Forestry BBO5T12

Syllabus topics (RTMNU)

• Silviculture – General: General silvicultural principles: ecological and physiological factors influencing vegetation, natural and artificial regeneration of forests
• Silviculture systems: Management of silviculture systems of temperate and tropical with special reference to plantation silviculture
• Silviculture – Mangrove and Cold desert: Mangrove: Habitat and characteristics, silvicultural systems for mangrove. Cold desert – characteristics, identification and management of species
• Silviculture of trees: Acacia catechu, Anogeissus latifolia, Butea monosperma, Shorea robusta, Tectona grandis

General silvicultural principles

Silviculture is the art and science of establishing, growing and tending forest crops — controlling their composition, structure and growth to meet human needs.

Ecological factors influencing vegetation:

• Climatic: rainfall (amount and distribution decide forest type — evergreen above about 2,000 mm, moist deciduous, dry deciduous, thorn forest below about 700 mm), temperature (frost kills sal and teak seedlings), light (light-demanders like teak, khair vs shade-bearers like many evergreen species), wind, humidity.
• Edaphic (soil): depth, texture, drainage, pH, fertility, moisture — teak needs deep, well-drained soil; sal avoids waterlogging.
• Topographic: altitude, aspect (north vs south slopes), slope.
• Biotic: grazing, browsing, fire, lopping, human interference, insects and fungi, competing weeds.

Physiological factors: photosynthesis and light requirement, water relations (drought tolerance), seed dormancy and viability, germination needs, phenology (flowering/seeding years), root development and nutrient uptake, mycorrhizal association, capacity to coppice or produce root suckers.

Natural and artificial regeneration

• Natural regeneration: renewal of the forest by natural means — (a) from seed falling from standing trees (sal, deodar); (b) vegetative — coppice shoots from stumps (teak, khair, eucalyptus), root suckers (palas, Dalbergia sissoo). Cheap, uses local adapted stock, but slow and uncertain.
• Artificial regeneration: renewal by human effort — direct sowing of seed (broadcast, line, dibbling, patch sowing), or planting of nursery-raised seedlings, stumps (root-shoot cuttings, e.g. teak stumps), cuttings, or tissue-culture plants. Steps: species choice, nursery, site preparation, planting at proper spacing in monsoon, weeding, protection (fencing, fire lines), casualty replacement. Gives quick, uniform, high-yield crops (plantations).

Silvicultural systems — temperate and tropical; plantation silviculture

A silvicultural system is the process by which a forest crop is tended, removed and replaced, producing a crop of a distinctive form.

Temperate forests (Himalaya): shelterwood and selection systems for deodar, blue pine, fir and spruce; slow growth, long rotations (100–150 years); snow and slope problems. Tropical forests: selection or selection-cum-improvement felling in evergreen forests; clear-felling and plantation for teak; coppice for fuelwood; the taungya system (from Burma, Brandis 1856) — farmers raise agricultural crops between young tree rows for the first 2–3 years, keeping the plantation weed-free.

Plantation silviculture: raising even-aged crops of fast-growing or valuable species (teak, eucalyptus, poplar, casuarina, bamboo, acacia) — site selection, improved seed/clones, nursery (polybags, root trainers), spacing (e.g. 2 × 2 m, 3 × 3 m), fertiliser, weeding, cleaning, thinning, pruning, protection, and harvest at rotation age. High yield per hectare but risk of pests in monocultures.

Silviculture of mangroves

Habitat: tidal, saline, muddy coasts and estuaries in the tropics; daily flooding, poorly aerated soil. India: Sundarbans (West Bengal), Bhitarkanika (Odisha), Pichavaram (Tamil Nadu), Andaman–Nicobar, Gujarat coast, Konkan (Maharashtra).

Characteristics: evergreen halophytes — Rhizophora, Avicennia, Bruguiera, Sonneratia, Heritiera fomes (sundari), Ceriops, Excoecaria; stilt roots, pneumatophores (breathing roots), vivipary (seeds germinate on the parent tree), salt glands/salt exclusion, thick succulent leaves. Functions: coastal protection from cyclones and tsunami, fish nursery, carbon storage.

