Study on modern vegetation distribution in Sevan Tal area, Raebareli District, Uttar Pradesh

Abstract

Pollen analysis of ten surface sediment samples from Sevan Tal, Raebareli District (U.P.) reveals a good assemblage of arboreals (trees & shrubs) comprising Holoptelea integrifolia, Acacia nilotica, Syzygium cumini, Madhuca indica and Shorea robusta, etc. However, plant diversity in forest groves has been observed in eastern and southern fringes but are less diversified in northern and western flanks due to arable and heathland, respectively in the area. Together with av. 4% shrubs, the trees constitute av. 23.3% arboreal pollen. Even then, in general, the reduced frequencies of the trees could be ascribed to their low pollen productivity since they portray a strong tendency of entomophily. Among the non–arboreals, Poaceae with av. 35% pollen subdues the other herbaceous elements. The substantially increased frequencies of cultural taxa, viz. Cerealia, Chenopodiaceae/Amaranthaceae (Cheno/Am), Artemisia, Cannabis sativa and Brassicaceae, more particularly on the northern and western flanks, truly reflect the intensive agriculture practice in the region. The consistent presence of marshy taxa such as Cyperaceae coupled with Polygonum plebeium, P. serrulatum and Liliaceae suggests the intermittent wetlands in the proximity of the lake. In all, the representation of the non–arboreals corresponds closely with their factual occurrence in the ground flora, constituting the largest chunk of av. 75% pollen. The frequent record of Potamogeton together with Lemna, Typha, etc. denotes the existence of the lakes around the sampling provenance. This comparative database on pollen vis–à–vis vegetation relationship serves as modern analogue for the appropriate assessment of the pollen sequence from the sediment deposit in terms of past vegetation and climate change in the Central Ganga Plain. Moreover, the representation of the arboreals, particularly trees, in the spectra symbolizes the prevailing climatic condition in the study area.