Thèse de doctorat : Université de Fribourg, 2009 ; no 1644.
Trees’ mechanical stability is essential for the benefits provided by forests including wood and pulp products, specific ecosystems, recreation areas for people, and protection against natural hazards. Since tree growth depends on the environment in which the tree grows, it is possible to influence the mechanical stability of trees and forests. Different forest management strategies affect the...
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In: Tree Physiology, 2009/29//doi:10.1093/treephys/tpn030
A new method for investigating the detailed reaction and the energy absorption of trees during a rock impact was developed and applied to 15 subalpine Norway spruce (Picea abies L. Karst) trees. A wedge-shaped trolley, guided by prestressed steel wires, was mounted on a forested slope to simulate a falling rock. The trolley accelerates down the wires and hits a tree at a preselected stem height...
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In: Journal of Experimental Botany, 2008, vol. 59, no. 9, p. 2513-2528
Thirteen Norway spruce [Picea abies (L.) Karst.] trees of different size, age, and social status, and grown under varying conditions, were investigated to see how they react to complex natural static loading under summer and winter conditions, and how they have adapted their growth to such combinations of load and tree state. For this purpose a non-linear finite-element model and an extensive...
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In: Tree Physiology, 2008, vol. 28, no. 3, p. 355-366
The bending and growth characteristics of large fresh stems from four silver fir (Abies alba Mill.) and three Norway spruce (Picea abies (L.) Karst.) trees were studied. Twenty logs taken from different stem heights were subjected to four-point bending tests. From the bending test records, we calculated stress–strain curves, which accounted for detailed log taper, shear deformation and self...
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In: Plant and Soil, 2007, vol. 300, no. 1-2, p. 35-49
The reactions of trees to wind, rockfall, and snow and debris flow depend largely on how strong and deformable their anchorage in the soil is. Here, the resistive turning moment M of the root–soil system as a function of the rotation ϕ at the stem base plays the major role. M(ϕ) describes the behavior of the root– soil system when subject to rotational moment,...
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In: Tree Physiology, 2007, vol. 27, p. 1229-1241
To provide data and methods for analyzing stem mechanics, we investigated bending, density and growth characteristics of 207 specimens of fresh wood from different heights and radial positions of the stem of one mature Norway spruce (Picea abies L. Karst.) tree. From the shape of each stress–strain curve, which was calculated from bending tests that accounted for shear deformation,...
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