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1.
Trees outside forests: agro-, community,and urban forestry   总被引:5,自引:0,他引:5  
Long  Alan J.  Nair  P.K. Ramachandran 《New Forests》1999,17(1-3):145-174
Planted forests are often considered to consist of tree plantings at a scale large enough to satisfy such objectives as commercial production of timber and fiber, protection of watersheds, and preservation of natural habitats. However, trees are planted also at greatly reduced scales in agroforestry systems or as community woodlots to provide a mixture of products and services to resident households, local communities, and regional cultures.Agroforestry systems represent a major form of small-scale tree planting, where trees are grown in purposeful combinations with agricultural crops and/or livestock in order to take advantage of tree-crop interactions, and thereby enhance crop production, diversify farm output, stabilize or improve soils, or ameliorate harsh environmental conditions. Some important examples of these systems in tropical countries include homegardens, alley cropping, improved fallows, intercropped trees for shade and fodder production, and trees planted in hedgerows and along fence lines. Throughout the tropics, there is a large variety of indigenous practices and species mixtures that represent adaptations of these systems to meet localized needs and opportunities. Research and development programs have supported the expansion and refinement of many of these systems during the last 20 years, but substantial constraints on tree planting still exist in the form of land-tenure practices, population pressures that relegate agroforestry practices to degraded lands, subsistence needs that prevent extended periods of tree growth, and insufficient technical information or technology dissemination.Agroforestry systems in temperate, industrialized countries include combinations of trees, pasture, and livestock; fruit or nut trees interplanted with vegetable or grain crops; windbreaks and shelterbelts; multispecies riparian buffer strips; and forest farming systems for specialty crops. Compared to the tropics, however, temperate-zone systems tend to focus on one or two high-value crops, often involve some level of mechanization, and frequently represent an opportunistic approach to improving the economic profitability of farms rather than meeting subsistence needs. In both tropical and temperate regions, agroforestry systems and community woodlots will be an important component of new sustainable agriculture and environmental protection programs.Although species diversity is an essential feature of all agroforestry systems, community forests generally involve planting only a few species in small woodlots near farms, around villages, along roads, and as riparian buffers. Provincial or state governments and the local populace are often involved in landownership and plantation establishment. Major objectives of these forests are production of fuelwood for local consumption and of other tree products for market; soil stabilization, reclamation, or improvement; and protection of water quality. As with many other planted forests, the number of species widely used in community forests has been relatively small, with the genera Eucalyptus, Pinus, and Acacia providing the bulk of the species. Major issues with these planted forests focus on rights for use of the products, tending responsibilities once trees are established, protection until trees are large enough for their designated use, increasing interest in using native species, and greater community involvement in planning and management.Trees planted along streets and waterways, or as woodlots in parks and other public places, represent a major group of planted forests in many urban and periurban landscapes. In addition to providing many of the same environmental services that agroforests and community forests do, these urban plantings have unique aesthetic and recreational value. For much of the world's ever-increasing urban population, these may be the only tangible reference points for understanding planted forests.These relatively little-recognized forms of planted forests -- planted trees, to be more appropriate -- are now receiving much greater attention. There are, however, some serious technical and sociopolitico-institutional constraints to their development as more widely adopted systems in both tropical and temperate regions.  相似文献   

2.
The developing countries of the Pacific Region consist of 27 countries and territories with a total nd area of 542 000 km2 and over 5 million inhabitants. Though highly variable in physical characteristics and land-use pattern, these countries, in general, give a higher priority for production of export crops over other agricultural crops, so that they are net importers of food. Natural forests of the region are luxuriant and floristically rich, but the level of their commercial exploitation is low. Swidden cultivation is the mainstay of subsistence livelihood, but with the increase in population, the system is now causing severe environmental and land-use problems.The major agroforestry systems and practices in the region include various forms of combination of tree crops such as coffee, coconut and cacao with nitrogen fixing trees such as Casuarina, Gliricidia and Leucaena, and food crops (mostly tubers) such as cassava, taro, sweet potato and yams. Additionally, some improvements to swidden (shifting) cultivation are also being tried in several places, the most common being the u use of Casuarina oligodon before abandoning the swidden as in PNG highlands, and intercropping food crops in tree crop stands.Land tenure system in most of the countries is the traditional clan of extended family control over land. This can have either positive or negative influence on the adoption of agroforestry practices depending on the extent and duration of tenancy tenure enjoyed by the assignees of land.Several governments of the region are now promoting the agroforestry approach. In hilly areas with poor access, farmers are forced to produce most of their basic necessities locally. On the other hand, the lack of roads and communication facilities can pose a problem in marketing any surplus products they have.The immediate opportunity in agroforestry in the region lies in making better use of the unexplored potential of a large number of locally available trees and agricultural crops. Intercropping in tree crop stands and the taungya system seem to propromising m methods for the Pacific region.Researh Fellow, July–September, 1984  相似文献   

