Competitive ability of natural Douglas fir regeneration in central European close-to-nature forests

Douglas fir (Pseudotsuga menziesii) has regenerated naturally in European forests since the middle of 20th century. Some cases an invasive character species have been reported under specific site conditions, but systematic data on extent natural regeneration and spread across different forest communities are largely lacking. Due to its potential tolerance increasing summer droughts, suggested as a sustainable future tree for Central forests. In this study, we investigated comparison native 39 stands Switzerland belonging communities. We analyzed success fir, Norway spruce (Picea abies), silver (Abies alba), beech (Fagus sylvatica) with respect ecological conditions. The proportion seedlings (<130 cm height) was <5% majority stands; four stands, most abundant among seedlings. other (occurring 37 stands/dominant 10 stands), (38/2 stands) (35/10 were more than Saplings (?130 height <12 diameter at breast observed five proportions between 10% 23% eight <10%, particular high seed trees. Beech saplings occurred 28 eleven stands. (24/3 (19/6 less frequent. abundance correlated positively proximity trees light transmission canopy, negatively understory vegetation cover litter abundance. Ungulate browsing did not significantly affect any study On Plateau, mainly planted productive where it is strongly limited due low competitiveness compared fast-growing deciduous species. dry sites, canopy closed, able establish successfully. such close monitoring implementation control measures recommended.