Kim Tae-su, former director of the Forest Genetic Resources Division at the National Institute of Forest Science
Single-cut timber forests can be generally defined as either fast-growing forests or single-cut dwarf forests. The goal of single-cut timber forests is to harvest sustainable, renewable timber resources within a short rotation period. In Germany, single-cut timber forests are only permitted on agricultural land, and are legally managed as crop cultivation rather than being considered forest afforestation. Therefore, single-cut timber forests can only be established on idle or abandoned agricultural land, and are prohibited within forests designated as forests.
1. Composition species
Species suitable for single-cut timber forests must possess the following characteristics: rapid growth and excellent sprouting ability after logging, resulting in high stand regeneration potential. Poplar and willow are the two species that meet these requirements, and in Germany, these two species are primarily used to create single-cut timber energy forests. However, acacia, birch, and alder are also recommended as recommended species in some regions.
Poplars also come in a variety of varieties, depending on the species and breeding method. Western balsam poplar, Populus maximowiczii, and its hybrids with Populus nigra are primarily used as foundation trees. These hybrids grow much faster than Populus nigra or other poplar species and require less light, allowing for dense planting. Currently, breeders are continuously developing new varieties that boast high biomass production, resistance to diseases and pests, high planting densities, and high germination capacity. Furthermore, breeding goals include varieties with high firepower and low ash content.
2. Composition method
Land for single-cut timber forests should be cultivated as deeply as possible using a soil cultivator. Germany recommends a minimum depth of 25 centimeters. Deeper tillage facilitates early establishment, promoting vigorous growth and increasing yield. Well-planted single-cut timber forests can reach a height of 1.5 meters or more in the year of planting. This vigorous growth in the year of planting also helps prevent weeds from squeezing the seedlings.
Single-cut timber forests are usually established in the spring (late March to early June). Poplar cuttings are typically 20 to 35 centimeters long, although larger cuttings may be used in some cases. When planting, care must be taken to keep the cuttings as vertical as possible, leaving no gaps between them and the soil surface to prevent drying out. The harder the soil and the less fertile it is, the longer the cuttings should be. The cuttings should be planted so that approximately one-third of their length is above ground level. In extreme conditions, cuttings may be planted as deep as one meter. The planting density is typically 2,000 to 3,500 plants per hectare, taking into account weed conditions, light requirements, and sprouting rates. Poplar seedlings are rarely planted in single-cut timber forests. This is because, in the case of poplar and willow, seed storage is difficult, and germination is almost lost a few weeks after seed collection, etc. Single-cut wood energy forests are generally created using cuttings taken from mother trees of promising poplar or willow species or hybrids of these species. Recently, there have been cases of creating forests using tissue-cultured seedlings of highly productive hybrids, but this is not economical due to the high production cost, and is mainly attempted for research purposes.
3. Protection of single-story buildings
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