High altitude forest sensitivity to the recent warming: A tree-ring analysis of conifers from Western Himalaya, India

An unprecedented enhancement in growth during the last few decades is detected in the five tree-ring width chronologies of Himalayan conifers (Cedrus deodara D. Don; Picea smithiana Boiss) from the high altitude areas of the Kinnor and Gangotri regions, Western Himalaya. These chronologies indicate a strong positive relationship to the mean annual and winter (December-February) temperatures of the concurrent year. A 553-year-long master chronology prepared from the five individual chronologies shows few decadal and longer epochs of Little Ice Age (LIA) cooling during A.D. 1453-1590 and AD. 1780-1930. Many of these events have been observed to be well related to the other proxy records of glacial fluctuations of the region. Analysis of instrumental period surface air temperature data over the region indicates significant increasing trend during the last century with a noticeable enhanced warming in the recent four decades. The time series of annual highest values of daily maximum and minimum temperatures also show increasing trend. Direct significant relationship of winter temperature to the tree growth is mainly because of moisture availability for a longer period due to higher degree of snow melt in winter and early spring. Therefore, accelerated tree-ring growth during the last few decades can partially be attributed to the overall warming trend over the region. (C) 2010 Elsevier Ltd and INQUA. All rights reserved.