Download Riparian flora of perennial rivers in Western Ghats: Floristic diversity

The paper submitted to the convenor , National Symposium “Lake-2006” to be held from
28th to 30th December, 2006 at Indian Institute of Science , Bangalore, India
Riparian flora of perennial rivers in Western Ghats: Floristic diversity,
ecological uniqueness & conservation strategies.
* Keshava. H. Korse1 & Krishnakumar G.2
1. Department of Pharmcognosy, S.D.M.College, Ujire (D.K.), Karnataka-574240, India.
2. Dept. of Applied Botany, Mangalore University, Mangalore, Karnataka, India.
Introduction:
Documentation, conservation and finding enhancement strategies of biodiversity is
considered to be one of the important challenges in present day conservation biology
research and policy making process. Their importance is continuously being shown as they
are found to be keystone for the sustainability of biosphere (Swaminathan, M.S., 1992).
Tropical evergreen forests are found to be most significant repository of such huge life
forms across the globe, as these primary climax ecosystems show high endemism of flora
and fauna and microbe, having unique structures, functions and relatively high
productivity. Evergreen forests regions of India especially in Eastern Himalaya and
Western Ghats are found to be such huge biodiversity points, as they are assigned one of
the biodiversity hotspots at global scale (Myers et. Al 2002). Western Ghats alone, for
instance, has nearly 4800 species of flowering plants; nearly 2100 species among them are
considered to be endemic (Ramesh, B.R. & Pascal, J.P., 1996).
The ecological uniqueness of Western Ghats is the function of different factors
namely, its origin, geological past, climate, impact of monsoon and anthropological
activities and so on (Radahakrishna, B.P., 1993). High species diversity seen here is, thus,
also attributed diverse ecosystems evolved here like shola, grasslands, vallies, marshy
lands, different forest ecosystems, riverbeds and banks etc. Riparian ecosystem is one such
vital component of Western Ghats, which has unique ecological characters.
Riparian zones of evergreen forest are the unique zones, where interface of water
and land is seen.
They are considered to be performing many vital functions like
regulating water cycle of the forest floor, nutrient cycles of the lower command area,
acting as breeding sites for many sensitive organisms etc. These ecosystems are now being
widely studies across the tropical region due to their increasingly evident significance
(Subramanian, K., 2005, Jaffer et. Al., 2002 and Maso-aki et al., 1997). Because of that
unique physico-chemical and biological properties, they are found to be contributing much
to the biodiversity of the Western Ghats too, especially the floristic diversity (Pascal, J.P.,
1986). This is a concept paper just to press for the need of bringing these issues to the
larger domain of conservation biology. It is based on the experience of larger ongoing
study Netravati river systems in central Western Ghats region in Karnataka. It tries to
shed more light on the ecological uniqueness of these riparian zones with special reference
to floristic composition and their interaction, the different threats casting over these
ecosystems and also some possible conservation strategies.
Materials & Methods:
Some aspects of taxonomy, ecology and conservation strategy of riparian flora are
discussed here based on the field study done during 2004 –06 in Mundaje up stream zone
of Netravati river valley in the foothills of central Western Ghats in Dakshina Kannada
(120 29’ 36” & 130 49’ 22” N and 740 37’ 24” & 750 41’ 00” E).(Gazette of D.K.) These are
the observations made as part of larger ongoing taxonomical and ecological investigations
in the riparian zone of Netravati valley. The floristic study is done by laying 6 transects
(100M X 5M) at each site for assessing tree species (Having dbh 10 cm or more). The
species diversity, species abundance, relative dominance of species, population density etc/
are assessed. Ecological studies are done by physic-chemical analysis of water and soil
samples from each study sites in the riparian zone of this perennial river system in the
evergreen forest of foothills of Western Ghats. And some basic studies on anthropogenic
pressure is also done in order to asses the threat status and to develop the conservation
strategy for the same. Though, some taxonomical studies on the evergreen forest
ecosystem of this region are done by earlier workers (Arora, R.K.1967), this is the first
integrated taxonomical and ecological investigation done in these riparian zones.
Results:
The riparian zone of this perennial river system of Netravati valley is found to be
very much rich in terms of floristic diversity. More than 50 Angiosperm tree species and
12 shrub species are reported from this region. The most abundant tree and shrub species
are listed in Table1. Several species like Cinnamomum ripaium and Ochlandra species are
found only in this ecological zone indicating the significance of these microhabitats. It
seems to be the reproductive biology of these species is very much linked to the dynamics
of water in the stream and allied ecological functions. Therefore, the slope, water
temperature, flow rate etc. are being asses to constrict the concrete characters of these
riparian zone ecology.