3.
Three production systems (robusta coffee, cattle pastures and swidden agriculture), all associated with trees, have provided a strategy for regional development in the Ecuadorian Amazon. Feedback from more than 250 on-farm demonstrations, project evaluations and visitors have all contributed to strengthening the ability of the Ecuadorean Ministry of Agriculture's Forestry Directorate to provide colonists and indigenous groups with management guidelines for low-input sustainable agroforestry production. The existing market for 20 fastgrowing native tree species presents an opportunity for the diversification of farm income (currently dependent on robusta coffee) and for the development of a forest industrial base.The collective area of land owned and operated by these small holders constitutes a national resource and a Collective Forest Estate that can be individually managed. Commercial timber production in these extensive secondary forests can help alleviate conversion of primary forest without taking agricultural land out of production.  相似文献   

4.
Planning optimal economic strategies for agroforestry systems   总被引:1,自引:0,他引:1  
Design of agroforestry systems requires a land management planning process that clearly specifies wants, needs and objectives along with the land's suitability for potential agroforestry practices. Within this planning process economic analysis can be used to analyze agroforestry alternatives to help determine the proper system to apply. Specifically, production economics coupled with capital theory and valuation techniques can provide measures of economic performance in terms of present net values, benefit-cost ratios and internal rates of return. These economic performance measures can be used to determine the best joint production level for a particular agroforestry practice. Once these best combinations have been defined, linear programming can be applied using these best joint production combinations as decision variables along with considering a wide range of additional constraints and requirements. A hypothetical example is used to illustrate the planning process and how these economic tools can be combined as a package to help determine optimal agroforestry strategies.  相似文献   

5.
The Rwandan farmers, faced with a perpetual land shortage, have evolved certain intensive systems of organic agriculture. These systems, particularly the homestead (compound) farming, involve the combination of food, fodder and tree crops. to a certain extent these systems can satisfy the multiple needs of the subsistence farmers living under several risks and constraints. However, they cannot cope with the expanding food demand of the rapidly increasing population. Some multipurpose, low-input technologies and agroforestry approaches have been designed to improve the productivity of these traditional systems; these include inter/mixed cropping systems and rotations, alley cropping with leguminous trees and shrubs, use of planted fallow, planting tree legumes on anti-erosive lines, mixed farming,community forestry and woodlots, and tree planting on farm/field boundaries. The essential aspects of these technologies are briefly discussed.ISAR-IITA FSR PROJECT, B.P. 629, Kigali RwandaISAR-Swiss Intercooperation, c/o Forestry Department, B.P. 617, Butare, Rwanda  相似文献   

6.
Agroforestry has been incorporated in education and training programs at an unprecedented level since 1982. A survey of educational institutions conducted by ICRAF in 1987 revealed that agroforestry is found as an option for specialization in undergraduate as well as in postgraduate M.Sc, diploma programs in forestry, agriculture, natural resources, and others. Courses and special seminars in agroforestry are organized in degree programs. Full undergraduate and postgraduate programs in agroforestry are being formulated and implementation started in quite a few universities, and many students are choosing agroforestry-oriented research projects for their dissertations. A good setting for higher degree training in agroforestry requires, however, staffing from combined faculties of at least agriculture, animal science and forestry; faculty commitment to a farming systems approach; and inter-departmental cooperation in teaching and research. It was difficult to asses whether these and other elements are present in existing programs where agroforestry has been incorporated. Emerging trends indicate that traditional forestry programs are broadening the scope of the discipline (from forests to integrated land-use systems) while agriculturists are recognizing that trees play important roles as soil improvers and protectors, fodder, food, fuel and other domestic and commercial purposes. New institutional structures are evolving to allow for educational programs with coursework and research projects spanning many disciplines. Nondegree training in agroforestry has seen an upsurge of activities equal, if not larger, to that in education. Attempts are being made by different institutions worldwide to inventory training opportunities; still the collection and dissemination of information is difficult. Efforts are needed at the international, regional, and national levels, to address training issues that if addressed collectively can improve the quality and effectiveness of human resource development efforts. ICRAF's approach to promote agroforestry research through education and training is an example of an action program currently under application.  相似文献   