Silvicultural systems: natural regeneration by propagules is good where tidal flushing exists; historically coppice-with-standards and selection felling with felling cycles were used for fuel and poles (e.g. Sundarbans). Today the aim is conservation and restoration: planting propagules/nursery seedlings of Rhizophora and Avicennia at the right tidal level, the fishbone canal method (developed at Pichavaram) to restore tidal flow in degraded areas, protection from cutting, grazing and aquaculture conversion, community participation.

Silviculture of cold desert

Characteristics: trans-Himalayan Ladakh, Lahaul–Spiti and parts of Kinnaur; altitude about 3,000–5,000 m; very low rainfall (often below 150 mm, mostly as snow), extreme cold (−30 °C or lower), strong winds, intense UV, thin sandy soils, short growing season (May–September); natural tree cover is very sparse.

Identification and management of species: species tolerant of cold, drought and wind — willows (Salix), poplars (Populus), seabuckthorn (Hippophae rhamnoides — soil binding, nitrogen-fixing, vitamin-C-rich fruit), junipers (Juniperus), Robinia pseudoacacia, Elaeagnus, elm (Ulmus), Myricaria, Caragana. Management: plantations along irrigation channels (kuhls) using cuttings of willow and poplar; nurseries in polyhouses/greenhouses; protection from grazing (fencing); planting in pits with organic manure; windbreaks; soil conservation; harvest of fuelwood and fodder on rotation; community participation.

Silviculture of economically important Indian species

Likely exam questions

1. (Long, 8 marks) What is silviculture? Explain the ecological factors influencing vegetation and the methods of natural and artificial regeneration.
2. (Long, 8 marks) Describe the silviculture of Tectona grandis and Shorea robusta.
3. (Short, 4 marks) Write a note on mangrove silviculture.
4. (Short, 4 marks) What is the taungya system?
5. (Short, 4 marks) Describe the characteristics of cold desert and species suitable for it.

Syllabus topics (RTMNU)

• Agroforestry: Scope and necessity; role in the life of people and domestic animals and in integrated land use. Selection of species and role of multipurpose trees
• Social/Urban Forestry: Objectives, scope and necessity; people's participation
• Tribology: Tribes in Vidarbha; cultural tradition, customs and participation in forestry programmes
• Forest Management: Role of forests in conserving soils. Maintenance and buildup of soil organic matter. Concepts of watershed, watershed management and environmental functions of forests
• Environment Conservation: Principles of conservation, impact of deforestation; forest fires and various human activities and man-animal conflict

Agroforestry — scope and necessity

Agroforestry is a land-use system in which trees/shrubs are deliberately grown on the same land with agricultural crops and/or animals, in a spatial or time sequence, with ecological and economic interaction between them.

Systems: agri-silviculture (trees + crops, e.g. poplar with wheat, teak/subabul with crops), silvi-pastoral (trees + pasture/livestock), agri-silvi-pastoral, horti-silviculture (fruit trees + forest trees), home gardens, boundary/bund plantation, alley cropping, windbreaks and shelterbelts.

Necessity and scope in India: forest cover is below the national goal of 33% of land area; rising demand for fuelwood, fodder, timber and small wood can be met from farms; farmers get extra income and risk insurance; reduces pressure on natural forests; combats soil erosion and degraded land. National Agroforestry Policy (2014) supports it.

Role in the life of people, domestic animals and integrated land use

• People: fuelwood, timber, poles, fruits, fibre, medicines, gums, employment, cash income; shade and shelter.
• Domestic animals: leaf fodder in the dry season (subabul, Ailanthus, neem, Ficus, Albizia, Acacia nilotica pods), shade, grazing on silvi-pastures.
• Integrated land use: trees improve soil fertility (leaf litter, nitrogen fixation by legumes), conserve soil and water, act as windbreaks, recycle nutrients from deep layers, store carbon, support biodiversity; land produces several products at once — sustainable and diversified farming.

