A compilation of 2610 TRW series from 40 sites covers the Alpine arc and the 951-2004 period. Application of the RCS method resulted in a chronology that preserves inter-annual to multi-decadal scale variability. Since sample size and diversity in sample compensates for spatiotemporally asynchronous insect-induced 'noise', reconstructed summer temperatures show, for example, the cold and hot extremes of 1816 and 2003, respectively, as well as episodic warming during medieval times and towards present with prolonged Little Ice Age cooling in between.
This reconstruction validates earlier work and also improves our understanding of past climate variability across the Greater Alpine Region and back in time. This study exhibits that larch TRW measurements can robustly model summer temperature variations if enough data (i.e. evenly distributed and well replicated site chronologies) are carefully selected (i.e. based on their individual temperature response) and age-related composite detrending properly applied (i.e. tests of the RCS method using various data subsets).
Conversely, this study supports the 'epicenter' hypothesis of traveling waves in population dynamics (Johnson et al. 2004), and the 'altitude' hypothesis, which postulates that most severe LBM epidemics are concentrated at ~1800 m asl (Weber 1997). While the first hypothesis is affected by the complex landscape geometry of the Alpine arc that dampens the direction and speed of traveling waves (Bjørnstad et al. 2002, Johnson et al. 2006), the later is affected by local weather conditions that shift outbreak foci to lower or higher elevations, and modulate populations at different slope exposures (Baltensweiler et al. 2008).