Sustainability & Environment (Agri-Food Systems) · Natural Resources & Biodiversity · also Soil Conservation and Land Management, Wasteland Management, Land Degradation Neutrality
Why land degrades and how whole landscapes are restored. The engineering of bunds, terraces, waterways and spillways and the USLE calculation are taught in the Agricultural Engineering track (soil-water-conservation-engineering, watershed-planning-management); this subject covers the drivers, assessment and policy of degradation, desertification and restoration.
In the exams: ICAR AICE subject 71 Unit 1 (land degradation, wasteland reclamation); UGC NET Unit 1; UPSC CSE environment
Land degradation is the reduction or loss of the biological or economic productivity and complexity of land -- cropland, pasture, forest and woodland -- caused by land uses or by processes arising from human activities and their interaction with climate. It includes soil erosion by water and wind, salinisation and waterlogging, compaction, loss of soil organic matter and nutrients, pollution, and the long-term loss of natural vegetation. The Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) concluded in 2018 that land degradation was harming the well-being of at least 3.2 billion people and cost more than a tenth of annual global gross product in lost ecosystem services. In India, the Space Applications Centre's Desertification and Land Degradation Atlas (2021) mapped about 97.85 million hectares -- nearly 30% of the country's geographical area -- as undergoing degradation in 2018-19.
This subject explains why land degrades and how whole landscapes are restored. It covers the forms of degradation and their drivers, desertification in drylands, how degradation is assessed and mapped, reclamation of salt-affected and waterlogged soils, reclamation of mine spoils and wastelands, sustainable land management practices, restoration ecology and landscape restoration, Land Degradation Neutrality under the UN Convention to Combat Desertification (UNCCD), the Bonn Challenge and other restoration commitments, and the economics of degradation and restoration.
The engineering of soil and water conservation structures -- contour and graded bunds, terraces, grassed waterways, check dams and spillways -- and the calculation of soil loss with the Universal Soil Loss Equation are taught in the Agricultural Engineering track (Soil and Water Conservation Engineering; Watershed Planning and Management). Soil properties and the chemistry of saline and sodic soils are in Soil Science and Soil Health; sediment and nutrient pollution of water in Water Quality and Agricultural Non-point Source Pollution; and the economic theory of valuation in Natural Resource and Environmental Economics. This manual covers drivers, assessment, policy and restoration.
The subject is examined in the ICAR PhD paper in Environmental Sciences (Unit 1: land degradation and wasteland reclamation), UGC NET Environmental Sciences, UPSC Civil Services (desertification, LDN, the Bonn Challenge and India's targets), state forest and agriculture services, and is central to the work of watershed agencies, forest departments, development banks and restoration programmes. Statistics on degraded area differ widely between assessments because of different definitions and methods; figures quoted are from named sources and should be cited as such.
Soil erosion -- the detachment and transport of soil particles by water or wind -- is the most widespread form of land degradation. The Global Assessment of Human-induced Soil Degradation (GLASOD, Oldeman and colleagues, 1991), the first global map, estimated about 1,964 million hectares of human-induced soil degradation, of which water erosion accounted for roughly 56%, wind erosion 28%, chemical degradation 12% and physical degradation 4%. Water erosion takes the forms of splash, sheet, rill and gully erosion, and also stream-bank erosion and mass movement (landslides); wind erosion moves soil by suspension (fine particles carried as dust), saltation (bouncing sand grains, the main process) and surface creep. Erosion removes the most fertile topsoil, rich in organic matter and nutrients, reduces rooting depth and water-holding capacity, exposes less productive subsoil, and causes off-site damage: sedimentation of reservoirs and canals, pollution of water, and dust storms.
Rates are expressed in tonnes per hectare per year. Because soil forms slowly, the 'tolerable soil loss' used in conservation planning is commonly a few to about 10 t/ha/yr, depending on soil depth and country; actual losses on steep cultivated land without conservation often far exceed this. A loss of 10 t/ha/yr on a soil of bulk density 1.3 g/cm3 removes about 0.8 mm of soil a year -- invisible from season to season but amounting to several centimetres of topsoil within a generation.
