Studies on peripheral vegetation have already taken place in America, but only a few partial studies have been carried out in Europe. It is clear from them that the structure of forest edges is different than inside the stand. In general, there is greater biodiversity, greater static stability (by which we mean the ability to withstand abiotic influences - storms, snow, icing, fire) and greater ability to intercept, that is, to retain the part of precipitation that never hits the soil surface. On the other hand, the edges of the stands may also be more fragmented and may therefore reduce the total afforestation area.
The investigated areas were selected in floodplain forests due to a more natural species composition, which was not dramatically changed compared to other stands. Selected stands are in southern Moravia near the town of Kroměříž and have wood production function. The age of the stands in which the test plots were located ranges from approximately 70 to 130 years. The main woody plants that grow here are summer oak (Quercus robur) and ash (Fraxinus excelsior).
The actual measurements were performed on rectangular test plots (10 x 50 m). For each tree, the thickness at the enumeration height, the height of the tree, the height of the first green branch, the inclination of the tree and the cavity in the trunk were measured, then the crown length ratio, slenderness coefficient and planting density were calculated. The natural regeneration and the shrub layer were also evaluated.
The research results show a clear existence of a boundary between the edges of the forest and the inner part of the stands. The part of the forest that is affected by the peripheral effect is a strip of vegetation with a width between 4 and 18 m, on average 8 m wide. As for the density of natural regeneration, it is constant for the first 15 meters and then descends further into the vegetation. The height of the shrub layer decreases with increasing distance from the edge of the forest. On the contrary, the peripheral effect has a significant negative effect on the production function, especially on the basal part of the tree and its volume. The density of the stand and the volume of biomass are higher here, but this is also the cause of the deteriorating quality of the wood mass.
The proposal of the authors of the study regarding management is the possibility to exclude 8 m wide edges of the forest from intensive forest management, mainly due to poorer properties of the stand in terms of wood production. By leaving the edges of the forest with a reduced number of interventions, biodiversity and natural regeneration of the stand can be positively supported.
Ing. Lubomír Šálek, Ph.D. (* 1956)
Mr. Šálek graduated from the Faculty of Forestry of the Mendel University of Agriculture and Forestry in Brno. From 1980 to 2004 he worked in the Forest Management Institute. After a short stint at the Lesy ČR as a press spokesperson, he worked at the Faculty of Forestry and Wood Sciences at the CULS in Prague as an assistant professor.
Prepared by: Michaela Veselá