The tree-ring growth responses to climate in the timberline ecotone of Babia Góra Mountain

Abstract

The growth/climate response of Norway spruce in the timberline ecotone of Babia Góra Mountain was examined. Based on a pool of 708 trees from 10 sites, the influence of age, exposure, and method of computing chronology, was assessed. Gridded data and 12 instrumental series were used to study the spatiotemporal relationship of the tree growth and climate. Temperature mainly controls the growth of the Norway spruce in the timberline ecotone at Babia Góra Mountain. The most important factors were the June and July temperatures (r = 0.57) and of the entire growing season April-September (r = 0.52). The precipitation of late winter (Marchand correspondingly the January-March season) had a positive influence on the tree growth. The previously reported negative correlation with the summer precipitation was found but it was less important. The mature trees growing on the northern slope showed a response to the summer temperature in a stronger manner than all the other groups. The low-frequency SPL chronologies (detrended using the cubic smoothing splines method) performed better than the RCS (regional curve standardisation) of the high-frequency SPL. A strong correlation was found with Obidowa, the nearest located instrumental data (a distance of 35 km), and the Hala Gąsienicowa, the station located at a similar elevation a.s.l. (1508 m a.s.l.), but also with the Krakow located farther away and at a lower elevation (237 m a.s.l.). The TRW/temperature correlation was temporally most stable in the case of Zakopane.