7.2.3.2 Forestry products

Figure 7.7 Forestry produce

Technically, in forestry and the wood industry, woody materials (usually valuable, fig 7.7) are those which derive from the felled tree (above the cutting plane). Woody fragments are the residues from what remains below which, in a given season or economic/technological situation, it may not be viable to collect and use. Stumps and roots are hard to extract and manage. Often they remain in place, with a beneficial role in recultivating and improving the ground. If eradicated in the forest, roots and stumps are chopped up and can supply further combustibles. The woody material obtained above the cutting plane is used partly for industrial purposes, partly as firewood. Of course, thin branches and bark appear as waste material. The proportions are roughly: 20% wastes, 35% firewood, 45% industrial wood [ref 7.1]. The firewood, which is usually burned in domestic fires, is available as: traditional firewood, split firewood, woody briquettes and woody pellets.

 

In order to minimize the environmental impact of forest exploitation and eradication, the massive probable utilization of woody biomass in the future will imply the plantation of new short rotation forests and coppices dedicated entirely to energy purposes. Otherwise forest eradication, exercised without discrimination and precaution, will lead to environmental and social crisis with predictable catastrophic consequences.

 

7.2.3.3 Energy crops

Energy crops are crops developed and grown specifically for fuel, carefully selected to be fast growing, drought and pest resistant, and readily harvested to allow competitive prices when used as fuel. They include fast-growing trees, shrubs, and grasses. Examples under development include hybrid poplar, willow, eucalyptus and energy grasses. Energy crops can be grown on agricultural lands not needed for food, feed, or fiber. These include lands taken out of service for price control reasons and other agricultural lands that are considered marginal for food production. Compared to traditional agricultural crops, energy crops are lower maintenance and require less fertilizer and pesticide treatment.

Energy grasses include switchgrass, reed canary grass, giant reed, and herbaceous ligno-cellulosic crops such as miscanthus. They offer many advantages over other bioenergy sources. As a convincing example, we present a Hungarian novelty in the field of energy grasses, the so-called "Szarvasi-1" energy grass (fig 7.8), a promising new species of plant obtained by hybridization and selection in the Mezõgazdasági Kutató-Fejlesztõ Kht., Szarvas, Hungary. The resistance of this grass to drought, soil salinity, frost and other extremal abiotic environments is surprisingly good. The crop survives in the same field for 10-15 years continuously, can be harvested every year, and the plantation costs are only 20-25% of those for forestry. The harvesting technology is simple; and the bio-improvement effect is very strong and beneficial. The social impact on regions with low-valued fields is also beneficial due to higher employment.

Four years of harvesting have shown that yields of Szarvasi-1 exceed those of all other energy crops. Even when compacted into combustible pellets, prices per unit of energy are comparable with firewood and significantly less than for fossil fuels (e.g. brown coal or natural gas).