Forestry & Forest Sciences · Forest Ecology & Biology · also Environmental Conservation and Biodiversity, Biodiversity Conservation, Forest Genetic Resources
Why forest biodiversity matters, what threatens it, and how genes, species and ecosystems are conserved in situ and ex situ, under national law and international conventions. The Sustainability track's biodiversity-conservation is the general version; this subject focuses on forest species and forest genetic resources.
In the exams: IFoS Forestry Paper I Section B (environmental conservation and biodiversity); ICAR AICE-JRF 59 Unit 11 (in situ and ex situ conservation, sacred groves); GATE EY Section 5
Conservation biology is the science of protecting biological diversity: understanding what it is, why it is being lost and how to keep it. For foresters it has a particular focus. Forests hold most of the world's terrestrial species, and trees themselves are a vast reservoir of genetic diversity on which future forestry, adaptation to climate change and many livelihoods depend. Yet roughly a third of the world's tree species are threatened with extinction, and many forest populations that hold valuable genetic variation are being lost before they are even studied.
This subject covers the levels of biodiversity; the main threats to it; the theory of island biogeography, metapopulations and minimum viable populations as applied to forests; the IUCN Red List categories and criteria; in situ conservation in protected areas, biosphere reserves and sacred groves; ex situ conservation in arboreta, seed banks, clone banks and cryopreservation; the conservation of forest genetic resources; the Convention on Biological Diversity, the Nagoya Protocol and India's biodiversity law; environmental impact assessment for forest projects; and ecosystem services. Related topics are covered in other subjects of this track: genetics, provenance and breeding in forest-genetics-tree-improvement; seed storage behaviour in tree-seed-technology; forest types and hotspots in forest-types-biogeography; ecological concepts in forest-ecology; wildlife populations and protected-area management in wildlife-biology-ecology and wildlife-management-protected-areas; and forest and biodiversity law in forest-policy-law-governance. The Sustainability track's biodiversity-conservation gives the general version of this subject.
The manual is written for students preparing for the Indian Forest Service, the ICAR AICE-JRF forestry paper (whose conservation unit covers in situ and ex situ conservation and sacred groves) and the GATE Ecology and Evolution paper, and for foresters and conservation professionals. Thresholds in the IUCN criteria and in national law are quoted from the current versions and should be checked when they are revised.
The Convention on Biological Diversity defines biological diversity as the variability among living organisms from all sources, including terrestrial, marine and other aquatic ecosystems and the ecological complexes of which they are part; this includes diversity within species, between species and of ecosystems. These three levels, genetic, species and ecosystem diversity, are the standard framework. Some authors add functional diversity (the range of ecological roles) and cultural diversity related to biodiversity.
Genetic diversity is the variation in genes within and among populations of a species. It is the raw material of adaptation and of tree improvement. It is measured with molecular markers as the proportion of polymorphic loci, the number of alleles per locus, expected heterozygosity (gene diversity) and differentiation among populations (such as FST). Forest trees, especially widespread, outcrossing, wind-pollinated species, typically hold most of their genetic diversity within populations rather than among them, while species with restricted ranges, selfing or limited gene flow show more differentiation among populations. The principles of population genetics, including Hardy-Weinberg equilibrium, drift and gene flow, are covered in forest-genetics-tree-improvement.
Species diversity combines species richness (the number of species) with evenness (how equally individuals are distributed among species). About two million species have been described worldwide, and estimates of the total number of eukaryotic species are often in the region of eight to nine million, most of them insects and other invertebrates and many in tropical forests. India, one of the megadiverse countries, has roughly 7 to 8 percent of recorded species, including around 20,000 flowering plants and a high proportion of endemic species in the Western Ghats, the Himalaya, the North-east and the islands.
