It is proved that plantation density greatly influences the DBH, tree height, volume growth of the individual plant and timber yield per unit area. Therefore, designing a reasonable plantation density (planting distance of paulownia and planting interspaces of paulownia) plays an important role for fast-growing and high yield of paulownia.
- To design plantation density according to paulownia varieties
For different paulownia varieties, the growth-development patterns of the tree crown are different. There are two categories of tree crowns for different paulownia varieties: one is called the narrow crown paulownia with smaller width of crown, including the narrow crown paulownia and middle crown paulownia; the other is called wide crown paulownia with bigger width of crown. In general, the crown width of narrow crown paulownia is 40% smaller than the wide crown paulownia. The plantation density of narrow crown paulownia shall be larger while the plantation density of wide crown paulownia shall be smaller.
- To design plantation density according to site condition
Under different site conditions, growth of paulownia will be different as well. When paulownia growing fast provided with favorable water, fertilizer and sunshine, the plantation density shall be smaller. On the contrast, the plantation density shall be larger. Generally speaking, plantation density of the fast-growing and high-yield forest shall be smaller in plain areas, while the plantation density should appropriate to be larger in hill and mountain areas.
- The plantation density of 2 * 4 m
- To design plantation density according to afforestation type
Each type of afforestation is based on relevant terrain, soil, the geographical environment and business purpose. So the plantation density will be different as well. For example: the fast-growing and high-yield forest giving priority to forest is to obtain most quality timber in the shortest period and its initial planting density should be 4×4m while the intercropped forest giving priority to farming is in a structure combining farming with forestry where farming enjoys the priority and its initial planting density should be 4×30m.
- To design plantation density according to afforestation purpose
Business objective of afforestation refers to requirements on height and width of the trunk. The plantation density shall be in accordance with relevant requirements. For example: requirements on diameter and length of the timber are different from each other between enterprises on stationery, sports equipment, decoration material and plywood.
In the practical production, there are two kinds of cultivation for quality paulownia timber: one is small dimension timber which meets the requirements of daily necessities; the other is large dimension timber which utilized by enterprises on plywood.