Forest protection: fire, pests and diseases

In short

Forest protection is the body of law, silvicultural practice and technology used to guard a forest crop against damaging agencies — fire, insects, pathogens, grazing, illicit felling, encroachment and climatic injury — so that the growing stock and the site survive to rotation age. Fire, insect pests and diseases are the three biotic/abiotic agencies that cause the largest recurring loss of increment in Indian forests: the Forest Survey of India reports that a very large share of India's forest cover is fire-prone to some degree, and outbreaks such as the sal heartwood borer and sandal spike have destroyed lakhs of trees in single episodes. It is examined in B.Sc Forestry forest protection papers, in the Indian Forest Service (IFoS) Forestry paper, and in state forest service and ACF/RFO recruitment tests. On the job it is applied by forest range officers, FSI and ICFRE/IFGTB/FRI researchers, plantation managers (ITC, JK Paper, WIMCO-type agro-plantation schemes), CAMPA-funded project staff and NDRF/state fire control units.

Explained

Agencies of damage and the scope of forest protection

• Protection = preventing or minimising damage; conservation = wise use; the two are distinct in exams. Protection acts against *damaging agencies*, classified as:
• Abiotic (physical): fire, frost, snow and hail, drought, lightning, wind (windthrow, windsnap), insolation and sun-scald, flooding and waterlogging, salinity, air pollution and smelter fluorides, landslip and erosion.
• Biotic: humans (illicit felling, encroachment, shifting cultivation, lopping, NTFP over-extraction), domestic grazing and browsing, wild animals (elephant debarking, porcupine, rodents, hare), insects, fungi and other pathogens, parasitic and epiphytic plants (*Loranthus*, *Dendrophthoe*, *Cuscuta*), and weeds (*Lantana camara*, *Chromolaena*, *Mikania*, *Prosopis juliflora*, *Parthenium*).
• Legal framework: the Indian Forest Act, 1927 (Chapter II–IV) makes kindling or leaving fire, trespass, cattle grazing and felling in reserved/protected forest offences; the Forest (Conservation) Act, 1980 — renamed the Van (Sanrakshan Evam Samvardhan) Adhiniyam in 2023 — governs diversion of forest land; the Wild Life (Protection) Act, 1972 covers protected areas; the Environment (Protection) Act, 1986 and the Biological Diversity Act, 2002 supply allied powers. Working Plan prescriptions and the National Working Plan Code 2023 require a fire protection and pest chapter for every forest division.
• Forest Fire Prevention and Management Scheme (FPM) is the centrally sponsored scheme (successor to the earlier Intensification of Forest Management) that funds fire lines, watchers, equipment and crew camps; FSI runs the Forest Fire Alert System (FAST) and the Van Agni geo-portal using MODIS and SNPP-VIIRS satellite detections, sending SMS/email alerts to registered field staff.