Selection of species and role of multipurpose trees (MPTs)

Criteria: fast growth; deep tap root (less competition with crops); light, open crown; tolerance to lopping and coppicing; nitrogen-fixing ability; provides more than one product; adapted to local climate and soil; acceptable to farmers; no allelopathic effect on crops; marketable products.

Multipurpose trees give several products and services: Leucaena leucocephala (subabul — fodder, fuel, pulpwood, green manure), Gliricidia sepium (green manure, live fence), Azadirachta indica (neem — timber, oil, pesticide, shade), Acacia nilotica (babul — fuel, gum, fodder, tannin), Dalbergia sissoo, Melia dubia, Populus deltoides (poplar), Eucalyptus, Casuarina, bamboo, Moringa oleifera (drumstick), Prosopis cineraria (khejri).

Social / urban forestry

Social forestry (term used by the National Commission on Agriculture, 1976) means raising trees on public and community lands, farms and along roads, canals and railways, by and for the people, to meet their needs of fuel, fodder, small timber and to improve the environment.

• Components: farm forestry, community/village woodlots, extension forestry (strip plantations along roads, canals, railway lines), rehabilitation of degraded forests, recreation forestry.
• Urban forestry: planting and managing trees in cities — avenue trees, parks, green belts, institutional campuses; reduces pollution, dust, noise and heat island effect; aesthetic and recreation value. Species: neem, peepal, banyan, gulmohar, karanj, kadamb, jamun.
• Objectives: meet rural needs of fuel, fodder, small timber; reduce pressure on forests; generate rural employment; improve environment and land; involve people.
• People's participation: village panchayats/forest committees, distribution of free/subsidised seedlings, school nurseries, women's groups, sharing of benefits (usufruct rights). Success depends on people's sense of ownership.

Tribology — tribes in Vidarbha, culture and participation in forestry

(Here "tribology" means the study of tribal communities in relation to forests.) Vidarbha has a large tribal population, especially in Gadchiroli, Chandrapur, Gondia, Bhandara, Yavatmal, Nagpur and Amravati (Melghat) districts.

• Major tribes: Gond (largest group), Madia (Madia Gond) and Pardhan in Gadchiroli–Chandrapur; Korku in Melghat (Amravati); Kolam and Andh in Yavatmal; Halba in Gondia/Bhandara; Gowari and Banjara communities also depend on forests.
• Cultural traditions and customs: worship of nature and forest deities (Gond deity Persa Pen); sacred groves (devrai/devrahati) where no tree is cut; youth dormitory ghotul among Madia/Gond; festivals linked to crops and forests — Dandar, Pola, Diwali dances, Holi; folk dances (Rela, Dhemsa); traditional healers using medicinal plants; shifting cultivation was practised earlier; collection of mahua, tendu leaves, honey, bamboo is central to their economy.
• Participation in forestry programmes: Joint Forest Management committees, Sant Tukaram Vangram Yojana (Maharashtra), tendu and bamboo collection, fire protection, plantation work. Under the Forest Rights Act 2006, gram sabhas got Community Forest Resource rights — Mendha-Lekha (Gadchiroli) was among the first villages to get community rights and to sell its own bamboo; many villages now manage tendu and bamboo trade themselves. PESA (1996) also strengthens gram sabhas in scheduled areas.

Forest management — role of forests in conserving soil

• Canopy intercepts rain and breaks the force of raindrops (reduces splash erosion).
• Leaf litter and undergrowth protect the soil surface, slow runoff and increase infiltration.
• Roots bind soil and stabilise slopes, preventing landslides and gully formation; windbreaks reduce wind erosion in dry areas.
• Forests reduce siltation of reservoirs and rivers.

Maintenance and build-up of soil organic matter: continuous litter fall and root turnover add organic matter; decomposition by soil fauna and microbes forms humus that improves soil structure, water holding and nutrient supply; nitrogen-fixing trees add N; practices — leaving litter and slash, avoiding burning, mulching, mixed planting, controlled grazing.

