Late holocene vegetation and climate in Dewar Tal area, inner lesser Garhwal Himalaya

Abstract

Pollen analysis of 1.8 m deep sedimentary profile from Dewar Tal situated in the subtropical belt of Garhwal Himalaya has revealed that between 2,500 to 2,300 years BP, open mixed chirpine and oak (Quercus) forests coexisted in the region. the former inhabiting sunny hill slopes and the latter occupying moist valleys under cool and dry climate. Subsequently, between 2,300 to 2.000 years BP these forests expanded in response to the amelioration in climate which probably turned warm and moist. Thereafter, between 2,000 to 1,400 years BP. the climatic condition deteriorated as witnessed by sudden decline in prominent arboreals like chirpine and oak. besides simultaneous improvement in grasses as well as other herbaceous elements. During the period 1400 to 400 years BP, maximum development of oak forests indicates enhancement in the precipitation. resulting in the onset of warm and moist climate in the region. The latter pan of this phase coincides closely with European Medieval Warm Period or Little Climatic Optimum of America. The constructed pollen diagram demonstrates that since 400 years BP (1.550 A.D.) cool and dry climate was restored as evidenced by gradual decline in mixed oak forest along with simultaneous expansion of chirpine forest in the region.