The aim of the international EU project titled "Sustainable bio-technologies against forest regeneration decline in North-Eastern Bohemia" was (I) to characterize the status, conditions, and constraints for natural regeneration of Norway spruce (Picea abies [L.] K a r s t.) ecosystems in different stage of forest decline on three permanent research plots in the Krkonose Mts, (2) to assess whether the bio-technological measures are necessary to support a natural regeneration at each plot. Three research plots, established in 1992 by the Institute of Landscape Ecology, were selected: a) a slightly damaged forest stand with abundant natural regeneration (Modry dul), b) declining forest with poor natural regeneration (Alzbetinka plot), and dying forest without natural regeneration (Mumlavska hora plot). In the course of three year project, the following tasks were investigated: a) pedological conditions and soil variability connected with forest decline, b) reconstruction of the response of Norway spruce forest stands to multiple stress impacts, c) status and constraints for natural regeneration of Norway spruce, d) content of elements, fine root distribution and root regenerative potential of adult trees, and e) fungal and bacterial rhizospheric populations and ectomycorrhizal conditions of seedlings and adult trees. No fundamental differences in the chemical properties of the soils of three permanent research plots were ascertained. However, on the most heavily damaged plot, Mumlavska hora, only soil profiles in the close vicinity with the last surviving trees retained of podzolic characteristics, common on les disturbed plots. On the contrary to decreasing number of natural spruce seedlings on plots Modry dul - Alzbetinka - Mumlavska hora, the highest seedling mortality was observed in the Modry dul plot and the lowest in the Alzbetinka plot. No significant differences were observed in diversity of fungal and bacterial rhizospheric populations, including ectomycorrhizal symbionts. At this time a possible hypothesis is that the principle cause of weak, eventually lacking natural regeneration, is more connected with the crown cover and status of surviving trees (and quantity and quality of produced seeds) than with the status of soil microflora. On this account the biotechnological measures do not seem to be necessary to support a natural regeneration.