Paulownia Overview

What is Paulownia Tree?

The Genus Paulownia is of the Paulowniaceae family, related to and sometimes included in the Scrophulariaceae family.  The tree is native to southeast China where it has been cultivated for the past 3000 years. 
It is of interest to foresters, plantation managers and gardeners alike for its rapid growth, versatile timber, coppicing characteristics, beautiful flowers and large leaves.

 

There are nine major species of Paulownia, which include fast and slow growing types. The tree grows so rapidly that, in good growing conditions, it can produce harvestable timber in 7 - 10 years.  The Chinese are growing 2.5milliion hectares of Paulownia to satisfy the huge demand for timber in the country.

 

The timber is light in weight but very strong and is ideal for situations where a high strength to weight ratio is of importance.  The wood can be machined and finished to a high specification and takes most types of paint and varnishes.  It is used in manufacture of furniture, mouldings, veneers, musical instruments, log homes, plyboard, paper, the biofuel and other industries.  Its high strength to weight ratio means it is invaluable for marine and aircraft applications, surf boards, caravans and light weight pallets, etc.

 

The wood is dimensionally stable and is resistant to cupping and warping.  It can take nails and screws, without fear of splitting, and has very few knots so is ideal for fine work from window frames to woodcarving. Unlike most tree plantations the crop can be harvested more than once in your own lifetime. The ability of the tree to regrow from the cut stump means that several crops can be harvested from one planting.



The many uses of Paulownia Tree


Remediation/Land Reclamation

Paulownia’s ability to improve the soil and its tolerance and adaptability to grow in poor soil conditions made it the ideal tree for remediation and reclamation of spoil heap sites. With its quick growing and deep rooting nature, Paulownia has also been found to be extremely beneficial in areas of soil erosion. Paulownia is also grown on salt affected areas where other trees would not survive, to quickly lower the water table and provide protection to the fragile soil which would otherwise be lost. Because of Paulownia’s deciduous nature, its leaf fall also helps to regenerate an otherwise barren earth by building up a natural humus which in a short time can provide a suitable environment for the re-growth of native grasses and sages.

The large hairy leaves of Paulownia play a very helpful role in purifying dust and smoke. Paulownia has become the main tree species for afforestation in many industrial center’s in mainland China, Singapore and the United States where dust and smoke pollution are comparatively serious. By comparison, the airborne sulfur dioxide content in clean areas where Paulownia has been extensively grown and the polluted districts, were 0.169% and 1.410% respectively. Paulownia still grows naturally in the polluted areas of these countries whereas many other trees drop their leaves or fail to grow under the same conditions.

Paulownia’s natural deep rooting characteristic, which absorbs large amounts of water and nitrates and the natural filtering effect through transpiration of its leaves make it an ideal crop for use in areas where large amounts of manures have to be spread.

Bee Keeping

The Paulownia tree makes a delightful, quick growing addition to any medium to large garden or landscape. Its abundant flowers in spring, which range in colour from mauve to cream, depending on variety, are very fragrant and attract bees and the honey from this crop is a connoisseur’s choice. In addition the large leaves of this tree, up to 75cms across, make it an ideal quick growing tree where shade is required.


Inter-Cropping

In some countries intercropping is practiced either to produce an agricultural crop between the trees that are more widely spaced for timber production or by sowing clover or other legumes between those grown for biomass. The legume would provide a valuable source of nitrogen, a nutrient to which this crop is particularly responsive.

The Paulownia trees create a microclimate. In the dry season, Paulownia absorbs underground water from greater depths than other crops and humidifies the air by transpiration, which is beneficial to the growth of the food crops. In summer, in the inter-copped land, the temperature has been shown to be reduced by 0.2-1.2° C during the day.

This also helps to guard against natural disasters such as drought, sandstorms, dry hot winds and early and late frosts.

In addition to increasing the crop yield, the Paulownia is also a valuable asset to the farmer. Besides the timber produced the leaves and flowers are rich in nitrogen (4%) which is returned to the soil. Thus, the vast area of farmland will be used for producing both food crops and timber.


Animal Fodder

Paulownia leaves have a similar food value to Lucerne and are suitable for combining with wheat straw or hay for feeding out to cattle, sheep or goats. If planted at 540 trees per ha (180 per acre) Paulownia will produce 1220 kg DM per ha with a protein level of 20% and digestibility of 60%. Although any trimmings obtained through the years can be used for fodder, leaves should not be harvested in the spring and summer as it inhibits timber growth.


Forestry


The world’s current and future shortage of timber is offered a lifeline with investment in the Paulownia tree.This has been recognised by the Chinese who have a huge demand for timber and to help satisfy this have planted some 2.5 million hectares of Paulownia. The rapid growth of this hardwood tree makes it an ideal candidate for governments, corporations and private investors alike. With the tree able to reach a harvestable size in 8 to 15 years, depending on growing conditions, a rapid return on investment is possible. Furthermore the tree will re-grow from the stump, so replanting is unnecessary. It is just a matter of pruning to encourage re-growth by the favored stem. The wood has many and varied uses.


Log Homes

Log homes constructed from Paulownia offer very comfortable homes or offices with a high insulation value. The timber has a high resistance to rot, can be milled to a high standard and takes a wide range of external finishes. The lightweight materials used in the construction of these homes means that delivery and erection costs are low.

Recreation Industries

Paulownia timber and plywood offers the marine, surfboard, caravanning, and other industries substantial advantages in terms of high strength with lightness in weight. With the timbers’ resistance to cupping, warping and splitting, manufacturers find this an ideal material for the reliable construction of high quality, durable, lightweight equipment. In addition Paulownia plywood can be prepared with a wide range of decorative finishes and can be manufactured to marine standard.


Biomass

The biomass can be used in several forms as it can be:

  • burnt for the direct generation of heat for an individual home or for a community heating scheme
  • burnt for the generation of steam for the production of electricity
  • as a feedstock for the process of pyrolysis for the generation of gas and liquid fuels.


















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