The potential of using Pinus sylvestris L. from the High Coast region as a climate proxy for studying hydroclimatic variability

Abstract

It is of importance to get more detailed information on past spatio-temporal hydroclimatic changes in northern latitudes to understand the hydroclimatic regimes working there. This can be done by studying proxy data from tree rings. One place suitable for such research is the High Coast region which has many sites with thin soil cover on bedrock and therefore has low water storage capacity. Thus, trees growing here are dependent on precipitation and sensitive to drought events. Furthermore, the most common tree species here is Scots pine (Pinus sylvestris L.) which is a drought sensitive species and commonly used within the field of dendrochronology. The aim of this thesis was to examine the potential of using Scots pine from the High Coast region as a climate proxy. This was done by dating and measuring the tree-ring widths and calibrating these against precipitation, temperature, and the drought index Standardised Precipitation-Evapotranspiration index (SPEI). The dated samples expanded the existing swed324 chronology that previously stretched between 1448–1998 to 1403–1998 (i.e., 45 years) and further complemented the sample depth by 18 samples which gave it a higher reliability. The sample depth has especially been strengthened between 1480 and 1700 (i.e., 220 years). The results showed the strongest correlation with SPEI in the period of 1901-1998 for the month of June. Furthermore, the calibration between the tree-ring width, temperature and precipitation (1860-1998) showed a slightly lower correlation, although a significant climate signal could be found. Lastly the results showed a potential of tree-ring research in this region, which suggests further studies with methods such as blue intensity will be necessary to enhance the signal.