VEGETATIONAL AND SEASONAL CLIMATIC CHANGES SINCE THE LAST FULL GLACIAL IN THE THAR DESERT, NORTHWESTERN INDIA

Studies are presented from Didwana salt lake, Rajasthan, India, showing a sequence of changes reflecting the history of summer and winter precipitation, in the Thar Desert, since the Last Full Glacial. Steppe vegetation, mainly of Chenopodiaceae/Amaranthaceae, grasses, Artemisia, Aerva and Ephedra, grew simultaneously with hypersaline lake conditions between about 20,000 and 13,000 yr B.P., indicating a considerably weakened summer monsoon and a higher winter precipitation than at present. A rise in precipitation is evidenced by the intermittent filling of the lake from c. 13,000 yr B.P. followed by nearly permanent freshwater between c. 9000 and 6000 yr B.P. The vegetation changed to a savanna grassland in which Prosopis cineraria formed the bulk of tree vegetation from c. 7500 yr B.P. Taxa indicative of both increased summer and winter precipitation rose during the mid-Holocene and declined during the late Holocene in harmony with a declining lake level. The lake became ephemeral c. 4000 yr B.P. © 1990.