Pollen records of vegetation and inferred climate change in southwestern Madhya Pradesh during the last ca. 3800 years

Abstract

Pollen analysis of 1.5m deep sediment core from Sapna Lake, Betul District (M.P.) has demonstrated that between 3,800 and 2,700 yr BP, open Acacia-dominant scrub forests interspersed with stretches of herbaceous vegetation comprising grasses, sedges, Asteraceae, Cheno/Am, etc., occurred in the region under a regime of dry climate. A few trees of Madhuca indica, Holoptelea, Shorea robusta, Lagerstroemia parviflora, etc. were also sparingly distributed therein. The vicinity of the lake was under cereal-based agricultural practice as portrayed by the presence of Cerealia and other culture pollen taxa viz., Cheno/Am, Caryophyllaceae, Artemisia and Cannabis sativa. Around 2,700 to 1,260 yr BP the Acacia-dominant scrub forests were succeeded by the open mixed deciduous forests as evidenced from the improvement in frequencies of Madhuca indica, Sapotaceae, Holoptelea, Shorea robusta as well as sporadic invasion of Terminalia, Mitragyna, Flacourtia, Grewia, Lannea coromandelica, etc. This enhancement in the forest floristic reflects the initiation of a warm and humid climate possibly in response to increasing monsoon precipitation. Owing to the prevailing favourable climatic condition there was acceleration in the agricultural practice as indicated by the rising trend of Cerealia and other culture pollen taxa. Since 1,260 yr BP onwards the depletion in the prominent forest constituents such as Madhuca indica, Sapotaceae, Shorea robusta, Holoptelea and other associated trees implies that the forests turned more sparse and less diversified due to the inception of a warm and less humid climate, attributable to reduced monsoon precipitation. However, the agricultural practice continued with almost same intensity as before, because the Cerealia and other culture pollen taxa remain unchanged.