Would tree ring data of Betula utilis be potential for the analysis of Himalayan glacial fluctuations

Abstract

TREE line in the Himalayan region varies from site to site depending on the position of the snow line. Its location in the western part of the Himalayas is at about 3600 m. It descends as low as 2550 m in Gilgit or is as high as 5000 m at Thalle La in the Karokoram range 1 . Trees confined at the upper tree line ecotone are found to be much sensitive to both climatic changes and glacier fluctu ations. Hence tree ring data of these tree s seem to be potential archives to analyse temporal variations of climate as well as gl acial advance and retreat. Most of the tree studies from this r egion are confined to conifers 2–8 and from sites located far away from the present-day glacier snout. No a ttempt had been made earlier to analyse tree ring data of broad -leaved taxa growing close to the glacier snout from the Himalayan r egion. Birch (Betula utilis) is a medium sized deciduous tree that often forms an open forest at the upper tree line 9 close to the snout of many glaciers extending over the e ntire Himalayan region. Due to its close proximity to the glaciers, temporal growth behaviour of this tree might be linked with the glacial dynamics of the Himalayan r egion. Here tree ring analysis of birch , a broad-leaved taxa growing at 3900 masl about 3 km south of the snout of the Gangotri glacier, has been discussed in terms of its de ndroclimatic perspective and its probable linkage with the climatic changes of the region and fluctuations of the Gangotri glacier.