The study analyses the development of previously managed forest towards so-called secondary old-growth forests. How fast do typical characteristics of old-growth forest develop when we decide to introduce a non-intervention management, by means of ‗strict forest reserves‘? Spontaneous developments in these formerly managed forests are clearly different from primary old-growth sites. Whereas the latter are considered to be in a dynamic equilibrium, the newly established reserves are still developing in a more unidirectional way towards this equilibrium. Their development thus may be considered as a successional pathway rather than the typical disturbance dynamics of a climax vegetation. The study focuses on the development of the two predominant structural features that distinguish old-growth forests from close-to-nature managed forests: the amounts of dead wood and the presence of large, overmature trees.