Forestry & Forest Sciences · Forest Management, Policy, Economics & Society · also Agroforestry, Agroforestry Systems, Agroforestry and Social Forestry
Trees on farms and in landscapes: definitions and history of agroforestry, classification of systems, diagnosis and design, and the major agroforestry systems of the world's agro-ecological zones. The Sustainability track has a single overview subject (agroforestry-trees-on-farms); this track treats agroforestry as a forester designs and manages it, in two subjects.
In the exams: ICAR AICE-JRF 59 Unit 5 and Unit 1 (National Agroforestry Policy 2014); ICAR AIEEA-PG Group 09 (agroforestry); IFoS Forestry Paper I Section B; ICAR AIEEA-PG Group 05 Agronomy Unit IX (agroforestry systems)
Agroforestry is the forester's discipline of trees outside the forest: trees grown with crops and livestock on farms, on field boundaries, around homesteads and across rural landscapes. For India it is not a niche. Trees outside forests supply a large share of the country's timber and fuelwood, much of the raw material for plywood, paper and match industries comes from farms, and India in 2014 became the first country to adopt a national agroforestry policy. Foresters in state forest departments, research institutes and extension services are now expected to design agroforestry systems as routinely as they design plantations.
This subject treats agroforestry as a forester designs it. It covers the concept and history of agroforestry, its benefits and constraints, the classification of systems, the main system types and practices, the diagnosis and design methodology developed by ICRAF, land capability classification as a basis for land-use decisions, multipurpose tree species, the agroforestry systems of India's and the world's agro-ecological zones, temperate agroforestry, and national agroforestry policies. Its companion subject, agroforestry-management-economics, covers tree-crop interactions, tree management on farms, productivity, carbon and economics. The Sustainability track's agroforestry-trees-on-farms gives a shorter overview with emphasis on carbon, biodiversity, tenure and policy barriers, and forest-economics-valuation covers discounting and cost-benefit methods; this manual refers to them rather than repeating them.
The manual is written for students preparing for the ICAR AIEEA-PG forestry and agronomy papers, the ICAR AICE-JRF forestry paper and the Indian Forest Service and state forest service examinations, and for foresters and extension staff who plan agroforestry on the ground. Species recommendations depend on site, climate and markets, so the examples given are illustrations, not prescriptions.
The most widely quoted definition comes from the International Council for Research in Agroforestry (ICRAF), associated with Lundgren and Raintree in the early 1980s: agroforestry is a collective name for land-use systems and technologies where woody perennials (trees, shrubs, palms, bamboos and so on) are deliberately used on the same land-management unit as agricultural crops and/or animals, in some form of spatial arrangement or temporal sequence. In agroforestry systems there are both ecological and economic interactions between the different components. Three ideas are central: at least one woody perennial is present; the combination is deliberate; and the components interact.
Several attributes are usually expected of an agroforestry system. Productivity: it should maintain or increase production of preferred commodities. Sustainability: it should conserve the production potential of the land. Adoptability: it should fit farmers' practices and be acceptable to them. Agroforestry systems also usually involve two or more species, have two or more outputs, have a cycle longer than one year, and are more complex, ecologically and economically, than monocropping. Later definitions by ICRAF widened the scale to trees on farms and in agricultural landscapes, including scattered trees, woodlots and boundary plantings.
Growing trees with crops and animals is ancient. Shifting cultivation, in which forest is cleared, cropped for a few years and then left to regrow as a tree fallow, is the oldest form of rotational agroforestry and is still practised as jhum in north-eastern India. Homegardens in Kerala, Java and East Africa, Sahelian parklands, and the dehesa of Spain are centuries old. Traditional Indian systems include khejri in the fields of Rajasthan, babul on tank beds in the Deccan and fodder trees on terrace risers in the Himalaya.
The taungya system, in which farmers grow crops between the rows of young forest tree seedlings in return for planting and tending them, was formalised in Burma (Myanmar) in the 1850s under Dietrich Brandis for teak plantations, and spread to India, where it was used widely to establish teak, sal and other plantations, and to Africa. The modern science of agroforestry dates from the 1970s. A study commissioned by Canada's International Development Research Centre, published as Trees, Food and People (Bene, Beall and Côté, 1977), identified the need for research on combined production systems, and K. F. S. King, who wrote on taungya and 'agri-silviculture', helped establish the field. ICRAF was founded in Nairobi in 1977-78, the journal Agroforestry Systems began in 1982, and P. K. R. Nair's books and classification became the standard reference.
