In some areas, forests and agroforests provide a large proportion of rural households’ food needs. These contributions come in two major forms: (a) the environmental protection role of trees and forests that enhance water and soil conservation to maintain high levels of productivity; (b) the direct food commodity contributions which can supplement normal farm yields or serve as substitute products in the event of crop failures due to floods, droughts or insect infestation (Hoskins 1990). Also of major importance are the socioeconomic contributions of forestry to food security.
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Watershed Protection Functions of Forests/Agroforests
Forests are especially important in protecting the natural resource base upon which sustainable agriculture depends. No aspect of this protection is more crucial than the watershed protection functions provided by forests. Without adequate protective forest vegetation that insures sound watershed management, it will be impossible to increase crop yields, or even to sustain current yield levels.
Uplands and lowlands are intimately linked in hydrologic terms. Adverse land-use changes and practices in uplands almost inevitably affect the agricultural potential of lowlands for the worse. Deforestation and poor land-use practices in water catchments greatly accelerate erosion and site degradation, and often lead to reduced storage capacity in reservoirs, lowered irrigation potential, and increased incidence of downstream flooding. Examples from Asia are numerous. High sediment loads of rivers draining the Himalayas, where land use is intense and erosion is high, have caused problems for agriculture in the lowland plains of Pakistan, India, and Bangladesh (Ball et al. 1995). Similarly, intensive land use in watershed areas has accelerated siltation of reservoirs along the Yellow River in China, thus affecting irrigation potential along the river.\
The Soil’s Shield: Trees
Rapid agricultural expansion and deforestation in China have contributed to increased soil erosion, runoff, siltation of rivers and flooding. Reservoirs along the Yellow River basin (draining the heavily eroded Loess plateau) and the Yangtze River are showing alarming siltation rates which affect their storage capacity. In response, the government of China has launched massive forestry and agroforestry programs, including the “Three North” project, located in the arid and semi-arid zone of the northwest, north central, and northeast China. Started in 1978, it is now perhaps the world’s largest agroforestry program. Large-scale farm shelterbelt systems have been established, sand-dunes have been stabilized, forests have been planted for soil and water conservation, and other watershed rehabilitation works have been carried out. The results have been very positive. An estimated 6.7 million ha of farmland and 3.4 million ha of pastures have been protected. Yield increases due to shelterbelt establishment, averaging 16.4 percent for maize, 36 percent for soybeans, 42.6 percent for sorghum, and 43.8 percent for millet, have been reported. (Ball, et al. 1995)
Responsible forestry practices are key elements of watershed protection and rehabilitation. They include strict protection of all forest vegetation on critical steep slopes, application of low-impact logging practices, afforestation or revegetation for water catchment protection, fire control, and adoption of agroforestry systems to reduce soil erosion. By contributing to sound watershed management, healthy upland forests can help regulate river flows which feed downstream agricultural areas. They may also assist to some extent in reducing the frequency and intensity of floods.
Protection against Water and Wind Erosion
Soil erosion caused by water runoff is a serious problem for agricultural production throughout Asia and the Pacific. It strips away the most fertile top layers of soil, robbing the land of its capacity to produce food and other crops. Forests and trees can provide protection against some types of water-induced soil erosion. It is widely recognized that combining trees with other soil conservation measures can greatly extend the possibilities for sustainable crop production on sloping land.
The incidence of shallow landslides and land slips is greatly influenced by the vegetation (or lack thereof) growing on slopes. Tree roots can isubstantially increase the stability of slip-prone slopes. Studies in New Zealand have shown that tree roots provide up to 80 percent of the soil shear strength under saturated soil conditions (O’Loughlin and Watson 1981).
Trees also protect crops from wind damage. Some of the most dramatic crop yield increases attributable to windbreaks have been reported from China, where Paulownia spp. has been planted to protect more than 13 million ha in the windy central Plains. Grain yields increased 60 percent or more in fields protected by windbreaks, and cotton output has tripled (Wang 1988).
Support and Enhancement of Farming Systems on Marginal Lands
As population pressures on land have increased in Asia and the Pacific, farmers have been forced to cultivate ever steeper slopes and less fertile sites. Successful farming of such steep, infertile uplands often depends on the use of trees and living hedgerows, planted in combination with food crops. Sloping Agricultural Land Technologies (SALT), developed in the Philippines using hedgerows of nitrogen-fixing trees and shrubs, are now widely applied throughout the region. In addition to holding the soil in place, the leaves of the hedgerow species are used as green manure to enrich the soil and enhance crop production. Various such agroforestry techniques–purposely combining trees with agricultural crops or animals–are becoming increasingly important in the drive to maintain and expand food production on marginal farm sites throughout the region.
Forests and Trees as Sources of Animal Feeds
Trees and shrubs indirectly contribute to food production by providing fodder for livestock which supply meat and milk for food, or for livestock used as draft animals in farm production. Fodder-producing tree plantations provide feed either by the “cut and carry” method for stall-fed animals, or through open browsing among free-ranging animals.. As much as 50 percent of all animal fodder in Nepal and parts of India comes from trees.