7.
Practices that minimize the rate of soil degradation, increase crop yields and raise farm income are key to sustaining agricultural productivity in the hills of Nepal. The use of farmland is undergoing rapid changes in response to increasing population pressure, deforestation and subsistence needs. Against this background, this study examined the impact of an agroforestry intervention project on farm income based on a sample of subsistence farm households in Dhadhing district. The project was implemented by Nepal Agroforestry Foundation in 1993/94 to increase fodder production through the promotion of agroforestry. A total of 223 households (82 with project and 141 without project) were interviewed during May–October 1998 to collect information on production and agroforestrys' impact on farm income. The benefit-cost analysis showed that the agricultural system including agroforestry was more profitable than the conventional one. The results also showed that the introduction of mulberry trees for sericulture could further enhance the profitability of an agroforestry-based system. Thus, agroforestry has great potential for enhancing food production and farmers' economic conditions in a sustainable manner through its positive contributions to household income.This revised version was published online in November 2005 with corrections to the Cover Date.  相似文献   

8.
Integrated land uses, many now referred to as agroforestry, have a long history in Europe. In the past, the main trend was the movement of agricultural and pastoral activities into forests. The introduction of trees into non-forested (or once forested) lands is a much more recent occurrence, particularly the cultivation of high value fruit and nut trees in the Mediterranean countries, hedgerows/windbreaks in northwestern Europe and windbreaks in eastern Europe and the southern Soviet Union. Environmental concerns of intensive agriculture are increasing the demand for alternate production systems such as agroforestry. Education and training in agroforestry in Europe is very diverse because of the country specific issues regarding land use.  相似文献   

9.
An integrated tree plantation approach combining indigenous livelihoods and industrial wood production is being implemented in West Kalimantan, Indonesia. In this study the economics of land-use was investigated in villages within the plantation scheme. The effect of three alternative land-use scenarios and costs and benefits of each land-use type were studied using linear programming. The scenarios were based 1) on the current land-use, 2) on the integrated tree plantation system with incentives and government regulations, and 3) on a financially optimal land-use distribution. Additionally, plant species richness in different land-use types was surveyed. The scenarios had different kinds of effects on villages varying in respect to their possibilities for land-use intensification. In villages with extensive land use, establishment of tree plantations without any land-use regulations increased the potential economic return on land, resulting in conversion of natural and man-made semi-natural forests into swidden fields. In villages with more sedentary agriculture, the plantation scheme did not create pressures towards remaining forests even in the case of financially optimal land-use distribution. Incorporation of land-use regulations prevented further deforestation but also decreased households' economic returns. The results also showed that conversion of Imperata grasslands to any other land-use increased species richness. Incentives, restrictions or regulations aiming at conserving natural and semi-natural forests are needed to ensure conservation of biodiversity and long-term improvements in local livelihoods. It can be concluded that tree plantations can be combined with other land-use practices: They can improve the economic return on land without further degradation of the environment.This revised version was published online in November 2005 with corrections to the Cover Date.  相似文献   

10.
Summary

Finding sustainable land-use systems within the Panama Canal Watershed will be necessary for future management by the Panamanian government. Agroforestry is a land-use option for small-scale farmers living within the Watershed that can help achieve the goals of both conservation and productivity. This case study qualitatively evaluates current agroforestry projects in the Canal Watershed using an analytical framework based on other evaluations of agroforestry systems in Central America. Designated criteria for the analysis include: management objectives, project life span, incentives, technology, economic feasibility, community involvement, and extension. These factors can present obstacles to wide-scale adoption of agroforestry systems by small-scale farmers, thus preventing the realization of associated benefits of agroforestry. The analysis of the three field sites visited in March 1998 is followed by recommendations for expanding agroforestry practices among farmers in the Watershed.  相似文献   