Salinisation and sodification occur where evaporation concentrates salts at the surface, especially under irrigation with poor drainage or saline water, and where rising water tables bring salts up (secondary salinisation); waterlogging, often from canal seepage and over-irrigation without drainage, accompanies them. Nutrient mining -- removal of nutrients in harvests faster than they are replaced -- depletes soils in low-input systems, notably across much of sub-Saharan Africa. Acidification results from leaching, ammonium fertilisers and removal of bases. Loss of soil organic matter follows conversion of natural vegetation to cropland, residue removal and burning, and intensive tillage. Pollution includes heavy metals from industry, mining and sewage sludge, pesticide residues, plastics and oil.
Physical degradation includes compaction by heavy machinery and livestock trampling, which reduces infiltration and root growth; surface sealing and crusting, which increase runoff; and soil sealing by buildings and roads, which removes land from production permanently. Biological degradation -- loss of soil fauna, microbial activity and vegetation cover -- accompanies all of these. In practice, forms of degradation interact: erosion removes organic matter and nutrients; compaction increases runoff and erosion; salinity reduces vegetation cover and so increases erosion.
Consider a 50 ha catchment of sloping cropland losing an average of 25 t/ha/yr of soil. On site, at a bulk density of 1.3 g/cm3, this is a loss of about 1.9 mm of topsoil a year, or nearly 4 cm in twenty years -- a large fraction of a shallow soil's fertile layer. The total eroded is 1,250 t/yr. If the sediment delivery ratio to the stream is 0.3, about 375 t/yr reaches the stream and eventually a downstream reservoir; at a deposited density of about 1.2 t/m3 that is roughly 310 m3 of lost storage a year from this small catchment alone. If the eroded soil contains 0.1% nitrogen and 0.05% phosphorus, the catchment loses 1.25 t of N and 0.6 t of P a year, part of which pollutes water downstream. Such simple calculations show why erosion matters both to the farmer and to downstream users, and why conservation programmes are often justified by reservoir protection as much as by farm productivity.
Analyses distinguish proximate (direct) causes of degradation from underlying (indirect) drivers. Proximate causes are the land-use actions and processes that directly damage land: expansion of cultivation onto steep, fragile or marginal land; deforestation and removal of woody vegetation for fuel and timber; overgrazing; inappropriate irrigation and drainage; intensive tillage and residue removal; excessive or unbalanced fertiliser and pesticide use; mining; and urban and infrastructure expansion. Biophysical factors set vulnerability: steep slopes, erodible soils, intense rainfall, high winds, drought and variable rainfall make some land far more prone to degradation than others. Climate change increases risk through more intense rainfall, higher temperatures and longer droughts.
Underlying drivers explain why land users act as they do: population growth and density (which can either increase pressure or, in some cases, drive investment in conservation, as studies in Machakos, Kenya, suggested); poverty and lack of capital, which force short time horizons; insecure land tenure, which removes incentives to invest; market and price policies that reward short-term extraction or subsidise inputs such as water and electricity; weak institutions for managing common lands; and inequitable access to land. Geist and Lambin's synthesis of desertification case studies found that degradation usually arises from a combination of a few proximate causes driven by several underlying factors, with climate variability as a frequent trigger, rather than from any single cause.
Many degraded lands in South Asia and Africa are common lands -- village pastures, forests and wastelands -- whose management institutions have weakened. Garrett Hardin's 'tragedy of the commons' (1968) predicted degradation of open-access resources, but Elinor Ostrom's work showed that many communities manage commons sustainably when institutions with clear rules, monitoring and sanctions exist; degradation is often the result of open access or of the breakdown of community control after nationalisation or privatisation (see Natural Resource and Environmental Economics).
Degradation also involves feedback loops. Declining soil fertility reduces yields, pushing farmers to cultivate more land or shorten fallows, which degrades further land -- a poverty-degradation trap. Loss of vegetation in drylands increases surface albedo and reduces evapotranspiration, which may locally reduce rainfall (a hypothesis proposed for the Sahel by Charney). Conversely, successful restoration can create positive loops: improved soil cover raises infiltration and biomass, which supports livelihoods and investment. Understanding these drivers and feedbacks determines whether interventions address root causes or only symptoms. In India, for example, free or flat-rate electricity for pumping has driven groundwater depletion and waterlogging-salinity problems in different places, minimum support prices for rice and wheat have favoured water-intensive monocultures, and weak management of village commons has allowed overgrazing; each requires a policy response as well as field measures.