Forest fire: nature, classes and causes

• Fire triangle: fuel + oxygen + heat; removing any one side extinguishes the fire. Fire behaviour triangle = fuel, weather, topography.
• Fuel classes: *ground fuel* (humus, peat, roots), *surface fuel* (litter, grass, slash, shrubs), *aerial/ladder fuel* (branches, climbers, crowns). Fuel is described by fuel load (t/ha), size class (1-hour to 1,000-hour fuels), moisture content and compactness. Fine, dry, loose fuel burns fastest.
• Types of fire:
• Ground fire — burns the organic layer and roots below the litter; smouldering, slow, little flame, very destructive and hard to detect (peaty soils, deodar/khasi pine humus).
• Surface fire — burns litter, grass, herbs and seedlings; the most common Indian fire (sal, teak, dry deciduous, chir pine needle beds).
• Crown fire — spreads through tree crowns, often running ahead of the surface fire; *dependent* (needs the surface fire) or *running/independent*. Typical of chir pine and conifer forests.
• Spot fire — started ahead of the main front by firebrands lifted by convection or wind.
• Causes in India: overwhelmingly anthropogenic — burning to flush fresh grass for cattle, to ease collection of mahua flowers and tendu leaves, shifting cultivation (jhum), clearing for charcoal, smoking out bees for honey, carelessness with bidis and camp fires, boundary disputes and deliberate incendiarism. Natural causes (lightning, rolling stones sparking, spontaneous heating of peat, friction of bamboo culms) are rare.
• Season: generally the dry pre-monsoon — February to mid-June in most of India (peaking March–May), November–January in the Western Ghats and parts of the south, and a distinct winter–spring season in the Himalaya.
• Fire effects: loss of regeneration and seedlings, cambium killing and fire scars leading to butt rot and hollow boles, loss of increment, degradation into fire climax (sal savanna, chir pine grassland), killing of soil fauna and mycorrhizae, loss of nitrogen by volatilisation, hydrophobic crust formation, increased runoff and erosion, carbon and black-carbon emission, wildlife and habitat loss, smoke and health costs.
• Beneficial/prescribed use: controlled burning reduces hazardous fuel, prepares seed beds for chir pine and teak, controls *Lantana* thickets and some pathogens, and maintains grasslands for ungulates. "Early burning" (burning when fuel is just dry enough, early in the season, against the wind, in strips) is the classic Indian prescription for sal and chir pine.

Fire protection: prevention, detection, suppression and rehabilitation

• Fire danger rating: classes from *no danger* to *extreme*, computed from fuel moisture (10-hour fuel sticks), relative humidity, temperature, wind speed and days since rain. FSI issues pre-fire-season fire-prone area maps (very high, high, moderately fire-prone classes).
• Prevention (silvicultural and engineering):
• Fire lines (fire breaks): cleared strips along compartment boundaries, roads and ridges. *Kachcha* fire line = vegetation cut and burnt annually; *pucca* fire line = kept bare by hoeing; *inspection paths*; *fire traces*. Width is commonly 5–15 m for surface fires and much wider (30 m and above) where crown fire is possible — exact widths are prescribed by the division working plan, not fixed nationally.
• Controlled/early burning of fire lines and fuel-heavy compartments, counter-firing, raking needles into heaps in chir pine, removing climbers and ladder fuel, pruning low branches, mixing fire-hardy broadleaved species as fire belts (*Shorea*, *Syzygium cumini*, *Mangifera*, *Ficus* green belts), and avoiding highly inflammable monocultures.
• Social prevention: Joint Forest Management committees and Van Suraksha Samitis, fire watchers hired locally for the season, awareness in the "Fire Protection Week", regulated tendu/mahua collection, fire penalty and reward schemes.
• Detection: watch towers with sighting boards (alidade) and triangulation, patrolling, lookout systems, and modern satellite alerts (MODIS at ~1 km, SNPP-VIIRS at ~375 m resolution) plus drones, CCTV and GIS dashboards.
• Suppression methods:
• Direct attack: beating with green branches and fire swatters, water from backpack pumps and tankers, soil throwing, foam and wetting agents.
• Indirect attack: control line/fire line construction ahead of the front, back-firing (counter-firing) from the control line so the two fronts meet and die, burning out, and natural barriers (streams, roads, ridges).
• Crew organisation: fire boss/incident commander, crews of 10–20, tools (McLeod rake, Pulaski, fire rake, swatter, drip torch), fire-resistant clothing, escape route and safety zone discipline. Attack the head only when safe; otherwise pinch the flanks and work towards the head; always mop up and patrol the perimeter to kill smouldering stumps and roots.
• Post-fire: damage appraisal (area burnt by severity class, stems scarred, regeneration lost), salvage felling of fire-killed timber before borers attack, soil conservation measures (contour trenches, brush checkdams), assisted natural regeneration and replanting, and compensation/offence registration under the Indian Forest Act, 1927.