Whittaker distinguished alpha diversity (within a habitat or site), beta diversity (the change in species composition between sites or along gradients) and gamma diversity (of a whole landscape or region). In Whittaker's multiplicative form, beta diversity equals gamma divided by mean alpha: if a landscape has 60 species and its sites average 20 species each, beta diversity is 3, meaning the landscape holds the equivalent of three completely distinct communities. Diversity indices such as Shannon and Simpson are covered in forest-ecology.
Ecosystem diversity is the variety of habitats, communities and ecological processes in a region. In India it ranges from tropical wet evergreen forests to alpine scrub, mangroves, deserts, grasslands and wetlands; Champion and Seth's classification recognises 16 major forest type groups, described in forest-types-biogeography. Conservation of ecosystem diversity requires representative protected area networks and attention to ecosystems that are often neglected, such as grasslands, wetlands and dry forests.
The Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES), in its 2019 global assessment, estimated that around one million species are threatened with extinction and ranked the direct drivers of change in nature, globally, as: changes in land and sea use, direct exploitation of organisms, climate change, pollution, and invasive alien species. E. O. Wilson's acronym HIPPO (habitat destruction, invasive species, pollution, human population, overharvesting) summarises similar drivers. For forest species, habitat loss and degradation are usually the most important.
Habitat loss removes the places where species live; fragmentation divides remaining habitat into smaller, more isolated pieces. Fragmentation reduces patch size, increases isolation and increases the proportion of edge. Edge effects include higher light, temperature and wind, drier conditions, more tree mortality and invasion by weeds and edge species, and they can penetrate tens to hundreds of metres into forest. The Biological Dynamics of Forest Fragments Project near Manaus in Brazil, begun in 1979, showed that small fragments lose species, large trees and forest-interior birds over time. Extinction debt describes species that persist in fragments for a time but are destined to disappear because the habitat can no longer support them.
Overexploitation includes illegal and unsustainable logging of valuable timbers such as red sanders, sandalwood and rosewoods; overharvesting of medicinal plants, such as Taxus wallichiana for taxol and Himalayan herbs such as Nardostachys and Saussurea; overgrazing; and hunting and wildlife trade, discussed in wildlife-management-protected-areas. Overexploitation of a tree species also erodes its genetic diversity, especially when the best trees are cut first (dysgenic selection).
Invasive alien species are introduced species that spread and cause harm. In Indian forests, Lantana camara, Prosopis juliflora, Chromolaena odorata, Mikania micrantha, Parthenium hysterophorus and Senna spectabilis are among the most damaging, suppressing native regeneration and reducing forage. Their control is covered in restoration-difficult-sites.
Climate change shifts suitable climates upslope and poleward faster than many trees can migrate, alters flowering and fruiting, and increases drought, fire and pest outbreaks. Species with narrow ranges, such as high-altitude and island endemics, are most vulnerable. Pollution, including nitrogen deposition, acid rain and pesticides, affects sensitive species. Threats often interact: fragmentation makes species more vulnerable to climate change by blocking movement, and disturbance favours invasive species. Conservation planning must address multiple threats together.
The number of species in an area increases with area, often described by the power function S = cA^z, where S is the number of species, A the area, and c and z constants; z is commonly between about 0.15 and 0.35 for islands and habitat isolates. Using z = 0.25, reducing a habitat to one tenth of its area is predicted to leave 0.1^0.25 = 0.56 of its species in the long term, a loss of about 44 percent; halving it leaves about 84 percent. Such estimates are rough but explain why habitat loss drives extinction.
MacArthur and Wilson's theory of island biogeography (1967) proposed that the number of species on an island reflects a dynamic equilibrium between immigration, which is lower on islands far from the mainland, and extinction, which is higher on small islands. Forest fragments and protected areas surrounded by farmland behave partly like islands, so small, isolated reserves are expected to lose species. These ideas, the SLOSS debate and corridor design are discussed further in wildlife-management-protected-areas.