Forests and Trees as Direct Sources of Food
People living in and near forests traditionally obtain significant portions of their diets from forests. Forest foods are particularly important in predominantly subsistence economies in remote areas. Dependence on these foods is epitomized by the isolated “hunter-gatherer” communities that still exist in parts of India, Papua New Guinea, Sarawak, and a few other locations in Asia. In the Indian states of Bihar, Orissa, Madhya Pradesh, and Himachal Pradesh, most forest dwellers still depend on the forest for 25 to 50 percent of their annual food requirements (Malhotra et al. 1992). As recently as 1988, people in the wooded areas of northeastern Thailand were getting as much as 60 percent of their food directly from the forests (FAO 1988).
In modern times, it is unusual for people to still get that much food directly from forests, but most rural people still depend on forest-based foods to supplement their regular diets. Such forest foods can, therefore, be important elements of sustainable and nutritionally balanced diets. Moreover, they contribute to diet diversity and flavor.
In agricultural areas, the most widespread direct contribution of forestry to food production is through food-producing trees on farm and fallow land and around homes. The extent of this contribution varies widely. At one end of the spectrum are the sophisticated “home gardens” [of which the Javanese home gardens are the best known], which provide more than half of some families’ food (Widagda 1981). At the other extreme, is the single mango tree, or other fruit tree, planted in the family backyard.
Trees and Nutrition
Forest foods rarely supply the main part of a family’s diet, but tree and forest products have an important role in ensuring adequate and balanced nutrition for rural people. A recent study of northeast Thailand villages revealed that the nutritional status of preschool children in villages near forests (with 30 percent of their diet coming from the forest) was considerably better than that of children living in villages far from the forests (Saowakontha, et al. 1989) Similar results were found in studies in Bangladesh (Hassan et al. 1985).
One of the most common uses of forest foods, especially fruits and insects, is as snacks. For example, people frequently eat fruit collected from the forest while they are working, herding animals, gathering fuelwood, or tending their fields. In some areas where crop failures are not uncommon, certain forest perennials are important as “emergency foods,” or “famine foods.” In India, Malaysia, and Thailand, about 150 wild plant species have been identified as sources of emergency food (FAO 1984).
Forests as Pools of Genetic Resources Important for Agriculture
One of the most important connections between forests and long-term agricultural stability is their role as pools of genetic diversity. Modern agriculture continues to depend on periodic infusions of “new” genes from wild relatives to combat outbreaks of disease and susceptibility to insect attack. Major agricultural crops that have “borrowed” significantly from wild relatives include tomatoes, maize, peanuts, potatoes, wheat, rice, and sugarcane. In the late 1980s, for example, researchers in Mexican forests discovered a wild species of maize that is resistant to five major diseases of domestic maize. Many of these wild relatives are found only in forests and the margins around forests. When the forests are destroyed, irreplaceable genetic resources are also lost along with the forest.
From the point of view of future agricultural production, the wide variety of species that forests contain – both known and yet to be discovered – may have critical roles to play in providing the genetic variability and biological diversity needed to combat the ever-adapting pests and diseases that prey upon food crops (FAO 1989). A major challenge lies in safeguarding and conserving these valuable genetic resources for potential future use in the face of pressing immediate needs by current generations.
Socioeconomic Links between Forestry/Agroforestry and Food Security
Fuelwood and charcoal
Wood is important to food security in many ways. In developing countries of Asia and the Pacific, it is not uncommon for at least 75 percent of the population to depend on fuelwood for cooking. Shortages of fuelwood may mean that food is inadequately cooked, or is only cooked once a day. The excessive time and effort spent by women to gather and transport fuelwood for cooking family meals leaves them very little time to engage in other important home tasks, such as cooking meals, caring for the young children, cleaning house, etc.
In areas where fuelwood is scarce, people may turn to dried animal dung for fuel. The burning of dung deprives farmers of an important fertilizer that would normally be returned to fields to nourish crops. Shortages of fuelwood therefore may not only mean more difficulty in cooking food, but may lead to less food being produced.
Income and employment
Food security implies both physical and economic access to food. Forests in Asia and the Pacific generate huge amounts of income and employment that place people in a better position to purchase rather than produce their own food. Income and employment are generated when people become involved in family- or community-oriented forestry activities such as harvesting, processing and marketing forest products. Common features of such enterprises are that they are small-scale (often employing family labor), flexible, and seasonal (operates only when family labor is not engaged in other farm activities.) A broad estimate suggests that forestry currently provides the equivalent of 60 million work-years worldwide, of which about 80 percent is in developing countries (FAO 1994a).
Collecting forest products from the natural forests serves as an important income source for many traditional societies. Gathering or harvesting non-wood forest products is especially important. Some of the most extensive examples of forest products gathering come from India, where at least 3 to 4 million people are involved in the commercial woodfuel trade (FAO 1994b) and up to 7.5 million people are involved in the collection of tendu leaves (Diospyros melanoxylon) used in making bidi cigarettes (FAO 1989).
An important way of increasing the cash-generating potential of forest resources is through the development of processing enterprises. The processing of rattan into furniture, for example, employs at least half a million people in Southeast Asia (IDRC 1980). Other examples of important export crops arising from the forest include bamboo shoots, honey, spices, gums, and resins.
Cash cropping of trees by rural people is another viable source of income and employment under certain circumstances. In many countries of Asia, farmers are planting large numbers of trees-not for subsistence fuelwood-but for cash income. In some areas, farmers earn far greater returns from growing trees than from traditional agricultural crops. Fruit trees are especially popular in many areas, providing farmers with income from the both the fruits and the wood of trees.