Biotic and abiotic effects on tree regeneration vary by life stage in European primary forests.

An observed acceleration of tree mortality rates in European forests has been attributed to the impacts of climate change and extreme disturbances. Ecosystem recovery depends on regeneration success, but the recruitment of juveniles has been recognized as bottleneck in the development of forests. We investigated the potential importance of biotic (canopy tree abundance, ungulate herbivory) and abiotic (light, soil nutrients) factors in the limitation of regeneration in montane primary forests in central Europe. We used widely distributed forest inventory data (n = 348 plots) for two forest types, multiple tree taxa, and two life stages (seedlings and saplings). Seedling densities were promoted by more abundant parent trees, but saplings were either negatively influenced or unaffected by the number of conspecific adults. Browsing intensity (per capita defoliation severity) strongly limited the density of seedlings, but not saplings, at a community level. Low understory light levels were positively associated with seedling densities, but either did not affect or depressed sapling abundance A tolerance of shading was enhanced by nitrogen availability in some taxa. Our findings reflect highly complex, context‐specific regeneration processes that vary by species and life stage within species. [ABSTRACT FROM AUTHOR]