A metapopulation is a set of local populations in habitat patches connected by dispersal. In Levins' model, the equilibrium proportion of occupied patches is p* = 1 - e/c, where e is the local extinction rate and c the colonisation rate; with e = 0.2 and c = 0.5, about 60 percent of patches are occupied at equilibrium. If extinction rises or colonisation falls, as when patches become more isolated, occupancy declines, and the metapopulation goes extinct when e exceeds c. For trees, which are long-lived and sessile, metapopulation dynamics operate through seed and pollen dispersal among stands, and fragmentation can disrupt pollinator and disperser movement.
These theories have practical implications for forest management. Large, intact forest blocks should be kept whole where possible, since dividing them creates edges and isolates populations. Where forests are already fragmented, corridors of natural vegetation along streams and ridges, scattered trees in farmland and agroforestry can improve connectivity for animals and the pollen and seed flow that trees depend on. Small fragments still have value as stepping stones and as refuges for plants with limited ranges, so they should not be written off. Monitoring regeneration in fragments shows whether populations are replacing themselves or slowly dying out.
Shaffer (1981) defined a minimum viable population as the smallest isolated population having, for example, a 99 percent chance of remaining extant for 1,000 years despite demographic, environmental and genetic stochasticity and natural catastrophes. Population viability analysis (PVA) uses simulation models to estimate extinction risk and compare management options. For genetic viability, the effective population size (Ne) is what matters; the 50/500 rule and its later revisions, discussed in wildlife-biology-ecology, apply to trees as well. Tree populations can persist for long periods at low numbers because individuals live long, which can hide genetic and demographic decline; small isolated stands may suffer inbreeding, reduced seed set and poor regeneration long before the last tree dies.
The IUCN Red List of Threatened Species, using the categories and criteria of version 3.1 (2001), classifies species into nine categories: Extinct (EX), Extinct in the Wild (EW), Critically Endangered (CR), Endangered (EN), Vulnerable (VU), Near Threatened (NT), Least Concern (LC), Data Deficient (DD) and Not Evaluated (NE). CR, EN and VU are the threatened categories. A species qualifies for a threatened category if it meets any one of five criteria, A to E, at the relevant threshold.
Criterion A is population reduction measured over ten years or three generations, whichever is longer. Under A2 (reduction observed or suspected in the past where causes may not have ceased), the thresholds are at least 80 percent for CR, 50 percent for EN and 30 percent for VU; under A1 (causes reversible, understood and ceased), they are higher (90, 70 and 50 percent).
Criterion B is a small geographic range combined with fragmentation or few locations, continuing decline, or extreme fluctuations. The extent of occurrence (EOO) thresholds are under 100 km2 for CR, 5,000 km2 for EN and 20,000 km2 for VU; area of occupancy (AOO) thresholds are under 10, 500 and 2,000 km2.
Criterion C is a small population size with continuing decline: fewer than 250 mature individuals for CR, 2,500 for EN and 10,000 for VU, with specified rates or patterns of decline. Criterion D is a very small or restricted population: fewer than 50 mature individuals for CR, 250 for EN and 1,000 for VU, or for VU a very restricted AOO (typically under 20 km2) or number of locations (typically five or fewer). Criterion E is a quantitative analysis showing a probability of extinction in the wild of at least 50 percent within ten years or three generations for CR, 20 percent within 20 years or five generations for EN, and 10 percent within 100 years for VU.
For example, a tree species whose population fell by 85 percent over three generations through continuing logging qualifies as CR under A2; one with only 180 mature individuals in continuing decline qualifies as CR under C; one with 800 mature individuals and no decline qualifies as VU under D.