In India, the All India Coordinated Research Project on Agroforestry was launched by ICAR in 1983, the National Research Centre for Agroforestry was established at Jhansi in 1988 and later became the ICAR-Central Agroforestry Research Institute (CAFRI), and social forestry programmes of the late 1970s and 1980s promoted farm forestry, often with eucalyptus. The National Agroforestry Policy of 2014 followed (see the last chapter).
Related terms are often confused. Social forestry, a term popularised in India by the National Commission on Agriculture (1976), refers to forestry for the benefit of rural communities and includes farm forestry (trees grown by farmers on their own land), community woodlots on common land, extension forestry along roads, canals and railway lines, and recreational forestry. Farm forestry is tree planting on private farmland, often in blocks or on boundaries, and overlaps strongly with agroforestry. Agroforestry emphasises the deliberate integration and interaction of trees with crops or animals on the same unit of land.
Agroforestry offers productive benefits: a wider range of products from the same land (food, fodder, fuelwood, timber, poles, fruit, fibre, gums, medicines); more total output per unit area when components use resources complementarily; production spread through the year and across years; and products that can be sold when cash is needed. It also offers service or protective benefits: soil conservation and fertility improvement through litter, nitrogen fixation and nutrient cycling; reduced wind and water erosion; microclimate moderation that reduces heat and water stress for crops and animals; watershed protection; carbon storage; habitat for biodiversity; and reduced pressure on natural forests for fuelwood and fodder.
Socio-economic benefits include diversification of income and reduced risk, employment in tree management and processing, and supply of raw material to wood-based industries. In India, agroforestry has been credited with supplying a large share of the country's industrial wood and much of its fuelwood, and with providing a buffer to farmers in years when crops fail. The environmental and social dimensions are discussed in the Sustainability track's agroforestry-trees-on-farms.
Agroforestry also has constraints. Biophysical constraints: competition between trees and crops for light, water and nutrients can lower crop yields; some trees have allelopathic effects; trees may harbour pests, diseases or birds that damage crops; trees occupy land that could be cropped; and fast-growing species can use a lot of water. Management constraints: systems are more complex to design and manage, mechanisation may be hindered, and tree management (pruning, lopping, root pruning) adds labour.
Socio-economic and institutional constraints are often decisive: the long gestation period before trees yield income; uncertainty about markets and prices for farm-grown wood; restrictions on felling and transit of trees under forest laws; insecure land tenure; lack of quality planting material; limited credit and insurance for tree crops; and weak extension. These constraints, especially the policy and tenure ones, are discussed in agroforestry-trees-on-farms, and the management of tree-crop competition in agroforestry-management-economics.
A balanced assessment compares benefits and constraints for a specific site and farmer. A system that suits an irrigated farm near a plywood market in Haryana may fail on a rainfed farm far from markets in central India. This is why agroforestry design begins with diagnosis of the farm and its constraints.
Benefits that are easily counted, such as timber and crop yields, can be compared in a cost-benefit analysis. Others, such as soil conservation, risk reduction and environmental services, are harder to value but can be decisive. Foresters planning agroforestry should state which benefits they expect, how they will be measured, and how long they will take to appear, and should not promise every benefit from every system.
Classification groups the many agroforestry systems into categories that can be compared, studied and recommended. P. K. R. Nair's scheme, presented in the 1980s and refined later, classifies systems on four bases, and a system can be described on all four at once.
The structural basis considers the nature of the components and their arrangement. By components: agrisilvicultural systems combine trees (including shrubs and vines) with agricultural crops; silvopastoral systems combine trees with pasture and/or animals; agrosilvopastoral systems combine trees, crops and pasture or animals; and 'other' systems include apiculture with trees, aquaforestry (trees with fish, for example trees on pond bunds whose leaves feed fish) and multipurpose woodlots.
By arrangement in space, components may be in dense mixtures (homegardens), sparse mixtures (scattered trees in fields or pastures), strips (alley cropping, boundary planting, windbreaks) or blocks. By arrangement in time, components may be: coincident (occupying the land together throughout, as in shade trees over coffee), concomitant (together for part of the time, as in taungya), overlapping (one starts before the other ends, as with pepper trained on shade trees), separated or sequential (one after another, as in improved fallows and shifting cultivation) and interpolated (spatially and temporally mixed, as in homegardens).
