Forestry & Forest Sciences · Silviculture · also Silviculture of Trees, Silviculture of Indian Trees, Species Silviculture
Species by species: distribution, site requirements, phenology, regeneration, nursery and planting technique, tending, growth and uses of the important trees of tropical and temperate forestry.
In the exams: IFoS Forestry Paper I Section A (silviculture of named trees, a long species list); ICAR AICE-JRF 59 Unit 2 (Populus, Eucalyptus, Dalbergia, Acacia, Tectona, Shorea, Prosopis, Casuarina, Pinus, Gmelina, Azadirachta and others); state forest service exams
Silviculture of species brings together, for each important tree, what a forester needs to grow it: its distribution and site requirements, its silvicultural characters such as light demand and frost and drought tolerance, its phenology and seed, natural and artificial regeneration, nursery and planting technique, tending, growth and rotation, main pests and diseases, and uses. It is the practical companion to silviculture principles, silvicultural systems, stand tending, nursery and plantation establishment, and tree seed technology, and it relies on dendrology for identification. Where a species is also a medicinal plant, such as neem, sandalwood or red sanders, its classical Ayurvedic properties are described in Laisha's dravya pages; this manual covers its cultivation.
The UPSC Indian Forest Service Forestry optional asks for the silviculture of a long list of named trees, and ICAR's AICE-JRF names Populus, Eucalyptus, Dalbergia, Acacia, Tectona, Shorea, Prosopis, Casuarina, Pinus, Gmelina and Azadirachta among others. Answers are expected to follow a standard order: distribution, climate and soil, silvicultural characters, phenology, seed, natural regeneration, artificial regeneration (nursery and planting), tending, growth and rotation, pests and diseases, and uses. This manual follows that order for the main species, more briefly for others, and adds key species of forestry outside South Asia.
Values such as rainfall ranges, spacings, rotations and yields vary widely with site, purpose, genetic material and region; they are given here as typical ranges from standard texts, and local working plans, yield tables and research institute guidelines should be consulted for prescriptions.
Teak (Lamiaceae) is native to peninsular India, Myanmar, Thailand and Laos, and is planted throughout the tropics. In India natural teak occurs in moist and dry deciduous forests of the Western Ghats, central India and the Deccan. It grows best with annual rainfall of roughly 1,200 to 2,500 millimetres and a distinct dry season, on deep, well-drained, fertile soils, especially alluvial and those derived from trap and other basic rocks, rich in calcium. It does poorly on waterlogged, heavy clay, laterite and shallow soils. Teak is a strong light demander, intolerant of suppression and frost-tender when young; it is fairly fire-hardy when older, and coppices vigorously when young. It is deciduous in the dry season.
Teak flowers during the monsoon and its fruits, hard drupes in an inflated calyx, ripen in the cool season. Germination is slow and uneven because of the hard, thick endocarp; seeds are pre-treated by alternate soaking and drying, or by weathering, and only a modest proportion germinate. Natural regeneration is often scarce because of fire, grazing, weeds and the light requirement, so teak is raised mainly by planting. The usual stock is stumps (root-shoot cuttings) prepared from one-year-old nursery seedlings about 1 to 2 centimetres thick at the collar, with a root of roughly 15 to 25 centimetres and a short shoot; container seedlings and clonal plants are also used. Plantations are established by clear felling and planting, historically with taungya; Nilambur in Kerala has the oldest teak plantations, begun in the 1840s. Close spacings such as 2 × 2 metres were traditional, with wider spacings now common; weeding and climber cutting are needed in the early years, followed by mechanical first thinnings and then silvicultural thinnings. Rotations in India range from about 50 to 80 years for large timber in state forests, while short-rotation plantations elsewhere are harvested much younger with smaller, lower-quality heartwood. Main pests are the teak defoliator (Hyblaea puera) and the teak skeletoniser (Eutectona machaeralis); the golden-brown, oily, durable, stable heartwood is used for ship-building, furniture, joinery and veneer.
