Early Holocene pollen record of vegetation and climate history in response to the monsoonal activity in East Garo Hills, Meghalaya, India

Abstract

This study presents a palynological analysis in 2.0 m deep sedimentary soil profile procured from Rongre Swamp of East Garo Hills to document changes in vegetation and climate in response to the monsoonal activity since 10,640 cal. BP. Four palaeovegetation and climate zones were recorded based on the frequencies of major pollen taxa in the region. The first phase was around 10,640–7,540 cal. BP broadly shows the existence of tropical forest in the region under the onset of warm and humid climatic condition. Subsequently, between 7,540–5,490 cal. BP, the forest got enriched with increased values of tropical mixed deciduous and evergreen elements. The vegetation scenario as marked by both deciduous and evergreen elements in increased values support the warm and humid climate in response to the relatively high monsoonal activity. Accordingly, in the third phase between 5,490–1,120 cal. BP, the values of major arboreal pollen taxa, Shorea, Mesua, Elaeocarpus and Duabanga have declined as compared to the preceding phase in relation to the relatively less warm and humid climate than the preceding phase in the region. In the last phase around 1,120 cal. BP to present, the forest got deteriorated as evidenced by the decreased values of arboreal pollen taxa. This phase clearly depicts the high anthropogenic activity as evidenced by the abundance of cultural pollen like cereal and Brassica.