The functional basis refers to the main role of the woody component. Productive functions include food, fodder, fuelwood, other wood, and other products such as gums and medicines. Protective functions include windbreaks and shelterbelts, soil conservation, moisture conservation, soil improvement and shade for crops, animals or people. Many trees serve both functions.
The socio-economic basis groups systems by the scale of production and management: commercial systems produce mainly for the market, often at large scale with hired labour (poplar or eucalyptus with crops for industry, rubber or coconut with cash crops); intermediate systems are medium-scale with mixed market and subsistence orientation; and subsistence systems mainly meet household needs (many homegardens and shifting cultivation).
The ecological basis groups systems by agro-ecological zone: for example, humid and subhumid lowlands, semi-arid and arid lands, tropical highlands, and temperate zones. Certain systems are characteristic of each zone, such as homegardens and plantation crop combinations in the humid tropics, parklands and silvopasture in the semi-arid tropics, and fodder trees on terraces in highlands.
Other schemes have been used. ICRAF's agroforestry systems inventory in the 1980s described systems worldwide using the components and arrangement approach. Some authors distinguish 'agroforestry practices' (a specific arrangement, such as alley cropping) from 'agroforestry systems' (a practice in a particular locality, such as Leucaena alley cropping in southern Nigeria). Exam questions often ask students to classify a given system on all four bases, so it is worth practising with examples.
Agrisilvicultural systems combine woody perennials with agricultural crops. They include: improved fallows; taungya; alley cropping (hedgerow intercropping); multipurpose trees on farmland, whether scattered or in rows; plantation crop combinations, such as coconut with cacao, pepper, banana or pineapple, and shade trees over coffee or tea; agrihorticulture, combining fruit trees with crops, such as mango, guava, aonla (Indian gooseberry) or ber with pulses or vegetables; agrisilviculture in the narrow sense, combining timber trees such as poplar, eucalyptus, Melia or teak with field crops; shelterbelts and windbreaks; and soil conservation hedges.
In north-western India, poplar (Populus deltoides) with wheat in winter and fodder crops or sugarcane is the best-known commercial agrisilvicultural system; eucalyptus clones are widely grown on boundaries and in blocks in Punjab, Haryana, Andhra Pradesh, Telangana, Tamil Nadu and Karnataka; and Melia dubia is spreading in southern India. In the semi-arid tropics, aonla, ber and tamarind are combined with pulses and oilseeds. The design and management of these systems, including spacing and pruning, are discussed in agroforestry-management-economics.
Silvopastoral systems combine trees with pasture and livestock. Types include: protein banks or fodder banks, in which multipurpose trees are planted densely and their foliage is cut and carried to animals; live fences of fodder trees and shrubs; trees and shrubs on pastures, scattered or planted in rows; and grazing in plantations, such as cattle under coconut or rubber. Benefits include dry-season fodder, shade, timber and fuel, and better use of land unsuitable for crops.
In India, silvopasture on degraded and marginal lands combines grasses such as Cenchrus ciliaris, Cenchrus setigerus, Panicum maximum, Dichanthium and Stylosanthes legumes with trees such as Hardwickia binata, Albizia lebbeck, Leucaena leucocephala, Acacia nilotica and, in arid areas, Prosopis cineraria and Ailanthus excelsa. Research at institutes such as the Indian Grassland and Fodder Research Institute at Jhansi and the Central Arid Zone Research Institute at Jodhpur has developed silvopastoral models for wasteland development. Grazing must be controlled to protect young trees, and stocking rates matched to forage production.
Agrosilvopastoral systems include all three components. Homegardens are the main example: multistorey combinations of trees, crops and animals around homesteads, discussed in the next chapter. Others include woody hedgerows for browse, mulch and green manure on crop-livestock farms; trees on field boundaries grazed after harvest; and farming systems in which crop residues, tree fodder and grazing are integrated, as in many mixed farms of the Indian Himalaya and semi-arid regions, where fodder trees on terrace risers and field boundaries supply animals that provide manure for crops.
Agrosilvopastoral systems are the most complex to design, because animals, crops and trees all compete for and contribute to resources, and because livestock can damage trees. Their strength is close nutrient cycling within the farm, which suits smallholders with limited purchased inputs.
