| Abstract: | The Bia
owie
a Primeval Forest, Poland, is the only forest area in temperate Europe where large tracts of natural forest communities have been conserved. The concept of silvatic mosaic Oldeman, R.A.A., 1990. Forests: Elements of Silvology. Springer, Berlin] was applied in order to characterise the structure of stands representing oak–lime–hornbeam forest in both, the restricted area of Bia
owie
a National Park (BNP) and the commercial forests (CF), as well as to indicate a holistic approach towards protection and restoration of natural areas.Six developmental phases of stands were distinguished and defined: regeneration, young, pole, late pole, optimal, and terminal. Compositional and structural differences between the first five phases were also evaluated and visualised. Moreover, the considerable differences between analogous phases in BNP and CF were found. The uniform stand patches were mapped into two plots in BNP (25 ha each) and two in CF (25 and 20 ha), with a resolution of 10 m× 10 m pixels.The mosaic composition of natural communities indicates close-to-the equilibrium stage: the biostatic optimal phase occupies 33–40% of the area, while aggradational younger phases share nearly the same portion of the area as the senescent phase does. Although small, 0.01–0.04 ha eco-units dominate in BNP, there is a considerable portion of intermediate and large patches, indicating a complex character of factors responsible for the mosaic structure of natural stands in BNP. Both, composition and texture analyses indicate that the area of 25 ha is close to the minimum structure area specific for the communities studied.The comparison of natural and managed stands revealed large deficits of the optimal phase (only 19%) and a total absence of the terminal one in the managed area (20–35% in natural forest). Also the mosaic texture of CF plots was simplified because of standardisation of the management unit size. The modification of developmental phases, mosaic composition, and structure must lead to changes in the dynamics of the entire community. The present study demonstrates that the natural forest should be considered as a dynamic supersystem, covering a sufficient area to allow the developmental phases to perform in correct proportions. Because of differences in the durability of various phases, the natural cycle of forest development has an asynchronous and highly unpredictable character. Indeed, the applicability of multipurpose forestry rules as a tool of nature conservation has been questioned. An absolute ban on cutting in the remaining old-growth stands should be a basic rule for the restoration management. |
