The increase in interest in the issue of disturbances and the dynamics of forest stands raises many questions, and one such question was also asked by a research group of scientists from the Department of Forest Ecology, Faculty of Forestry and Wood Sciences, CULS. Their aim was to find out how disturbances affect the ways of loosening the canopy and the subsequent growth of individuals into it, both in time and in the space inside the primeval forest.
The predominant type of disturbances in the spruces of our temperate zone are wind disturbances and they are often paired with the subsequent infestation of the weakened vegetation by insects or fungi. This is a violation of varying extent and strength. Less frequent are less severe or local disturbances, which do not cause the disintegration of the entire stand, but only the emergence or enlargement of stand gaps in the canopy with the subsequent support of the regrowth of regeneration. In contrast, large disturbances, such as Hurricane Kyril in 2007, are less common. The sum of all disturbances at a given locality during the observed time interval is called the disturbance mode.
For the implementation of the project, the researchers chose the core zone of the Šumava National Park and placed the experimental areas in a mountain range at an altitude of about 1250 m. The areas were chosen to be located in the range of primeval spruce stands, which have been affected by disturbances as little as possible in recent years. These forests have not been managed at least since 1933, when they entered the intensive protection program. However, according to historical sources and due to the very poor accessibility of the stands, it is assumed that even before this date, the extent of the interventions was not significant. Shortly after data collection, there was a large-scale decay and death of most adult trees in the study site.
Based on the way juveniles grow into the canopy and the change in the width of the growth of annual rings in older individuals, a picture of the approximate development of natural spruce stands after disturbances was created with the help of dendrochronological analyses. The result of the research was the finding that the moderately strong disturbances coincide relatively accurately on all three test plots and at the same time agree with the historical sources. They were unambiguously dated between 1750 – 1770 and 1810 – 1830. Between 1770 and 1800, due to the previous disintegration of the canopy, the lighting conditions improved significantly, and thus a massive increase in individuals, which, even with subsequent disturbances, lasted until the end of the 19th century. The most dynamic period of vegetation development was its first half, when moderate disturbances formed vegetation groups with a similar age of juveniles into the canopy, and there was also a gradual widening of vegetation gaps. The 20th century was peaceful and there was a sporadic disruption of the canopy and the resurgence of renewal. After a period of rest, however, a big change came…
It was very interesting to find out that it was a vegetation protected from severe disturbances for more than 300 years, but in the end, after 2007, it was hit by a large-scale disintegration. The authors explain this drastic change in the regime of disturbances in several possible ways: by the long-term development of the stand without stronger disturbances with the subsequent development of the stand structure to a more susceptible state of decay or by climate change. Alternatively, an indirect anthropogenic influence could play a role.
The study also shows that although these were stands (very old, weakly or moderately disturbed), which are now rather minor in our territory, their importance for the ecosystem is unquestionable. They are characterized by high biodiversity, they are an ideal environment for various species of fungi and lichens, larger areas present refuge for some species of mammals and birds. The key question remains how much of the landscape mosaic of stands of different ages in natural conditions should be occupied by these very old stands.
What are the recommendations for mountain spruce areas where there is an effort to lead nature-friendly management? From an ecological point of view, it is appropriate to keep old stands with a long continuity of development in the landscape. This will create not only an environment friendly to some plant and animal species, which are in decline due to the intensity of management, but also a very diverse landscape mosaic. However, can this knowledge be applied and used for commercial forests? If we want to approach management closer to natural processes and the associated benefits, it would be appropriate in certain stands to use mixed intensities of combined cultivation-restoration practices in different time and space scales with an extension of the restoration period.
Janda, P; Svoboda, M; Bače, R; Čada, V; Peck, JE (2014): Three hundred years of spatio-temporal development in a primary mountain Norway spruce stand in the Bohemian Forest, central Europe ;Forest ecology and management,330 304–311.
Ing. Pavel Janda, Ph.D.
He obtained a university degree at the Faculty of Forestry and Wood Sciences at the CULS in Prague in the field of Forest Engineering, in which he also continued his doctoral studies. He finished this in 2012 with a dissertation on "History of disturbance and structure of mountain spruce forests". He has been a researcher at FLD since 2008, first at the Department of Forestry and since last year at the Department of Forestry and since last year at the Department of Forest Ecology.
Prepared by: Dominika Hetešová