Homegardens are intimate, multistorey combinations of trees, shrubs, herbs and often livestock around homesteads, managed mainly by family labour. They are common throughout the humid tropics: Kerala and coastal Karnataka in India, Sri Lanka, Java (pekarangan), the Chagga homegardens on the slopes of Kilimanjaro, and the Pacific islands. A Kerala homegarden may combine an upper canopy of coconut and arecanut, a middle layer of jackfruit, mango, cashew and nutmeg, climbers such as black pepper, and lower layers of banana, tapioca, yams, ginger, turmeric and vegetables, with cattle, goats or poultry. They provide food, cash, fuel and timber through the year with low external inputs, and support high species diversity. Design principles include using vertical space, selecting shade-tolerant species for lower layers, mixing species with different harvest times, and recycling household and animal wastes.
In alley cropping, crops are grown in alleys between hedgerows of trees or shrubs, usually nitrogen-fixing species such as Leucaena leucocephala, Gliricidia sepium, Cassia siamea or Calliandra calothyrsus. Hedgerows are pruned periodically to reduce shading, and prunings are applied as mulch or green manure or fed to livestock. Typical designs space hedgerows a few metres apart (often about 4 to 6 m), with trees close within the row, oriented east-west or along the contour on slopes. Alley cropping was promoted from the late 1970s, notably by the International Institute of Tropical Agriculture in Nigeria, but adoption was limited by labour for pruning, competition for water in drier areas and the time before benefits appear. It works best on sloping land, where the hedgerows also control erosion (contour hedgerows), and in humid areas.
Boundary planting puts trees along field or farm boundaries, bunds and farm roads. It is the most widely adopted form of agroforestry in India because it takes little cropland, marks the boundary, provides wood and protects fields. Common species include eucalyptus, poplar, Melia dubia, Dalbergia sissoo, teak, Acacia nilotica, neem and Casuarina. Design questions include spacing within the row (often 1 to 3 m for eucalyptus or poplar boundary rows), row orientation, pruning to reduce shade on crops, root pruning or trenching to reduce competition, and the effect on neighbours' fields, which can cause disputes.
Windbreaks are single or few rows of trees or shrubs; shelterbelts are wider, multi-row belts. They reduce wind speed in the protected zone on the leeward side for a distance commonly given as about 10 to 20 times the barrier height (H), with some effect upwind, and so reduce evaporation, mechanical damage to crops and wind erosion. Design factors are height, which sets the protected distance; density or porosity, with moderate porosity often cited around 40 to 50 percent for crop protection; orientation at right angles to the damaging wind; length, at least about ten times the height to limit end effects; continuity without gaps; and cross-section, with multi-row belts of tall trees in the centre and shrubs on the sides giving a sloping profile.
In the Thar desert, shelterbelts of Acacia tortilis, Prosopis juliflora, Azadirachta indica, Albizia lebbeck, Dalbergia sissoo, Tamarix and Cassia siamea have been planted on field boundaries and along canals. A typical multi-row shelterbelt design may have three to five rows, with tall species in the middle rows and shrubby species on the windward and leeward edges. Benefits, costs and large programmes are discussed in agroforestry-trees-on-farms.
Diagnosis and design (D&D) is a methodology developed by ICRAF in the early 1980s, with J. B. Raintree as its main architect, for diagnosing land-management problems and designing agroforestry solutions to them. It applies a systems approach, starting from the farmer's goals and constraints rather than from a technology looking for a place to be used. It is meant to be iterative: designs are tested, evaluated and redesigned as knowledge improves. It can be applied at the scale of a household (micro D&D), a landscape or watershed, or a region (macro D&D).
D&D proceeds through five broad stages. The pre-diagnostic stage defines the land-use system to be studied, its boundaries and its distinctive features, based on secondary data and reconnaissance; it identifies the dominant land-use systems in an area and selects representative ones. The diagnostic stage analyses how the system works and why it falls short of its production or sustainability goals, by studying production objectives and strategies, problems, causes and potential interventions; farmer interviews, field observation and analysis of resource flows are used to build a problem-cause diagram. The design and evaluation stage specifies agroforestry interventions that address the diagnosed constraints and evaluates them for productivity, sustainability and adoptability, including technical feasibility, economic returns and farmer acceptability. The planning stage prepares a plan for research, extension and development activities, including on-station and on-farm trials. The implementation stage carries out the plan, monitors results and feeds them back into further diagnosis and redesign.
