K.P.N. Kumaran

Mangrove Responses to Climate Change along the Southwestern Coast of India during Holocene: Evidence from Palynology and Geochronology

Mangrove vegetation is an important component of the coastal ecosystem and is associated with near-shore marine habitat in the tropics and subtropics of the world. Indian mangrove vegetation covers about 6749 km2 along the 7516 km long coast line, including Island territories (Mandal and Naskar, 2008). The distribution of mangrove areas along the Indian coast is influenced by physical forces such as geomorphology, climate, tidal amplitude and duration and quantity of freshwater inflow (Selvam, 2003). In fact, the geomorphic setting of the mangroves of east coast of India is different from that of the west coast (Ahmed, 1972). The coastal strip of west coast is narrow, and steep in slope as compared to the gentle slope of east coast. Though there are large number of small rivers bringing enormous quantity of sediment to the Arabian Sea along the west coast, deltas are not developed, possibly due to the high-energy conditions of the coast. This topographic set up gives a contrasting pattern of mangrove vegetation in India. Accordingly, the mangrove wetlands of west coast are small, less diverse and less complicated in tidal creek network, while the east coast has larger mangrove wetlands with high species diversity. Besides, beach morphological changes along the west coast are controlled by the southwest monsoon. Therefore it is interesting to ascertain the consequences of mangroves in response to climate changes along the Kerala coast, southwestern India using the sedimentary archives of the coastal plains.

Climate and Sea Level Changes in a Holocene Bay Head Delta, Kerala, Southwest Coast of India

The Holocene epoch, all over the world, has witnessed exceptional climate and sea level changes. Although the south-west coast of India has a fairly thick deposit of Holocene sediments of 50-60 m in the South Kerala Sedimentary Basin (SKSB) and its adjoining coastal lowlands (see inset in Fig. 13.1), not much focus has been given to unfold its palaeo-climatic and palaeo-environmental potential till the beginning of the present century (Joseph and Thrivikramji, 2002; Nair and Padmalal, 2003; Nair et al., 2006; Kumaran et al., 2005; Limaye et al., 2007). South-west coast of India was affected significantly by sea level and climate changes which in turn had a strong bearing on human settlements/migration in the area. Recent advances in archaeological investigations in the Pattanam-Kodungallur stretch in Central Kerala (Shajan et al., 2004; Abraham, 2006) gave indications of shifts in human settlements in accordance with changing climates and/or sea level positions.

Two New Combinations in Arisaema (Araceae) from India

Abstract Taxonomic and palynological studies on Arisaema Martius (Araceae) from the Western Ghats, India, distinguish two taxa belonging to section Tortuosa Engler. Arisaema sahyadricum S. R. Yadav, K. S. Patil & Bachulkar var. ghaticum Sardesai, S. P. Gaikwad & S. R. Yadav, a recently described variety in 2006, is treated here at the species level as A. ghaticum Punekar & Kumaran. Arisaema sivadasanii S. R. Yadav, K. S. Patil & Janarthanam, previously considered as a synonym of A. tortuosum (Wallich) Schott, is recognized here as the subspecies A. tortuosum subsp. sivadasanii (S. R. Yadav, K. S. Patil & Janarthanam) Punekar & Kumaran. Taxonomic implications are discussed and a key to the Arisaema taxa of the North Western Ghats is provided.