Models For The Evaluation Of Productivity And Costs Of Mechanized Felling On Poplar Short Rotation Coppice In Italy

The forest biomass, as a renewable energy source, can significantly contribute to the progressive replacement of fossil fuels in energy production, with a positive final balance in terms of greenhouse gas emissions. One of the different sources of woody biomass supply is represented by short rotation coppices (SRC) plantations, currently present in various European countries for a total of about fifty thousand hectares. In Italy, part of the SRC surface has been converted into other more profitable crops, both the low levels reached by the woodchips market price and the scarce availability of specific public incentives. In this study, the authors expose the results of the models for evaluating work time, productivity, and costs of the felling operation on SRC poplar plantations with 8- and 11-year-old trees. The aim is to evaluate the economic sustainability in the use of advanced mechanization on these plantations. The machine was a crawler excavator equipped with a shear head. In the 11-year-old plantation, the productivity estimation model returned a range of 1.09-18.93 Mg h(-1) (average 5.56 +/- 3.88 SD) when the weight variation of the trees was 20-491 kgw (average 100.41 +/- 87.48 SD). In the 8-year-old poplar, the range was 1.02-11.60 Mg h(-1) (average 3.80 +/- 1.71 SD), for weight variation of 17-137 kgw (average 50.57 +/- 18.82 SD). The consequent variation in unit cost was EUR 2.82-51.63 Mg-1 and EUR 4.05-49.65 Mg-1, corresponding to EUR 1252.17-3463.78 ha(-1) and EUR 922.49-2545.11 ha(-1) for 11- and 8-year-old trees, respectively.