Watershed and watershed management

A watershed (catchment) is the area of land that drains all its water to a common outlet such as a stream, river or reservoir, bounded by a ridge line. Watershed management is the planned use of land, water and vegetation in a watershed to conserve soil and water and improve production sustainably with people's participation.

Measures: ridge-to-valley approach — afforestation and pasture on upper slopes, contour trenches, bunds, terracing, gully plugs, check dams, percolation tanks, farm ponds, vegetative barriers (vetiver), agroforestry on farm lands. Examples: Ralegan Siddhi and Hiware Bazar (Maharashtra); Jalyukt Shivar Abhiyan.

Environmental functions of forests

Climate regulation and carbon sequestration; oxygen release; rainfall and hydrological cycle regulation (recharge of groundwater, steady stream flow); soil conservation; habitat for biodiversity and wildlife; pollution and noise reduction; moderating temperature; flood control; recreation and cultural value; livelihoods.

Environment conservation — principles and threats

Principles of conservation: sustainable use (use no more than the forest can regenerate), protection of biodiversity and habitats (in-situ — national parks, sanctuaries, biosphere reserves; ex-situ — botanical gardens, seed banks), restoration of degraded lands, precautionary principle, people's participation and equitable benefit sharing, legal protection (Indian Forest Act 1927, Wildlife (Protection) Act 1972, Forest (Conservation) Act 1980, Biological Diversity Act 2002).

• Impact of deforestation: soil erosion and loss of fertility, floods and droughts, siltation, loss of biodiversity and extinction, climate change (CO₂ release), lowering of water table, loss of tribal livelihoods, desertification.
• Forest fires: mostly man-made (burning for mahua collection, grazing grass, carelessness); effects — loss of regeneration, humus and wildlife, soil exposure, air pollution. Control: fire lines, early (controlled) burning, fire watchers, community participation, satellite fire alerts.
• Human activities: encroachment, over-grazing, illegal felling, mining, dams, roads, shifting cultivation, over-extraction of NTFPs.
• Man–animal conflict: crop raiding and attacks by tigers, leopards, elephants, wild boar and bears as habitats shrink and fragment — a serious issue around Tadoba–Andhari and Brahmapuri (Chandrapur). Remedies: corridors, habitat improvement (water, prey base), solar fencing, early warning, quick compensation, awareness, relocation of villages with consent.

Likely exam questions

1. (Long, 8 marks) What is agroforestry? Explain its scope, necessity and the role of multipurpose trees.
2. (Long, 8 marks) Describe the major tribes of Vidarbha, their culture and their participation in forestry programmes.
3. (Short, 4 marks) Define watershed. Write the measures of watershed management.
4. (Short, 4 marks) What is social forestry? Give its components.
5. (Short, 4 marks) Write the impact of deforestation.

Syllabus topics (RTMNU)

• Forest Management and Management Systems: Objective, principles and techniques; Joint Forest Participatory Management. Concept of tree improvement
• Forest Working Plan: Forest planning, evaluation and monitoring tools and approaches for integrated planning
• Forest Mensuration: Methods of measuring diameter, girth, height and volume of trees; Sampling methods and sample plots
• Remote Sensing: Concept and use of remote sensing

Forest management — objectives, principles and techniques

Forest management is the application of scientific, economic and social principles to the administration and working of a forest for specified objectives.

Objectives: sustained yield of timber, fuel and NTFPs; conservation of soil, water and biodiversity; meeting local needs; revenue; recreation; climate (carbon) benefits. India's National Forest Policy (1988) gives first priority to environmental stability and ecological balance, and to meeting the needs of local and tribal people.

Principles: (1) sustained yield — harvest only the growth (annual increment); (2) normal forest concept — equal areas of all age classes so equal annual yield; (3) multiple use; (4) economy and efficiency; (5) protection; (6) people's participation; (7) adaptive management based on monitoring.