Red List status is only one way to set priorities. Biodiversity hotspots, defined by Myers and colleagues as regions with at least 1,500 endemic vascular plant species that have lost at least 70 percent of their original habitat, focus global attention on places where many unique species are under threat; they are described in forest-types-biogeography. Key Biodiversity Areas are sites identified by standard criteria as contributing significantly to the global persistence of biodiversity. The EDGE approach ranks species that are both Evolutionarily Distinct and Globally Endangered, giving weight to species with few close relatives. Systematic conservation planning, developed by Margules and Pressey, selects sets of sites that together meet explicit targets for representing species and ecosystems at least cost, using the principles of complementarity (each new site should add features not already protected) and irreplaceability (how essential a site is to meeting targets); software such as Marxan is widely used. These approaches help managers decide where limited resources will achieve most for conservation.
Because trees have long generation times, three generations can span centuries, which complicates the application of criterion A. The Global Tree Assessment, whose results were published by Botanic Gardens Conservation International in the State of the World's Trees report (2021), assessed nearly 60,000 tree species and found that about 30 percent are threatened with extinction. Countries also produce national red lists and red data books; in India, the Botanical Survey of India and Zoological Survey of India have published red data books, and regional assessments of medicinal plants have been carried out through conservation assessment and management prioritisation (CAMP) workshops. Red List status is one input to conservation priorities, alongside ecological role, evolutionary distinctiveness, economic value and feasibility of action.
In situ conservation conserves species and genetic resources in their natural habitats, where they continue to evolve with their environment, interact with pollinators, dispersers and pests, and maintain large populations. It is the primary strategy for most species, especially trees, whose large size, long generation times and often recalcitrant seeds make ex situ conservation difficult. Its main forms are protected areas, biosphere reserves, sacred groves and community conserved areas, and gene conservation units within managed forests.
Protected areas, IUCN categories and India's network are described in wildlife-management-protected-areas. For forest biodiversity, the representativeness of the network matters: India's network was planned by biogeographic zone, but some forest types, grasslands and dry forests remain under-represented. Biosphere reserves under UNESCO's Man and the Biosphere programme, begun in 1971, combine a strictly protected core, a buffer zone where compatible activities such as research and education are allowed, and a transition area where sustainable development is promoted with local communities. India's first biosphere reserve was the Nilgiri Biosphere Reserve, established in 1986; India now has 18 biosphere reserves, many of them in the UNESCO world network.
Sacred groves are patches of forest protected by local communities for religious and cultural reasons, often dedicated to a deity or ancestral spirits, with taboos on cutting trees or removing material. India has a very large number of sacred groves, with estimates ranging up to around 100,000 or more, most of them small. They have local names such as kavu in Kerala, devrai in Maharashtra, devara kadu in Karnataka, orans in Rajasthan, law kyntang in Meghalaya (the Mawphlang grove is well known) and sarna in Jharkhand. Sacred groves often hold relict vegetation, rare and endemic species and water sources, and serve as refuges in heavily modified landscapes. Many are threatened by erosion of traditional beliefs, encroachment, invasion by weeds and development.
Other community traditions include the Bishnoi community of Rajasthan, whose principles forbid cutting green trees and killing animals; the Khejarli sacrifice of 1730, in which Amrita Devi and many Bishnois gave their lives to protect khejri trees, is commemorated as an early example of conservation. The Biological Diversity Act allows states to notify biodiversity heritage sites, areas of significant biodiversity managed with local communities; the Nallur Tamarind Grove in Karnataka, notified in 2007, was the first. Medicinal Plant Conservation Areas, established in southern India from the 1990s, protect populations of medicinal plants in situ in forest areas.
For forest genetic resources, in situ conservation is implemented through gene conservation units or gene reserve forests: designated stands managed to maintain the genetic diversity and evolutionary processes of target tree species. European guidelines developed through EUFORGEN set minimum requirements such as a designated management plan, regeneration by natural means where possible, and minimum population sizes, commonly a few hundred reproducing trees for common, stand-forming species and fewer, around 50, for scattered or rare species. Seed production areas and preservation plots of important species, established by forest departments and research institutes in India, serve partly as in situ genetic reserves.
