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Abstract:We set out to determine the particle-size distribution, the fiber, the bark and the leaves content, the heating value, the CNH and the ash content of a wide sample of wood chips, collected from 10 forestry and 10 agroforestry production sources. This sampling focused on two main production types: forestry (Full Tree System-FTS-and logging residues-LR) and agroforestry (Short Rotation Coppice-SRC). For the forestry production wood chips from coniferous and broadleaf species were considered. For the agroforestry production wood chips from poplar plantations were examined (different clones with two different harvesting intervals). Overall, we collected 400 samples. Particle size distribution was determined with an automatic screening device on 200 samples. The higher heating value was determined on 200 subsamples using an adiabatic bomb calorimeter. The CNH and the ash content was ascertained on another 200 subsamples. FTS and SRC (with three year old sprouts) offered the best quality, with high fiber content (71%-80%), favorable particle-size distribution and good energetic parameters. On the contrary, both logging residues and SRC (with two year old sprouts) presented a high bark content (18%-27%) and occasionally a mediocre particle-size distribution, being often too rich in fines (6%-12%), but the energetic parameters are in the normal range. OPEN ACCESSEnergies 2012, 5 3804

The aim of this paper was to compare cable yarders and helicopters during extraction activities in steep terrains. The harvesting was carried out in two different situations: 1) clear cutting in a fir plantation; 2) thinning in a black pine plantation. Three helicopters (Agusta Bell 412, Aérospatiale AS 332 L and Aérospatiale AS 350 Ecureuil) and two cable yarders were compared (Greifenberg TG 430 and Vallauri VS 10 Endmast) were compared. In the first area the helicopter AS 332 L was more affordable than the Greifenberg TG 430 cable yarder for the extraction, while the Agusta Bell 412 was the most expensive. In the second area, the extraction by Vallauri VS 10 Endmast cable yarder was the most affordable, but the costs were similar at the extraction by helicopter AS 350 Ecureuil. The extraction by Agusta Bell 412 was the most expensive. In thinning the direct costs of helicopter and cable yarder were similar, but in a clear cutting the use of helicopter was more affordable than cable yarder. In both situations, the Agusta Bell 412 helicopter was the solution with the highest direct costs. In difficult forest areas poorly served by roads, heli-logging can be an option in timber extraction because it reduces the need to construct new tracks. The construction of new roads can be invasive especially in mountain areas with steep slopes.

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