Techniques: division of the forest into working circles, compartments and coupes; fixing rotation (age of harvest), felling cycle and annual yield (by area or volume — e.g. Von Mantel's formula Y = 2G/R, where G = growing stock and R = rotation); prescribing silvicultural systems, thinning, regeneration and protection; record keeping (control forms, compartment histories).

Joint Forest (Participatory) Management (JFM)

JFM is a partnership between the Forest Department and local village communities to protect and regenerate forests and share the benefits. Origin: the Arabari experiment (West Bengal, early 1970s) where villagers protected sal forest in return for a share of produce; Government of India JFM circular of 1 June 1990.

• A Forest Protection/Joint Forest Management Committee (JFMC) is formed in the village, often under the gram sabha, with women members.
• Villagers protect the forest from fire, grazing and illicit felling, and help in plantation work.
• In return they get free NTFPs, grass and fuelwood, and a share (often 25–50% or more, varying by state) of final timber/bamboo harvest; funds for village development.
• Maharashtra adopted JFM in 1992; the Sant Tukaram Vangram Yojana rewards good JFM villages.

Benefits: forest regeneration, reduced conflict, livelihoods, people's ownership. Problems: unequal benefit sharing, weak legal status, dependence on officials.

Concept of tree improvement

Tree improvement is the application of genetics and breeding to forestry to produce trees with better growth, form, wood quality and resistance. Steps: selection of plus trees (superior phenotypes) in natural stands → provenance trials (testing seed sources) → seed production areas and seed orchards (clonal or seedling) → progeny testing → hybridisation (e.g. eucalyptus hybrids, poplar clones) → vegetative/clonal propagation (cuttings, grafting, tissue culture) → biotechnology (marker-assisted selection, genetic engineering). Example: clonal eucalyptus and teak plantations giving much higher yields.

Forest working plan

A working plan is a written scheme of management for a forest division for a fixed period (usually 10 years), prepared according to the National Working Plan Code (latest code issued by the Ministry of Environment, Forest and Climate Change — check latest version) and approved by the government.

• Part I — Summary of facts: the tract (location, geology, soil, climate), forest types and composition, growing stock, past management and its results, rights and concessions, socio-economic conditions, statistics of yield and revenue.
• Part II — Future management: objectives, division into working circles (each with its own silvicultural system, e.g. teak plantation WC, coppice WC, protection WC, bamboo overlapping WC, NTFP WC, JFM WC), rotation, felling cycle, calculation of yield, felling series, regeneration and tending prescriptions, protection, establishment and finance; maps.

Forest planning, evaluation and monitoring tools; integrated planning: stock mapping and enumeration surveys; GIS and remote sensing maps; growth and yield models; permanent sample plots for monitoring increment; control forms and compartment histories; mid-term review and deviation statements; Criteria and Indicators for Sustainable Forest Management (Bhopal–India process); integrated planning combines silviculture, wildlife, soil and water conservation, NTFP, people's needs and microplans of JFM villages in one plan with stakeholder consultation.

Forest mensuration — diameter, girth, height and volume

Forest mensuration deals with the measurement of trees, logs and stands to estimate volume, growth and yield.

• Diameter at breast height (DBH): measured at 1.37 m (4′6″) above ground in India (1.3 m in many countries), on the uphill side on slopes, over bark. Instruments: calipers (fixed and movable arm), diameter tape (graduated in π units), Biltmore stick.
• Girth = circumference at breast height, measured with a tape; diameter = girth/π.
• Height: measured with hypsometers — based on similar triangles (Christen's hypsometer, Ravi multimeter) or trigonometry (Abney's level, Haga altimeter, Blume–Leiss, clinometer, laser rangefinders). By trigonometry, height = horizontal distance × (tan α_top + tan α_base) when the base is below eye level.
• Basal area g = πd²/4 (cross-sectional area at breast height).
• Volume of a standing tree = basal area × height × form factor (ratio of actual volume to volume of a cylinder of same basal area and height; often about 0.4–0.6).
• Volume of logs: Huber's formula V = A_m × L (mid area); Smalian's V = (A₁ + A₂)/2 × L (end areas); Newton's V = (A₁ + 4A_m + A₂)/6 × L (most accurate); quarter-girth formula used in Indian timber trade V = (g/4)² × L (g = mid-girth) — gives about 78.5% of true volume (allowance for wastage). Volume tables are also used.