Teak is increasingly grown on farms, field boundaries and private plantations in India and in many tropical countries in Asia, Africa and Latin America. Farm teak is usually planted in single rows along boundaries or at wide spacing with crops, and grows faster than in dense plantations but needs pruning to produce clean stems. Clonal teak, propagated by rooted cuttings or tissue culture from selected trees, gives more uniform growth, though gains depend on testing clones on the sites where they are planted. Short-rotation teak grown in some countries is harvested at 15 to 25 years, giving logs with a high proportion of sapwood and lower durability and colour than old-grown teak; markets distinguish these grades. Investors have sometimes been promised unrealistic returns from teak schemes; realistic growth and price assumptions, secure tenure and the right site are essential.
Sal (Dipterocarpaceae) forms extensive gregarious forests in northern, central and eastern India and Nepal, in moist and dry deciduous types, with annual rainfall of roughly 1,000 to 3,000 millimetres. It needs deep, moist, well-drained soils and does poorly on waterlogged or very dry soils and heavy clays. It is a light demander in later life but its seedlings benefit from side shade and are sensitive to frost and drought. Sal is briefly deciduous in the hot dry season, flowers then, and sheds its winged fruits at the start of the monsoon; the seed is recalcitrant, germinates almost at once and loses viability within weeks, so it must be sown immediately. Natural regeneration is abundant in good seed years, but seedlings often show repeated die-back, dying back to ground level and resprouting for several years before establishing a vigorous shoot; fire, grazing, weeds, frost and drought prolong this stage. Sal has been managed under the uniform and other shelterwood systems and under coppice and coppice with standards in drier areas; artificial regeneration is by direct sowing of fresh seed in lines or patches. Sal coppices well. The sal heartwood borer (Hoplocerambyx spinicornis) causes periodic epidemics that kill large numbers of trees and is controlled by felling and removing infested trees and by trap trees. Sal timber is heavy, strong and durable and is used for construction and railway sleepers; its seeds yield sal butter and its leaves are made into plates.
Other dipterocarps of South Asia include Dipterocarpus species (gurjan) of the North-East and Andamans and D. indicus of the Western Ghats, Hopea species, and Vateria indica. In South-East Asia, dipterocarps dominate lowland rain forests and are managed under selective logging systems with diameter limits, reduced-impact logging and enrichment planting, as described in silvicultural systems. Their silviculture is shaped by irregular mast fruiting, recalcitrant seed, the need for some shade in early growth, and dependence on ectomycorrhizal fungi. Enrichment planting with dipterocarp seedlings or wildings in lines and gaps, with careful release from competition, has been used to restore logged forests.
Failure of sal natural regeneration has been one of the oldest problems of Indian silviculture. In moist sal forests, dense undergrowth of shrubs and grasses, frost in low-lying areas, waterlogging and the weed Lantana camara suppress seedlings; in dry sal, drought and fire kill them; and grazing and repeated lopping prevent recruitment everywhere. Research and practice have shown that regeneration improves with fire protection, control of grazing, removal of weeds, soil working to expose mineral soil before seedfall, and opening the canopy enough to give light while keeping side shade. Because the seed cannot be stored, these measures must be timed to good seed years. Coppice regeneration from stumps and advance growth also contributes, and supplementary direct sowing of fresh seed in prepared patches is used where natural regeneration is lacking.
Eucalypts (Myrtaceae) are native mainly to Australia and are the most widely planted hardwoods in the world, for pulpwood, poles, fuel, timber and oil. Species must be matched to site. In India the most planted are Eucalyptus tereticornis (including the Mysore gum land race), adapted to a wide range of tropical and subtropical sites; E. camaldulensis (river red gum), tolerant of drought, waterlogging and some salinity; E. grandis, for higher-rainfall, fertile sites; E. globulus (Tasmanian blue gum) in the cool Nilgiris and other southern hills; E. citriodora (now Corymbia citriodora) for oil; and above all clones and hybrids of E. camaldulensis, E. tereticornis, E. grandis and E. urophylla selected for growth and disease resistance. Eucalypts are strong light demanders, generally intolerant of frost (except some temperate species), fast-growing, and coppice well.