Ex situ conservation maintains species or genetic material outside their natural habitats. It complements in situ conservation by providing insurance against loss in the wild, material for research, breeding and restoration, and a last resort for species whose habitats are destroyed. Its limitations include cost, the small samples it can hold, loss of evolutionary interaction with the environment, and genetic changes in storage or cultivation.
Botanical gardens and arboreta grow trees and other plants in collections, often with good documentation; Botanic Gardens Conservation International coordinates a global network. Field gene banks, clone banks and conservation stands hold living trees of selected genotypes, provenances or populations; clone banks of teak, sandalwood, eucalyptus and other species are maintained by Indian research institutes and forest departments, often grafted from plus trees, and also serve breeding programmes. Living collections are essential for species with recalcitrant seeds and for clonally propagated material, but they need space, maintenance and protection from pests, and often hold only a few individuals per population.
Seed banks store seeds under conditions that slow ageing. Orthodox seeds, which tolerate drying, are dried to low moisture content and stored cold; FAO genebank standards recommend drying to about 3 to 7 percent moisture content and storing at about -18 degrees C for long-term collections. Harrington's rules of thumb state that, within certain ranges, each 1 percent reduction in seed moisture content and each 5 degree C reduction in temperature roughly doubles seed storage life; reducing moisture from 10 to 6 percent would, by the first rule, increase storage life about 16-fold. Recalcitrant seeds, such as those of many tropical forest trees including sal (Shorea robusta), many dipterocarps, mango, jackfruit and Syzygium, cannot be dried without losing viability and cannot be stored in conventional seed banks. Intermediate seeds, such as those of neem, tolerate partial drying but are damaged by cold. Storage behaviour is described in detail in tree-seed-technology.
Major seed banks include the Millennium Seed Bank at Wakehurst, run by the Royal Botanic Gardens, Kew, which holds seeds of tens of thousands of wild plant species; the Svalbard Global Seed Vault in Norway, opened in 2008 as a backup for crop collections; and in India the national gene bank of the National Bureau of Plant Genetic Resources in New Delhi, which stores seeds of crops, their wild relatives and some trees. Seed collections should sample enough individuals and populations to capture genetic diversity; Marshall and Brown suggested that collecting from about 50 randomly chosen individuals per population captures, with 95 percent probability, alleles at frequencies above 5 percent.
In vitro conservation maintains plant tissue cultures under slow-growth conditions (low temperature, growth retardants, reduced nutrients), which reduces the frequency of subculturing. Cryopreservation stores material such as embryonic axes, shoot tips, somatic embryos, pollen or seeds in liquid nitrogen at about -196 degrees C, where metabolism effectively stops; it is the main long-term option for recalcitrant-seeded and vegetatively propagated species, using techniques such as vitrification and encapsulation-dehydration. Pollen banks and DNA banks complement these methods. Each technique requires validation for the species and regular testing of viability, and none conserves the ecological interactions that in situ conservation maintains.
Forest genetic resources (FGR) are the heritable materials maintained within and among tree and other woody plant species that are of actual or potential economic, environmental, scientific or societal value. They include the genetic variation that allows species to adapt to changing climates, pests and diseases, and that breeders use to improve growth, form and wood quality. Unlike most crops, most tree species are undomesticated, and their genetic diversity exists mainly in wild populations, so conservation of FGR depends heavily on managing natural forests.
FAO's first report on The State of the World's Forest Genetic Resources (2014) found that information on FGR is limited for most species and that many populations are threatened by deforestation, degradation and climate change. It led to the Global Plan of Action for the Conservation, Sustainable Use and Development of Forest Genetic Resources (2013), with four strategic priority areas: improving the availability of, and access to, information on FGR; in situ and ex situ conservation of FGR; sustainable use, development and management of FGR; and policies, institutions and capacity-building. Regional networks, such as EUFORGEN in Europe and APFORGEN in Asia and the Pacific, coordinate national programmes.