Raintree summarised the logic of D&D in a set of key questions: what is the system to be improved, and how does it work (pre-diagnosis and diagnosis); what are the problems and their causes (diagnosis); what interventions could address them, and what would an improved system look like (design); and what is needed to develop and disseminate the improved system (planning and implementation).
D&D draws on tools that are now common in rural appraisal: secondary data review, transect walks, sketch maps, seasonal calendars of labour, rainfall, fodder and cash, problem and objective trees, ranking exercises and household interviews. Since the 1990s, the approach has become more participatory, with farmers involved in identifying problems, choosing species and arrangements, and evaluating trial results, and with attention to differences between men and women and between richer and poorer farmers. Participatory tree domestication, in which farmers and researchers select and propagate superior individuals of indigenous fruit trees, grew out of this approach.
An example illustrates D&D. In a semi-arid village, diagnosis might find that livestock lack fodder in the dry season, that fuelwood collection takes many hours of women's time, and that field bunds are eroding. Design might propose fodder trees such as Hardwickia binata or Leucaena on bunds, a fuelwood woodlot on degraded common land, and grass strips with trees on contour bunds. Evaluation would check water competition with crops, labour needs, the time to first harvest and acceptability to households, and planning would set up on-farm trials with interested farmers.
Land capability classification groups land according to its suitability for sustained use without degradation, based on the limitations of soil, slope, erosion hazard, wetness and climate. The system most taught in India is the USDA land capability classification developed by Klingebiel and Montgomery (1961). It has eight classes, numbered I to VIII, in which the degree of limitation and hazard increases and the range of safe uses decreases.
Classes I to IV are suitable for cultivation. Class I has few limitations and can be cultivated safely with ordinary good practices. Class II has some limitations that reduce the choice of crops or require moderate conservation practices. Class III has severe limitations that reduce the choice of crops or require special conservation practices, such as terracing or contour farming. Class IV has very severe limitations and is suitable for occasional or limited cultivation with very careful management. Classes V to VIII are generally not suited to cultivation. Class V has little erosion hazard but other limitations, such as wetness, stones or flooding, that restrict use largely to pasture, range, woodland or wildlife. Class VI has severe limitations that make it generally unsuited to cultivation and limit its use to pasture, range, woodland or wildlife. Class VII has very severe limitations, with use restricted to grazing, woodland or wildlife under careful management. Class VIII has limitations that preclude commercial plant production and restricts use to recreation, wildlife, water supply or aesthetic purposes.
Subclasses indicate the kind of limitation: e for erosion hazard, w for wetness or drainage problems, s for soil limitations in the root zone (shallowness, stones, low water holding, salinity or sodicity) and c for climatic limitations. A unit of class IIIe, for example, is cultivable with special practices, the main hazard being erosion. Capability units group soils with similar management needs within a subclass. India's soil survey organisations have used the classification in land-use planning and watershed projects, often alongside land irrigability classes for irrigation planning.
Land capability guides the choice between crops, agroforestry, pasture and forest. On class I and II land, agroforestry is usually limited to boundary planting, windbreaks or wide-spaced commercial trees such as poplar, so that crop production is not compromised. On class III and IV land, where erosion or shallow soils limit cultivation, agroforestry with contour hedgerows, trees on bunds, agrihorticulture and alley cropping can combine production with conservation. Class V and VI land suits silvopasture, fodder banks, fruit and fuelwood trees. Class VII land suits protective tree cover, controlled grazing and silvopasture with conservation measures, and class VIII is best left under natural vegetation. Wastelands, of which India has large areas classified by the national wastelands atlas, are often class V to VII land and are a major target for silvopasture and tree planting.
Land suitability evaluation, as in the FAO Framework for Land Evaluation (1976), complements capability classification by assessing land for specific uses, such as a particular tree species or agroforestry system, in classes from highly suitable (S1) to not suitable (N). Both approaches are inputs to the diagnosis stage of D&D.