Example 1. DBH = 40 cm, height = 20 m, form factor = 0.5. Basal area = π × 0.4²/4 = 0.1257 m²; volume = 0.1257 × 20 × 0.5 = 1.257 m³.

Example 2. Log 4 m long with end diameters 30 cm and 40 cm (Smalian): A₁ = 0.0707 m², A₂ = 0.1257 m²; V = (0.0707 + 0.1257)/2 × 4 = 0.393 m³.

Sampling methods and sample plots

Measuring every tree in a large forest is impossible, so a sample is measured and the results are expanded. Intensity of sampling is often 0.5–10% of the area.

• Simple random sampling — plots chosen at random (each unit equal chance).
• Systematic sampling — plots at regular intervals along lines/grid (easy in the field; commonly used).
• Stratified sampling — forest divided into strata (forest type, density, age) and sampled separately — more precise.
• Multistage/cluster sampling and point sampling (Bitterlich angle-count method for basal area).

Sample plots: circular, square or rectangular plots (e.g. 0.1 ha) or strips (line transects). Temporary sample plots are measured once for inventory; permanent sample plots are marked and re-measured periodically to study growth, increment and effect of treatments.

Remote sensing — concept and use in forestry

Remote sensing is obtaining information about the earth's surface without contact, by recording reflected or emitted electromagnetic radiation with sensors on satellites, aircraft or drones. Healthy vegetation absorbs red light and strongly reflects near-infrared (NIR), so it appears bright in NIR images and red in false colour composites. NDVI = (NIR − Red)/(NIR + Red), ranging from −1 to +1; higher values = denser green vegetation.

Platforms/sensors: Indian Remote Sensing satellites (Resourcesat — LISS-III, LISS-IV, AWiFS; Cartosat), Landsat, Sentinel-2, MODIS; LiDAR and drones for canopy height. Combined with GIS and GPS for mapping.

Uses: forest cover and type mapping (the Forest Survey of India's biennial India State of Forest Report uses satellite data), change detection and deforestation monitoring, forest fire detection and alerts, estimating growing stock and biomass/carbon, mapping mangroves and wetlands, wildlife habitat and corridor planning, working plan preparation, watershed planning, monitoring plantations and encroachment.

Likely exam questions

1. (Long, 8 marks) What is forest mensuration? Explain the methods of measuring diameter, height and volume of trees.
2. (Long, 8 marks) What is Joint Forest Management? Explain its principles, working and benefits.
3. (Short, 4 marks) What is a working plan? Give its main parts.
4. (Short, 4 marks) Write a note on remote sensing in forestry.
5. (Short, 4 marks) Calculate the volume of a tree with DBH 30 cm, height 15 m and form factor 0.5.

Syllabus topics (RTMNU)

• Forest Resources and Utilization: Environmentally sound forest harvesting practices; logging and extraction technique
• Non-Timber Forest Products (NTFPs) – definition and scope; Commercial importance of NTFPs like Gums, Mahua flower and Bidi leaves
• Need and importance of wood seasoning and preservation
• Forest Protection and Wildlife Biology: Role of afforestation and effect of wild animals on forest regeneration and human impacts
• Forest economics: Fundamental principles, cost-benefit analyses; estimation of demand and supply; Socio-economic analysis of forest productivity and attitudes; valuation of forest goods and services

Environmentally sound forest harvesting practices

Harvesting must remove produce while protecting soil, water, regeneration and wildlife (often called reduced impact logging).