Seed is tiny and is sown in germination beds or trays, and seedlings are pricked out into containers; most plantations now use clonal plants from rooted mini-cuttings raised in root trainers. Planting is at the onset of the rains, in pits, at spacings typically around 2 × 2 to 3 × 3 metres for pulpwood, with wider spacing in agroforestry and on farm boundaries. Weeding, fertiliser at planting and protection from termites and grazing are important in the first years. Pulpwood rotations are short, often around five to eight years, and stands are then coppiced for one or two further rotations before replanting with improved clones. Major problems include the gall wasp Leptocybe invasa, which spread to India in the 2000s and severely damaged susceptible clones; Cylindrocladium leaf blight in nurseries and young plantations; pink disease (Corticium salmonicolor) in high-rainfall areas; termites; and stem cankers. Debate about eucalypts' water use and effects on soil and biodiversity has been intense; their water use per unit of growth is not unusual, but fast-growing plantations do use much water and can reduce streamflow and groundwater recharge where rainfall is low, so siting and scale matter.
Poplars (Salicaceae) are fast-growing, deciduous, dioecious light demanders of temperate and subtropical regions, regenerating easily from cuttings and root suckers. In India, Populus deltoides from eastern North America, grown as selected clones, is the main agroforestry poplar of the north-western plains (Punjab, Haryana, western Uttar Pradesh, Uttarakhand foothills), where it is planted on farm boundaries and in blocks with wheat, sugarcane and other crops; native Himalayan poplars include P. ciliata. Poplars need deep, fertile, well-drained but moist alluvial soils and irrigation in dry seasons, and do poorly on heavy, waterlogged or saline soils.
Plants are raised in nurseries from cuttings and planted as entire transplants (ETPs), whole one-year-old plants with roots and shoots, in the dormant winter season (January–February in north India), in deep holes made with an auger, often around a metre deep, so that roots reach moist soil. Block plantings are often at about 5 × 4 metres or wider, allowing intercrops for the first years; boundary plantings use single rows. Rotations are short, about six to eight years for plywood and match industries. Pests and diseases include defoliators such as Clostera species, stem borers such as Apriona, and leaf rust (Melampsora) and leaf spots; clonal diversity and resistant clones reduce risk. Poplar agroforestry has given high incomes to farmers but depends on fluctuating wood prices.
Willows (Salix) grow along streams and on moist soils, and are raised from cuttings or sets. The cricket bat willow, a form of Salix alba, is grown in Kashmir and in England for bats, needing moist, fertile soil and careful pruning to produce clean, knot-free stems; other willows are planted for fuel, fodder, basketry and stream-bank protection, including in the cold deserts of Ladakh and Lahaul along irrigation channels. Willows are also used in short-rotation coppice for biomass in Europe.
Babul (Vachellia nilotica, formerly Acacia nilotica) grows on a wide range of soils in dry and moist regions, including black cotton soils and periodically flooded sites such as tank beds, and tolerates some salinity and alkalinity. It is a light demander, drought-hardy and frost-sensitive. Its hard seeds need scarification by hot water or acid, or pass through the guts of goats and cattle, which spread it. It is regenerated by direct sowing of treated seed in lines or patches or by planting container seedlings, and is managed for fuel, fodder, tannin, agricultural implements and gum. Khair (Senegalia catechu) grows on dry, gravelly and riverine soils in the sub-Himalayan tract, central India and elsewhere, often as a pioneer on new alluvium with sissoo. Its seeds germinate readily when fresh; it is raised by direct sowing or container seedlings and grown for katha and cutch from its heartwood, fuel and fodder, under rotations long enough to form heartwood.
