Root-Rot and Increment in a Thinned Spruce Stand After Tractor Logging

1986

S. 3-17

7 Abb., 5 Tab., 19 Lit. Ang.

Unselbständiges Werk

200054404

Sveriges Skogsvardsfoerbunds Tidskrift 1986 ; Nr. 4, S. 3-17

In the autumn of 1966 an experiment was initiated to estimate tractor- logging damage in a 39-year-old stand of planted spruce. The experimental site was located 1 km S of Vae Church in the eastern part of the province of Scania. Three strip roads, approx. 100 m long, were opened in conjunction with stand thinning. All timber was transported out along paths running at right angles to the strip roads. The strip roads, cleared of logging residue, received the following treatments: 0: No hauling; control. 1: Hauling of 5 loads (M.F. Robur with Rossoe trailer, weight 14 metric tons). 2: Hauling of 50 loads (M.F. Robur with Rossoe trailer, weight 14 metric tons). The stumps remaining after thinning were treated with fungicide. Stand measurements were taken in the autumns of 1977 and 1978. No parallel experiments were conducted, which decidedly increased the difficulty of the analysis. The following results were obtained, however. 1. After 11 years, evidence of tracks remained in the two treated strip roads. The track depth was 2-5 cm in the most severely-damaged road and 2 cm for the first trial. 2. The strip road of the control plot was almost totally free of vegetation, while a considerable amount of bushes, herbs and grasses were found in the other two cases, which indicates a lessened competition among the roots and reasonably good access to nitrogen. The degree of coverage in the field- layer reached 1-2% in the control parcel. The road which had been subjected to 5 haulings was covered to 5-6% by field-layer species, while the comparable figure for the road subjected to 50 haulings was 15-20%. 3. Between 10% and 17% of the stand's stems showed rot damage at stump height. The spread of the rot showed no relation to the tractor hauling, but rather was judged to be an effect either of unsuccessfull fungicide treatment or of an earlier undocumented cleaning or thinning. 4. Excavation of the strip roads showed that where hauling had been conducted 50 times, 47% of all of the coarser roots had suffered mechanical damage. Most of the injuries were healed. Four edge trees (15.3%) had suffered rot damage in the stem base and stem, most likely as a result of the tractor logging. On plot 1, where a more normal tractor logging was conducted in 1966, 35% of all coarser roots were damaged. Two edge trees (8.6%) had received injuries resulting in rot in the stam base or stem. The majority of the mechanical root injuries had led to rot, but this was contained within the root systems. 5. A calculation example shows that this rot damage, under certain suppositions, has led to a loss, which at the time of logging amounted to 20 Swedish crowns per cubic metre extracted wood. Despite the limited occurrence of rot induced by tractor logging, it is not without economic significance. 6. The occurrence of windfalls and dead trees in the stand had no connection......