12-14 September, 2011, Lucknow - Earth Science India

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National Conference on Science of Climate Change and Earth’s Sustainability: Issues and Challenges ‘A Scientist-People Partnership’ 12-14 September, 2011, Lucknow the region in between 11,000- 8500 yr BP. The grasses, other herbs (aquatic or terrestrial) and ferns profoundly thriving suggesting high humidity and temperature increase due to high SW monsoon activity. Subsequently, the area witnessed sudden decline in vegetation concentration during 8500 to 7000 yr BP. The floristic composition indicates the alteration of deciduous forest into tree savannah type of vegetation almost certainly due to small spell of cooler and dryer climate which corresponds to 8.2 ka short global cooling event. During 7000 to 5100 yr BP, the alteration in palaeofloristic pattern from tree savannah type of vegetation to dry deciduous forest has occurred due to warm and humid but probably not as humid as Early Holocene. The moist tree taxa have certainly decreased although dry deciduous taxa flourished suggesting less precipitation in the region as compared to early Holocene. Kusumelli Swamp trench profile (KDT) endowed the floristic composition which reveals the grasses and other herbs with intermittent trees and shrubs constituted tree savannah during 4000 to 3100 yr BP (KDT-1). The profound growth of grasses, Chenopodiaceae /Amaranthaceae, Artemisia sp. while strewn record of other herbs and hostile conditions for trees growth portrays cooler and dryer climatic conditions. However, ameliorating trend of climate could be inferred towards the end of zone. Subsequently, KDT-2 pollen zone show recurrence of both moist and dry deciduous trees such as Tectona grandis, Shorea robusta, Lagerstoemia sp., Diospyros sp., Lannea coromendalica, Buchnania lanza, Flacourtia sp., Mangifera indica, Azardirachta sp., Emblica officinalis, Meliacaea, Syzygium sp., Butea monosperma and Acacia. In addition, increase of Terminalia sp, Madhuca indica and Holoptelea sp. have prompted towards increase in total diversity of flora. The floristic composition envisages that tree savannahs transformed into open mixed deciduous forest. The depletion in Chenopodiaceae/Amaranthaceae growth accompanied by profound occurrence of grasses exhibit amelioration of climate towards warmer and wetter conditions with improved monsoon during 3100 to 1350 yr BP. Later on during 1350 to 377 yr BP (KDT-3), the association of tree taxa suggests the recuperated growth of dry deciduous trees with inter dispersed moist taxa and shrubs. The floristic composition shows improving trends of vegetation enhancement towards edifice of dry deciduous forest. The whole vegetational assemblage suggests a warm and humid climate coupled with active inception of south west monsoon i.e. more or less similar to climatic condition prevailing today. 64
National Conference on Science of Climate Change and Earth’s Sustainability: Issues and Challenges ‘A Scientist-People Partnership’ 12-14 September, 2011, Lucknow POLLEN DEPOSITION PATTERN IN TROPICAL DECIDUOUS SAL (SHOREA ROBUSTA GAERTN.) FORESTS IN SHAHDOL DISTRICT, MADHYA PRADESH, INDIA M.S. Chauhan and M.F. Quamar Birbal Sahni Institute of Palaeobotany, 53, University Road, Lucknow 226 007 email: mschauhan_2000@yahoo.com This paper describes the results of a modern pollen survey of plant communities in tropical deciduous sal (Shorea robusta Gaertn) forests in Shahdol district through the pollen analysis of 6 surface samples (moss pollsters). The pollen assemblage reveals the relatively lower frequencies of arboreals in contrast to the non-arboreal taxa. Among the arboreals, Shorea robusta, a dominant forest constituent, is not represented honestly in the pollen-rain and encountered with av. 1.5% pollen only in the sediments. This underrepresentation of Shorea robusta pollen, despite being an enormous pollen producer, could be attributed to its poor preservation in the sediments as well as low dispersal efficiency. On the other hand, the consistent presence of Madhuca indica, a common associate of sal and Sapotaceae with highest frequencies of 30% and 13%, respectively corresponds more or less to their frequent presence in the forest coupled with good preservation of their pollen in the sediments. However, the other associates of sal viz., Terminalia, Lagerstroemia, Emblica officinalis, Syzygium, Holoptelea, Sterculia, etc., occurring in good proportion in the forest, are marked by their sporadic presence owing to their low pollen productivity, since majority of them show a strong tendency of entomogamy. The representation of grasses, sedges, Tubuliflorae, Cheno/Am, etc. in good numbers exhibits more or less the actual composition of ground flora in the forest floor. The consistently high frequencies of Cerealia pollen and concomitant crop weeds such as Artemisia, Cannabis sativa, members of Cheno/Am, Caryophyllaceae and Urticaceae are the indicative for the proximity of cultivated land and human habitation to the study area. 65
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12-14 September, 2011, Lucknow - Earth Science India

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