Pollen analysis of a 2 m deep sedimentary core from Kerha Swamp, Sidhi (M. P.) has
unravelled the short-term vegetation and climatic alterations in the region since last 1,600 years. Around
1,600 to 850 years B.P., this region had open tropical deciduous sal forests which were mainly constituted of
Shorea robusta (sal), Madhuca indica, Holoptelea, Emblica officinalis, etc. The overall vegetational
composition signifies that a warm and moist climate prevailed in the region during this period in response to
moderate summer monsoon rainfall. Around 850 to 400 years B.P., the decline in Shorea robusta (sal)
together with its associates and a contemporary expansion of Bombax malabaricum, an important
constituent of tree-savannah, imply that these sal forests turned more open owing to the prevalence of warm
and dry climate in the region. This could be attributed to late and weak summer monsoon. Since 400 years
B.P. onwards, the timely arrival of strong summer monsoon favoured maximum proliferation of sal forests
and the climate became warm and more moist similar to present day.