Acacia auriculiformis and A. mangium, from Australia and New Guinea, grow fast on poor, degraded and acidic soils, fix nitrogen and are planted for pulp, fuel and rehabilitation; A. auriculiformis is widely grown in India, and A. mangium and the A. mangium × A. auriculiformis hybrid in South-East Asia. Their seeds need hot-water treatment. They can become invasive and A. mangium suffers heart rot and Ceratocystis wilt in some regions. Albizia lebbeck (siris), A. procera and Falcataria moluccana (formerly Albizia falcataria) are fast-growing nitrogen-fixing trees for timber, fodder, shade and agroforestry. Leucaena leucocephala (subabul) is grown for fodder, fuel and pulp but is invasive in some regions and suffered heavy damage from the leucaena psyllid in the 1980s. Other leguminous trees of silvicultural importance include Pongamia, Hardwickia (dry-zone species chapter) and Dalbergia and Pterocarpus (rosewoods chapter). Most leguminous trees benefit from rhizobial inoculation in the nursery on soils where suitable rhizobia are absent.
Pongamia (Millettia pinnata, formerly Pongamia pinnata), karanja, is a medium-sized, nearly evergreen leguminous tree of riverbanks, coasts and plains throughout India. It is hardy, tolerating drought, waterlogging, salinity and poor soils, and fixes nitrogen. Its seeds, borne singly in thick woody pods, yield a non-edible oil used for soap, lamp oil, leather tanning and as a biodiesel feedstock, and the seed cake is used as manure. It is raised easily from fresh seed in containers or by direct sowing, and is planted along roads, canals and field boundaries and on degraded land. Programmes promoting pongamia for biodiesel have met with mixed success because yields from unselected trees vary widely; selection of high-yielding trees and grafting are being developed.
Casuarina equisetifolia (Casuarinaceae) is native to coastal South-East Asia, northern Australia and the Pacific, and is planted extensively along the sandy coasts of Tamil Nadu, Andhra Pradesh, Odisha and Gujarat. It tolerates sandy, nutrient-poor and salt-sprayed soils and fixes nitrogen through Frankia in root nodules; it is a strong light demander, drought-tolerant but not frost-hardy. Its tiny seeds are collected from the cone-like fruits, sown in sand beds, and seedlings pricked out into containers; nursery inoculation with Frankia improves growth. Clonal plants of C. equisetifolia and of C. junghuhniana and their hybrids, developed by Indian research institutes, are now widely planted. Traditionally planted very close, around 1 × 1 metre, for poles and fuel on rotations of about three to five years, it is now often grown at wider spacing for pulpwood. It is also planted as coastal shelterbelts, though its value for coastal protection depends on belt width and site. Casuarina does not coppice well and is replanted after harvest.
Gmelina arborea (Lamiaceae), gamhar, is a fast-growing deciduous tree of moist and dry deciduous forests in India and South-East Asia, planted widely in the tropics, including West Africa and Central America, for pulp, light timber, plywood and furniture. It is a light demander and coppices well and produces root suckers. Its yellow fleshy drupes are depulped, and the stones are soaked before sowing; germination is fairly good. Plants are raised as stumps or container seedlings and planted at the onset of the rains; growth is fast on deep, moist, well-drained soils, and poor on dry, shallow or waterlogged ones. Rotations range from about 6 to 15 years for pulp and small timber to longer for sawlogs. The main pest is the defoliator Calopepla leayana, and stem form can be poor without genetic selection and good site matching.
Shisham (Dalbergia sissoo, Fabaceae) is a deciduous light demander of the sub-Himalayan tract and riverine alluvium, a pioneer on new sandy and gravelly river deposits, where it grows with khair in seral riverine forests. It tolerates drought and some frost, produces abundant root suckers and coppices well. Seed is collected from the flat pods and sown fresh or after soaking; it is raised by root-shoot cuttings (stumps), container seedlings or root suckers, and planted on farms, along roads and canals, and in plantations. Its strong, durable heartwood is valued for furniture. Since the late 1990s, extensive die-back and mortality of shisham have been reported in Pakistan, northern India and Nepal; fungi such as Fusarium and Ganoderma, waterlogging and site degradation have been implicated, and the causes are still debated. Indian rosewood (D. latifolia), a slower-growing tree of moist and dry deciduous forests of peninsular India, yields a dark, beautifully figured heartwood; it regenerates from seed and root suckers, and its trade is regulated.
