Mass and density of pine pulpwood harvested in selected stands from the forest experimental station in Murowana Goślina

Abstract

In 2012 because of increasing transport problems the Ministers of the Environment and of the Economy announced the regulation concerning the wood density in transport (Rozporządzenie..., 2012). A series of technical roadside inspections showed that the total mass of vehicles together with their cargo substantially exceeded admissible limits. According to a study by Trzciński (2010Trzciński ( , 2011, the mass of trucks with timber ranged from approx. 40 ton to approx. 60 ton and the mean loading of a single axle vehicle ranged from 70 kN to 120 kN. The discrepancies resulted mainly from the diff erence in mass typical of individual wood species. Within the same species diff erences were also observed for individual sortments. Trzciński (2011) also stated that transported loads of large-sized pine timber of min. 21 m 3 exceed the admissible mass of the vehicle and cargo set. This would result in a considerable reduction of loads in relation to transportation vehicles' capacity. ABSTRACTThe aim of this analysis was to determine the mass of pine pulpwood, harvested from fresh-cutting trees. Analyses were made in four pine stands (aged 45, 47, 55 and 56). In each plot a total of 30 model trees were selected from among trees to be felled as a part of planned intermediate cutting. The average mass of one log of 2.5 m length ranged from 26.3 kg to 44.0 kg, at a mean of 33.9 kg. The total volume of timber harvested was 21.68 m 3 with a total mass of 21 222.4 kg. When converted to 1 m 3 the mass of timber was assessed at 979 kg. The ratio of actual density (979 kg/m 3 ) to tabular density (740 kg/m 3 ) was thus 1.3:1. As a result the actual mass of timber is approx. 30% higher than the mass that may be estimated based on the tabular density of wood assessed for the purpose of road transportation. At the stem profi le the mass of logs decreases (which is the result of stem diameter decreasing with height), while green density increases. The increase in green density of logs is probably the result of changes in porosity and moisture content of wood, as well as changes in the proportion and properties of bark.

Total Weight and Axle Loads of Truck Units in the Transport of Timber Depending on the Timber Cargo

“…Calculated per 1 m 3 , the weight of the wood raw material was estimated at 0.979 Mg. The ratio of the actual density (0.979 Mg/m 3 ) to the density provided in the tables (0.740 Mg/m 3 ) amounted to 1.3:1 [26]. The actual weight of the wood raw material was therefore about 30% higher than the weight that can be estimated on the basis of the wood density tables developed for the needs of road transport.…”

“…In the studies carried out for the same species of Scots pine, as well as the large-sized assortments, statistically-significant differences were found for the tested parameters in different periods of the year, as evidenced by the study results of Owusu-Ababio and Schmitt [30]. Research conducted by Tomczak et al [26] indicates a large variation in the density of pine wood. On a longitudinal section of the trunk, the highest density was found for wood at breast height (0.816 Mg/m 3 ), whereas the lowest was from the section closest to the apex (0.707 Mg/m 3 ).…”

“…It should also be noted that when selling timber in Poland and later when it is transported, the given volumes and conversion factors do not apply to the bark. The share of bark is significant and can range up to a dozen or so percent for pine logs [26], influencing the weight of the transported cargo. Therefore, the analysis refers to the weight of the entire load (wood, bark, water) or the weight of 1 m 3 of the load.…”

“…In reality, however, when transporting timber, the high variability of the transported assortments made of different species and the variable moisture content of wood do not allow a precise determination to be made of the weight of the transported raw wood material [23][24][25][26]. These differences very often influence the excessive weight of the truck unit [27][28][29][30].…”

Multi-Factorial Load Analysis of Pine Sawlogs in Transport to Sawmill

“…At the same time, it should be noted that when timber is sold in Poland and subsequently transported in Poland, the reported volumes do not include bark. The share of bark is significant and may be as high as several dozen percent [36,37] of the pine stem, affecting the mass of the transported cargo. Therefore, in the analyses, we discuss the mass of the whole load (wood, bark, moisture) or the mass of one cubic meter of the load (kg•m −3 ).…”