Mechanical stability of Scots pine, Norway spruce and birch: an analysis of tree-pulling experiments in Finland

Tree pulling experiments were conducted in Eastern Finland (1995–1996) involving 51 Scots pines ( Pinus sylvestris L.), 33 Norway spruces ( Picea abies (L.) Karst.) and 11 birches ( Betula spp.) under unfrozen soil conditions and 20 Scots pines when the (podzol) soil was frozen. The trees were pulle...

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Bibliographic Details
Published in:Forest ecology and management 2000-09, Vol.135 (1), p.143-153
Main Authors: Peltola, Heli, Kellomäki, Seppo, Hassinen, Alpo, Granander, Markku
Format: Article
Language:English
Subjects:
Betula
Biological and medical sciences
Fundamental and applied biological sciences. Psychology
Maximum resistive bending moment
Modulus of rupture
Phytopathology. Animal pests. Plant and forest protection
Picea abies
Pinus sylvestris
Tree pulling
Weather damages
Weather damages. Fires
Winch system
Wind damage
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Summary:Tree pulling experiments were conducted in Eastern Finland (1995–1996) involving 51 Scots pines ( Pinus sylvestris L.), 33 Norway spruces ( Picea abies (L.) Karst.) and 11 birches ( Betula spp.) under unfrozen soil conditions and 20 Scots pines when the (podzol) soil was frozen. The trees were pulled over with a winch attached at a stem height of 6 m and the force required to uproot or break the tree was recorded, together with detailed measurements of the physical characteristics of the tree. Analysis of the data showed that the maximum resistive bending moment was most significantly and positively correlated with diameter at breast height (DBH) and tree height ( H). Tree height multiplied by the second power of DBH provided the best prediction of the maximum resistive bending moment required for uprooting, allowing the species to be ranked in the following decreasing order of resistance: Scots pine>birch>Norway spruce. Correspondingly, the third power of breast height diameter served best to explain the maximum resistive bending moment for stem breakage, with the following decreasing order of resistance: birch>Scots pine>Norway spruce. Highly tapering trees were more liable to stem breakage than uprooting, and vice versa. All the Scots pines broke under frozen soil conditions, and higher bending moments were needed for stem breakage than under unfrozen soil conditions. The modulus of rupture of the broken stems, as derived from the maximum resistive bending moments for stem breakage, showed the following decreasing order of resistance: birch>Scots pine>Norway spruce.
ISSN:0378-1127
1872-7042
DOI:10.1016/S0378-1127(00)00306-6