Red sanders (Pterocarpus santalinus) is endemic to a small area of dry deciduous forests on the hills of the southern Eastern Ghats in Andhra Pradesh and adjoining Tamil Nadu, on dry, gravelly and lateritic soils. It is a slow-growing light demander; its seed needs pre-treatment and germination is poor and slow; seedlings are raised in containers and planted in the rains. Its deep red heartwood, valued for carving, dye and medicine (described as rakta chandana in Ayurvedic texts), has been heavily smuggled; the species is protected in India and listed in CITES Appendix II. Bijasal (Pterocarpus marsupium), a large deciduous tree of central and peninsular India, yields timber and a red kino with medicinal uses; it regenerates poorly in many forests. Other legume timbers include Xylia xylocarpa and Hardwickia binata (treated with dry-zone species).
Sandalwood (Santalaceae) is a small evergreen tree of dry deciduous forests and scrub, mainly in Karnataka, Tamil Nadu, Kerala and Andhra Pradesh, and also grows in Indonesia and Australia (where related species occur). It grows on a range of soils but prefers well-drained red soils and does poorly on waterlogged ground. Sandalwood is a root hemiparasite: it photosynthesises but attaches to the roots of other plants by haustoria and takes water and nutrients from them, so it needs suitable hosts throughout its life. Its value lies in the fragrant heartwood and roots, from which sandalwood oil is distilled; heartwood formation begins after some years and increases with age, and is variable between trees. Its classical properties as chandana are described in Laisha's dravya pages.
Seeds are dispersed by birds; natural regeneration occurs under bushes that act as hosts and protect seedlings from grazing. In the nursery, seeds are often treated with gibberellic acid or by other methods to improve germination, and seedlings are given a primary host, a small plant grown in the same container, before planting. In the field, sandalwood is planted with medium- and long-term hosts, such as Casuarina, Melia, Pongamia, Cassia and other species, and protected from grazing and fire. Spike disease, caused by a phytoplasma and spread by insects, has killed large numbers of trees, shrinking leaves and making shoots spike-like; infected trees are removed. Sandalwood has long been a state-controlled tree in Karnataka and Tamil Nadu, with ownership and harvest regulated; reforms in the early 2000s eased the rules for growers on private land, and plantations on farms have expanded. Theft and illegal harvest of mature trees remain major problems.
Neem (Azadirachta indica, Meliaceae) is a hardy, evergreen to briefly deciduous tree of dry regions of South Asia, planted throughout India and the dry tropics for shade, timber, fuel, and seed oil and leaves with insecticidal and medicinal properties (described as nimba in the dravya pages). It tolerates drought, poor and shallow soils and high temperatures but not waterlogging or frost. Its seed loses viability within weeks to a few months under ordinary conditions, so it is sown fresh after depulping; plants are raised in containers or as stumps and planted in pits with moisture conservation in dry areas. Neem grows moderately fast, coppices and pollards well, and is widely planted along roads and in agroforestry.
Melia dubia (Malabar neem), native to the Western Ghats and other moist regions, is a fast-growing deciduous tree planted on farms in southern India for plywood, packing cases and pulp on rotations of roughly five to eight years. Its hard drupes give low and slow germination; pre-treatments such as soaking, partial cracking and composting have been used, and clonal propagation from selected trees is increasing.
Ailanthus excelsa (Simaroubaceae), maharukh, is a fast-growing deciduous tree of dry regions of western, central and southern India, tolerant of drought and poor soils. Its winged seeds are sown fresh, as viability is short, and plants are raised in containers and planted in the rains. Its soft, light wood is used for matchwood, packing cases and fishing floats, and its leaves for fodder.
Simarouba glauca, introduced from Central America and the Caribbean, is an evergreen, dioecious oilseed tree whose seeds yield an edible fat, promoted in India in recent decades on degraded lands. Seeds are sown fresh in containers, and both male and female trees are needed for fruiting; selecting female plants and grafting can improve seed production. Its value depends on oil processing and markets, which have developed unevenly.
