Common Name: Sal Tree

General Information

Shorea robusta is an evergreen tree with an elongated crown when young, becoming more rounded as the tree ages. It can grow up to 50 metres tall in fertile soils, but is more likely to be 20 - 25 metres tall in poorer soils. The straight, cylindrical bole can be unbranched for up to 25 metres and up to 200cm in diameter[, , ].
Sal is a very important multi-purpose tree. It is one of the main commercial timbers of India, being harvested from the wild for local use and export. It also yields a resin that is traded and an oil that is used locally as well as being exported in large quantities. It addition, it supplies tannins, an edible seed and medicines for local use. The leaves are used commercially for making plates and containers[].
The sal tree is often the dominant species in the forests of the sub-Himalayan tract, but overutilization of it for fuel, timber, fodder etc is becoming a cause for conservation concern in some areas[]. It is classified as being of 'Least Concern' in the IUCN Red List of Threatened Species(2010)[].

Known Hazards

None known

Botanical References

Range

E. Asia - Indian subcontinent to south-western China[].

Habitat

A rare plant in China, it is gregarious in savannah woodlands at elevations below 800 metres in south-eastern Xizang[]. Often the main tree in forests of Nepal at elevations up to 1,400 metres[].

Properties

Conservation Status	Least Concern
Edibility Rating
Medicinal Rating
Other Uses Rating
Habit	Evergreen Tree
Height	40.00 m
Growth Rate	Fast
Self-fertile	No
Cultivation Status	Wild

Cultivation Details

A plant of the tropics, where it is found at elevations up to 2,000 metres. It grows best in areas where annual daytime temperatures are within the range 28 - 34°c, but can tolerate 7 - 47°c[]. The plant can survive temperatures down to about -1°c[]. It prefers a mean annual rainfall in the range 1,500 - 3,500mm, but tolerates 1,000 - 7.300mm[]. There is usually a dry season of 4 - 8 months[].
Prefers a position in full sun, but tolerates light shade[]. Succeeds in most well-drained, fertile soils, though it prefers a moist sandy loam with good subsoil drainage[, ]. Prefers a pH in the range 5 - 6.7, tolerating 4.5 - 7.5[].
Young trees grow quickly, developing a long taproot at a very young age and attaining top heights of up to 6 metres after 6 years[].
Fruit and seed bearing begins around the age of 15 years, the tree then bears fruit regularly every 2 years or so, and a good seed-bearing year can be expected every 3 - 5 years[].
The tree responds well to coppicing[].
Rotations of 30 - 40 years are used when coppice regeneration is practised, and 80 - 160 years for high forest regeneration[].
The tree is very tolerant of forest fires, usually surviving them if not too small[].

Edible Uses

Seed - roasted[]. The seeds are boiled into a porridge with the flowers of Bassia latifolia and the fruits of Dolichos biflorus[]. They can be ground into a coarse flour that is used to make bread, and the plant is used as a famine food[]. A de-fatted kernel powder, popularly known as sal seed cake, contains about 50% starch, in addition to proteins, tannins and minerals. The physico-chemical property of the starch can be exploited for preparing canned food products[].
The chemical composition of the seeds consists of 10.8% water, 8% protein, 62.7% carbohydrate, 14.8% oil, 1.4% fibre and 2.3% ash.

The seeds are a source of 'sal butter', an oil that is used in cooking like ghee and as a substitute for cocoa butter in making chocolate[].

Fruit - occasionally eaten[].

Medicinal

The resin is valued for its use in the treatment of dysentery, gonorrhoea, boils and toothaches[].

The leaf juice is used in the treatment of dysentery[]. The leaves are warmed and used as a poultice on areas of the body that are swollen[]. They have a quick effect[]. They are also applied to the stomach of children with dysentery[].

The oil from the seed is used to treat skin diseases[].

Other Uses

When tapped, the tree exudes large quantities of a whitish, aromatic, transparent resin known as 'lal dhuna'. It is used to caulk boats and ships and as incense. In some places in the Upper Tista forests of the Darjeeling District, large
pieces, often 450 - 600 cubic centimetres in size, are found in the ground at the foot of the trees[].

The leaves are widely used for making plates, cups and for wrapping[].

An oil obtained from the seed is used for illumination[].

The bark is a source of tannins[].

The heartwood is a dark, reddish brown; the thin band of sapwood whitish. The grain is strongly spiralled and rather coarsely structured. The wood is hard, heavy, very durable and highly resistant to termite attack. Seasoning can present problems. The wood is easy to saw, but because of its high resin content, it is difficult to plane and turn; it has a tendency to split when nails are driven into it. This important Indian hardwood is especially well suited for constructing structures subject to heavy stress in houses etc, it is also used in hydraulic engineering, ships and railway cars, poles, railway ties and posts, simple interior finishing such as window frames and floors, and many other applications[]. For making household or agricultural implements, the coppice shoots are used[, ].
The wood is an important local source of fuel[].

Propagation

We have no specific information for this species - the information below is a general guide for the genus.

Seed - best sown as soon as possible. It does not require pre-treatment, but it is recommended to soak the seed for 12 hours prior to sowing[]. The seeds are sown in seedbeds, where they are covered with a mixture of sand and soil (1:1) or with a thin layer of sawdust[]. Germination of fresh seeds is usually good and rapid. About two weeks after germination, when the seedlings are 5 - 6cm tall, they are potted up into individual containers about 15 x 23cm with good drainage holes at their base[]. It is normally recommended to use a mixture of forest soil and sand (at a ratio of 3:1) as the potting medium in order to introduce the appropriate mycorrhiza to the roots. The seedlings are placed in
50 - 60% sunlight and watered twice daily[].
Seedlings can be planted out when 30 - 40cm tall - harden the seedlings off in full sunlight for one month prior to planting[].

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