11.
This paper investigates the types of agroforestry system that exist in Gunung Salak Valley, West Java, Indonesia in order to characterize the differences in their basic structure and associated crop plant diversity. Data were collected through rapid rural appraisal, field observation and focus groups, followed by household survey of a sample of 20 agroforestry farmers. Five main agroforestry systems (homegardens, fruit tree system, timber tree system, mixed fruit–timber system, and cropping in the forest understory) exist in the study area, and all of them exhibit a noticeable diversity in terms of both species composition and utilization. Products from farming accounted for an average 24 % of household income. They comprised agroforestry products which contributed IDR 3.25 million/year and other agricultural products contributing IDR 1.66 million/year. The observed agroforestry systems include not only a form of forest dominated by ‘cultivated trees’, but also an anthropogenic vegetation formation derived from agricultural antecedents. In land-use classifications agroforestry systems are not recognized as forestry, but like forests they provide tree products and services. Classification will always be disfunctional if a binary system is applied, thus a more sophisticated approach should be adopted that incorporates the economic and environmental characteristics of a wider range of systems.  相似文献   

12.
As a system of land use which entails the deliberate association of trees with herbaceous field crops in time, shifting cultivation is one of the most ancient, widespread and, until recently, ecologically stable forms of agroforestry. However, under pressure of population and competing uses for land and labour, traditional swidden systems have been observed historically to undergo more or less predictable processes of intensification. Since shifting cultivation is an indigenous form of agroforestry, scientific agroforestry is not, strictly speaking, an alternative to shifting cultivation, but rather a systematic approach to the recombination of its basic elements into more intensive, sustainable and politically viable forms of land use, whenever pressures signal the need for change in traditional swidden systems.Different agroforestry options open up from different stages of intensification in swidden systems. A review of evolutionary typologies of shifting cultivation gives rise to a framework for the identification of agroforestry interventions and development pathways appropriate to specific systems. technological proposals are limited to a short list of the most promising agroforestry interventions in main sequence swidden systems. These include integral taungya, economically and biologically enriched fallows, variations on the alley cropping theme, and various tree crop alternatives to annual cropping systems. Examples and quantitative data are cited to substantiate the main hypotheses behind the proposals.  相似文献   

13.
Low external input agroforestry systems hold great promise as alternative, sustainable production systems for small-to-medium farmers in the Amazon Basin. The design of such systems is considered essential to stabilize agricultural production and avoid the cycle of continuing destruction of primary forest [Anderson A (1990) In: Anderson A (ed) Alternatives to Deforestation: Steps toward Sustainable Use of the Amazon Rain Forest pp 3–23. Columbia University Press, New York]. In order to be successful, these systems must be compatible with local ecological conditions and adoptable by farmers. Currently, many small-to-medium producers in the Amazon Basin use a slash and burn agricultural strategy that combines annual cropping with cattle grazing in mixed farming systems. While cattle play an important role in household economic survival, grazing-induced land degradation threatens the long-term viability of these farms [Loker W (1993) Human Organization 52(1)14–24]. This paper presents a model of a low external input agroforestry system that incorporates farmer preferences and practices but uses well-adapted grass-legume pastures, rotational grazing and the management of natural forest regeneration to enhance productivity in an ecologically sound manner. This system provides farmers with the benefits of both annual crops and cattle raising, avoids the land degradation that characterizes current practices and effectively incorporates trees into the production system.  相似文献   

14.
An agroforestry project was funded by the US Agency for International Development and implemented by the Pan American Development Foundation in Haiti from 1981 to 1991. This project is considered by many to be one of the most successful projects of its kind in Haiti, and in the tropics as a whole. Over the ten years of its implementation, the project, referred to in Haitian Creole as Pwoje Pyebwa (Tree Project), evolved from a tree production and planting project to a much broader soil-conservation-based program involving trees. This paper summarizes the training and extension systems that developed during that period. The socioeconomic background studies that were done before the project began, and the flexible, consultative mode of field-team implementation, incorporating elements of the learning process approach, were important to the success of the project. During the implementation of the project, however, concern for farmer input and participation should have been incorporated more systematically into the field operations of the regional teams.  相似文献   