Khejri (Prosopis cineraria), the key native tree of the Thar desert and dry north-western India, is extremely drought-hardy with a very deep tap root, slow-growing, and valued for fodder from lopped leaves, pods (sangri), fuel and soil improvement in agroforestry fields. Seeds are scarified and sown in containers, and plants are protected from browsing for several years; regeneration in fields is often from root suckers and natural seedlings protected by farmers. Prosopis juliflora (mesquite), introduced from the Americas, grows fast on saline, alkaline, degraded and dry land, coppices vigorously and spreads by seed dispersed by livestock. It has been planted for fuel and land reclamation but has become invasive, reducing grazing land and native vegetation; management now combines harvesting for fuel and charcoal with control in sensitive areas.
Anjan (Hardwickia binata) is a tall, graceful, deciduous legume of dry deciduous forests in peninsular India, on shallow, rocky and red soils. It develops a long tap root early and grows slowly above ground at first, so it is raised by direct sowing in situ or in tall containers, and protected from grazing. It is lopped for fodder and yields very hard, heavy timber. Dhaura (Anogeissus latifolia) of dry deciduous forests coppices well and produces gum ghatti; its tiny winged seeds have low viability. Kardhai (Anogeissus pendula) forms open forests on rocky hills in the Aravallis and Bundelkhand and is regenerated by protection and coppice. Other dry-zone species include rohida (Tecomella undulata), ber (Ziziphus mauritiana), Balanites aegyptiaca, Salvadora, Albizia lebbeck and neem. Dry-zone silviculture depends on drought-hardy species, water harvesting, larger pits, protection from grazing, and timing planting to the short rainy season, as described in nursery and plantation establishment.
Rohida (Tecomella undulata) is a valuable timber tree of the Thar desert and adjoining dry regions, tolerant of drought, heat and sandy soils, with showy orange-yellow flowers; its seed is sown fresh, as viability is short, and seedlings are raised in containers and protected from browsing. It is threatened by overexploitation and poor regeneration. Ber (Ziziphus mauritiana) is a hardy fruit and fodder tree that coppices and is widely budded with improved fruit varieties in dryland horticulture; wild forms are used as rootstocks. Other species used in dry-zone afforestation include Acacia tortilis (now Vachellia tortilis), introduced from Africa for sand-dune stabilisation; Colophospermum mopane, introduced from southern Africa; Balanites aegyptiaca; Salvadora persica and S. oleoides on saline soils; Capparis decidua; and Azadirachta indica. Choice of species follows rainfall, soil and the needs of local people for fodder and fuel.
Chir pine (Pinus roxburghii) forms extensive forests in the subtropical Himalaya, roughly between about 500 and 2,000 metres, on dry, shallow and rocky slopes. It is a strong light demander, frost-hardy and highly fire-resistant when older, with thick bark; its cones take about two years to mature and release winged seeds. It is regenerated naturally under the uniform shelterwood system with seed bearers, protection from fire and grazing for some years after regeneration, and later controlled burning to reduce fuel; it is also planted from container seedlings. Chir pine is tapped for resin and its wood is used for construction and packing. Its needle litter is highly flammable and fires are frequent; it also spreads into degraded oak forests. Blue pine (Pinus wallichiana) grows in the temperate zone, roughly 1,800 to 3,000 metres, is a light demander, regenerates freely on open and disturbed ground and is used for timber.
Deodar (Cedrus deodara) grows in the western Himalaya, roughly 1,500 to 3,000 metres, in areas of moderate rainfall and winter snow, on well-drained soils. It is moderately shade-tolerant when young, needing some shelter from frost, drought and weeds, and a light demander later. It regenerates naturally under shelterwood systems in seed years and is raised in nurseries and planted; its durable, fragrant timber is the classic building wood of the western Himalaya. Silver fir (Abies pindrow) and spruce (Picea smithiana) grow in cooler, moister sites at higher elevations; both are shade-tolerant, regenerate under shelter, and have been managed under shelterwood and selection; regeneration of fir is often difficult because of grazing, dense undergrowth and irregular seed years. Since the ban on green felling in many Himalayan states, these forests are managed mainly for protection, salvage and regeneration. Exotic conifers planted in the southern hills include Pinus patula and P. kesiya, and Cryptomeria japonica is planted in the eastern Himalaya.
