Holocene vegetation and climate fluctuations in northwest Himalaya,based on pollen evidence from Surinsar Lake,Jammu region,India |
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| Authors: | Anjali Trivedi M S Chauhan |
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| Institution: | 1.Department of Geology,Lucknow University,Lucknow,India;2.Birbal Sahni Institute of Palaeobotany,Lucknow,India |
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| Abstract: | Pollen analysis of a 33.21 m deep sediment core from Surinsar lake in Jammu region has revealed that between 9,500 and 7,700
yr BP (Pollen zone SL-I), the mixed oak-broad-leaved/chirpine forest occurred in the region under a warm and humid climate.
The record of aquatic plants viz. Potamogeton, Typha and freshwater alga Botryococcus in appreciable numbers denotes the existence of the lake since the Early Holocene. Subsequently, mixed chirpine/oak-broad-leaved
forests appeared in the area around 7,700 to 6,125 yr BP (Pollen zone SL-II) with the dominance of chirpine (Pinus cf. roxburghii) by the onset of cool and dry climate, attributed to decrease in monsoon rainfall. The expansion of oak and its broad-leaved
associates between 6,125 and 4,330 yr BP (Pollen zone SL-III) suggests that the climate turned moderately humid and warm,
presumably due to enhanced monsoonal effect. The region has witnessed a brief spell of pluvial environment between 4,330 and
4,000 yr BP (Pollen zone SL-IV) as evidenced by the presence of sandy layer at 15.4–14 m depths. The period of 4,000 to 2,100
yr BP (Pollen zone SL-V) is marked by the prevalence of cool and dry climate as depicted by a sharp decline in oak (Quercus cf. incana) and other broad-leaved taxa and a concurrent increase in chirpine. From 2,100 to 800 yr BP (Pollen zone SL-VI) no palaeofloristic
inferences could be drawn due to paucity of pollen, however, the presence of sandy deposit at the corresponding level in lithocolumn
implies a pluvial episode by this time. Since 800 yr BP to Present (Pollen zone SL-VII) the slight advance in the oak reflects
the ameliorating trend of climate, despite the existing cool and dry climate. |
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