Insect pests of forests, nurseries and timber

• Classification by feeding habit: *defoliators* (leaf eaters), *sap suckers* (aphids, psyllids, scales), *shoot and stem borers*, *root feeders* (termites, white grubs), *seed and cone insects*, *gall makers*, *sap/phloem borers*, and *timber/wood destroyers* (powder-post beetles, ambrosia beetles, marine borers).
• Classification by crop stage: nursery pests → plantation/young crop pests → mature crop pests → pests of felled timber and wood in service.
• Important Indian forest pests (standard exam list):
• *Hoplocerambyx spinicornis* — sal heartwood borer; the classic Indian epidemic pest, kills standing sal; controlled by trap trees (freshly felled sal billets to attract and then destroy beetles), sanitation felling of infested trees, removal of brood material before adult emergence with the first monsoon showers.
• *Hyblaea puera* (teak defoliator) and *Eutectona machaeralis* (teak skeletoniser/leaf skeletonizer) — repeated defoliation cuts teak increment substantially; managed by viral biocontrol (*Hyblaea puera* NPV) and by monitoring early-monsoon epicentres.
• *Dioryctria* and other cone/shoot borers of chir pine and deodar; *Pissodes* and *Ips/Polygraphus* bark beetles in spruce and fir of the western Himalaya.
• *Leucaena* psyllid (*Heteropsylla cubana*) on subabul; eucalyptus gall wasp (*Leptocybe invasa*) and *Thaumastocoris* bug in clonal eucalypt plantations; *Icerya* and *Aphis* on nursery seedlings.
• *Odontotermes/Microtermes* termites — the main killer of young plantation stock in dry zones and of poles in service; *Holotrichia* white grubs on nursery roots.
• Bamboo: *Dinoderus minutus* (bamboo powder-post beetle); timber in service: *Lyctus*, *Heterobostrychus*, and marine borers *Teredo*/*Sphaeroma*.
• Insect population concepts: endemic vs epidemic phase, economic threshold level (ETL) and economic injury level (EIL), key pest vs occasional pest, pest succession in a stand.
• Control methods:
• *Silvicultural/preventive:* site–species matching, mixed and uneven-aged stands, resistant clones and provenances, sanitation and thinning, timely harvesting and debarking, phytosanitary nursery practice.
• *Mechanical:* collection and destruction of egg masses, larvae and cocoons, trap trees and trap logs, light traps, pheromone and sticky traps, pruning and burning infested shoots.
• *Biological:* parasitoids (*Trichogramma*, *Bracon*), predators, entomopathogens — *Bacillus thuringiensis*, NPV, *Beauveria bassiana*, *Metarhizium*; conservation of birds and bats.
• *Chemical:* used as a last resort in nurseries, seed stores and timber depots; neem/azadirachtin and other botanicals first. Pesticide use in India is governed by the Insecticides Act, 1968 and the Central Insecticides Board and Registration Committee — only registered and labelled products at label dose.
• *Regulatory:* plant quarantine at ports under the Destructive Insects and Pests Act, 1914 and the Plant Quarantine (Regulation of Import into India) Order, 2003; ISPM 15 heat treatment or fumigation marking for wood packaging in export.
• IPM = monitoring and threshold-based use of all the above in combination, with chemicals last.
• Wood preservation (for timber in service): preservatives and treatment processes are standardised by BIS — the Indian Standard code of practice for preservation of timber and the pressure (Bethell full-cell, Rueping/Lowry empty-cell) and non-pressure (hot-and-cold open tank, diffusion, sap displacement) processes; CCA/CCB and boron salts for waterborne treatment, creosote for poles and sleepers. Quote the specific IS number only from the current BIS catalogue, as several older timber-preservation standards have been revised or withdrawn.

