ZLV Online

Abstrakt

Large-scale disturbances such as windthrows and bark beetle outbreaks influenced recently extensive areas of the mountain spruce forests in Central Europe. Currently, there are concerns about the forest management in relation to the ability of their recovery and resilience, in the conservation areas especially. The purpose of this study was to quantify the amount and height structure of the advanced regeneration (>0.5 m in height and <10 cm in diameter) potentially surviving the severe wind or bark-beetle disturbance in the natural mountain spruce forest in the Hrubý Jeseník Mts. (Czech Republic). We also tested the relationship of spruce regeneration with stand structure and physiographic factors. We collected data at 27 circular 1000 m2 plots. The trees were divided into three height categories. On 93% (25) of plots we found a sufficient number (i.e. more than 250 individuals per ha) of advanced regeneration needed for maintaining the continuity of the forest (excluding seedlings below 0.5 m height). We recorded more than 1000 individuals of advanced regeneration per ha on 44% of plots, and less than 250 individuals per ha were recorded only on 7% (2) of plots. The abundance of the advanced regeneration shows a high spatial variability, thus indicating a wide future variability of stand structural forms after potential disturbance. Abundance of the Norway spruce regeneration significantly increased with increasing basal area of snags and diameter of dead trees. Spruce trees higher than 2.5 m were more abundant at lower elevations and on steeper slopes. We confirmed that the dying trees are forming microhabitats important for tree regeneration and forest resilience generally. Even after severe disturbance, the continuity of mountain spruce forest is secure in the study area. The heterogeneous height structure of advanced regeneration also ensures the continuity of heterogeneous stand structures including the presence of relatively larger vigorous trees (10–25 cm in diameter) that can partly survive the potential disturbance and quickly recover the presence of mature trees in the forest.