The UN Convention to Combat Desertification (adopted in Paris on 17 June 1994, in force 1996) defines desertification as land degradation in arid, semi-arid and dry sub-humid areas resulting from various factors, including climatic variations and human activities. It does not mean the advance of sand dunes or the expansion of existing deserts, although that can occur locally; it is the degradation of productive drylands. Drylands are defined by the aridity index (AI), the ratio of mean annual precipitation to potential evapotranspiration: hyper-arid below 0.05, arid 0.05-0.20, semi-arid 0.20-0.50 and dry sub-humid 0.50-0.65. Excluding hyper-arid deserts, drylands susceptible to desertification cover a large share of the world's land surface (all drylands together are commonly estimated at about 40%) and are home to around two billion people, many of them among the poorest.
In India, arid and semi-arid areas cover a large part of Rajasthan, Gujarat, Punjab, Haryana, Maharashtra, Karnataka, Andhra Pradesh, Telangana and the cold desert of Ladakh. The Central Arid Zone Research Institute (CAZRI) at Jodhpur studies the Thar desert. World Day to Combat Desertification and Drought is observed on 17 June.
Dryland degradation results from overgrazing, cultivation of marginal land, removal of woody vegetation, poor irrigation and recurrent drought. The Sahel droughts of the 1970s and 1980s, with famine and loss of vegetation, led to the first UN conference on desertification (Nairobi, 1977) and to fears of advancing deserts. Later satellite studies showed a substantial 're-greening' of much of the Sahel from the 1980s as rainfall partly recovered and as farmers adopted practices such as farmer-managed natural regeneration (FMNR) -- protecting and pruning tree stumps and seedlings in fields, which spread across millions of hectares in Niger -- and zai pits and stone lines in Burkina Faso. This history shows the need to separate climate-driven fluctuations from human-induced degradation, and that farmers can reverse degradation when incentives and tenure allow.
Large programmes include the African Union's Great Green Wall initiative (launched in 2007), originally conceived as a belt of trees across the Sahel and later broadened to a mosaic of land restoration and livelihood projects; China's Three-North Shelterbelt programme; and India's Desert Development Programme and Integrated Watershed Management Programme. The US Dust Bowl of the 1930s, caused by ploughing of grasslands followed by drought, led to the creation of the Soil Conservation Service (now the Natural Resources Conservation Service) and remains a classic lesson.
Assessing degradation is difficult because it is a process with many forms, and because 'degradation' depends on the use and the reference against which land is judged. GLASOD (1991) was based on expert judgement and mapped human-induced soil degradation by type and severity; ASSOD extended it to South and South-East Asia. FAO's Land Degradation Assessment in Drylands (LADA) and the World Overview of Conservation Approaches and Technologies (WOCAT) developed field and participatory methods for assessing degradation and documenting sustainable land management. Remote sensing now underpins most assessments: long time series of the normalised difference vegetation index (NDVI) from satellites are used to detect trends in vegetation productivity, with corrections for rainfall such as rain-use efficiency (net primary productivity divided by rainfall) and residual trend analysis (RESTREND), which removes the part of productivity change explained by rainfall to reveal human-induced trends.
India's Desertification and Land Degradation Atlas (Space Applications Centre, ISRO) maps degradation processes from satellite imagery at 1:500,000 scale: in 2018-19, about 97.85 Mha (29.7% of the geographical area) was undergoing degradation, with water erosion the largest process, followed by vegetation degradation and wind erosion. The Wastelands Atlas of India (Department of Land Resources and NRSC) separately maps categories of wasteland.
