Long-term investigations in a strict forest reserve in the eastern Italian Alps: spatio-temporal origin and development in two multi-layered subalpine stands

1 Part of the forest reserve established in Paneveggio Forest (Trento, Italy) in 1992 has been allowed to evolve without human intervention. Inside this reserve, two 1-ha long-term monitoring plots were established in subalpine multi-layered forest stands. 2 To investigate the origin, spatio-temporal development and disturbance history of these plots, the present study combined dendroecological tree ring analysis with historical evidence. 3 One stand (VB3) had an uneven-aged population in which the oldest trees were more than 400 years old. Regeneration has been continuous both in time and space over the last three centuries, during which time the stand has been affected regularly by disturbances. This supports the information from historical documents, suggesting that a selection system was carried out in this area. 4 The second stand (BDO) also had an uneven-aged population, with trees up to 397 years old. Although this plot too had been affected quite regularly by disturbances, massive regeneration occurred only after 1920, suggesting that the land might previously have been exploited as pasture. 5 Despite their relatively similar structures, the two plots developed in entirely different ways. Our study confirmed that biological data can be used to identify the occurrence and intensity of prior localized disturbances in forest stands, but the precise causes of the disturbances can be determined only by comparing biological data and historical records.