15.
Agroforestry is a new name for a rather old practice. From a historical point of view, various agroforestry systems existed in Europe, of which the wood pastures (Neolithicum), the Dehesas in Spain (~4,500 years old) and the Hauberg of the Siegerland (established in the Middle Age) are the most prominent. Other widespread systems in Europe were hedgerows, windbreaks and Streuobst (orchard intercropping). Due to mechanisation and intensification of agriculture, trees have been progressively removed from agricultural fields and traditional agroforestry systems slowly disappeared. Today, agroforestry systems are again increasing in interest as they offer the potential to solve important ecological and, especially, biodiversity problems, while at the same time enabling the production of food, wood products and fodder for cattle. Although agroforestry systems offer many advantages, many farmers are sceptical of these systems and are critical and risk-averse with regard to adopting new practices. However, in comparison to traditional systems, modern agroforestry systems can be adapted to current farming practices. By selecting suitable trees and appropriate tree management, high-quality timber can be produced without influencing agricultural crops excessively. In future, agroforestry systems will become increasingly important as they offer the prospect of producing woody perennials for bioenergy on the same land area as food and/or fodder plants, while enhancing overall biodiversity.  相似文献   

16.
Few studies have included detailed investigations of the interactions of agroforestry techniques with pests and diseases, although the relevance of such interactions has long been recognized. The objectives of this review are to provide basic information on pests and diseases in tropical agroforestry systems and to develop concepts which can assist in the future in the systematic data collection and analysis in this field. The emphasis is on simultaneous agroforestry systems with annual and perennial crops, although rotational systems are also discussed. Crop rotation is an important pest and disease control strategy in annual cropping systems, and the principle of altering host with non-host plants can also be applied in improved fallow systems, provided that hosts of crop pests and diseases are avoided when selecting the fallow species. When annual cropping systems are transformed into simultaneous agroforestry, the control strategy of frequent disturbance of pest and disease populations is to some extent substituted for the strategy of increased stability and internal control mechanisms. However, reduced pest and disease risk is not automatically achieved by introducing perennial plants and increasing the plant diversity in a system. If plant species are introduced that harbor pests or diseases of other species in the system, the risk of pest and disease outbreaks may actually increase. For evaluating such risks, it is important to consider host-ranges of diseases on the pathovar instead of the species level. Beside the selection of compatible plant species, their spatial arrangement may be important for reducing the spread of pest and disease organisms through the system, although little information is available on such effects, and they may be largely irrelevant for organisms with efficient dispersal mechanisms such as wind-dispersed fungi. In addition to the species-specific, biological effects of plants on pests and diseases, their unspecific, physical effects can be of major relevance for pest and disease development as well as the susceptibility of the affected plant species. Increased pest and disease incidence has often been observed directly at the tree-crop interface, caused by the humid microclimate, physical protection of mammal and bird pests by the trees and eventually reduced pest and disease tolerance of competition-stressed crops. Linear tree plantings and hedgerows affect the wind transport of small insects and disease propagules, the active immigration and emigration of pest organisms as well as the populations of natural enemies. Similarly, overhead shade has a major effect on the micro-climatic conditions under which pest and disease organisms, their natural enemies and the crops themselves develop, and its optimization is a highly efficient control strategy for many pests and diseases. On infertile soils, the susceptibility of crops to pests and diseases is strongly affected by the availability of plant nutrients, which may be influenced by agroforestry techniques in various ways. Soil management measures such as mulching and planting cover crops may affect crop health by improving soil fertility and by directly acting on pest and disease populations. The importance of a more systematic collection of pest and disease related information for agroforestry, e.g., in a central database, and of the development of strategies for reducing pest and disease risks in agroforestry in cooperation with farmers is stressed.This revised version was published online in November 2005 with corrections to the Cover Date.  相似文献   

17.
Historical development of a permanent agriculture system based on the use of agroforestry in the temperate zone is traced. In general, reasons for a renewed interest in agroforestry include the end of cheap, subsidized fossil fuels; increased concern about soil erosion and marginal land use; an international awakening as to the dangers of indiscriminate use of pesticides, herbicides and other chemicals; and a need to balance food production with other land uses.For the forestry profession in particular, reasons for interest in agroforestry stem from a need to revitalize rural economies, the desire to increase timber exports, and potential resolution to land use conflicts between agriculture and forestry. Through use of agroforestry management systems, an increase in both economic and silvicultural benefits are obtainable.Two agroforestry management systems are reviewed which currently appear feasible for implementation in many industrialized countries of the temperate zone. These two systems include: 1) Animal grazing and intercropping under managed coniferous forests or plantations; and 2) Multicropping of agricultural crops under intensively managed, high value hardwood plantations.Michigan Agricultural Experiment Station Paper No. 12046.  相似文献   

