Intra-annual density fluctuations in silver fir are triggered by drought conditions

In Abies alba Mill. (silver fir), the frequency of intra-annual density fluctuations (IADFs) increases along latitudinal transect, from North to South, is higher in pure than mixed stands, and their formation linked spring and/or summer drought conditions. Trees respond climate, recording information tree rings anatomical features, such as IADFs. The IADFs are regions within ring where changes response physiological processes environmental objective this study was assess effect different forest-stand structures climate on IADF populations silver fir a gradient Italy (Trentino, Molise Calabria regions). doing so, we aimed compare or stands understand ability cope with fluctuations. Results showed (in Trentino Calabria) younger trees (namely stand Calabria), because sensitivity variability. emerged drought. Summer precipitation (both Trentino) early spring/summer played key role IADF-type E+. L+, other hand, related temperature/precipitation late autumn Molise) (pure Calabria). Our findings support theory that an important structural/functional mechanism for responding