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The delimbing and bucking of timber using a harvester head is very productive in comparison with a chainsaw operations, however it can cause damage to the outer layer of round wood. This damage can originate from the delimbing knives or from the feed roller spikes. As a consequence, grey fungi can develop on coniferous species, and faster wood drying is also observed (with no regard to the species). Feed roller spikes create cuts and dents on the outer layers of the wood. When plywood is processed, the cuts and dents are recognised as damage as a consequence, they lower the wood quality and value. The objective of the presented research was to find out: 1) the depth of cuts, 2) the potential loss of volume, and 3) product value loss due to damage to plywood caused by feed roller spikes. The research was carried out on alder (Alnus glutinosa Geartn.) plywood logs harvested by a Valmet 911.4 with a 360.2 head. Measurements were taken using an electronic calliper with an accuracy of 0.01 mm. 16 plywood logs were considered, on which 384 measurement points (depth of spike cuts) were selected on different areas along the length of the log: 1, 2, 3 and 4 m from the butt end. The maximum depth of the spike cut was observed on the bottom part of the logs (1 m from the butt end) and amounted to 3.9 mm. This damage depth was statistically different to those at the 2nd, 3rd and 4th metre points, amounting to 1.9, 1.9 and 2.1 mm, respectively. The biggest volume losses were on the 1st metre of the plywood assortments: 0.004 m³ (4% of the volume), while on the further parts (2nd, 3rd and 4th metres) only 0.002 m³ of the plywood had damage (2% of the volume). In addition, the highest product value loss was on the butt end logs and amounted to 302 PLN/€72 per 100 m³. The following plywood assortments (2 nd , 3th and 4 th metres) had a loss of 76 PLN/€18 per 100 m³. Therefore, when plywood assortments are processed using a Valmet 911.4 harvester with a 360.2 head, it is recommended that after cutting and felling a tree, the plywood section of the alder tree trunk is cut off without feeding it through the harvester head.
Creating strip roads in second age class stands is an indispensible operation for carrying out thinning. It is especially important in places where there is an intention to do a first thinning using mechanised thinning operations. Felling trees to create strip roads results in altered conditions for the tree growth of neighbouring trees.In particular, this is due to an increase in exposure to sunlight. This can lead to changes in the growth of trees and consequently changes in the morphology of the trunk and the development of defects. The objective of this paper was to analyse the frequency of the presence of particular defects in the structure and shape of spruce ina five-year period after the creation of a strip road. The research was carried out in an artificially regenerated spruce stand within the spruce’s natural, northern habitat in Poland. A 34-year-old stand underwent a systematic thinning scheme which involved the removal of every eighth tree row. The analysis was carried out on trees growing both adjacent to the strip roads (which had a greater growing area around them and greater access to sunlight) as well as trees from further within the stand. Diameter growth was taken in three places: at breast height, in the middle of the trunk between breast height and the base of the crown, as well as at the base of the crown. The average incremental growth, pith eccentricity taper and ovality were calculated. No statistically significant difference in defects between the trees growing by the strip road and those growing further in the stand was observed. Greater taper on mid-tree logs in comparison to butt logs was observed. Insignificant changes in the morphology of the trunks, supports the validity of cutting strip roads in second age class stands.
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