The Teak-Silviculture of Tectona grandis-Know your trees
Tectona grandis
Family : Verbenacea
Local names : Hindi - Sagon, sagon ; Kannanda- tegu , tegina
Malayalam-thekku, Marathi-sagwan ,sag,
Tamil- thekku, Telugu- teku.
Common/Trade/English Name Teak
Distribution
Teak is indigenous to Indian Peninsula-, its northern limit being the Western Aravallis in Rajasthan, then eastward through Central India to Jhansi and Banda districts in U.P. Then in south easterly direction to Mahanadi river, extending southward. It occurs in Madhya Pradesh, Tamil Nadu, Maharashtra, Kerala, Orissa, Uttar Pradesh and Rajasthan.
It has been introduced in moist deciduous forests of W. Bengal, Assam, Bihar, U.P. Orissa and the Andamans. It is an important species of Southern Tropical Moist and Dry Deciduous forest types.
Particulars About Seed:
Flowers appear during rainy season- June to September
Fruit, hard nut, ripens- November to January and falls gradually.
The seeds are collected of the cleared ground under the trees in January-February or lightly beaten off the trees with sticks; each containing 1 to 3, rarely 4, seeds ,weigh variable from 1850 to 3100 fruits weigh a kilogram.
Teak seeds almost ever year; produces fertile seed at an early age of about 20 years, coppice ones in about 9 years. Seeds (fruits) can be stored in gunny bags o sealed tins in a dry ventilated shed for at least 2 years; seeds stored for year germinate better than the fresh ones. Seeds lie dormant in the soil for one or more year up to even 4 or 5 year.
Germination percent is high in selected seeds; very variable according to source, 10 to 70%. Fruit being a hard nut, needs pre-sowing treatment to hasten germination; it may be done by one of the following methods:
(i) Boiling water treatment.
(ii) Immersion in cold water for several days.
(iii) Scorching in light fire of leaves and grass.
(iv) Alternate soaking and drying, 48 hours each, for 12 - 15 days.
(v) Placing seeds in a paste of cow-dung and water; or in fresh dung heap for a few days,
(vi) Weathering, i.e., exposing to sun and rain in the open for a few weeks or months
(vii) Acid treatment
(viii) Pit treatment (as practiced in West Bengal); alternate layers of teak leaves and seeds, final covering of 15 cm of earth; watered on alternate days through inserted hollow bamboo pipes for about 10 days.
Methods of Propagation
Natural Regeneration : In some teak areas of Madhya Pradesh, Tamil Nadu, Maharashtra and Kerala, appreciable quantities of natural regeneration come up under favorable conditions of seeding, light (canopy openings), soil moisture and aeration, weed and competing bamboo growth, fire and grazing; this can be tended intensively in clear felled regeneration areas, cut back in most cases, to give vigorous shoots which outgrow competing shrubs and form established advance growth, forming part of whole of the future crop. Regulated grazing and fire in moister types is beneficial, as it keeps weed growth under check. In drier types, these have advance influence on regeneration. In most cases, dry teak forests are worked under Coppice System, or Coppice-with-Standards or Coppice-with-Reserves, where the regeneration is mostly by coppice.
In both cases of natural regeneration, we may have to supplement it by artificial means to fill up the blanks and/or failures.
Artificial Reproduction : Teak can be raised by direct sowing, entire planting or stump planting.
Direct Sowing : As far as possible, only large sized seeds of genetically superior origin, suitably treated, should be used in the nursery as well as for field sowing. In high rainfall areas of Nilambur (Kerala), pre-sowing treatment of seed is not considered necessary.
Direct sowing may be done in patches, in soil-worked taungya lines, broadcast in ploughed up plain areas or in well dug up rabs in mixed teak forests for enrichment planting. In each case a good burn, and a reburn if necessary, of the plantation area is highly beneficial in controlling weeds, fertilizing the soil with ash and stimulating seed germination and seedling development. Best results are obtained if sowing is done soon after a good burn and early, to get the benefit of early showers in April-May in the South. In Patch sowing, 2 - 3 seeds are sown in each patch, spaced 2 m x 2 m or 2½ m x 1 ½ m.
