Current issue: 54(2)
The dependence of elastic and tensile properties of coniferous trees on the share of summer wood can be presented as linear functions, if the soft wood is considered as a statically indefinite structure. By eliminating the share of summer wood by a certain function presented in the article, the elastic and tensile properties are the linear functions of density.
The functions are proved right by conducting strength tests on pine. Practical implications of the derived functions in rating the quality of wood are also presented.
The PDF contains a summary in Finnish.
The aim of the present study was to investigate the trampling tolerance of forest ground cover of the Calluna, Vaccinium and Myrtillus type sites. Positive correlation was found between the site fertility and trampling tolerance of plant communities. Annual trampling at level of about 16,000 visits per hectare decreased the biomass of the ground cover to almost half of the original amount, and annual trampling of about 160,000 visits per hectare completely destroyed the forest ground cover irrespective of site fertility. Comparisons made between herb and grass dominated forest ground cover showed that herb and grass cover is in the long run the best alternative for the management of ground cover in intensively used recreation areas.
The PDF includes a summary in Finnish.
The study deals with the trampling tolerance of forest vegetation in a Myrtillus type closed forest of Norway spruce (Picea abies (L.) H. Karst.), based on the effects of simulated trampling on the coverage and biomass on the field and between layers of the vegetation. The reliability of the results from the simulated trampling was tested by comparing them with those obtained from real trampling.
According to the results, the trampling tolerance of the bottom layers is greater than that of the field layer. The trampling tolerance of different species varies, so that grasses and dwarf shrubs have a higher tolerance capacity than herbs. Even light trampling of short duration caused noticeable changes in the coverage and biomass of the ground vegetation. Despite certain deficiencies, the simulated trampling gave parallel results of those obtained for real trampling.
The PDF includes a summary in English.