DISTURBANCE HISTORY IN A LATE-SUCCESSIONAL KOREAN PINE-BROADLEAVED FOREST IN THE SOUTHERN SIKHOTE-ALIN

Relevance and objectives. Natural disturbances of the forest stand are the events that cause changes in the structure of the forest stand, the availability of resources and environmental conditions. These are key processes of the forest dynamics which ensure successful recruitment and coexistence of different species. The objective of this study was to reconstruct the disturbance history in the late-successional Korean pine-broadleaved forest of southern Sikhote-Alin. The study findings will help us to understand how forest ecosystems emerge and function without human influence and to take measures necessary to restore the forests that are already disturbed. Materials and methods. The disturbance history was reconstructed using the dendroecological approach. We analyzed 961 samples of 5 dominant species, i.e. Abies nephrolepis (Trautv.) Maxim., Betula costata Trautv., Picea jezoensis (Lindl. еt Gord.) Fisch. еx Carr., Pinus koraiensis (Siebold et Zucc.) – Korean pine, and Tilia amurensis Rupr. We identified growth releases using the boundary-line release criteria. Results. For the first time it was possible to reconstruct the history of natural forest stand disturbances on the area of 5 ha for 255 years. In most of the time, periods of sharp increase in radial growth occur in no more than 5–10 % of trees. At the same time, 4 periods of major natural disturbances were revealed, i.e. 1765–1774, 1845–1849, 1880–1889, and 1960–1964. The largest one occurred in 1960–1964, when more than 20 % of trees showed growth release. Conclusions. From 1750 to 2005, there were no catastrophic natural disturbances in the study area, but relative severe disturbances were detected with groups of trees having fallen out, as well as minor disturbances (loss of single trees). The loss of individual trees with subsequent formation of small gaps in the canopy contributes to continuous and stable existence of the stand. Most likely the gaps are formed due to strong winds. This provides stable generations flow of trees of different species.