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Forest structure in Europe has been shaped by forest management which may vary from intensive clearcuttings to single-tree selection cuttings. Most investigations on silver fir forests have been carried out in the mountains. Forests in lowlands have been less studied, although many of them are of natural origin. We investigated and assessed potential stand structural differences between managed and partially protected mixed silver fir stands. We also assessed the impact of silvicultural activities that led to the development of current stand structures of mixed Abies alba stands. The study was conducted in Janow Forests in south-eastern Poland. We randomly established 40 circular nested plots in three managed and three partially protected stands. Although both managed and partially protected stands differed in the intensity of management and the type of selection cuttings, we found little difference in the composition and stand structure. Regardless of management intensity all stands were characterized by diversified natural regeneration, where the main tree species, especially in the phase of seedlings, was silver fir. The basal area of standing dead trees was higher for the protected than managed stands, but the differences were not significant, whereas the mean volume of dead standing trees was significantly higher in the reserve. Both in managed and protected stands, silver fir benefited from the management measures mimicking natural processes. Our results suggest that low intensity forest management for silver fir dominated forests will be crucial for conserving these forests and their unique structure in the region.

ummary Tree regeneration on coarse woody debris (CWD) is considered to be one the most ecologically valuable aspects of CWD in forest systems. However, most studies have focused solely on uncovering the differences in establishment and growth on CWD (regarded as a homogeneous substrate) in comparison with the forest floor. Our study concentrates on the underlying mechanisms of germinant and seedling colonization patterns and demographic responses relative to various properties of CWD. We analysed the effects of CWD properties (decay class, form, species and diameter) on: (i) germinant and seedling annual counts; (ii) annual germinant and seedling survival; and (iii) seedling growth and height. Our study comprised three species (beech, fir and spruce) over 7-year span in two old-growth stands in the Western Carpathians, and employed generalized linear models and mixed models to test for differences between species. CWD properties affected regeneration at the germination stage. There were some demographic differences between species relative to CWD properties. Decay class had the most pronounced effect on beech, not only on its establishment but also survival and growth. Beech and spruce established and survived in higher densities on beech CWD, while their height growth was enhanced on conifer-derived CWD, particularly on spruce CWD. Stumps enhanced establishment of all species and survival of conifer seedlings. Synthesis. Our study shows that CWD properties do influence seedling establishment, growth, height distribution and survival. Moreover, there may be trade-offs between seedling growth and survival among tree species growing on different species of CWD. This highlights the need to include CWD heterogeneity as a factor that can affect the role of CWD in regeneration in forest ecosystems.

Key message In mixed forests, coarse woody debris promotes the successful establishment and growth of conifers and beech. In contrast to beech and fir, older spruce seedlings were only present on coarse woody debris and not on the forest floor. Context Coarse woody debris (CWD) is considered a suitable seedbed for small-seeded and light-demanding species. Its role in enhancing tree regeneration is well reported in boreal or subalpine spruce forests. Less is known about its role in the establishment, growth, and survival of other species, particularly in mixed forests. Aims We analyzed the role of CWD in seedling establishment, growth, and survival for European beech, silver fir, and Norway spruce. Methods We tracked the growth and survival of all germinants and seedlings over 5 years. Results Conifers were relatively more successful than beech at colonizing on CWD. The density of seedlings was variable in all CWD decay classes but was the highest on well-decomposed CWD. CWD supported the growth of all species. Beech cohorts and older seedlings had similar mortality rates on both microsites. Spruce germinants did not survive on the forest floor for more than a year, and older seedlings were only observed on CWD. Fir cohorts had similar mortality rates on both microsites, but older seedlings survived better on the forest floor. Conclusion Although the three species differed in their preferred microsite for establishment, CWD can be considered a suitable regeneration microsite for all three species by enhancing their growth and, in the case of spruce, both short- and long-term survival.