Teak is being raised in conjunction with agricultural crops by departmental, village or leased taungyas in Kerala, Tamil Nadu, Maharashtra and Madhya Pradesh for several decades by now, as also in Burma; and more recently in West Bengal, U.P., Bihar and Orissa. The details in respect of terms with cultivators, spacing, period and nature of agricultural crops to be raised, extent of area allotment, time-schedule of operations, method of raising teak (direct sowing, entire planting, dona or stump planting) vary from State to State and with the forest types. In the past, 3 teak seeds used to be sown at each stake, 2 m x 2 m in taungya lines, with good results, when sown after a good burn and early enough to get benefit dearly pre-monsoon showers.
In open gaps or clearings, teak seed may be dibbled in well-burnt and worked rub patches in mixed crops, by way of enrichment planting. Seeds are lightly covered, seedlings weeded thoroughly, followed by hoeing and mulching.
Entire Planting :
Burnt and re-burnt regeneration areas, 3 - 4 months old nursery seedlings, or dona plants, even as small as 5 - 8 cm tall, are fit for planting out in the field, in the very first monsoon rains; usually 30 cm3 pits are dug beforehand to allow the soil to weather, and refilled before planting in crow-bar holes made in the refilled pits; most usual spacing being 2 m x 2 m. To beat up failures, or in case of shortage of nursery stock, even wildings, 5 - 8 cm tall, growing on the fire lines or road sides may be uprooted in the rains and transplanted to supplement or beat up failures in sowings. It has been found by field trials that young natural Plants, killed back repeatedly by fire, frost or suppression, when their stems are pruned down and roots trimmed, and planted with the thickened root stock in cleared and burnt patches gave very good results.
Stump Planting :
One or two rains old nursery seedlings are fit for making stumps; 1.0 to 2.0 cm collar diameter is the optimum size of stumps; roots pruned and trimmed down to 20 - 23 cm and shoots 2 - 3 cm in length make ideal stumps. Stumps made from seedlings upto 4 cm collar diameter are also successful and acceptable. Split stumps (halves or quarters) have also given satisfactory results but involve much labour and are not in common use; for these minimum diameter should be about 4 cm. Stumps are planted in crow-bar holes made in refilled pits 30 cm' and buried up to collar, after good pre-monsoon showers (2nd fortnight of April in Nilambur), and soil thoroughly compacted around the stumps. It is the most suitable method of raising teak; giving up to more than 90% success. In transit, or for a temporary storage, stumps should be kept in moist gunny packing, if this becomes necessary; while planting the ends of root and shoot should be freshened with a sharp thin cut. Planting distance generally adopted is 2 m x 2 moreover, in good sites with medium or high rainfall areas, 2.5 m x 2.5 to or 3 m x 3 m is preferable, thereby obviating the first mechanical thinning.
Nursery Technique:
Commonest type in moist areas is the temporary dry nursery, and irrigated one in dry and drought prone areas. The soil is well dug up well then mixed with ashes in a well drained. Standard size of beds is 1.2 iii x 1.2 m; raised in moister localities to avoid water logging and that or slightly sunken in dry zone. Treated seeds are sown 7.5 cm x 7.5 cm in lines, or broadcast, about 1 cm deep, between February and May. Germination takes place in 10-20 days. Seedlings are pricked out in transplant beds during the first rains, 15 cm x 15 cm; two rains or one year old seedlings are fit for preparing stumps, 1.0 to 2.0 cm collar diameter; 3-4 months old seedlings are generally suitable for planting out entire. In M.P. and Orissa, dona (leaf cup) transplants are preferred to stumps under local conditions; 3 - 4 months old seedlings raised in indigenously prepared teak donas which are 6 - 8 cm diameter, 22 - 23 cm deep, filled with silt, earth and F.Y.M., are sown with 2 seeds (fruits) of teak each, in February-March, retaining only one healthy seedling well before planting.