Several other conifers are grown in Indian forestry. Pinus patula, from Mexico, and Pinus kesiya (Khasi pine), native to the North-East, have been planted in the Nilgiris, the Palnis and other southern hills and in the North-East for pulpwood and timber; Pinus caribaea has been tried on tropical sites. Cupressus torulosa (Himalayan cypress) is planted on limestone and other sites in the western Himalaya, and Cupressus lusitanica in the southern hills. Cryptomeria japonica, introduced to the Darjeeling hills in the nineteenth century, is widely planted there and in Sikkim. Exotic conifer plantations on montane grasslands of the southern hills have been criticised for replacing species-rich shola-grassland ecosystems and reducing water yield, and some are now being removed in restoration programmes.
Oaks are the most important broadleaves of the Himalayan temperate forests and support village life through fodder, fuel, leaf litter for fields, and water-holding forest soils. Ban oak (Quercus leucotrichophora) occupies lower temperate slopes, moru oak (Q. floribunda) middle elevations and kharsu oak (Q. semecarpifolia) the upper temperate belt near the treeline. Oaks are moderately shade-tolerant, regenerate from acorns and coppice and pollard well. Acorns are recalcitrant, germinating soon after falling and losing viability if dried, so they are sown fresh in the nursery or directly in the field. Regeneration of oak forests has declined in many areas because of heavy lopping for fodder, grazing, collection of litter, fire and the spread of chir pine onto oak sites; protection, controlled lopping, community management through van panchayats in Uttarakhand, and planting of nursery-raised oak seedlings are used to restore them.
Himalayan alder (Alnus nepalensis) is a fast-growing, nitrogen-fixing pioneer of landslides and moist slopes, used for stabilisation, in agroforestry with crops such as large cardamom in Sikkim, and for fuel and timber. Walnut (Juglans regia) is grown for nuts and valuable timber. Indian horse chestnut (Aesculus indica), maples, elms, Celtis australis (hackberry, an important fodder tree), Himalayan birch (Betula utilis) near the treeline, and rhododendrons are other components of temperate forests. Outside South Asia, the temperate broadleaves of Europe and North America, such as oaks, beech, ash and maples, are managed under shelterwood, group and selection systems, and quality timber production relies on careful thinning and, for oaks, protection from epicormic shoots, as discussed in stand tending.
Bamboos can be propagated by seed, by vegetative means and by tissue culture. Seed is available only after flowering, which in many species is gregarious and occurs at long intervals, and bamboo seed generally loses viability within months, so seed propagation is opportunistic; seedlings are raised in beds or containers. Vegetative methods are used routinely: offsets or rhizome cuttings, consisting of a rhizome with the base of a culm, are the traditional method for clump-forming bamboos but are bulky and limited in number; culm cuttings, segments of culm with one or more nodes bearing buds, and branch cuttings, especially from the thickened base of branches, are rooted in nursery beds, often with rooting hormones; and macroproliferation, the repeated division of seedlings or rooted plants into smaller units each with rhizome, roots and shoot, multiplies planting stock quickly. Tissue culture (micropropagation) produces large numbers of plants of selected clones and is used commercially for species such as Dendrocalamus asper and Bambusa balcooa. Plants raised from the vegetative parts of a clump will flower when the parent clump flowers, which matters for planning.
Bamboos are planted at the onset of the rains in pits, at spacings depending on the species and purpose, commonly 4 × 4 to 6 × 6 metres or more for large clumping species, and protected from grazing and fire. The first harvestable culms appear after a few years. In natural and planted stands, clumps are managed on a felling cycle of a few years: only mature culms, usually at least three years old, are cut; current-year and second-year culms are left; a minimum number of culms is retained in each clump; culms are cut low, just above the first or second node; and congested clumps are cleaned of dead, broken and malformed culms. Working plans in India often prescribe a bamboo overlapping working circle with such rules. After gregarious flowering and death, regeneration from seed is protected and supplemented by planting. Bamboo resources, processing and uses are described in non-timber forest products, and identification in dendrology.