• Fell only marked trees as prescribed in the working plan; keep within the annual yield (sustained yield).
• Directional felling away from regeneration, streams and other trees; low stumps.
• Leave buffer strips along streams and on steep slopes; avoid felling in the rainy season.
• Plan skid trails and roads to minimise soil disturbance; use cable or animal skidding on slopes.
• Retain seed trees, wildlife trees (with hollows, fruiting trees) and some dead wood.
• Prompt regeneration after felling; debris used or spread, not burnt carelessly.
• Certification of sustainable management (e.g. FSC, PEFC schemes).

Logging and extraction techniques

Logging is the felling of trees and conversion into logs, and extraction is moving them from the stump to a road or depot.

1. Felling: with axes, cross-cut saws or chain saws; a notch (undercut) on the side of fall, then the back cut.
2. Conversion: de-limbing (removing branches), cross-cutting into logs of standard lengths, sometimes debarking and sawing into sleepers/scantlings at site.
3. Extraction (skidding/yarding): manual (rolling, carrying), animal power (elephants, buffaloes, bullocks), tractors and skidders, cable systems and ropeways in hills, timber slides and chutes, water transport (floating and rafting along rivers).
4. Transport: by trucks/carts to depots; logs stacked, numbered and sold by auction.

Non-timber forest products (NTFPs) — definition and scope

NTFPs (minor forest produce) are all biological products other than timber obtained from forests — leaves, flowers, fruits, seeds, gums, resins, lac, tannins, honey, fibres, bamboo and canes, medicinal plants, grasses, mushrooms. Scope: about 275 million rural people in India depend on forests to some extent, and NTFPs provide a large share of the income of tribal households; they are collected without cutting trees and can be sustainable. Under the Forest Rights Act 2006 ownership of minor forest produce rests with forest-dwelling communities; Minimum Support Price for MFP schemes support collectors.

Commercial importance of gums, mahua flower and bidi leaves

• Gums: exudates obtained by tapping (blazing) the bark. Gum karaya (Sterculia urens) — India is a leading producer, used in food (stabiliser), pharmaceuticals, dentures adhesive; gum ghatti (Anogeissus latifolia, dhawda) — emulsifier; babul gum (Acacia nilotica) and khair gum; Butea gum (Bengal kino). Uses in food, textiles, paper, cosmetics, medicines; collection gives income in the summer season. Over-tapping can kill trees, so scientific tapping is needed.
• Mahua flower (Madhuca longifolia var. latifolia, Sapotaceae): fleshy, sugar-rich corollas fall in March–April and are collected from the ground; eaten fresh or dried, used as cattle feed, fermented to make liquor; seeds give mahua oil (cooking, soap). A major source of income and food security for tribals of central India; Maharashtra eased restrictions on mahua collection and trade. Problem: ground fires lit to clear leaf litter for collection.
• Bidi (tendu) leaves (Diospyros melanoxylon, Ebenaceae): leaves are used to roll bidis. Bushes are pruned (coppiced) before the season to get tender leaves, plucked in April–May, tied in bundles (standard bags) and sun-dried. Maharashtra (Vidarbha), Madhya Pradesh, Chhattisgarh and Odisha are major producers. It gives seasonal employment to lakhs of people; trade was a state monopoly and is now increasingly sold by gram sabhas holding community rights.

Need and importance of wood seasoning and preservation

Seasoning is the controlled drying of wood to reduce its moisture content to a level suited to its use (about 12–15% for furniture). Fresh wood may contain 50–100% or more moisture.

• Need: reduces weight (cheaper transport); improves strength, hardness and stiffness; prevents shrinkage, warping, splitting and cracking after use; makes wood resistant to fungi and insects; makes it ready for gluing, painting and preservative treatment.
• Methods: air (natural) seasoning — stacked with spacers under shade, takes months; kiln (artificial) seasoning — controlled heat, humidity and air circulation, takes days; solar kilns, water seasoning, chemical seasoning.

