Skidding operations in thinning and shelterwood cut of mixed stands - Work productivity, energy inputs and emissions

The present study was conducted on the slopes of the Bilogora mountain in the central region of Croatia. Logging operations were performed at two felling sites with two different silviculturual treatments: thinning was performed at worksite A, and a regeneration cut was performed at worksite B. A half-length harvesting method and the skidding of half-processed wood assortments were used in the study areas. At both sites, the timber extraction was performed by a rubber-tired mini-skidder (Ecotrac 55V, Hittner tractors, Bjelovar - Croatia). The main aims of the present study were to provide limited but significant data regarding the experiences related to working times, productivity, energy inputs, and greenhouse gasses (GHG) emissions for timber extraction using a skidder. This skidder was an average, compact and highly specialised machine, and, as shown by previous studies, this mini-skidder can effectively replace forestry-fitted crawler tractors, common agricultural tractors and cable yarders under particular conditions. In the context of small-scale forestry this mini-skidder as when compared with common agricultural tractor or forestry-fitted tractors, is more environmentally friendly in terms of energy inputs and GHG emissions during the wood extraction operation. In addition, the most important parameters that affect the use of a similar machine during wood extraction were evaluated in the present work. The average extraction net (PSH0) productivities (m3 h−1) were 3.20 m3 h−1 for worksite A and 4.95 m3 h−1 for worksite B. The energy consumptions were 113.4 MJ m−3 for worksite A and 56.1 MJ m−3 for worksite B. Lower pollutant emission values were calculated for worksite B. At worksite B, the minimum value of CO2 emissions on the environment caused by the skidding operation was determined.