Forest diseases: pathogens, symptoms and management

• Disease triangle: susceptible host + virulent pathogen + favourable environment (add *time* for the disease tetrahedron). Inoculum, infection, incubation, disease cycle (monocyclic vs polycyclic), sign vs symptom are standard definitions.
• Causal agents: fungi (majority), bacteria, phytoplasmas, viruses, nematodes, parasitic flowering plants, and abiotic/physiological disorders (nutrient deficiency, frost crack, sun-scald, waterlogging, pollution injury — non-infectious diseases).
• Nursery diseases: damping off (*Pythium*, *Phytophthora*, *Rhizoctonia*, *Fusarium*) — pre-emergence and post-emergence; managed by raised seed beds, well-drained light soil, soil solarisation and formalin/Trichoderma treatment, avoiding over-watering and dense sowing, seed treatment with a registered fungicide; also seedling wilt, root rot and web blight.
• Diseases of plantations and mature crops:
• Spike disease of sandal (*Santalum album*) — a phytoplasma disease transmitted by jassids (*Coelidia/Moonia*); shortened internodes and tiny stiff leaves giving a spike; no cure — rogue and destroy infected trees, control the vector; it devastated the Kodagu–Mysuru sandal tracts.
• Root and butt rots: *Ganoderma lucidum* (root rot of acacia, teak, dalbergia, shisham), *Polyporus/Fomes* heart rots, *Heterobasidion*-type butt rot in conifers; recognised by basidiocarps at the collar and by hollow boles; avoid root injury, remove stumps and infected material, trench round infection centres.
• Wilts: shisham (sissoo) mortality/wilt (*Fusarium solani* with *Ganoderma* and waterlogging interaction) — a major north Indian problem; *Eucalyptus* pink disease (*Erythricium salmonicolor*) and bacterial wilt in the humid tropics.
• Rusts and leaf diseases: chir pine needle blight/needle cast, *Melampsora* leaf rust of poplar, *Cronartium* type cone rust, teak leaf rust (*Olivea tectonae*), *Cylindrocladium* leaf blight in eucalypt nurseries, powdery and downy mildews in dalbergia and albizia.
• Cankers and diebacks: *Botryodiplodia*/*Lasiodiplodia* canker and dieback on many hardwoods; bacterial canker of poplar; top dying after drought.
• Stains and decay of wood: sap stain/blue stain fungi (*Ceratocystis*), soft rot, brown rot (cellulose attacked, cubical checks) vs white rot (lignin and cellulose, fibrous bleached wood) — a favourite comparison question.
• Mistletoes and parasites: *Loranthus/Dendrophthoe* on sal, teak and mango — pruned out below the haustorium; *Cuscuta* on shrubs; *Striga* in grasslands.
• Disease management: exclusion (quarantine, certified planting stock), eradication (rogueing, sanitation, stump removal), protection (fungicides, biocontrol — *Trichoderma*, *Pseudomonas fluorescens*, mycorrhizal inoculation), host resistance (resistant clones of poplar and eucalypt), and site modification (drainage, correcting waterlogging, balanced nutrition). Forest Pathology divisions of FRI Dehradun, IFGTB Coimbatore, TFRI Jabalpur and the other ICFRE institutes are the national reference centres.

Other protection problems and integrated approach

• Grazing and browsing: closure of regeneration areas, rotational grazing, grazing incidence/intensity surveys, stall feeding and fodder plots, grazing fees under state rules; tree guards and brushwood fencing against cattle and wild herbivores.
• Human-caused damage: illicit felling and smuggling (checkposts, transit passes under state Timber Transit Rules, hammer marks, timber depots), encroachment (boundary pillars, demarcation, satellite change detection), and shifting cultivation regulation.
• Man–animal conflict overlaps with wildlife protection: elephant trenches, solar fencing, early warning SMS; but the control of *pest* animals in plantations (porcupine, rodent, hare) is part of protection — barriers, baiting where permitted.
• Integrated Forest Protection: one plan per division combining fire management, pest/disease surveillance, boundary and grazing control, people's participation through JFM/Van Suraksha Samiti, remote sensing, and record keeping (fire register, offence register, pest incidence register), with CAMPA or FPM funding.