Tending
Young plantations need at least 3 weeding in the first year, 2 in the second and 1 in the third. In the first year, the lines are clean-weeded, soil being loosened. Second year weedings include climber cutting, cutting back of bad stems and removal of double leaders; climber cutting and cutting of bamboo growth is done in the third and subsequent years.
Tinnings : First thinning is done when the crop is 8 - 9 m high: second when the dominant height is 10 to 12 m; the first two thinnings are more or less mechanical, in which alternate diagonals and rows are removed; subsequent thinnings are D-grade.
Problem of Pure Teak Plantations:
The subject of relative merits and demerits of pure mixed teak plantations has long been debated by foresters. Drawbacks attributed to pure plantations are, in brief : deterioration of site, greater susceptibility to insect pests and epidemic diseases, fluting, epicormic branches, falling off rate of growth, Loranthus attack, fall in quality of timber, soil erosion, etc. Some of these charges have not been proved, others are exaggerated or due mainly to faulty silvicultural treatment. Taking into consideration all the advantages of pure plantations, viz., higher financial return, ease of tending operations and management in general, balance is still in favour of pare plantations. However, the objections can be met by under-planting teak with shade bearing indigenous species, though it will complicate management and reduce financial returns.
Rate of Growth:
Teak is a fast-growing tree, more so in early age.
Injuries, Pests and Diseases
Injuries : Climatic - Seedlings are sensitive to drought and frost; intolerant of shade and suppression by weeds; have wonderful power of recovery from damage by fire; trees are not wind-firm; frequent fires induce hollowness at the bottom; cannot stand water logging.
Animals : Teak is not browsed; can withstand mechanical injury rery well. Rats and pigs cause damage in seedling stage; bison, sambhar, ; cheetal and elephants cause damage in later stages.
Plant Parasites : Loranthus is a serious pest in Maharashtra.
Insects : Teak is subject to various insect attacks. Catepillars of Hyblea puera and Hapalia machaeralis are the commonest among defoliators; the latter skeltonises the leaves. These are more common in ure teak crops. Dihamus cervinus, a borer, is common in young lantations in W. Bengal; another borer, Hypophasus malaparicus, attacks young plants in South India.
Fungi : No significant fungal damage is reported; a mildew, Uncinula teclontie attacks leaves of teak; it is common in Madhya Pradesh.
General characteristics
(i) Teak is the most important and valuable tree of India occurs in Tropical moist and Dry deciduous forest types in central and southern India, seldom gregarious in natural forests: grows upto 1200 m elevation in Western ghats, its best Growth is at about 600 m and below
Teak seedlings are sensitive to frost and drought. It is a strong light-demander, intolerant of suppression and weeds; fire-resistant; seedlings and saplings killed back by fire and frost. When cut back give vigorous shoots. It coppices and pollards up to about middle age.
(ii) Uses : Teak wood is moderately hard: extremely durable; most important timber of India: unique for ship building. Extensively used for bridges, buildings, piles, cabinet work. beams, poles, railway carriages, decorative panelling, careing. Ordnance work, general carpentry, etc. Timber is easy to air-season. easy to work and saw, peel on a rotary lathe; makes excellent plywood.
(iii) Management : Teak forests are being worked under several Silvicultural Systems, depending on the forest types, ecological status of teak, environmental factors, topography, etc. These are : Clear felling followed by artificial regeneration, or natural regeneration from advance growth; Selection, including Selection-cum-Improvement; Two-storeyed High Forest; Conversion to Uniform and Coppice Systems. The most extensively adopted system is the clear felling followed by artificial regeneration by departmental or leased taungya.
