The spatio-temporal pattern of release signals and tree growth in Fagus-Abies-Picea old-growth forests reveals unsteady gap-phase dynamics

Life histories of Abies alba and Picea abies growing in old-growth forests driven by natural gap-phase dynamics

“…The structural features (Paluch et al 2015(Paluch et al , 2021 and reconstructed dynamics of the studied stands were similar (Jastrzębski and Paluch 2022), and preliminary analyses did not show substantial differences in the mean age, age span, growth rate and release frequency of species on the betweensite level. The calculations conducted for Gorce, Oszast and Żarnówka, where Norway spruce and silver fir co-occur, led to similar conclusions regarding both species as those conducted for all the stands.…”

“…Although the history of settlement here dates back to the sixteenth century and clear felling was initiated in the region in the middle of the nineteenth century, the studied stands have not experienced such anthropogenic disturbances. The reconstruction of the disturbance regime since 1850 indicates that all the stand fragments where this present research was conducted have been driven by gapphase dynamics (Jastrzębski and Paluch 2022). Specifically, the disturbance severity approximated by the frequencies of release events recorded in the increment chronologies of single trees varied between 5 and 30% per decade, and the distribution of release signals was slightly over-dispersed in comparison to a Poisson (random) distribution.…”

“…A random component dominates in the spatial pattern of canopy heterogeneity and only 9-39% of the total variation is attributable to structural variation. The trees reach a dbh above 100 cm, heights above 45 m and an age (determined by coring at a height of 130 cm) of above 300 years (Jastrzębski and Paluch 2022). Tree species forming the studied stands are randomly intermingled and do not form clearly distinguishable aggregations of more than several trees.…”

“…At present, the forest structure is very heterogeneous (Paluch et al 2015(Paluch et al , 2021 and characterized by a matrix of multilayered structure with scattered canopy openings of variable size and irregular shapes. The mean canopy openness determined for trees of diameter at breast height (dbh) ≥ 25 cm varies between 20 and 41% (Paluch and Jastrzębski 2022). A random component dominates in the spatial pattern of canopy heterogeneity and only 9-39% of the total variation is attributable to structural variation.…”

“…Natural beech-fir-spruce forests are driven by gap-phase dynamics with occasional more severe disturbances (Splechtna et al 2005;Nagel et al 2014;Frankovič et al 2021;Jastrzębski and Paluch 2022). This type of forest dynamics favors the formation of multi-aged and multi-storied stand structures with a quasi-continuous pattern of generation replacement (Král et al 2014;Parobeková et al 2018;Paluch et al 2015).…”