Multipurpose trees and shrubs (MPTs) are woody perennials grown deliberately for more than one product or service. Desirable characteristics for agroforestry include: fast growth and early yield; ability to coppice, pollard or tolerate lopping, so that foliage and wood can be harvested repeatedly; deep and narrow root systems that compete little with crops for water and nutrients near the surface; a light, open or narrow crown that casts little shade, or deciduousness when crops are growing; nitrogen fixation; tolerance of drought, salinity or other site stresses; absence of strong allelopathic effects; resistance to pests and diseases; and production of several useful products, such as fodder, fuelwood, timber, fruit, green manure or gum. No single species has all these characteristics, so selection balances them against the farmer's goals and site.
An 'ideotype' is a description of the ideal tree for a given system. For poplar in agroforestry, for example, an ideotype might include a straight bole, narrow crown with light branches, late leaf flushing and early leaf fall to reduce shading of winter crops, fast growth and resistance to defoliators.
Species commonly used in Indian agroforestry include, by main use:
Timber and pulpwood: Populus deltoides (poplar), Eucalyptus hybrids and clones, Melia dubia, Tectona grandis (teak), Dalbergia sissoo (shisham), Gmelina arborea, Ailanthus excelsa, Casuarina equisetifolia and C. junghuhniana, Acacia mangium and A. auriculiformis, and bamboos.
Fodder: Leucaena leucocephala, Albizia lebbeck, Hardwickia binata, Prosopis cineraria, Morus alba (mulberry), Grewia optiva, Celtis australis, Bauhinia variegata and Ficus species in the Himalaya, Sesbania grandiflora and Gliricidia sepium.
Fruit and other products: Emblica officinalis (aonla), Ziziphus mauritiana (ber), Tamarindus indica (tamarind), Mangifera indica, Azadirachta indica (neem, also for its oil and pesticide value), Pongamia pinnata (karanja, seed oil), Madhuca species (mahua), Simarouba glauca (oilseed) and Acacia senegal (gum arabic).
Nitrogen-fixing and soil-improving: leguminous trees such as Leucaena, Gliricidia, Sesbania, Albizia, Acacia, Dalbergia and Prosopis; and the actinorhizal Casuarina (with Frankia) and Alnus nepalensis (alder).
Some MPTs have drawbacks: Leucaena can become invasive and was devastated in many countries by the psyllid Heteropsylla cubana in the 1980s; Prosopis juliflora, introduced for fuel and soil stabilisation in dry areas, has become a serious invasive in many regions; and eucalyptus is debated for its water use in dry areas.
Species selection follows from diagnosis: what products and services the farmer needs, what the site can support, what markets exist, and how the species will interact with crops. Species-site matching uses information on rainfall, temperature, soil depth, texture, pH and salinity. Planting material should be of known, good genetic quality, such as clones of poplar and eucalyptus that have been tested, or seed from selected seed sources. Tree improvement for agroforestry is covered in the tree improvement subjects of this track.
Agroforestry systems differ with climate, soils and farming traditions. In the western Himalaya, fodder trees such as Grewia optiva, Celtis australis, Bauhinia variegata, Morus and Ficus are grown on terrace risers and field boundaries and lopped in winter for livestock; apple, walnut and other fruit trees are combined with crops (agrihorticulture), and Alnus nepalensis is used in the eastern Himalaya. In Sikkim, large cardamom is grown under the shade of Alnus nepalensis, a well-studied nitrogen-fixing system. In north-eastern India, shifting cultivation (jhum) is the traditional system; improved jhum and alder-based systems, such as those of the Angami Nagas at Khonoma in Nagaland, where Alnus nepalensis is pollarded and maintained in jhum fields, are notable examples.
In the irrigated Indo-Gangetic plains, commercial agrisilviculture with poplar, eucalyptus and Melia, block and boundary plantations, and fruit-based systems dominate, linked to wood-based industries. In the arid western Rajasthan zone, Prosopis cineraria (khejri), Tecomella undulata (rohida), Ziziphus, Acacia senegal, Salvadora and Capparis are retained in fields and pastures, with silvopasture on rangelands and shelterbelts against wind erosion. In the semi-arid Deccan plateau and central India, Hardwickia binata, Acacia nilotica (including babul in tank beds that dry in winter), tamarind, Azadirachta indica, aonla and ber are combined with rainfed crops and pastures. In the humid south and west coast, Kerala and coastal Karnataka homegardens, coconut-based multistorey systems with cacao, pepper and banana, rubber and arecanut combinations, and Casuarina along the east coast of Tamil Nadu and Andhra Pradesh are characteristic.
