Current issue: 54(2)
Harvesting residues collected from the final cuttings of boreal forests are an important source of solid biofuel for energy production in Finland and Sweden. In the Finnish supply chain, the measurement of residues is performed by scales integrated in forwarders. The mass of residues is converted to volume by conversion factors. In this study, weather based models for defining the moisture content of residues were developed and validated. Models were also compared with the currently used fixed tables of conversion factors. The change of the moisture content of residues is complex, and an exact estimation was challenging. However, the model predicting moisture change for three hour periods was found to be the most accurate. The main improvement compared to fixed tables was the lack of a systematic error. It can be assumed that weather based models will give more reliable estimates for the moisture in varying climate conditions and the further development of models should be focused on obtaining more appropriate data from varying drying conditions in different geographical and microclimatological locations.
The aim of the study was to explain the regression between the cubic content of the trunk of a tree and of logs cut from the trunk. The minimum size of trunk that can be used to saw logs has been 18 feet long and 5″ of top diameter in Finland (in 1930s). The average length of logs is 16‒18 feet. The data of this study was collected in seven areas around Finland. The results show that there is regression between the volume of the trunk, the volume and the logs cut from the trunk and the number of logs. Consequently, it is possible to determine the average regression between the trunk and log sizes for forest technical purposes. The regression varies in different parts of the country due to varying growth condition of the trees and different age classes. It is probable that the figures have to be re-examined in the future.
The PDF includes a summary in English.