A national FGR strategy typically begins by prioritising species, using criteria such as economic and social value, conservation status, threat, genetic uniqueness and the feasibility of conservation. For priority species, it assesses the distribution of genetic diversity using provenance trials and molecular markers, identifies populations to conserve, and chooses complementary methods: dynamic in situ conservation in gene conservation units across the species' range and environments, ex situ conservation in seed banks or clone banks for threatened populations, and conservation through use in breeding programmes and plantations.
Sampling for conservation aims to capture as much of the species' genetic variation as possible. Because widespread trees hold most diversity within populations, a moderate number of large populations spread across environmental gradients is often more efficient than many small samples, but populations at range margins and isolated populations may hold distinct adaptive variation and deserve priority. Core collections, small subsets of a large collection chosen to represent most of its diversity, help manage ex situ holdings. Genetic monitoring tracks changes in diversity over time.
Management can harm or help genetic resources. Selective logging that removes the best trees, reliance on a narrow genetic base in plantations and clonal forestry, uncontrolled seed transfer and hybridisation with exotic species can erode or contaminate local gene pools. Using local or appropriately matched seed sources, maintaining large effective populations in managed stands and documenting seed origin, as described in tree-seed-technology, help maintain FGR. Assisted gene flow, the deliberate movement of genotypes adapted to warmer climates into existing populations, is being considered as a climate adaptation measure. In India, research institutes of the Indian Council of Forestry Research and Education conserve FGR of important species such as teak, sandalwood, red sanders and bamboos through seed production areas, clonal banks and germplasm collections.
The Convention on Biological Diversity (CBD) was opened for signature at the Earth Summit in Rio de Janeiro in 1992 and entered into force in 1993. Its three objectives are the conservation of biological diversity, the sustainable use of its components, and the fair and equitable sharing of benefits arising from the utilisation of genetic resources. It affirms national sovereignty over genetic resources, and requires parties to prepare national biodiversity strategies and action plans, to conserve in situ and ex situ, and to carry out environmental impact assessment of projects likely to harm biodiversity. Its decisions are made by the Conference of the Parties.
The Strategic Plan for Biodiversity 2011-2020 set the 20 Aichi Biodiversity Targets, most of which were not met. The Kunming-Montreal Global Biodiversity Framework, adopted in 2022, sets four long-term goals for 2050 and 23 targets for 2030, including conserving 30 percent of land and sea (Target 3), restoring 30 percent of degraded ecosystems (Target 2), halving the introduction of invasive species (Target 6) and reducing pesticide risk (Target 7). The CBD's details are also covered in forest-policy-law-governance.
The Cartagena Protocol on Biosafety, adopted in 2000 and in force since 2003, regulates the transboundary movement of living modified organisms. The Nagoya Protocol on Access to Genetic Resources and the Fair and Equitable Sharing of Benefits Arising from their Utilization, adopted in 2010 and in force since 2014, implements the CBD's third objective: users must obtain prior informed consent from the country providing genetic resources and agree mutually agreed terms on benefit sharing, and parties must take measures to ensure compliance, including checkpoints and internationally recognised certificates of compliance. Benefits may be monetary (fees, royalties) or non-monetary (research collaboration, technology transfer, training). Associated traditional knowledge is covered. The International Treaty on Plant Genetic Resources for Food and Agriculture (2001) provides a multilateral system of access and benefit sharing for listed crops, separate from the Nagoya framework.
India implements the CBD through the Biological Diversity Act, 2002 and the Biological Diversity Rules, 2004, amended by the Biological Diversity (Amendment) Act, 2023. The Act establishes a three-tier structure: the National Biodiversity Authority in Chennai, which regulates access by foreign entities and approves applications for intellectual property rights based on Indian biological resources; State Biodiversity Boards, which regulate access by Indian entities for commercial use; and Biodiversity Management Committees in local bodies, which document local biodiversity and knowledge in People's Biodiversity Registers and are consulted on access. Benefit sharing is determined according to guidelines, with funds flowing to biodiversity funds and, where identified, to benefit claimers. The Act also provides for biodiversity heritage sites and notification of threatened species. The 2023 amendment eased provisions for the codified traditional medicine (AYUSH) sector and decriminalised several offences, a change that was debated.