Sustainable Development Goal target 15.3 aims to combat desertification, restore degraded land and soil and strive to achieve a land-degradation-neutral world by 2030. Its indicator 15.3.1, 'proportion of land that is degraded over total land area', is computed from three sub-indicators: trends in land cover (land-cover change, such as forest to cropland or vegetation to bare land), trends in land productivity (net primary productivity, usually from NDVI time series), and trends in carbon stocks above and below ground (soil organic carbon as the proxy). It applies a 'one out, all out' principle: a unit of land is counted as degraded if any one of the three sub-indicators shows significant negative change. Countries report to the UNCCD using national data or default global datasets, and tools such as Trends.Earth help calculate the indicator.
Assessment results differ between methods and datasets, so they should be validated with field data and local knowledge. Ground-based indicators include erosion features (rills, gullies, pedestals, exposed roots), changes in vegetation cover and composition, soil organic carbon, salinity, and crop yields. Participatory assessment with land users adds information on causes and on what has worked.
Salt-affected soils occur naturally in arid and coastal areas and are created by irrigation without adequate drainage. India has about 6.7 million hectares of salt-affected soils, roughly divided between saline and sodic, concentrated in Gujarat, Uttar Pradesh, Maharashtra, West Bengal, Rajasthan, Tamil Nadu, Haryana and Punjab, with saline soils in coastal and arid areas and sodic (alkali) soils in the Indo-Gangetic plains. In irrigated canal commands, seepage from unlined canals and over-irrigation raise water tables; when the water table rises to within about 1.5-2 m of the surface, capillary rise and evaporation bring salts to the root zone, and the land becomes waterlogged and saline. The criteria for saline and sodic soils and the chemistry of reclamation are in Soil Science and Soil Health; here the focus is on landscape-scale causes and reclamation programmes. Waterlogging alone also reduces yields by cutting oxygen to roots, delaying field operations and promoting denitrification losses of nitrogen; in canal commands of Haryana, Punjab, Rajasthan and Uttar Pradesh, and in the Indus basin of Pakistan, waterlogging and salinity developed together within decades of canal irrigation. Globally, FAO's salt-affected soils map indicates hundreds of millions of hectares of salt-affected topsoils.
Saline soils are reclaimed by leaching salts below the root zone with good-quality water, which requires adequate natural or artificial drainage to carry the salts away. The leaching requirement -- the fraction of applied irrigation water that must drain below the root zone to keep salinity at an acceptable level -- is estimated (FAO, Ayers and Westcot) as LR = ECw / (5 ECe - ECw), where ECw is the salinity of the irrigation water and ECe the threshold soil salinity for the crop. For example, irrigation water of 1.2 dS/m and a crop threshold of 3.0 dS/m give LR = 1.2 / (15 - 1.2) = 0.087, or about 9% extra water. Subsurface drainage, with perforated pipes laid 1-2 m deep, lowers water tables and removes salts; India's Central Soil Salinity Research Institute (CSSRI, Karnal) has developed subsurface drainage for waterlogged saline lands in Haryana and other states. Bio-drainage uses deep-rooted, high-transpiring trees such as eucalyptus planted along canals to lower water tables.
Sodic soils are reclaimed with gypsum (or other calcium sources or acids), followed by leaching; India's sodic land reclamation programmes in Uttar Pradesh, Haryana and Punjab reclaimed large areas using gypsum, rice in the first years (rice tolerates standing water during leaching), and salt-tolerant varieties. Salt-tolerant crop varieties, saline aquaculture, halophytes and agroforestry provide productive uses where full reclamation is uneconomic. Preventing salinisation is cheaper than reclaiming it: lining canals, controlling irrigation, providing drainage, conjunctive use of groundwater and surface water, and monitoring water tables.
Surface mining for coal, bauxite, iron ore, limestone and other minerals removes vegetation and soil and leaves overburden dumps, pits and tailings that are unstable, low in organic matter and nutrients, sometimes acidic or toxic, and prone to erosion. Acid mine drainage forms where sulphide minerals such as pyrite oxidise, producing sulphuric acid and mobilising metals that pollute streams. Fly ash from coal power stations occupies large areas in India and can be a source of dust and leachate, though it is also used in construction and, with care, as a soil amendment.