In the West African Sahel and Sudan savanna, parklands of Faidherbia albida, Vitellaria paradoxa (shea), Parkia biglobosa (néré) and Adansonia digitata (baobab) are retained in millet and sorghum fields. In the East African highlands, Chagga homegardens on Kilimanjaro combine banana, coffee and shade trees with livestock, and Grevillea robusta is widely planted on farm boundaries in Kenya and Uganda. In Latin America, coffee and cacao are grown under shade trees such as Inga, Erythrina and Cordia, and the cacao 'cabruca' system of Bahia in Brazil retains thinned native forest over cacao. In Southeast Asia, the Javanese pekarangan (homegarden) and talun-kebun (rotational tree-crop) systems, damar agroforests in Sumatra that produce resin from Shorea javanica, and jungle rubber in Indonesia are well-known. In the Philippines, the Sloping Agricultural Land Technology uses contour hedgerows on steep land.
The ecological basis of classification links these systems to zones. In humid zones, where water is less limiting, intensive multistorey systems and shade-based plantation crops are common. In semi-arid and arid zones, systems emphasise drought-hardy fodder and fruit trees, silvopasture and shelterbelts, with careful spacing to limit competition for water. In highlands, terrace-riser fodder trees and soil conservation hedgerows are typical. Foresters designing systems for a new area should study the traditional systems of the zone, which usually reflect long experience of what works.
In North America, five agroforestry practices are commonly recognised: alley cropping (trees in rows with crops between, such as black walnut, pecan or oak with grain, forage or specialty crops); silvopasture (trees, forage and livestock managed together, such as pine with grazing cattle in the south-eastern United States); windbreaks (field, farmstead and livestock windbreaks, including the shelterbelts of the Great Plains); riparian forest buffers (strips of trees, shrubs and grasses along streams); and forest farming (cultivating high-value specialty crops under a forest canopy). Some lists add special applications such as urban food forests. The USDA National Agroforestry Center in Lincoln, Nebraska, established under the 1990 Farm Bill, supports these practices.
In Europe, traditional systems include the dehesa and montado oak pastures of Spain and Portugal, wood pastures, orchards grazed by sheep, hedgerows and the bocage landscapes of western France and Britain, and Mediterranean olive and cereal combinations. Modern silvoarable systems with walnut, poplar or wild cherry in wide rows with cereals have been studied in France, Italy and the United Kingdom. In China, Paulownia intercropping with wheat and other crops on the North China Plain is a large-scale example.
Riparian forest buffers are designed to protect streams from adjacent land use: they filter sediment, nutrients and pesticides from runoff, stabilise banks, shade the water and provide habitat. A widely used three-zone design, described by the US Forest Service in the early 1990s, has: Zone 1 next to the stream, of undisturbed trees that stabilise the bank and shade the water, often given as about 15 feet (roughly 5 m) wide; Zone 2, a managed forest of trees and shrubs that takes up nutrients and can be harvested selectively, often given as about 60 feet (roughly 18 m); and Zone 3, a grass or herbaceous filter strip next to the field that slows runoff and traps sediment, often given as about 20 feet (roughly 6 m). Widths vary with slope, soil, stream size and objectives, and many programmes specify minimum total widths. Buffers work best where runoff enters them as shallow sheet flow rather than concentrated channels.
Forest farming manages the forest understorey for specialty crops while maintaining tree cover. Examples include medicinal herbs such as ginseng and goldenseal, mushrooms such as shiitake grown on logs, ornamental ferns and decorative materials, maple syrup, and nuts and berries. The forest canopy is thinned to give the right shade for the chosen crop. In India, comparable systems include growing medicinal and aromatic plants, turmeric, ginger and large cardamom under tree cover.
Temperate silvopasture deliberately combines trees, forage and livestock, rather than allowing unmanaged grazing in woodland, which can damage regeneration and soils. In the south-eastern United States, loblolly and longleaf pine are planted in wide rows or thinned to open spacings with improved pasture between; in New Zealand, radiata pine has been grown at wide spacing over grazed pasture. Benefits include income from both livestock and timber, shade for animals, and diversified risk; management must protect young trees from browsing and match stocking to forage.
