Comparison of short-wood forwarding systems used in Iberia

Abstract

Time studies were conducted to quantify the productivity and the operational cost of mechanized wood extraction in the Iberian Eucalyptus plantations. The key objectives were: to determine the significant variables that influence machine productivity and extraction costs in shortwood transport within the forest and to find the basis for optimization of shortwood transport with respect to Eucalyptus forest stands. Three machines were selected for study, each representative of the different log forwarding regimes that are used in Iberia and that could be extended to most of Southern Europe. These were: 1) a modified articulated dumper, 2) a purpose-built forwarder and 3) a farm tractor paired to a twin-axle forestry trailer. It was observed that the productivity and the cost of shortwood extraction may vary from 6 to 15 fresh tonnes/SMH and 3.5 to 6.5 Euro/fresh tonne, respectively. It was estimated that the optimal extraction route network covered approximately 10% of the forest surface. It was also observed that the modified dumper is the most-productive unit, and given its higher speed (> 5 km/h) and larger payload (16 tonnes), it is the economic choice for extraction distances in excess of 1000 m. However, it also generates the most severe rutting, hence it should be used with caution. For extraction distances below 1000 m, the light purpose-built forwarder compares favourably with the modified dumper, while generating less than half the site disturbance. The tractor-trailer combination is economically inferior to the modified dumper and the light forwarder, and should be regarded as a complement to the main extraction fleet and where short-haul operations are required. Under the assumptions of the study, light forwarders (8-tonne payload) may become competitive with heavier ones when road density is at least 6 m/ha, so that extraction distance does not exceed 1 km. This study provides a model for estimating the productivity and the cost of timber forwarding under varying conditions.