Reclamation aims to create stable, safe, productive land, whether for agriculture, forestry, grazing, recreation or wildlife habitat. Good practice begins before mining: stripping and separately storing topsoil, which contains seeds, organic matter and soil organisms, and planning final landforms. After mining, steps include regrading spoils to stable slopes, controlling drainage, replacing topsoil, applying organic amendments (manure, compost, sewage sludge where permitted) and lime or other amendments, and establishing vegetation -- often nitrogen-fixing grasses, legumes and trees as pioneers, followed by native species. Phytostabilisation uses metal-tolerant plants to bind contaminated tailings. In India, mining leases require approved mine closure plans and progressive reclamation under mining rules, and compensatory afforestation is required when forest land is diverted for mining.
'Wasteland' in India is an administrative category for land that is degraded or under-utilised and could be brought under vegetative cover with reasonable effort. The Wastelands Atlas of India (Department of Land Resources with the National Remote Sensing Centre) maps categories such as gullied and ravinous land, scrub land, degraded forest, degraded pasture, sands, salt-affected land, waterlogged land, mining wastelands, shifting cultivation areas, barren rocky land and snow-covered or glacial areas; the 2019 edition estimated wastelands at about 17% of the country's geographical area. The term is contested because much 'wasteland' is used by pastoralists, the landless and wildlife, and allocating it for plantations or industry can harm those who depend on it.
Reclamation approaches depend on the category: ravine reclamation in the Chambal and Yamuna valleys with peripheral bunds, gully plugging and afforestation; sand-dune stabilisation in the Thar with shelterbelts, grasses such as Lasiurus and Cenchrus and trees such as Prosopis cineraria; afforestation and silvipasture on degraded forest and grazing lands; and watershed development combining soil and water conservation with livelihoods. Community participation and secure rights over the reclaimed land are consistently found to determine success. The engineering of gully control and bunds is in Soil and Water Conservation Engineering (Agricultural Engineering track).
Sustainable land management (SLM) is the use of land resources -- soils, water, animals and plants -- for the production of goods to meet changing human needs while ensuring their long-term productive potential and environmental functions. WOCAT, the global network that documents SLM, classifies measures into four groups: agronomic measures (cover crops, mulching, intercropping, contour cultivation, conservation tillage, manuring, improved varieties), vegetative measures (grass strips, hedgerows, shelterbelts, agroforestry, revegetation of degraded land), structural measures (terraces, bunds, check dams, ditches, water-harvesting structures), and management measures (changes in land use, grazing rotation and exclusion, area closure, changes in timing and intensity). Many effective SLM technologies combine several groups, for example terraces stabilised with grass and trees and managed with improved fertility.
Common SLM practices include conservation agriculture (minimum soil disturbance, permanent soil cover and crop rotation), integrated soil fertility management, agroforestry and farmer-managed natural regeneration, water harvesting in drylands (zai pits, half-moons, farm ponds), rotational grazing and controlled stocking, area closures for natural regeneration, and integrated watershed management. India's watershed programmes, such as the Integrated Watershed Management Programme (now the watershed component of the Pradhan Mantri Krishi Sinchayee Yojana), combine these at micro-watershed scale.
SLM must suit the site and the land user. Technical effectiveness (does it reduce erosion or raise yields?) is necessary but not sufficient: adoption depends on costs, labour, time to benefit, land tenure, access to credit and markets, and social acceptability. Terraces and bunds, for example, may take years to repay their labour costs and may reduce cultivable area; conservation agriculture may need herbicides and new equipment and can reduce yields in the first years on some soils. Benefits may be largely off-site (reduced sedimentation downstream), which justifies public support or payments for ecosystem services. Assessments often find that farmers abandon structures built by projects without their involvement, whereas practices they choose and adapt persist.
Scaling up therefore relies on participatory approaches, farmer-to-farmer extension, secure tenure, incentives that reward long-term investment, and supportive policies, rather than technology alone. The WOCAT database documents hundreds of SLM technologies and approaches with their costs, benefits and conditions of success, and is a standard reference for practitioners and for national reporting to the UNCCD. Indian examples are often cited: at Sukhomajri in Haryana in the 1970s and 1980s, small water-harvesting dams, protection of hill slopes from grazing through 'social fencing', and fair sharing of harvested water and grass among villagers reduced siltation of Chandigarh's Sukhna Lake and raised incomes; at Ralegan Siddhi in Maharashtra, watershed works combined with community rules on grazing, tree felling and water use transformed a drought-prone village. Both show that institutions for sharing benefits matter as much as structures.