Key points

• Damaging agencies - abiotic (fire, frost, wind, drought, pollution) and biotic (humans, grazing, insects, pathogens, weeds, parasitic plants).
• Fire triangle - fuel, oxygen and heat; suppression removes one side, usually fuel (fire line) or heat (water, soil).
• Three fire types - ground (sub-surface, smouldering), surface (commonest in India), crown (through canopy, conifers); spot fires start from firebrands.
• Indian fire causes - almost entirely man-made: grazing flush, mahua/tendu collection, jhum, carelessness; natural causes are rare.
• Fire season - February to mid-June over most of India, peak March–May; shifted in the Western Ghats and the Himalaya.
• Fire lines - kachcha (cut and burnt) and pucca (hoed bare); supplemented by controlled/early burning and green fire belts.
• Counter-firing - deliberate burning from a control line towards the main fire so both fronts meet and extinguish.
• Mop-up - essential last step; unextinguished stumps and ground fire restart a "controlled" fire.
• FSI alerts - MODIS (~1 km) and SNPP-VIIRS (~375 m) detections delivered as SMS/email fire alerts to field officers; pre-season fire-prone maps.
• Fire climax - repeated burning degrades sal to savanna and chir pine to grassland; conversely controlled burning aids chir pine and teak regeneration.
• Sal heartwood borer *Hoplocerambyx spinicornis* - epidemic pest of sal controlled chiefly by the trap tree operation.
• Teak pests - *Hyblaea puera* (defoliator, managed with NPV) and *Eutectona machaeralis* (skeletoniser).
• Spike disease of sandal - phytoplasma spread by jassids; no cure, only rogueing and vector control.
• Damping off - nursery killer by *Pythium/Rhizoctonia/Fusarium*; drainage, thin sowing, solarisation, *Trichoderma*.
• Shisham mortality - *Fusarium solani* plus *Ganoderma* root rot aggravated by waterlogging in north India.
• Brown rot vs white rot - brown rot removes cellulose leaving brown cubical checks; white rot removes lignin too, leaving bleached fibrous wood.
• ETL/EIL - pest control is justified only when the population crosses the economic threshold; the basis of IPM.
• Legal base - Indian Forest Act, 1927 (fire, trespass, grazing offences); Van (Sanrakshan Evam Samvardhan) Adhiniyam, 1980 for land diversion; Insecticides Act, 1968 for pesticides; Destructive Insects and Pests Act, 1914 and PQ Order 2003 for quarantine.

Formulas and examples

Example 1 — Fuel load and fireline intensity. A 1 m × 1 m quadrat in a chir pine needle bed yields 1.6 kg of litter at 12% moisture (dry basis). The fire front advances 30 m in 5 minutes and consumes 80% of the fuel. Take H = 18,600 kJ/kg.

• Oven-dry mass = 1.6/1.12 = 1.4286 kg → fuel load w₀ = 1.43 kg/m² = 14.3 t/ha.
• Fuel actually consumed w = 0.80 × 1.4286 = 1.143 kg/m².
• Rate of spread r = 30/5 = 6 m/min = 0.10 m/s.
• I = 18,600 × 1.143 × 0.10 = 2,126 kW/m → a high-intensity surface fire; direct attack by hand crews is unsafe above roughly 2,000 kW/m, so indirect attack is indicated.
• Flame length L ≈ 0.0775 × 2126^0.46. ln 2126 = 7.662; 0.46 × 7.662 = 3.525; e^3.525 = 33.9 → L ≈ 0.0775 × 33.9 = 2.6 m.
• Fire line width at 2–3 × flame length ≈ 5–8 m for this fuel.

Example 2 — Fire damage appraisal and loss in rupees. A fire burns 240 ha of a 3,000 ha teak division. Of 180 sample stems, 45 are fire-scarred beyond salvage. Stand density is 300 stems/ha; average volume of a killed stem is 0.35 m³; roadside value of teak is ₹18,000 per m³, and salvage realises 40% of that.