Preservation is treating wood with chemicals to protect it from fungi (decay), insects (termites, borers) and marine borers, increasing its service life several times. Preservatives: oil-type (creosote), water-soluble (CCA — copper-chrome-arsenic, called ASCU in India; boric acid–borax), organic solvent types. Methods: brushing/spraying, dipping and soaking, hot and cold bath (open tank), and pressure methods — full-cell (Bethell) and empty-cell (Rueping, Lowry). Uses: railway sleepers, poles, fencing posts, building timber; allows use of less durable species.

Forest protection and wildlife biology

Role of afforestation: increases forest/tree cover, restores degraded land, controls soil erosion and floods, recharges groundwater, sequesters carbon, provides fuel and fodder (reducing pressure on natural forests), creates habitats and corridors for wildlife and employment (e.g. Green India Mission, CAMPA-funded plantations — check latest schemes).

Effect of wild animals on forest regeneration:

• Negative: browsing and grazing by deer (chital, sambar), nilgai, gaur and elephants damage seedlings and saplings; debarking by elephants and porcupines; seed eating by rodents, squirrels, wild boar (which also uproot seedlings); high herbivore density can prevent regeneration.
• Positive: seed dispersal by birds, bats, monkeys, elephants (e.g. figs, mango, sandalwood by birds); pollination by insects, bats and birds; predators control herbivore populations; trampling and dung help some seeds germinate.

Human impacts: illicit felling, encroachment, excessive grazing and lopping, fires, over-harvesting of NTFPs, mining, roads and dams, poaching, invasive weeds (Lantana, Parthenium), pollution. Protection measures: legal protection and patrolling, fire management, fencing and closure for regeneration, weed eradication, pest and disease control, awareness and community involvement, protected area network.

Forest economics

Forest economics applies economic principles to the use of forest resources — production, distribution and consumption of forest goods and services.

Fundamental principles: scarcity and choice among alternative uses; long production period (rotation) so time value of money and interest (discounting) are important; the forest is both capital (growing stock) and product; joint production of many goods and services; many benefits are public goods and externalities not priced in markets; sustained yield.

Cost–benefit analysis: all costs (planting, tending, protection, harvesting) and benefits (timber, NTFPs, environmental services) are listed over time and discounted to present value. Measures: Net Present Value NPV = Σ (B_t − C_t)/(1 + r)^t (accept if > 0); Benefit–Cost ratio = PV of benefits / PV of costs (accept if > 1); Internal Rate of Return (discount rate at which NPV = 0).

Estimation of demand and supply: demand for timber, fuelwood, pulpwood and fodder is estimated from population, per capita consumption, industrial demand, prices and incomes (consumption surveys, trend projection); supply from growing stock and increment of forests, trees outside forests (farm forestry) and imports. India has a gap between demand and domestic supply of wood, met partly by imports and farm trees.

Socio-economic analysis of forest productivity and attitudes: studies of how forests contribute to household income, employment and food security; dependence of tribal and rural people; distribution of benefits; attitudes and willingness of people to participate in protection; impact of JFM/FRA on productivity — done by household surveys and participatory rural appraisal (PRA).

Valuation of forest goods and services: Direct use values (timber, NTFPs — market prices), indirect use values (watershed protection, carbon storage, soil conservation — replacement cost, avoided damage), option and existence values (biodiversity). Methods: market price, travel cost method (recreation), contingent valuation (willingness to pay), hedonic pricing, replacement/restoration cost. In India, Net Present Value is charged when forest land is diverted for non-forest use (rates fixed by authorities — check latest).

Likely exam questions

1. (Long, 8 marks) What are NTFPs? Describe the commercial importance of gums, mahua flowers and tendu (bidi) leaves.
2. (Long, 8 marks) Explain the need for seasoning and preservation of wood. Describe the methods.
3. (Short, 4 marks) Write a note on environmentally sound logging practices.
4. (Short, 4 marks) Explain cost–benefit analysis in forestry.
5. (Short, 4 marks) What is the effect of wild animals on forest regeneration?