Natural vegetation in himachal pradesh

Answer 1

Pollen analysis of Sitikher bog near Kunzum Pass

(Himachal Pradesh) indicates that between 2300 and

1500 yr BP, cold and dry climate prevailed in the

upper Spiti region and glaciers advanced towards the

lower elevations. Between 1500 and 900 yr BP the climate changed to warm and moist, which resulted in

the retreat of glaciers and shift of tree line towards the

higher elevations. From 900 yr BP onwards the mountain glaciers/tree line descended with the return of

cold climate which continues until the present time.