Impact of disturbance signature on ring width and blue intensity chronology structure and climatic signal in Carpathians
Tree radial growth is influenced by various climatic and non-climatic factors, which can complicate the extraction of climate signals in tree rings. We investigated the disturbance impact on tree ring width (RW) and latewood blue intensity (BI) chronologies of Norway spruce in Carpathian Mountains. Aiming to explore the extent to which disturbance can affect the expression of temperature signals in tree rings. Nearly 15000 tree cores from 34 sites were collected and analyzed. Disturbance trends were detected by the curve intervention detection (CID) method. RW chronology structures were compared among disturbed, and disturbance corrected chronologies in spatial (region/site/subset) scales. Sites which showed apparent disturbance trends, structure comparisons were performed for BI chronologies as well. Temperature sensitivities have been assessed in chronologies of both parameters. Results showed disturbance trends can be observed in RW chronologies in site/subset scales with a relatively small replication compared with regional scale. BI chronologies were mostly unaffected by disturbance and contained quite stronger growing season temperature signals compared with RW chronologies. The temperature signals in BI appeared to be spatial-temporal coherent. Evidence of our research indicates that influence of non-climatic factors on tree ring series exist, especially in traditional ring width chronologies. Such influence should be considered when undertaking dendroclimatic research, especially involving in the reconstruction of historical climate. Blue intensity is a promising alternative tree ring parameter for dendroclimatological studies with stronger temperature signals and disturbance-cleaner chronology structures.