• Area burnt = 240/3,000 × 100 = 8% of the division.
• Mortality/severe scar incidence = 45/180 × 100 = 25%.
• Stems lost = 240 ha × 300 × 0.25 = 18,000 stems; volume = 18,000 × 0.35 = 6,300 m³.
• Full value = 6,300 × 18,000 = ₹11.34 crore; salvage recovery = 40% = ₹4.536 crore.
• Net timber loss = ₹11.34 − ₹4.536 = ₹6.804 crore, before counting lost increment, regeneration and soil values.

Example 3 — Trap tree operation for sal borer. A sal compartment of 500 ha shows 6% of 250 stems/ha with borer frass. The prescription is 1 trap tree per 4 ha, each trap tree attracting about 120 beetles, and the field count after debarking is 95 beetles per trap tree.

• Infested stems = 500 × 250 × 0.06 = 7,500 stems.
• Trap trees laid = 500/4 = 125; beetles destroyed = 125 × 95 = 11,875.
• Expected at design catch = 125 × 120 = 15,000 → trapping efficiency = 11,875/15,000 = 79%.
• Because the catch per trap tree is below design, the operation is repeated with additional trap trees in the next pre-monsoon window, and infested standing trees are sanitation-felled and debarked before adult emergence.

Example 4 — Nursery damping off and disease severity. In 10 beds of 500 seedlings each, 620 seedlings are killed; of the surviving 4,380, severity on a 0–4 scale is: 0 → 2,600, 1 → 900, 2 → 500, 3 → 280, 4 → 100.

• Total sown = 5,000; mortality (pre+post emergence) incidence = 620/5,000 × 100 = 12.4%.
• Σ(class × number) = 0 + 900 + 1,000 + 840 + 400 = 3,140.
• Severity index = 3,140/(4 × 4,380) × 100 = 3,140/17,520 × 100 = 17.9%.
• Both figures are needed: incidence shows how widespread, severity shows how badly affected — the bed-wise pattern (edge beds worse) points to waterlogging as the predisposing factor.

Example 5 — Fire protection cost and benefit. A 3,000 ha division spends ₹9.5 lakh on fire lines (120 km at ₹6,000/km), ₹3.6 lakh on 30 seasonal watchers (₹12,000 each for the season) and ₹1.9 lakh on equipment.

• Fire line cost check: 120 × 6,000 = ₹7.2 lakh; stated ₹9.5 lakh therefore includes ₹2.3 lakh of early-burning and labour charges.
• Total = 9.5 + 3.6 + 1.9 = ₹15.0 lakh → ₹500 per ha of protected forest.
• If this reduces burnt area from the earlier 240 ha to 60 ha, area saved = 180 ha; at the Example 2 net loss rate of ₹6.804 crore per 240 ha = ₹2.835 lakh per ha, value saved ≈ 180 × 2.835 = ₹510 lakh (₹5.10 crore) against ₹15 lakh spent — a benefit-cost ratio of about 34:1 on timber value alone.

Where it is used

• State forest departments: every territorial range runs fire lines, fire watchers, crew camps and an offence register under the Indian Forest Act, 1927; ACF/RFO duties include fire season plans and burnt-area reporting under the FPM scheme.
• Forest Survey of India and remote sensing cells: generating fire-prone maps, VIIRS/MODIS alerts on the Van Agni portal, and burnt-area assessment for the India State of Forest Report.
• ICFRE institutes (FRI Dehradun, IFGTB Coimbatore, TFRI Jabalpur, IWST Bengaluru) — forest entomology and pathology diagnosis, NPV and *Trichoderma* production, clonal disease screening, wood preservation research.
• Industrial and farm-forestry plantations: ITC Bhadrachalam, JK Paper, West Coast Paper and similar clonal eucalypt/casuarina/poplar programmes depend on gall wasp, psyllid and leaf-blight resistant clones and on nursery phytosanitation.
• Wood-based industry and exports: plywood, sleeper, pole and packing-case units use BIS-standardised preservative treatment; wood packaging for export must carry ISPM 15 heat-treatment or fumigation marking.
• Disaster and insurance roles: NDRF/SDRF fire response, plantation insurance and CAMPA-funded restoration, carbon project monitoring where fire emissions must be deducted from sequestration claims.

