Response Time of the Lys Glacier (Valle D’Aosta). An Example of a Dendrogeomorphological and Environmental Study

Abstract

Glaciers respond to climatic variations through process that first involves mass balance and later frontal variations. The objective of this study was an evaluation of the response time of frontal variations for the Lys Glacier, which is located in the Monte Rosa Group. Four mean dendrochronological curves were obtained by means of a dendrogeomorphological investigation carried out on over 200 larch trees sampled in the Gressoney Valley (AO, Western Italian Alps). These curves correspond to four morphological units left uncovered by the glacier in different time periods. The response time was obtained by correlating the dendrochronological data series obtained, with the glacier front variation data (time-distance curve). This showed that the response time was 5 years with a correlation coefficient of r = -0.511. Correlations using 5 Years moving averages confirmed the results and increased the level of significance to r = -0.693. This was also confirmed by the results obtained by correlating frontal variations with the Lake Gabiet (2340 m) meteorological station temperatures. In addition, the correlations between the temperature data and the dendrogeomorphological series demonstrated that the response of the trees to temperature was virtually immediate.