Current issue: 55(2)
Under compilation: 55(3)
The article presents six fasciations found in Finland on bird cherry trees. Based on the literature it seems that fasciations are the precondition for witches’ brooms. The witches’ brooms on bird cherry trees are rare, but they have been mentioned in literature. Some views on their occurrence and development are represented. Also the possible causes behind the developments are discussed based on literature.
The PDF contains a summary in Finnish.
The article discusses the adaptation mechanisms of the trees against storms or stormy winds. Two main aspects are revealed: the adjustments of stem and crone and the adjustments of the root system.
The shorter the stem the lower the danger of windfall or windbreak. The wind load of a tree depends on where it is situated; on the open field the wind is much stronger than in closed stand. The tree adjusts its height on the situation: where the wind load is high the trees remain smaller. A tree adjusts its crone also depending on the wind. The branches of spruce are relatively thin and very flexible. An alone standing trees have a flat or umbrella-like crone. Trees with a deep-going main root (tap root) are best protected against windfalls. When there is no tap root, the horizontal roots need to strengthen to offer the needed support.
The protection from windfalls is an important question in the practical forestry. Knowing the factors affecting the wind tolerance of a tree the forest management can be planned to support them.
The volume 34 of Acta Forestalia Fennica is a jubileum publication of professor Aimo Kaarlo Cajander.
The growth of a tree or a forest stand can be only fully understood when the form, encroachment and development of the root s in different environments are known. Research on roots has already yielded in practical silvicultural improvements and the purpose of this study is to discuss different factors about the roots.
The literature review deals with the depth of root system, extent of it, the relation between root system and the soil structure, the form and volume of roots and the phenomenon where roots from several tree individuals grow together.
The PDF contains the article also in Finnish.