Other laws relevant to conservation of forest biodiversity include the Wildlife (Protection) Act (Schedule III protects specified plants), the Forest (Conservation) Act and the Forest Rights Act, described in forest-policy-law-governance, and the Protection of Plant Varieties and Farmers' Rights Act, 2001.
Environmental impact assessment (EIA) is the process of identifying, predicting and evaluating the environmental and social effects of a proposed project before decisions are made, and of designing measures to avoid or reduce harm. In India, EIA is required under the EIA Notification of 2006, issued under the Environment (Protection) Act, 1986. Projects are classified as Category A, appraised at the national level by expert appraisal committees of the environment ministry, or Category B, appraised at state level by State Environment Impact Assessment Authorities; Category B is further divided into B1, which requires full EIA, and B2, which does not. The process has four stages: screening (deciding whether and at what level EIA is needed), scoping (setting terms of reference), public consultation (public hearing and written responses) and appraisal (examination by the expert committee leading to a recommendation). General EIA methods are covered in the Sustainability track's environmental-impact-assessment.
Separately, diversion of forest land for non-forest purposes requires approval under the Forest (Conservation) Act, 1980 (renamed the Van (Sanrakshan Evam Samvardhan) Adhiniyam in 2023), usually in two stages: in-principle (Stage I) approval with conditions, and final (Stage II) approval once conditions are met. Conditions typically include compensatory afforestation on equivalent non-forest land or on twice the area of degraded forest land, payment of the net present value of the forest lost, as directed by the Supreme Court and varying with forest type and density, and wildlife mitigation plans. Funds are managed under the Compensatory Afforestation Fund Act, 2016 (CAMPA). Projects in protected areas also need clearance from the National Board for Wildlife.
An EIA report describes the project and alternatives; establishes the environmental baseline (vegetation, wildlife, soils, water, air, socio-economic conditions), which for forest projects should include surveys of flora and fauna across seasons; identifies and predicts impacts using checklists, matrices (the Leopold matrix of 1971, relating project actions to environmental components), networks and overlays; evaluates significance; proposes mitigation; and sets out an environmental management plan and monitoring programme. For forest projects, key impacts include loss of forest cover and habitat, fragmentation and loss of connectivity, effects on threatened species and wildlife corridors, changes to hydrology and soil erosion, effects on forest-dependent people and their rights, and cumulative impacts of several projects in a landscape.
The mitigation hierarchy orders responses: first avoid impacts, for example by choosing an alternative alignment; then minimise them, for example by underpasses for wildlife; then restore affected areas on site; and only finally offset residual impacts elsewhere. Compensatory afforestation is a form of offset, but its effectiveness has been criticised because plantations rarely replace the biodiversity and ecosystem services of natural forest, sites are often poor, and survival is not always monitored. Other weaknesses of EIA practice include inadequate baseline surveys, consultants paid by project proponents, limited public participation and weak monitoring of conditions. Strategic environmental assessment of plans and programmes, and cumulative impact assessment for river basins or landscapes, address some of these limitations.
Ecosystem services are the benefits people obtain from ecosystems. The Millennium Ecosystem Assessment (2005) grouped them into four categories: provisioning services (products such as timber, fuelwood, food, fodder, fibre, medicines and fresh water); regulating services (climate regulation, carbon storage, flood and erosion control, water purification, pollination, pest and disease regulation); cultural services (spiritual, recreational, aesthetic and educational benefits); and supporting services (soil formation, nutrient cycling and primary production that underpin the others). Later frameworks, such as the Common International Classification of Ecosystem Services, drop supporting services to avoid double counting, and IPBES uses the broader term 'nature's contributions to people', which emphasises cultural perspectives and includes negative contributions.