The Society for Ecological Restoration (SER) defines ecological restoration as the process of assisting the recovery of an ecosystem that has been degraded, damaged or destroyed. Restoration aims towards a reference ecosystem -- a model, based on remnant sites, historical information or expected natural conditions, of the ecosystem that would be present without degradation -- recognising that the target may shift with climate change. Related terms differ in ambition: rehabilitation restores ecosystem processes and productivity without necessarily recovering native composition; reclamation stabilises and makes land useful, often for a new use, after severe disturbance such as mining; and revegetation simply re-establishes plant cover. SER's International Principles and Standards for the Practice of Ecological Restoration (second edition, 2019) describe a 'recovery wheel' and five-star system for assessing progress across attributes such as absence of threats, physical conditions, species composition, structural diversity, ecosystem function and external exchanges.
Restoration may be passive -- removing the cause of degradation (grazing, fire, drainage) and allowing natural recovery -- or active, involving planting, seeding, reintroduction of species, soil amendment and hydrological repair. Ecological theory shows that degraded ecosystems may cross thresholds into alternative stable states (for example, grassland to shrubland, or eroded land without soil), so removing the cause may not be enough; active intervention may be needed to overcome barriers such as lack of seed sources, soil loss or invasive species.
Forest landscape restoration (FLR) is a process that aims to regain ecological functionality and enhance human well-being across deforested or degraded landscapes. It works at landscape scale, involves stakeholders, and combines a mosaic of interventions -- natural regeneration, agroforestry, planted forests, improved agriculture and protected areas -- rather than single tree plantations. The Restoration Opportunities Assessment Methodology (ROAM), developed by IUCN and the World Resources Institute, helps countries identify where and how to restore.
Large-scale tree planting campaigns have been criticised when they plant monocultures of exotic species, plant trees in naturally treeless grasslands and savannas (which are ancient ecosystems with high biodiversity and carbon in soils), ignore survival rates, or displace local land uses. Good practice prioritises natural regeneration where feasible, native species, the right ecosystem for the site, local participation and long-term monitoring. The UN Decade on Ecosystem Restoration (2021-2030), led by UNEP and FAO, promotes restoration of all ecosystem types -- forests, grasslands, wetlands, farmland, rivers, mountains and coasts -- and the 'Ten principles for ecosystem restoration', which stress inclusive governance, multiple benefits and long-term commitment.
Land Degradation Neutrality (LDN) was adopted by the UNCCD at its twelfth Conference of the Parties (Ankara, 2015) and embedded in SDG target 15.3. It is defined as a state whereby the amount and quality of land resources necessary to support ecosystem functions and services and enhance food security remain stable or increase within specified temporal and spatial scales and ecosystems. Rather than requiring every hectare to improve, LDN balances anticipated losses from degradation with gains from restoration, so that there is no net loss -- measured against a baseline (commonly the average of 2000-2015) using the three indicators of land cover, land productivity and soil organic carbon.
The LDN scientific conceptual framework sets a response hierarchy: avoid degradation (through land-use planning and protecting healthy land), reduce degradation (through SLM), and reverse degradation (through restoration and rehabilitation). Counterbalancing should occur within the same land type -- 'like for like' -- so that degradation of one ecosystem is not offset by gains in a very different one, and should take place at the scale of land-use planning. Gains must be real and additional, and losses should be avoided wherever possible rather than compensated.
Over 100 countries have set voluntary LDN targets through the UNCCD's LDN Target Setting Programme. India hosted the fourteenth Conference of the Parties (New Delhi, 2019) and raised its target to restore 26 million hectares of degraded land by 2030. Implementation is supported by national action programmes, the LDN Fund (a public-private impact investment fund), the Global Environment Facility and the Global Mechanism of the UNCCD. The UNCCD also addresses drought: its drought initiative promotes moving from crisis response to drought preparedness and risk reduction. More recent COPs have emphasised land tenure, gender and drought resilience; COP16 was held in Riyadh in 2024.
