Mountains in the Chaning World, Mountains in the Chaning World

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Tree-ring studies of a central Himalayan Abies spectabilis treeline ecotone in Nepal
Niels Schwab, Ryszard J. Kaczka, Ram Prasad Chaudhary, Udo Schickhoff

Last modified: 2017-08-22

Abstract


Climate warming is expected to induce treelines to advance to higher elevations. Empirical studies in diverse mountain ranges, however, give evidence of both advancing alpine treelines as well as rather insignificant responses. The large spectrum of responses is not fully understood. In the framework of investigating the sensitivity and response of a near-natural treeline ecotone in Rolwaling Himal, Nepal to climate warming, we present results of tree-ring analyses of Abies spectabilis (Himalayan Fir). The aim of the study was to determine the dynamics of the treeline and assess the climate influence on the growth of the trees at different elevation. Two hundred trees were sampled at three slopes representing three elevational zones (4100 - 4000, 4000 - 3900 and 3800 - 3700 m a.s.l.). Tree ring width (TRW)and Blue Intensity (BI)were measured. The rate of the growth, the age structure and the forest density within the sites were analysed and compared between sites. After standardization, the chronologies were correlated with temperature and precipitation variables from local meteorological stations and grid data. We found positive correlations between fir growth and spring precipitation and negative with spring temperature, pointing to moisture limitation in consequence of increased evapotranspiration. In general, the climate signal was stronger for BI than TRW chronologies. Final results will contribute to improved knowledge of Abies spectabilis climate-growth relationships and increase the concerning database from the Himalayan region. Moreover, results will be used as an indication of future growth patterns and treeline dynamics under climate change conditions.


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