Abstract
The intensity of cyclic larch budmoth (Zeiraphera dinianaGuenée; LBM) outbreaksacross the European Alps has been reported to have weakened since the early 1980s. In additionto a warmer climate, changes in land-use cover over modern and historical times may haveaffected the LBM system. Here, we present tree-ring-based reconstructions of LBM outbreaksfrom a mixed subalpine larch−pine forest in the French Alps for the period 1700−2010. Temporalvariation in LBM outbreak severity was mainly driven by land-use changes, including varying for-est structure and species composition. Human population pressure and associated resourcedemands for fuel wood and construction timber not only resulted in a reduction of larch and sub-sequent suppression of pine, but also supported an overall grassland expansion for livestock.Superimposed on modern land abandonment and pine re-colonization is a strong warming trend,which may also contribute to the observed late 20th-century weakening of Alpine-wide cyclicLBM outbreaks. Our results suggest that a complex interplay of different factors triggered lesssynchronized LBM outbreaks at broader scales, with overall significantly lower intensities at localscales.