in summer. The location map of Thuppanad river is summarized in Fig. 1.

Methodology:-
Intensive seasonal floristic explorations and collections were carried out in riparian zones of Thuppanadpuzha during the period of December 2015 and May 2018. Inorder to review the vegetation of Thuppanad river, 12 sample plots were selected along the riparian zone ( Table 1). The specimens were identified using relevant literature and comparison with authentic specimen available at MH and CALI and enumerated as per APG IV (Chase et al., 2016). The nomenclature validation has been done with IPNI (www.ipni.org) and the plant list (www.theplantlist.org). The phytogeographical affinities of the vegetation was worked out (Cox, 2001) and the RET taxa assessment was based on IUCN (2017). Wetland elements were designated as per Cook (1996).  The monitoring of wetland vegetation revealed the presence of fifty six wetland taxa which contribute 20% of the total riparian flora of Thuppanad river. Systematic inquiry showed that 13% of the taxa are endemic to various geographical boundaries of India (Table 2) with a maximum share of Western Ghats. The profile of RET category taxa (IUCN, 2017) showed that 4% of the plant species belongs to endangered (2 species), vulnerable (8 species) or threatened (2 species) categories (Table 2). Eclipta prostrata (L.) L. Asteraceae * 84 Grangea maderaspatana (L.) Poir. Asteraceae * 85 Synedrella nodiflora (L.) Gaertn. Asteraceae * 86 Spilanthes vazhachalensis Sheela Asteraceae * * LC 87 Xanthium strumarium L. Asteraceae * CR-Critically endangered, EN-Endangered, LC-Least concern, NT-Near threatened, VU-Vulnerable The vegetation profile from upstream downwards elucidated structural transition from evergreen forest elements to the semi-evergreenriparianwetlandinvasive taxa. The lateral zonation of floristic elements exhibited the true riparian taxa near to the water body. The small shrub species like Homonoia riparia Lour. are seen on the rocky river bed between different water flowing areas. Continuity of true riparian evergreen plants is followed by tropical evergreen forest trees like Vateria, Madhuca, Hydnocarpus and Xanthophyllum. True riparian taxa were not recorded in the lower zones due to high disturbances caused by activities like sand mining, encroachment etc. In the lower zones, along with Cyperaceae and Poaceae members, species of Ficus, Saccharam, Pandanus etc. occupy the marginal positions.
Taxa subjected to habitual flooding produce various types of root adaptations as in Myristica, Holigarna, Madhuca and Pandanus. Rotula aquatica is having riparian endemism, showed morphological variations in accessions of same habitat and locality in a riverine system, and is adapted to monsoon floods and summer drought. The broad scale phytogeographical affinities of the riverine flora of Thuppanad river extend to African, Australian, Holarctic, Indo-Pacific and South American floristic kingdoms. Majority of the vegetation include Indo-Pacific elements with four African elements (Table 3). Raunkiaer's life form spectra analysis of the vegetation (Fig. 3) revealed that the biological spectra with dominance of phanerophytes (57.03%) followed by therophytes (33.33%), chamaeophytes (5.55%) and cryptophytes (4.07%).
This study analysed the impacts of alien invasive plants on riparian ecosystem of Thuppanad river basin and ten alien elements such as   Anthropogenic disturbances may introduce exotic species to riparian zones and natural disturbances may facilitate their spread throughout the drainage network. Indiscriminate sand mining, riverbank erosion, clearing of riparian vegetation and the reduction in the fisheries resource have become serious. This has reduced the quality of water and caused lowering of water table and the availability of water.

Discussion and conclusion:-
The riparian forest is a unique and rich natural ecosystem which has great influence on the adjacent aquatic as well as terrestrial systems. Most of the authors have reported the dominance of family Poaceae in Western Ghats vegetation (Nayar, 1980;Parthasarathy, 1983;Nair & Daniel, 1986;Ahmedullah & Nayar 1987;Karthikeyan, 1996) and in contrast, the present study recorded the dominance of Euphorbiaceae (19 species) followed by Fabaceae (18 species), Asteraceae (17species), Rubiaceae (17 species) and Acanthaceae (16 species). This vegetation profile modification may be due to the frequent floodplain disturbances, which prevents the establishment of Poaceae and promote woody vegetation that can withstand the flood current.
Comparison of angiosperm diversity and percentage endemism between Thuppanad river basin and three main rivers of Kerala, such as Chalakkudy river (Bachan, 2003), Pamba river (Paul, 2013) and Meenachil river (Vincy et al., 2014) showed significant reduction in the percentage of endemics and occurrence of RET category taxa. The general observations suggest that this may be due to habitat loss, over exploitation, invasion by exotics and fragmentation of population.
In addition to stabilizing and safeguarding the riverbank from erosion, the riparian ecosystem increases the biotic productivity and the biodiversity potential of the river. They also have a major role in influencing the water quality of the river. Further documentation to reveal the longitudinal, lateral and vertical zonations in vegetation present 57% 33% 6% 4%

Raunkiaer's life form spectrum
Phanerophytes Therphytes Chameophytes Cryptophytes 538 over here along with studies on seasonal and successional community patterns are inevitable to make any conclusions on the health of the vegetation along Thuppanad river basin.