Izvorni znanstveni članak
Tree Damage in Mechanized Uneven-aged Selection Cuttings
Matti Sirén
; Natural Resources Institute Finland Vantaa, PB 18 01301 Vantaa, FINLAND
Juha Hyvönen
; Natural Resources Institute Finland Rovaniemi, PB 16 96301 Rovaniemi, FINLAND
Heikki Surakka
; Ramboll Finland Oy, PB 25 02601 Espoo, FINLAND
Sažetak
The amount of selection cuttings in uneven-aged forest stands is supposed to increase in Finland with the new Forest Act. In uneven-aged management, it is estimated that the cutting could be repeated every 15–20 years with the removal of around 100 m3/ha, depending on the site type and stand growth. This interval and volume highly depend on survival of lower canopy trees in cuttings. The number of these trees (2.5–15 m in height) is typically limited.
Felling larger trees from above means a high damage risk for smaller trees and also restricts the harvesting outside the heavy frost period due to top damage risk. Damage to trees taller than 2.5 meters was studied in three selection cutting stands. Mechanized harvesting (harvester–forwarder) was carried out in late winter with no frost, which is the optimal time for selection cuttings. On the average 21.5% of the remaining trees were damaged. The percentage of damage to smaller (2.5–10 m) trees was highest, 28.4%. Stem damage and breakage were the most common types of injury. A logistic mixed model was used to model the probability of tree injury (uninjured/injured). Distance from the nearest removed tree, harvested basal area within 25 m of the tree and diameter of the tree were the explanatory variables taken into the model. The model discrimination ability by the ROC curve was 72.2%. With a classification cutpoint of 0.5 for the model fitted injury probabilities, the rate of correct classification was 79.1%. There is a need to develop optimal working practices for mechanized selection cuttings. Information on the stand structure, practical operator tutoring and knowledge of the goals of the forest owner are needed for successful harvesting implementation.
Ključne riječi
uneven-aged forest management; selection cutting; mechanized harvesting; tree damage; spatial analysis
Hrčak ID:
136125
URI
Datum izdavanja:
24.2.2015.
Posjeta: 1.133 *