EN
The paper is a review and it focuses on the most important factors responsible for the process of colonization of recent, post-agricultural woods by woodland species. Furthermore, it presents the results of the studies on habitat conditions and on the pace of the colonization by woodland herbs of post-agricultural black alder woods in the Oleśnica Plain and Żmigród Valley. Migration of woodland species into recent woods is a combined result of dispersal and recruitment limitation. However, in alder woods the herb layer recovery proceeds faster than in forests with lower fertility and moisture content. An important condition for the effective formation of understory in alder woods is the direct proximity of ancient forests, the establishment of shady conditions and the maintenance or restoration of natural high water levels. A high groundwater level suppresses the negative impact of competitive species, which otherwise develop vigorously in drained, eutrophic woods with a high illumination level on their forest floor. A better understanding of the mechanisms responsible for the biotic diversity of forests is possible due to the knowledge of their history, especially when we know the length of their existence in the landscape.