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close this bookCasuarinas: Nitrogen-Fixing Trees for Adverse Sites (BOSTID, 1984, 114 p.)
View the document(introduction...)
View the documentNotice
View the documentStudy participants
View the documentPreface
View the document1. Introduction
View the document2. Experiences with Casuarinas
View the document3. The Plants
View the document4. Management
View the document5. Uses
View the document6. Best-Known Species
View the document7. Other Promising Species
View the document8. Recommendations and Research Needs
View the documentAppendix A
View the documentAppendix B
View the documentAdvisory Committee on Technology Innovation
View the documentBoard on Science and Technology for International Development

5. Uses

FUEL

Casuarina wood, as mentioned, has been called the best firewood in the world, and fuel is its most universal use. It is very dense, with a specific gravity ranging from 0.8 to 1.2. It is easy to split, has a high calorific value (about 5,000 kcal per kg), and tends to burn slowly with little smoke or ash. It also can be burned when green, an important advantage in fuel- short areas.

When large trees are cut, the branches and brushwood are often used for fuel. In addition, the needles and cones burn well, so that the trees provide fuel even before they are cut down. From their fourth year, trees shed cones in quantities amounting to almost 4,000 kg per hectare. In India the cones are a cheap and handy fuel for hawkers selling roasted peanuts (groundnuts) from carts. They are also used to fuel pottery kilns.

Casuarina wood is excellent for charcoal making. Whereas most woods lose about three- quarters of their weight when made into charcoal, casuarinas lose only about two-thirds. The entire tree - stems, branches, and roots - can be converted to charcoal.

WOOD

The wood of most casuarinas is so hard and heavy that it is difficult to saw and is not a good source of lumber. Moreover, it tends to split, crack, and warp as it dries.

Nevertheless, this dense, straight-grained wood has many important uses. Australian aboriginals use it to make boomerangs, and the first Europeans to settle in Australia found it useful to have about their farms for shingles, tool handles, fences, farm buildings, masts and oars, yokes, walking sticks, and other items. Even today in Western Australia, casuarina wood is commercially valued for wood turnery, tool handles, piano legs, shingles, veneer, and panelling.

In general, casuarina wood is useful as roundwood for fencing, pilings, beams, and rafters; as split wood for fencing, pilings, and roofing shingles; and as comminuted wood for particle board, pulp, and parquetry. In India it is used for scaffolding and structural members for buildings, as well as for masts for country fishing boats. In Egypt three particle-board factories are consuming casuarina windbreaks and shelterbelts so excessively that agronomists are becoming concerned that crops will suffer. The wood of Casuarina equisetifolia has been found to make a good paper pulp through use of the neutral sulfite semichemical process. But, as noted earlier, the difficulty of breaking up this extremely hard wood complicates pulping.

SHELTERBELTS

Casuarina equisetifolia is often planted as a windbreak in North Africa, West Africa, Yemen, Somalia, the Middle East, India, and South China. In southern Australia Casuarina stricta has been widely used as a windbreak. The abundance of highly branched twigs on casuarinas absorbs wind energy amazingly well. A wind strong enough to blow hats off can be stripped of? its force by a belt of casuarinas two or three deep, leaving the leeward air calmed. By reducing windspeed to almost zero, the shelterbelts stop wind erosion, and in areas with hot, dry winds they protect crops and animal herds and increase yields.

An advantage of casuarinas is that their roots do not readily harbor nematodes that affect the neighboring crops, a problem that is increasingly recognized as a serious limitation of shelterbelts. (In Egypt, however, Casuarina equisetifolia has been found to carry some nematodes, although Casuarina glauca has not.)

Egyptian farmers have solved the problem of root suckers coming up in their fields. They dig a ditch between the crop and their Casuarina glauca shelterbelts. Sheep and goats then eat the exposed shoots and keep them from becoming pests.

In addition to their wind firmness casuarinas have desirable characteristics for shelterbelts: adaptability to many soils and climates, self-sufficiency for nitrogen, rapid early growth, adequate height and longevity, dense crown, and useful wood. It is most unusual for a single tree to have all of these attributes; to reduce wind adequately, shelterbelts normally require two or more species.

EROSION CONTROL

Casuarinas can protect soil by reducing wind erosion, but they also do it with their network of fine subsurface roots and by building up a litter of intertwined needles that protects against rain and wind.

Casuarina equisetifolia is much used for stabilizing sandy soils (see below) and Casuarina cunninghamiana is valued for protecting riverbanks. For erosion control, the copious root suckering of species such as Casuarina glauca can be an advantage, because it helps the trees spread and hold down the land, especially on severe slopes or washed areas. In addition, the litter from the trees blows over the bare ground, protecting it from erosion and providing a good seedbed for natural reproduction.

SAND DUNE STABILIZATION

Because it is salt- and drought-tolerant and can grow and reproduce in sand, Casuarina equisetifolia is used to control erosion along coastlines and estuaries. Thousands of square kilometers of casuarina forests have been planted in coastal sand dunes in southern China (see chapter 2). Casuarina is also used in Egypt to stabilize sand dunes that are drifting into the Nile Delta and Nile Valley. And in Mexico it is being planted in saline sandy areas near Mexico City to reduce dust storms. Casuarina equisetifolia is also stabilizing moving dunes on the coast of northern Senegal.

On the leeward side of sand dunes, when lower branches touch the ground they often root and develop upright branches. In this manner, they firmly fix the shifting sand with an expanding cover of trees.

TANNING

The bark of Casuarina equisetifolia contains 6-18 percent tannin and has been used extensively in Madagascar for tanning purposes. In Australia the tannin content is considered too low for commercial interest; however, casuarina bark enjoys a certain standing among amateur tanners. The tannins penetrate hides quickly and furnish a swollen, pliant, and soft leather of pale reddish-brown colon Other casuarina species probably could also be used for tanning.

HONEY PRODUCTION

Casuarinas furnish no nectar for honeybees. However, Casuarina littoralis and Casuarina cunninghamiana are rated as having medium value as pollen sources; Casuarina glauca and Casuarina torulosa are rated as being of minor value.

FODDER

While domestic animals will graze seedlings and suckers of casuarinas, the foliage is high in tannin and is astringent and constipating and may interfere with the animal's ability to utilize protein.