Do altered prices and logging costs for logs of small diameters affect the optimum rotation of Norway Spruce in mountainous regions?

Lemberg

2009

S. 33-43

8 Abb., 11 Lit. Ang.

Artikel aus einer ZeitschriftUnselbständiges Werk

200162536

Rotation as the planned average production period of a management unit within the age-class system, and as a central control value for the forest enterprise, has always been a key factor of forest sustainability. It determines, for instance, growing stock, timber yield, tree dimensions and economic success. As a consequence of changes in sawmilling technology, price relations between dimensional assortments of Norway spruce, which is Austria's most abundant tree species, have altered in favour of low diameter logs at least for medium and low quality timber. This trend has been accompanied by advantages in the efficiency of fully mechanized timber harvesting technology for smaller dimension timber in particular. As early as in the 1990s a first comprehensive analysis of possible consequences of these changes for the rotation period of highest income from the forest came to the conclusion that shortening the rotation period would not be recommendable. A more recent study was designed to consider also the changes of the past 15 years and compare the results with those of the former study. For calculating the net income excluding costs for harvesting (Contribution margin I) and silvicultural measures (Contribution margin II), the stand development and stand valuation program FOWISIM was applied. The timber prices used were based on forest statistics and expert consultations. Newly available timber harvesting productivity models (Stampfer, 2001) were integrated into the simulation model. The consequences of changes in the rotation period (decrease, increase) for the sustainability of the enterprise (felling quantities, growing stock, finances, etc.) are demonstrated by means of the dynamic transition model FOBSl. The results of the first study have been fully confirmed. There are only small differences between the net income values around the maximum value, which offers a wide range of two or three decades for the choice of the rotation. The develonment of price relations for dimensional assortments and harvesting cost relations tends to reduce the optimum length of rotation, while a decreasing timber price level increases the optimum rotation period. However, the changes of the factors investigated during the last two decades were so small that they do not give any reason for decreasing or increasing the rolation period.