PaulowniaElongata Fast Growth and even faster re-growth a great producer of light versatile wood
Origin 1983, the International Development Research Centre of Canada has supported a program of research by the Chinese Academy of Forestry. This has resulted in many new developments in the breeding, propagation, cultivation and management of small plantations of the tree. The genus Paulownia is represented by nine species of fast growing timber trees which are indigenous to China. It is very adaptable, widely distributed and extremely fast growing both in south and north China. Presently, the genus is either naturally distributed or cultivated in 23 provinces, municipalities and autonomous regions. It grows equally well on the plains as well as in mountainous regions up to 2,000 m high. Therefore, the genus provides a great potential for extensive cultivation all over China.
Growth Under normal conditions, a 10-year old Paulownia tree can measure 30-40 cm diameter at breast height (dbh) and will have a timber volume of 0.3-0.5 m3. However, under optimum conditions, they can produce useful timber within five to six years. For example, in Lankau County, Honan Province, Paulownia was planted over a large area from 1963 to 1965 the total area under mixed cultivation had already reached 20,000 hectares. Felling started in 1971 and it yielded almost 148,000 m3 of timber by 1976 for the local people, effectively solving years of timber shortage.
Expansion of population Current locations growing Paulownia
It is estimated that 2.5 million hectares of Chinese farm land now has paulownia shelter belts planted on it, from which up to 10 million cubic metres of logs may be produced each year. Within Asia, paulownia is grown in Taiwan, Vietnam, Cambodia, Laos, Korea and Japan. Elsewhere, paulownia is grown commercially in South America and the United States, where it has naturalised in Appalachian forests. Plantations have also cropped up in Australia, New Zealand, Chilie and Spain. Along side these sites, projects for large plantations being implemented across large parts of southern Africa.
Wood properties Lightness — Paulownia is about 2/3 the weight of the lightest commercial wood in the U.S. The specific gravity of paulownia wood ranges from 0.23 to 0.30 (23 to 30 percent of the weight of water). Average cubic foot weight is 16.55 lbs. The bulk weight of lumber averages 1,382 lbs per thousand board feet compared to yellow poplar (tulip poplar), which weighs 2,190 lbs, or white oak, which weighs 3,337 lbs.
Strength and stability — Although the wood is light, it is extremely strong and will not split even when spikes are driven into it. Unlike other commercial woods, paulownia does not split and crack with rapid drying. Easily dried and reduced warping — Paulownia will air dry in about 30 days with no warping. This reduces the cost of kiln-drying. furniture made of dried Paulownia wood is very good even under humid conditions. It resists warping, cracking and deformation unlike poplar wood which cupped badly and cracked at the ends, oak checked and honey-combed and wood of other kinds which can be severely damaged by changes in humidity.
Easily worked — Another unique quality is the ease with which it can be worked, especially when green. It is suitable for carving, woodworking, model airplane construction, and peeling for veneer. As it dries, it becomes considerably harder, but not as hard as most domestic woods.
• Good Insulator, Thermal and electric — Paulownia wood has very high heat insulation properties (with the thermal conductivity of the eight Paulownia species at 0.063-0.086 Kcal m-1 lu'1 °C'1, one of the lowest values for wood).
Uses - Environmental The Paulowniatree could be considered the ultimate environmental tree. 1. Each tree removes 21.7 kg. of carbon dioxide per day. 2. Each tree releases about 5.9 kg. of oxygen per day. 3. Each hectare of trees will scrub 32 636.8 kg. of harmful CO2, gases and dust from the air per year. 4. Each tree can absorb 56.8 liters of wastewater per day. 5. The large and hairy leaves of Paulowniaplay a very useful role in purifying dust and smoke. 6.Paulowniaelongataprevents erosion and enriches the soil with humus. It has a high tolerance to drought, soil content and temperature amplitudes (from –20oC to + 40oC), this make the species Paulownia elongata and its hybrids highly beneficial to environmental recovery.
Uses – Beautification The tree develops many lateral branches, thick crown with cluster flowers which vary in color from creamy to deep violet. The blossoms last 2-4 weeks then the tree re-foliates with it's enormous lush and exotic leaves creating a luxuriant, cool Summer shade.
Uses - Functional 1. For handicrafts - The people in China, Japan and some other countries in South East Asia have a long tradition of making handicrafts with Paulownia wood such as flower vases, statue of Buddha or deities, wooden fish, medal boxes, dressing boxes, TV and radio boxes etc. 2. For farm implements – Aquaductsmade of Paulownia wood do not subside and crack, are durable and retain their shape. Threshing tubs of Paulownia wood are more durable than those of Cunninghamialanceolata. People in some provinces and the dockers in China are very fond of using the poles made of Paulownia wood.
3. Paulownia wood can also be used to make blackboards, life rafts, sleds and surfboards. Paulownia charcoal can make charcoal crayons, black powder and fireworks and can also be used in industries as active carbon. Paulownia bark can be used to make dye
4. For house construction – As the strength of wood is not high, it is not suitable for uses which require mechanical strength but it is quite widely used for houses. Roof beams and purlin made of Paulownia wood are light and keep in shape for many years so they do not put the house out of shape. There is no decay in houses more than 100 years old which are completely made of Paulownia wood. Paulownia wood is very good for making doors, windows, partition boards, ceilings and inner roofs due to the woods insulation properties. 5. Fodder – The leaves and flowers of Paulownia are good fodder for pigs, sheep and rabbits (Fig. 73). The flower buds, flowers and the leaves of Paulownia contain fat, sugar and protein. The nitrogen content in Paulownia leaves can be compared favourably with some leguminous plants. 6. Medicinal uses – Medicines made of Paulownia leaves, fruits and wood have certain effects on bronchitis especially on relieving the cough and reducing phlegm. They are made into tablets and injections. 7. For furniture – Paulowniais used to manufacture tables and chairs. It is especially suitable for cases and cupboards which are smoke-proof and are little attacked by insects
8. Musical instruments – Paulowniawood has good resonance properties and is often used in making musical instruments.