Challenges include data limitations for setting baselines and tracking change, the difficulty of ensuring counterbalancing is like-for-like, financing, and integrating LDN into land-use planning across sectors. The concept has been criticised for potentially legitimising new degradation if offsets are promised but not delivered, which is why the hierarchy prioritises avoiding and reducing degradation over offsetting it. Integrating LDN into district and state land-use plans, budgets and environmental impact assessment -- so that new roads, mines and settlements are sited to avoid the most valuable land and planned restoration is funded in matching land types -- is where neutrality is ultimately won or lost.
A district of 400,000 ha is assessed for 2015-2023. Satellite analysis finds 30,000 ha with a significant decline in land productivity, 12,000 ha with negative land-cover change (8,000 ha of which also show productivity decline) and 6,000 ha with soil organic carbon loss (all within areas already counted). Under 'one out, all out', the degraded area is 30,000 + (12,000 - 8,000) = 34,000 ha, or 8.5% of the district. If restoration over the same period produced significant improvement on 20,000 ha of the same land types, the district has a net loss of 14,000 ha relative to neutrality; to reach LDN it must both avoid further losses and expand restoration in matching land types, rather than, for example, counting wetland restoration against cropland degradation. The example shows why overlapping indicators must not be double counted and why like-for-like accounting matters. In practice, statistical significance thresholds, the choice of baseline years and the resolution of satellite data all change the result, so national reports state their methods and validate a sample of areas in the field.
The Bonn Challenge, launched in 2011 by Germany and IUCN, set a global goal to bring 150 million hectares of deforested and degraded land into restoration by 2020; the New York Declaration on Forests (2014) extended it to 350 million hectares by 2030. Countries, sub-national governments and private organisations have made pledges, with restoration understood broadly as forest landscape restoration rather than only planting trees. Regional initiatives contribute: AFR100 (the African Forest Landscape Restoration Initiative, launched in 2015) aims to restore 100 million hectares in Africa by 2030, and Initiative 20x20 aimed to restore 20 million hectares in Latin America and the Caribbean by 2020. The Kunming-Montreal Global Biodiversity Framework (2022) includes a target to have at least 30% of degraded ecosystems under effective restoration by 2030.
India joined the Bonn Challenge in 2015 with a pledge to restore degraded land, later raised to 26 million hectares by 2030, linked to its LDN target and to its NDC goal of creating an additional carbon sink of 2.5-3 billion tonnes of CO2-equivalent through additional forest and tree cover by 2030. Programmes contributing include the Green India Mission, compensatory afforestation funds, watershed development and agroforestry.
Pledges are easier to make than to deliver. Tracking progress requires agreed definitions of what counts as 'under restoration', baselines, monitoring of survival and ecological outcomes, and reporting. IUCN's Barometer of Progress and national systems attempt this, but data are incomplete. Studies of pledges have found that much of the area committed under some national programmes was planned as commercial plantations of a few species, which store far less carbon and support less biodiversity than natural forests and may be harvested; natural regeneration, by contrast, is often cheaper and more effective where seed sources and protection exist.
Good restoration commitments therefore specify outcomes (ecosystem function, biodiversity, carbon, livelihoods) rather than only hectares or trees planted; respect the rights and priorities of local communities; choose appropriate ecosystems; and secure long-term finance and protection. Restoration also requires addressing the drivers of degradation -- otherwise restored land may be degraded again. Independent monitoring, for example by remote sensing of canopy cover combined with field surveys of survival and species, is increasingly expected by funders.
Land degradation imposes costs on-site, borne by land users (lower yields, higher input needs, lost land), and off-site, borne by others (sedimentation of reservoirs and irrigation canals, flood damage, water treatment costs, dust, loss of biodiversity and carbon). On-site costs can be estimated by the productivity-change approach (yield loss multiplied by crop value) or the replacement-cost approach (the cost of fertiliser needed to replace nutrients lost in eroded soil). For example, if 20 t/ha of soil is eroded with 0.1% nitrogen, 20 kg N is lost per hectare, equivalent to about 43 kg of urea; at current prices this gives a lower-bound cost that ignores lost organic matter, water-holding capacity and soil depth.