India's National Agroforestry Policy was approved in February 2014, making India the first country to adopt such a policy. Its goal is to encourage and expand tree planting in complementarity and integration with crops and livestock, to improve productivity, employment, income and livelihoods of rural households, especially smallholders, and to protect and stabilise ecosystems and promote resilient cropping and farming systems. It noted that trees outside forests supply a large share of the country's wood and that agroforestry can help meet the National Forest Policy goal of bringing a third of the country's area under tree cover.
The policy's main strategies included: setting up an institutional mechanism for coordination, convergence and synergy among ministries and schemes; simplifying regulations on harvesting, transit and marketing of farm-grown trees, and exempting a wider list of species from such rules; improving security of land tenure and tree rights; creating a database and information system on agroforestry; strengthening research, extension and capacity building; improving the quality and availability of planting material; providing access to credit, insurance and incentives; involving industry for market linkages; and strengthening farmers' access to markets for agroforestry produce.
The Sub-Mission on Agroforestry was launched in 2016-17 under the National Mission for Sustainable Agriculture to implement the policy, supporting farmers in planting trees on farms, with emphasis on quality planting material and on states that had relaxed transit regulations for selected species. Many states have since relaxed or removed transit permits for common farm-grown species such as poplar, eucalyptus, Melia and others. The Indian Forest Act was amended in 2017 so that bamboo grown outside forest areas is no longer defined as a tree, removing felling and transit permits for farm bamboo, and a restructured National Bamboo Mission followed. ICAR-CAFRI at Jhansi coordinates research through the All India Coordinated Research Project on Agroforestry. Implementation remains uneven between states, and the policy and tenure challenges are discussed further in the Sustainability track's agroforestry-trees-on-farms.
Other countries have followed with their own policies or programmes. Nepal adopted a national agroforestry policy in 2019. Kenya's Farm Forestry Rules of 2009 aim for at least 10 percent tree cover on agricultural land. In the European Union, agroforestry establishment and maintenance have been supported under rural development measures of the Common Agricultural Policy, and France adopted a national agroforestry development plan in 2015. In the United States, agroforestry practices are supported through Department of Agriculture conservation programmes and the National Agroforestry Center. International frameworks, including restoration commitments such as the Bonn Challenge and countries' nationally determined contributions under the Paris Agreement, increasingly include agroforestry.
Common elements of successful policies are coordination across agriculture, forestry, environment and rural development; simplification of rules on growing, cutting and selling farm trees; secure rights to trees and land; quality planting material; research and extension; and market development. Foresters often serve as the link between these policy goals and farmers' fields.
Learn the ICRAF definition and the three attributes, Nair's four bases with examples, the five temporal arrangements, the D&D stages, the eight land capability classes and four subclasses, MPT characteristics and the main species by use, the characteristic systems of each Indian zone, the five temperate practices and the three-zone riparian buffer, and the strategies of the 2014 policy. Practise classifying real systems and drawing layouts of homegardens, alley cropping and shelterbelts.
As a range officer, extension forester or project staff member you diagnose farm constraints, recommend species and arrangements, plan boundary plantations, windbreaks and silvopasture on wastelands, supply quality planting material and explain felling and transit rules to farmers. Judgement is needed to match species to site and markets and to avoid designs that farmers cannot manage or that compete too strongly with their crops.
At senior level you design state agroforestry programmes, nursery and planting-material systems, watershed and wasteland projects, and partnerships with wood-based industries. Decisions include species and zone strategy, regulatory simplification, convergence of schemes, monitoring of survival and adoption, and integration of agroforestry into state forest and climate plans.
Research questions include designing systems for new climates and markets, evaluating traditional systems, improving MPTs through selection and domestication, landscape-scale planning with land capability and suitability data, and the effectiveness of policy reforms in increasing tree cover on farms. Rigorous work combines long-term trials, farm surveys, mapping and participatory research.
Species recommendations, spacings and buffer widths vary with site, climate and objectives; values given are indicative. State-level transit and felling rules in India change often and are not listed. Tree-crop interactions, tree management, productivity, carbon and economic evaluation are covered in agroforestry-management-economics; carbon, biodiversity, tenure and policy barriers in more depth in the Sustainability track's agroforestry-trees-on-farms; and discounting and cost-benefit methods in forest-economics-valuation. Silviculture of individual species and tree improvement are in their own subjects. The exact dates and contents of some foreign agroforestry policies are given only 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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