Forests provide some of the most important ecosystem services: they store large amounts of carbon and regulate climate; regulate water flows and quality, as upland forests protect drinking water supplies and reduce erosion and sedimentation of reservoirs; provide habitat for pollinators that support agriculture; supply timber, fuelwood, fodder and non-timber forest products that support hundreds of millions of people; and provide cultural and recreational values. Many of these services are public goods that markets do not price, which is one reason forests are converted to uses with lower total value to society.
Valuing ecosystem services, in money or other terms, can show their importance to decision-makers. Costanza and colleagues estimated in 1997 that global ecosystem services were worth about 33 trillion dollars a year, more than global GDP at the time, and an update in 2014 gave a much higher figure; such global estimates are illustrative rather than precise. The Economics of Ecosystems and Biodiversity (TEEB) initiative, reporting from 2008 to 2010, promoted recognising, demonstrating and capturing the value of nature in policy. Valuation methods, such as market prices, replacement cost, travel cost and contingent valuation, are covered in forest-economics-valuation.
Ecosystem services can be conserved through protected areas, sustainable forest management, payments for ecosystem services (such as watershed payments by downstream water users), including services in environmental impact assessment and land-use planning, and natural capital accounting, in which countries record changes in ecosystem assets alongside economic accounts, as under the UN System of Environmental-Economic Accounting. In India, the Finance Commission has included forest cover as a criterion in the transfer of funds to states, rewarding states that maintain forests. Conservation of ecosystem services and of biodiversity usually go together, but not always: a fast-growing plantation may store carbon and control erosion while supporting little native biodiversity, so both must be considered explicitly.
Learn the three levels of biodiversity and alpha, beta and gamma diversity, the IPBES drivers, the species-area and Levins equations, the IUCN categories and the thresholds for each criterion, the forms of in situ and ex situ conservation with Indian examples, seed storage standards and Harrington's rules, the CBD objectives and protocols, the three-tier structure of the Biological Diversity Act, EIA stages and the mitigation hierarchy, and the MEA categories of ecosystem services.
As a forest officer, research scientist or conservation professional, you identify and protect populations of threatened species, establish seed production areas and gene conservation units, collect and document seed for gene banks, support Biodiversity Management Committees and People's Biodiversity Registers, prepare inputs for EIA and forest clearance, and plan compensatory afforestation. Judgement is needed to choose populations and methods that capture genetic diversity and to make mitigation real rather than nominal.
At senior level you set state or national strategies for biodiversity and forest genetic resources, decide on forest diversion proposals and their conditions, oversee access and benefit-sharing applications, and integrate ecosystem services into planning and accounting. Decisions include priority species and areas, the balance of in situ and ex situ investment, and responses to climate change such as assisted gene flow.
Research questions include patterns of genetic diversity in forest trees, effects of fragmentation and logging on gene flow and regeneration, effectiveness of protected areas, sacred groves and gene conservation units, seed storage and cryopreservation of recalcitrant species, extinction risk assessment for long-lived trees, and valuation and mapping of ecosystem services. Rigorous research combines field ecology, population genetics, modelling and policy analysis.
IUCN thresholds are summarised; the full criteria include sub-conditions not reproduced here. Numbers of sacred groves, biosphere reserves and threatened species vary with source and year and are approximate. Net present value rates for forest diversion and compensatory afforestation rules change and are not tabulated. Population genetics, provenance and breeding are in forest-genetics-tree-improvement; seed storage in tree-seed-technology; protected area management in wildlife-management-protected-areas; and detailed law in forest-policy-law-governance. The effects of the 2023 amendments to the Biological Diversity Act and the Forest (Conservation) Act are still being interpreted and are described in outline.
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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