The Economics of Land Degradation (ELD) Initiative estimated in 2015 that land degradation costs trillions of US dollars a year globally in lost ecosystem services, and IPBES (2018) put the cost of land degradation at more than 10% of annual global gross product. Such estimates depend heavily on assumptions and valuation methods, but consistently show that costs are large and that much of the burden falls on poor rural people. The methods of economic valuation -- productivity change, replacement cost, contingent valuation, benefit transfer -- are taught in Natural Resource and Environmental Economics.
The ELD Initiative's '6+1 step' approach compares the cost of action (investing in SLM and restoration) with the cost of inaction (continued degradation) over time, using cost-benefit analysis with discounting. Many studies find that the benefits of SLM and restoration exceed costs, often by a large margin, especially when off-site and non-market benefits are included. Yet degradation continues because of market failures and other barriers: land users bear the costs of conservation while many benefits accrue to others or in the future; high discount rates of poor households favour short-term extraction; insecure tenure prevents capturing long-term returns; credit is unavailable; and subsidies (for water, energy or fertiliser) may encourage degrading practices.
Policy responses therefore include secure tenure, payments for ecosystem services (for example, downstream water users paying upstream farmers), public investment in watershed development, reform of perverse subsidies, credit and insurance, and integration of land degradation costs into national accounts (the System of Environmental-Economic Accounting). Restoration finance, including blended finance and carbon and biodiversity credits, is growing but small relative to need (see Carbon Markets, Offsets and Payments for Ecosystem Services).
Learn the definitions (land degradation, desertification, LDN, ecological restoration, SLM), the GLASOD figures, aridity index classes, the three SDG 15.3.1 sub-indicators and 'one out, all out', India's numbers (97.85 Mha degrading in 2018-19, 6.7 Mha salt-affected, 26 Mha target), the dates of the UNCCD, COP12, COP14 and the Bonn Challenge, and the steps of mine and salt-land reclamation. Practise simple calculations: erosion rate to soil depth, sediment delivery, leaching requirement, nutrient replacement cost and degraded-area proportions, and be ready to write balanced answers on tree-planting campaigns.
As a watershed officer, forest or soil conservation officer, restoration project manager or consultant, you assess degradation in the field and from satellite data, design and cost SLM and restoration interventions with communities, plan salt-land drainage or mine reclamation, monitor survival and outcomes, and report against LDN, Bonn Challenge and SDG indicators. Your success depends on working with land users and securing their rights and incentives as much as on technical design. Clear documentation of costs, adoption and outcomes builds the evidence that secures continued funding.
As a director of a land-use, forest or watershed agency, or a development-bank or NGO programme lead, you set national targets and priorities, allocate funds between avoiding, reducing and reversing degradation, negotiate in UNCCD and restoration fora, reform policies that drive degradation (subsidies, tenure, grazing rules), and judge restoration claims. You are accountable for outcomes measured years later and must defend investments to finance ministries, explaining why prevention is cheaper than cure and why community institutions need long-term support beyond the life of a project.
As a researcher you work on degradation processes and thresholds, remote-sensing methods for productivity and soil carbon trends, the effectiveness and economics of SLM and restoration, socio-ecological drivers and feedbacks, natural regeneration, drylands under climate change, and indicator and policy design for LDN. You contribute to IPBES, IPCC land assessments and UNCCD science, run long-term restoration trials, evaluate national programmes, and train practitioners and policy makers in the science, monitoring and economics of land degradation and restoration across drylands and humid regions.
Degraded-area statistics differ widely between assessments and are quoted only from named sources; global estimates of salt-affected land and drylands are approximate. The manual does not cover the engineering design of conservation structures or the USLE calculation (Agricultural Engineering track), the chemistry of saline and sodic soils in depth (Soil Science and Soil Health), or forest restoration silviculture (Forestry track). Tolerable soil loss values vary by country and soil and are not tabulated. Policy facts (LDN targets, Bonn pledges, UNCCD decisions after COP16) change and should be checked.
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. Every numerical answer was computed by script; Areas, thresholds and coefficients are stated in each stem because estimates differ between assessments; every numerical answer was computed by script.
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