Douglas-fir (Pseudotsuga menziesii) of western North America is one of the world's most important timber conifers. It is moderately shade-tolerant when young on some sites but generally regenerates best in openings, and in the Pacific Northwest it has been managed by clear felling and planting, with thinning and rotations commonly of about 40 to 80 years; retention and longer rotations are now used on public lands. It is planted in Europe, New Zealand and Chile. Loblolly pine (Pinus taeda) is the main plantation species of the south-eastern United States, managed intensively with improved seedlings from several generations of breeding, site preparation, herbicide competition control, fertilisation with nitrogen and phosphorus, thinning, and rotations of roughly 20 to 35 years; it is a classic example of how genetics and silviculture together have raised plantation productivity.
Pinus radiata, native to a few sites in California and Mexican islands, is the main plantation species of New Zealand and Chile and important in Australia and Spain, grown on rotations of roughly 25 to 30 years. New Zealand developed intensive regimes combining improved breeds, wide initial spacing, early heavy thinning and pruning of selected crop trees in successive lifts to produce clearwood, as described in stand tending. Its main threats include needle diseases such as Dothistroma. Spruces are central to northern forestry: Norway spruce (Picea abies) in central and northern Europe, often in even-aged plantations that have suffered heavy losses to storms, drought and bark beetles in recent years, prompting conversion to mixed forests; Sitka spruce (Picea sitchensis), native to the Pacific coast of North America, is the most planted timber tree in Britain and Ireland; and white and black spruce dominate managed boreal forests in Canada. These species illustrate the global themes of plantation forestry: matching species to site, genetic improvement, intensive establishment, and the growing need to manage risks from climate change, pests and storms.
The choice of bamboo species depends on purpose and site. Dendrocalamus strictus is planted in dry areas and on poor soils for poles and pulp; Bambusa bambos and Bambusa tulda on moister sites for construction and pulp; Dendrocalamus asper and D. giganteus for large culms and edible shoots; Bambusa balcooa and Dendrocalamus hamiltonii in the North-East for construction; and Bambusa vulgaris and its yellow forms for ornamental and general use. Thin-walled species are favoured for weaving and crafts, thick-walled ones for structural use. Because many bamboos flower gregariously, planting a mixture of species or clones of different flowering cohorts reduces the risk of a whole plantation flowering and dying at once.
A student should be able to write, for each important species, its distribution, climate and soil, silvicultural characters, phenology, seed and pre-treatment, natural and artificial regeneration, nursery and planting technique, tending, rotation, pests and diseases, and uses, in the standard order expected in examinations, and to compare species for a given site and objective. Visits to nurseries, plantations and natural forests of key species fix the facts.
A forester five years into practice chooses species for planting sites, raises their nursery stock correctly, times planting to their requirements, protects plantations from their known pests and diseases, prescribes tending and harvest according to their growth, advises farmers on agroforestry species such as poplar, eucalyptus, Melia dubia and bamboo, and manages natural regeneration of species such as sal, chir pine and deodar.
A senior forester sets species policy for a division, state or company: deciding which native and exotic species to plant where, balancing productivity with risks from pests, invasiveness, water use and climate change, guiding research on clones and improved seed, and revising silvicultural prescriptions in working plans as new knowledge accumulates.
A researcher studies the silvics and silviculture of key species: regeneration ecology, nutrition and water use, genotype by environment interaction of clones, pest and disease dynamics, growth and yield, and adaptation to climate change. Such work updates the species-by-species knowledge on which plantation and natural forest management rely.
This manual summarises the silviculture of representative species; it does not give the full detail of Troup's or Luna's accounts, local yield tables, clone recommendations or state-specific prescriptions, which should be consulted for practice. Rainfall and elevation ranges, spacings and rotations are typical values that vary widely with site, purpose and genetic material. Many regionally important species (for example Terminalia, Lagerstroemia, Michelia, Toona, Bombax, mangroves and many tropical species outside India) are not covered individually. Pest and disease control measures are described in principle; chemical recommendations belong to forest entomology and pathology and to current label approvals.
Original practice questions written to the syllabus and pattern of the exams named in each question's examTags. They are not past papers and do not reproduce any board's questions.
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