18.
Agroforestry and portfolio theory   总被引:1,自引:0,他引:1  
Portfolio theory is used to analyse the risk of hypothetical agroforestry systems. It is shown that the relationship of the returns of the components of an agroforestry system, expressed in terms of the covariance or correlation of returns, is of vital importance in correctly defining risk. Agroforestry systems can be classified as efficient or inefficient. Inefficient systems are such that an alternative system exists which has a greater return for the same level of risk. Thus, inefficient systems do not represent rational choices for agroforestry systems. Finally, the conclusion is reached that it is impossible to design a best system, but rather a set of efficient systems of differing risk and return can be defined. This set of efficient systems is referred to as the efficient frontier.  相似文献   

19.
Since 1985, Ecuador's Ministry of Agriculture has undertaken a demonstration project to promote improved agroforestry practices in already cleared lands of Ecuador's Amazon lowlands to promote regeneration of deforested areas. An important expected outcome of this project is to ameliorate growing population pressures on remaining national forests and natural reserves. These practices include managing natural regeneration of marketable timber trees intercropped to Coffea canephora var. robusta and grass-legume associations, using adequate techniques of coffee pruning, and planting Desmodium ovalifolium CIAT 350 as a ground cover crop or a forage legume in paddocks of the genus Brachiaria. This research was conducted to assess the potential economic impact of such a strategy and to feed back information on research and policy issues.Improved agroforestry practices in this region are not only technically practicable but also economically feasible. Proposed technologies enhance long-term productivity of both land and labor while saving on external inputs and hired labor, making on-going systems more adoptable and sustainable. Future land-use policies should consider on-farm primary forest preservation and controlled natural regeneration of high-value timber in secondary forests as socially efficient land-use patterns. Future research must address germplasm of grass and forage legumes both shade tolerant, and less field management-demanding than current ones.To have a lasting effect this technology should probably be incorporated into a Regional Forest Management Plan, for sustainable production at the secondary forests created with agroforestry technology.in cooperation with Fundación para el Desarrollo Agropecuario del Ecuador, FUNDAGRO, Casilla No. 219, Suc. 16 CEQ, Quito, Ecuador  相似文献   

20.
Agroforestry offers unique opportunities for increasing biodiversity, preventing land degradation, and alleviating poverty, particularly in developing countries, but factors explaining the adoption by farmers are not well understood. A survey of 524 farm households was conducted in Bhakkar district of Punjab, Pakistan to study factors that determine the adoption of agroforestry on the sand dunes in the resource-deficient region of Thal. Two types of agroforestry systems were studied: intercropping and border cropping (also known as boundary or perimeter planting). Both agroforestry systems included irrigated cultivation of the timber trees Eucalyptus camaldulensis (local name: sufeda) and Tamarix aphylla (local name: sars) with wheat, chickpeas (Cicer arietinum) (local name: chana) or cluster beans (Cyamous tetragocalobe) (local name: guars). The majority of the farmers was in favour of intercropping and border cropping. Most farmers reported the protection of nearby crops from dust storms as the most important positive perception about both agroforestry systems. Age, education, and farm to market distance were significant determinants of agroforestry adoption. Older and less-educated farmers, with farms closer to markets were less likely to adopt tree planting or border cropping in Thal. In general, the agroforestry systems examined were more likely to be adopted by farmers who can wait 3–4 years for harvesting crop outputs, but not by poorer farmers who are totally dependent on subsistence agriculture and cannot afford the high initial cost of agroforestry establishment, nor can they wait for crop output for extended periods. Furthermore, the adoption of both agroforestry systems was more likely in remote marginal areas than in areas close to markets. To increase agroforestry adoption rates, government policies should strengthen farmers’ knowledge of every stage of agroforestry through extension services, focusing particularly among the prime prospects, i.e. farmers who will be most likely to adopt agroforestry. Once the prime prospects have adopted it, the older, less-educated, and poor farmers of the rural population can be also focused on to motivate adoption.  相似文献   

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