The dynamics of a mountain mixed forest under wind disturbances in the Tatra Mountains, central Europe - a dendroecological reconstruction

Windstorms are among the most severe disturbances that affect mountain forests in central Europe. This study was conducted in a windthrow area resulting from a windstorm of an enormous scale in November 2004 in the Slovakian High Tatras Mountains. In this study, we used dendrochronological methods to determine the age structure and growth pattern of 529 Norway spruce (Picea abies (L.) Karst) and 103 European larch (Larix decidua Mill) during the last 200 years by examining cross sections of stumps. The multiage structure of the spruce indicated that this species regenerated constantly throughout the reconstruction period. The age structure of the larch was distinctly bimodal with only two ca. 20 year periods of regeneration. The initiation of larch recruitment overlapped in time with release pulses and showed severe disturbance events. A sudden and simultaneous production of compression wood and resin pockets in survivor trees indicated that wind was the most probable disturbance factor. The current composition of the stand with coexisting spruce and larch was a result of infrequent and severe windstorms events. Larch benefits from broader openings and regenerates in recruitment pulses once or twice per century, whereas spruce may regenerate constantly taking advantage of small-scale, gap-phase processes. Such a disturbance scenario allows the light-demanding larch to coexist among the more shade-tolerant spruce.