Natural disturbances, such as storms or calamitous spreading of pests, are very important factors in shaping the structure of the forest ecosystem. Their monitoring can significantly help in the cultivation of healthy and quality vegetation and the management of protected areas. Although they occur irregularly, it is very important to map them, as they usually have a long-term effect on the structure, composition and dynamics of the forest. Scientists from the Faculty of Forestry and Wood Sciences tried to estimate the extent of past disturbances and describe the spatial and temporal variability of the frequency of events and their impact on beech forests.
The research area was located in fragments of primary forests in the Western Carpathians in Slovakia. There are a large number of endangered species in this area and it is biologically diverse, therefore it was selected as a suitable area for research. Only localities without direct human intervention in the canopy were selected. The forest inventory included a comprehensive field survey, aerial photographs and records from historical maps. To create permanent study sites, the researchers divided the area into areas of one hectare and then established 42 circular research areas of 1000 m2. To analyze the disturbance history, samples of annual rings were taken with special drills, which subsequently provided insight into the history of tree growth. Intervention in the vegetation reveals either release from the shade, characterized by a sudden increase in growth, or rapid initial growth, indicating the existence of a gap in the canopy.What did the annual rings tell the scientists? The reconstructed chronological order of disturbances covered 250 years. In total, researchers collected 1139 samples of tree cores. The results clearly show that in all studied forest stands there is evidence of the occurrence of serious natural events, which took place at regular intervals. Scientists recorded 144 disturbances in the studied area, from a slight effect to a very serious impact on beech stands. Small and medium disturbances with the area of ??removed crown canopy exceeded up to 40%, in some areas events with very high severity were discovered, with above 60% of removed crown canopy. These interventions significantly contribute to the creation of gaps in the canopy of crowns, which can range from several tens to several hundred square meters. The observed spatial and temporal variability of disturbances suggests that mixed beech forests were primarily formed by diverse disturbance regimes, with windstorms being a major factor in removing crown canopy.The study aimed to capture the extent of past disturbances and to compare differences in the frequency and severity of interventions in primary beech forests. The results provided an overview of past regimes and processes in stands that can serve as a starting system for forest ecosystem management. Mimicking natural events is key to maintaining the forest without significant loss of biodiversity. Forestry should therefore recognize natural disturbance by natural influences as an integral part of the dynamics of mixed beech stands in Central Europe.
Ing. Michal Frankovič
Ing. Frankovič is currently studying for a doctorate in Forest Ecology at the Faculty of Forestry and Wood Sciences, CULS, Prague, where he specializes in the detection of disturbances in natural forest ecosystems within the REMOTE Forest project (https://www.remoteforests.org/). Research work is enriched by interesting field trips to the forests of Europe. He works with colleagues from the Department of Forest Ecology on further research to help clarify the issue of disturbances in primary forests in times of climate change and thus contribute to the protection of these rare ecosystems.
Prepared by: Kateřina Krulišová