The motivation for developing fuel supply systems horizontally and vertically integrated with forest activities include opportunities for further development of the traditional activities themselves and future industrial expansion. Section 7.4 summarized some of the studies carried out with the purpose of evaluating resource

Table 7.1. Assessing forest fuel production in Rokiskis forest enterprise Study Main questions being asked Methodologies used

Source: Based on Studies on forestry, technology and economy of forest fuel production in Rokiskis forest enterprise prepared by the Lithuanian Forest Research Institute.

potentials and models for forest management. The models are aimed at a sustainable exploration of residues for energy purposes while also improving traditional forestry activities. Analyses and tests were conducted to screen the most cost-efficient methods and most suitable equipment for local conditions, and to verify the best ways to introduce the new practices. This section provides a brief review of the results obtained.

The extraction and processing of logging residues, such as round wood or small trees, for fuel purposes can technically be carried out in many different ways. The amount of fuel supply depends largely on the size of the felling operations, level of mechanization and how forestry activities are carried out. The main factors influ­encing the cost of forest fuel production for boiler houses include worker skills, methods used for felling, intensity of extraction, extraction distance, actual pro­ductivity of the wood chipper and transportation distance to boiler houses. The extraction costs are lowest in final cuttings due to the concentration of fuels.

Precommercial thinnings are first of all aimed at improving conditions for tree growth, but may yield a profit if aimed at fuel production. This will depend on stand conditions, productivity of machinery and labor, and fuel prices. Considering the effects on the whole forest productivity, the option should be economically attractive even if the chip price only covers production costs. In fact, producing forest fuel may considerably reduce the costs of precommercial thinnings (see Table 7.4).

More time is used to handle the felled trees in precommercial stands than in commercial or final cuttings. This is due to the small diameter breast height (dbh) and large number of stems and longer distance to the technical corridors. In addition, the collection of trees is more complicated due to the remaining stands. Forest fuel production in precommercial thinnings using hand tools diminishes the losses by 61 Lt/ha as the income for the forest fuel covers some of the traditional cost for this measure. Motor chainsaw with felling handle tools should only be used in precom­mercial thinning stands where silvicultural measures have been carried out before or in conflict stands where dbh are no less than 5 cm.

Forest fuel production in precommercial thinnings is a novelty for foresters and workers in Lithuania. The forest workers can increase their productivity by 30 per cent when using machinery. Even when handle tools are used, such as in precommercial thinnings, and additional operations need to be performed, a pro­ductivity increase of 20 per cent can be achieved among workers performing tree cutting and storage operations. But there is no sufficient knowledge of working under these new technological requirements yet. Observations indicated that the psychological attitude of the worker towards the new technologies and practices affected the results significantly but, in general, comfort levels could be achieved after a couple of days of experience, which indicates that productivity increases can be made normative rather rapidly.

The cost of forest fuel extraction depends on many factors. In Rokiskis forests, the structure of forest fuel cost was analyzed following logging operations and various cost factors from cutting to handling and transporting to boiler houses. First of all, the cost will depend on the type of cuttings. The cost is lowest in Final cuttings, and highest in precommercial cuttings for reasons explained earlier. The total cost of forest fuel produced in commercial thinning with integrated methods is 34-35 Lt/solidm3 (excluding overhead costs) chipped and transported to the heat­ing plant, while in the clear cutting the cost is 30Lt/solidm3.

Another important cost factor is machinery productivity. When the productivity of the chipper is increased from 10 to 50m3/h, the fuelwood cost may fall approx­imately 1.5 times. A third cost factor is extraction distance. With an increased transportation distance from 5 to 30 km, the cost increases by more than 50 per cent. Forest fuel transportation cost is greatly influenced by the transport equipment used. When transporting by MAZ 5516 with the trailer of 45 m3 for 30 km, forest fuel costs decrease by 25 per cent in comparison with transportation by the tractor T-150 with a trailer of capacity 25.3 m3.

In short, chipping accounts for 38.7 per cent of the final forest fuel cost in Final cuttings, this being the most significant cost factor. Transportation and extraction make up about 23-24 per cent of the total cost each (see Figure 7.2). A closer inspection indicates that machinery costs excluding fuel account for 60 per cent of the cost composition while raw material costs amount to 17.6 per cent of the total only (see Figure 7.3). This means that increased productivity of machinery through longer hours and more days of operation per year can have a substantial impact on the Final fuelwood cost.

Lithuanian stand thinning models already have high productivity. There is no particular need for radical changes here but some modifications of thinning systems

can bring advantages. This refers not to the intensity of cutting, but to the aspects of stand species composition. In addition, it is not advisable to extract all non­merchantable wood from the forests in Lithuania, not even in commercial thinnings. Forest soils can be exhausted after taking out the wood without compensation for fertilization. Some experts in Lithuania are in favor of extracting all merchantable branches and up to 30 per cent of nonmerchantable branches. However, it is advis­able that the amount of nonmerchantable branches used as fuelwood in thinnings be reduced down to 20 per cent. At this moment, there are no obstacles for forest fuel extraction in forestry legislation.

A number of advantages were observed in cuttings with integrated forest fuel production. For example, in final cuttings, lesser quantity of branches were used for technical corridors and this avoided the so-called “widening” of technical corridors. In conflict, for stands of spruce with broadleaves, some amount of broadleaves can be left to reach 15 years of age to accumulate additional amount of wood and keep the productivity of the stand at a homogeneous level. In general, the amount of produced forest fuel increases with integrated forest fuel handling technology. Table 7.2 shows the observed variations in the amount of cubic meters of forest fuel obtained per hectare when applying traditional and integrated technologies in commercial and final cutting. Integrated technologies can help increase the amount of fuel extracted to a factor of 15.

The smallest amount of forest fuel was produced in typical commercial thinnings where technical corridors had been made in the previous cutting. The amount of forest fuel produced in clear cutting areas was 58-112 solid cubic meters per hectare.

The largest amount of forest fuel was produced in aspen stands with dense understorey while smaller amounts were produced in spruce and pine stands. The amount of forest fuels increases with extraction from precommercial thinning stands, the average figure of extracted forest fuel from the precommercial thinning stands being 56 m3 solid volume per hectare.

The production cost for traditional industrial assortments decreases with inte­grated forest fuel handling. Due to more rational handling, some cost for handling the traditional industrial assortment turns over to the forest fuel assortment at the same time as the total productivity increases. Table 7.3 shows the gains obtained at each step. As shown, using integrated technology, the costs for extraction of indus­trial wood can be reduced by up to 15 per cent while fuelwood is also generated.

Comparing with traditional technology, when all branches and tops are used for technical corridors, the technology with integrated forest fuel production is very promising. However, it requires a new way of thinking about silviculture. The inte­gration of forest fuel handling requires a mobile drum wood chipper for acceptable decomposition of the forest fuel. With a better knowledge of the methodology and more skilled personnel performing the operations, the results from the integrated forest fuel handling methods can be further improved.