Economic methods for the utilisation of logging residues

There are several ways of using logging residues, and the two most common ones in the State Forests are wood chip production for energy purposes by mobile machinery and crushing by tractor-powered crushers. In this research, an economy based approach was used to compare these methods and assess whether chip production is superior to crushing for clearing a felling area. The average revenues from the sale of wood biomass in the form of wood chips and the average costs of crushing in the Pomorze Forest District were analysed for the period from January 2012 until June 2014. Both revenues and costs (such as fuel, operator’s wage, piling costs, depreciation, insurance and garaging costs) were extracted from the State Forests’ database using data-mining software. The highest price for wood biomass was achieved in 2012 (104.00 PLN m-3), and the lowest one was reached in 2014 (16.00 PLN m-3). Revenues amounted to 1,353.87 PLN ha-1 on an average, whilst the average logging efficiency was 25.60 m3 ha-1 with a share of logging residues compared to the total logged volume of 11.14%. The highest costs for crushing (1,894.14 PLN ha-1) incurred for clearing gaps in a stand after removing spruces infested with bark beetles. Labour productivity in this case was 0.07 ha pmh-1. Significantly lower costs (1,256.42 PLN ha-1) and greater productivity (0.16 ha pmh-1) were achieved when clearing clear-cut areas. Considering the above results, it is recommended to compress the logging residues into chips instead of crushing them. The removal of the residues from clear-cut sites may additionally affect forest health positively