Interview questions

• Q: What is the fire triangle, and how does each suppression method relate to it? A: Fuel, oxygen and heat; fire lines and controlled burning remove fuel, soil throwing and foam smother oxygen, and water or wetting agents remove heat.
• Q: Which fire type is commonest in Indian forests and why? A: Surface fire, because most Indian forests are dry deciduous with a heavy, quick-drying litter and grass layer and a pre-monsoon dry season.
• Q: Difference between a kachcha and a pucca fire line? A: A kachcha line has its vegetation cut and then burnt each season; a pucca line is kept permanently bare by hoeing or scraping, so it is costlier but more reliable.
• Q: What is counter-firing and what is the risk? A: Lighting a fire from a control line so it burns towards the main front and the two extinguish on meeting; if wind shifts or the line is weak, the counter-fire itself escapes.
• Q: Is fire always harmful in forestry? A: No — controlled early burning reduces fuel load, prepares seed beds for chir pine and teak, suppresses *Lantana* and maintains grasslands; the harm comes from uncontrolled, repeated, late-season fire.
• Q: How does FSI alert field staff to fires? A: Through satellite thermal-anomaly detections from MODIS and SNPP-VIIRS, pushed as SMS and email alerts and plotted on the Van Agni/forest fire geo-portal, along with pre-season fire-prone maps.
• Q: Explain the trap tree method for the sal heartwood borer. A: Freshly felled sal billets are laid out before the monsoon to attract egg-laying beetles; the billets are then debarked and the beetles and grubs destroyed, cutting the next generation.
• Q: What causes spike disease of sandal and can it be cured? A: A phytoplasma transmitted by jassid vectors; there is no cure, so infected trees are rogued out and the vector controlled.
• Q: How do you distinguish brown rot from white rot in wood? A: Brown rot consumes cellulose leaving dark, brown, cubically cracked wood; white rot removes lignin as well, leaving pale, bleached, fibrous and stringy wood.
• Q: Why does shisham mortality occur mainly in canal-irrigated plantations of north India? A: Waterlogging and root injury predispose trees to *Fusarium solani* wilt and *Ganoderma* root rot; improved drainage and avoiding root damage are the primary remedies.
• Q: What is the economic threshold level and why does it matter in forestry? A: The pest density at which control cost equals the loss prevented; in a long-rotation, low-value-per-hectare crop it is reached only in outbreaks, so forest pest control is largely preventive and silvicultural.
• Q: Which Acts would you invoke against someone who set fire to a reserved forest? A: The Indian Forest Act, 1927 provisions on kindling or leaving fire and on forest offences, with the Wild Life (Protection) Act, 1972 added if a protected area or wildlife was affected.

Common mistakes

• Confusing ground fire with surface fire — a ground fire burns the organic layer *below* the litter, smoulders and is the hardest to detect and kill.
• Treating the fire line as the whole of fire protection; prevention, detection, suppression, mop-up and rehabilitation are five linked stages, and missing mop-up causes most re-ignitions.
• Writing that Indian forest fires are mostly natural or lightning-caused; they are overwhelmingly anthropogenic.
• Quoting a single nationwide fire line width or a precise nationwide "percentage of forest burnt"; widths are prescribed in the division working plan and burnt-area figures vary year to year and come from the FSI report of that year.
• Saying controlled burning is prohibited — it is a recognised prescription, while uncontrolled or late burning is the offence.
• Mixing up sign and symptom, or incidence and severity, in pathology answers; and calling a phytoplasma disease like sandal spike a fungal or viral one.
• Reaching for a chemical spray as the first answer for a forest pest, when silvicultural and biological measures and the economic threshold must come first, and any pesticide must be a product registered under the Insecticides Act, 1968.

Related topics

Silviculture and regeneration systems · Forest mensuration and growing stock estimation · Agroforestry systems · Wildlife conservation · Forest policy, Acts and administration · Remote sensing and GIS in forestry