These riparian zones also show some unique ecological characters also. The
floristic composition in the spray zone is found to be decisive in the functions like river
bank stabilization and landscape stabilization of the adjacent regions. They also supply
woody debris, organic matter, nutrients and also the shade to maintain the water
temperature. Therefore, these dynamics forest and stream interactions are being further
studied with special reverence to the evergreen forests of Western Ghats region.
Threat assessment to these ecosystem is also done by documenting the
anthropogenic pressures. Several factors like encroachment, unsustainable harvest of minor
forest products (MFP) like Cinnammomum, timber logging, extended cultivation, poor
river bank management etc. are found to be major caused for the degradation of many
spots in these zones. Apart from the biodiversity and ecological value, the conservation of
these habitats is very much directly linked to the livelihood security of the people too.
Studies elsewhere have shown the that the distruction in the upper reaches of any river
valley region in Western Ghats region could lead to severe water scarcity in the down
stream. As the entire Dakshina Kannada population depend upon Netravati river for its
water security, the conservation of the riparian zone in upper reaches is of immediate
concern.
Therefore , there is an urgent need of developing conservation strategies for these
fragile ecosystems, specially in these Western Ghats region. The forest department can
come up with micro planning for all these habitats in association with civil society
organizations and also the Biodiversity Committees of Grama Panchyatas. The Village
Forest Committees (VFC) can also join for this purpose. The local academic institutions
like schools and colleges can constantly monitor the status of the ecosystems by gathering
data and regularly upgrading it.
Conclusions:
Riparian ecosystems form very unique ecosystems in the evergreen forest region of
perennial rivers of Western Ghats. There is need of further carrying out wider studies and
designing conservation strategies. Keeping the increasing water scarcity in the coastal and
central Deccan Pleatue in peninsular India, the conservation of riparian zones assumes high
significance. The educational institutions need to take part in this conservation process of
these unique aquatic regions by regular feed back to the local management practices.
Reference:
1. Anonymous, 1973. Gazette of India, South Kanara district of Karnataka.
2. Arora, R.K.1967. The vegetation of South Kanara district, Western Ghats, Journal
of Indian Botanical Society, Vol.46, pp15-24.
3. Jaffery, S., Welty Timothy Beechic, Kathleen Sullivan, David M. Huink, Roberts E.
Bill, Chip Andrus, George Press, 2002. Riparian aquatic interaction simulator
(RAIS): A model of riparian forest dynamics for the generation of large woody
debris & shade, Forest Ecology& Management, 162, 299-318.
4. Myers, N., Mittermier R.A., Mittermeir C. G. Kent J, 2002. Biodiversity hotspots
for conservation practices, Nature, 403, 853-857.
5. Pascal, J.P, 1986. Forest Ecology, Vol. II, Institute de Francis, Pondicherry.
6. Radahakrishnan, B.P., 1993. Neogeo uplift & geomorphic rejuvenation of Indian
peninsula, Current Science, Vol 64 (11&12) pp787-793.
7. Ramesh B.R. & Pascal J.P., 1997. Atlas of endemics of Western Ghats, India.
Institute de Francis, Pondicherry.
8. Subramanian K., K.G. Shivaramkrishanan, & Madhava Gadgil, 2005. Impact of
riparian land use on stream insects of Kudurmukh National Park, Karnataka, Indian
Journal of Insect Science, 5: 49 .
9. Swaminathan M.S. & Jana S.(Eds) , 1992. Biodiversity: Implications for the global
food security, Macmillan India Ltd., Chennai Indian,
Table 1. Check list of Angiosperm plant species with high occurrence in riparian zone
of Mundaje stream in Netavati river Valley in central Western Ghats, Dakshina
Kannada,Karnataka, India.
Sl .No.
Species
Tree Species
1
Madhuca nerifoila H.J.Lam.s
2
Syzygium cumini L.
3
Holigarna arnotiana Hook.
4
Holigarna grahmii Kurz.
5
Ochreinauclea missionis Ried.
6
Actinodaphne bourdillonii Gamble.
7
Ochlandra scriptoria Fischer.
8
Neolamarkia cadamba Roxb.
9
Callophyllum inophullum L.
10
Cinnammomum riparium Nees.
Shrubs
1
Psychotria trucata Wallin.
2
Homonoia riparia Lour.
3
Polygonum glabrum Willd.
4
Rotula aquatica Lour.
* Korse, Keshava, H. & Krishnakumar, 2005.