法国、欧盟的农业政策及其对我国的借鉴作用

探讨了法国农业政策的渊源、法国与欧共体的农业政策及其运行机制、法国与欧共体农业政策与农村政策的改革,介绍了法国农业社会化服务体系,同时指出了法国与欧共体的农业政策及农业服务对我国农业发展的参考和借鉴作用。     

Prospects for easing land tenure conflicts with agroforestry in Mediterranean France: a research approach for intercropped timber orchards

Agroforesty plots offer the opportunity to combine annual agricultural production and long-term wood capitalization. The fallow scheme now in operation in Europe intends to reduce the surplus of agricultural products. Agroforestry management could be a valuable alternative to fallow or to forestry plantations on agricultural land.Agroforestry is attractive to agricultural landowners in Mediterranean France, as agroforestry stands are less costly than forestry plantations, are less prone to fire hazards, provide agricultural returns from intercropping during the first twenty years and have many environmental benefits.An experimental network of on-farm agroforestry plots has been set up since 1988 in the Mediterranean part of France. These plots include grazed paddocks (silvopastoral systems) and ungrazed fields (silvoarable systems). They gained support both from landowners and tenants: the former expect a high value treestock, while the latter have a free use of the space between plantation lines. Plantations have been designed to allow easy mechanical intercropping. First results from two experimental sites are discussed. The growth of the trees in the agroforestry plots is much higher than in the control forestry plots.     

Potentials and limitations of agroforestry for changing land-use in the tropics: experiences from Central America

With increasing population pressure, the agricultural frontier in tropical countries is being expanded into previously untouched or little changed areas, frequently resulting in environmental degradation. At the same time, the use of agricultural lands is undergoing rapid changes in response to increasing environmental concerns and external market forces. In large areas of Central America, for example, the production systems for coffee have lost much of their biological diversity in the last couple of decades. Observations of apparently higher yields in high-input and low-diversity systems resulted in recommendations to eliminate trees. In recent years, however, as a result of low coffee prices and environmental concerns, calls to reverse this trend have been made in many countries and research and implementation initiatives are being developed to, once again, increase the diversity of the systems by incorporating trees.The necessary changes in the objectives and management of land-use systems must be gradual to assure high acceptability of the new practices. Under such conditions, which are typical for most traditional land-use systems, the development of practices which integrate trees into the agricultural land-use systems assumes special importance. Agroforestry practices can help to improve land-use systems towards higher sustainability and/or provide a stepping stone towards other, often tree-based, land-use systems of higher viability.Using examples from the research and extension experiences at CATIE, some silvopastoral and agrisilvicultural systems are discussed with their potentials and limitations. To help evaluate improved systems, promising methodologies for appropriate research and extension are outlined. New research has shifted the focus to on-farm experimentation, and economic and extension aspects of agroforestry.     

国外农林间作研究进展

本文总结了近年国外农林间作在以下几个方面的研究进展:(1)多用途树种选择方面的重点是选择适合农林间作的豆科树种;(2)农作物产量研究方面主要是在3种间作形式下如何提高农作物产量;(3)农作物生长环境方面的研究重点是林木对农田小气候的影响;(4)间作对杂草的控制作用方面的研究是如何利用林木枝叶施入农田和林木遮荫对田间杂草进行控制;(5)农林间作模型等方面的研究.     

The farming system and traditional agroforestry systems in the Maya community of San Jose, Belize

Shifting slash-and-burn agriculture is likely one of the main causes of forest degradation in southern Belize. Although many development projects have attempted to reduce the impacts of agriculture on the tropical rainforest, the situation is still a cause for concern. A study of the farming system of the San Jose Maya community was therefore carried out to examine agricultural production in its social, cultural, economic, and political context. Results demonstrate that agricultural production contributes to forest degradation because of the limited availability of agricultural land, the low level of investment in agricultural production, the land tenure system, limited marketing opportunities, and the exclusion of Mayas from the country's political and economic domains. Agroforestry could, however, offer a partial solution to the problem of forest degradation. Three types of traditional agroforestry systems are practised in San Jose: the milpa (a slash-and-burn agriculture system), cacao (Theobroma cacao) cultivation under shade trees, and the homegarden. These traditional agroforestry systems almost entirely meet a family's needs for food and wood, and generate at least 62% of family income. Improving the productivity of these systems could help to reduce pressure on the forest in southern Belize.This revised version was published online in November 2005 with corrections to the Cover Date.     

Trees as an agriculture sustaining activity: the case of northern China

The nearly complete removal of forest cover from China's northern plains before the renewal of household incentives and subsequent reforestation in the late 1970s provides an unusual broad-scale opportunity to examine the impact of forest-based environmental services on long-term agricultural productivity. This paper uses a Cobb-Douglas agricultural production function with a measure of forest cover as a production shifter to test the hypothesis that forest-related environmental services make a positive contribution to agricultural output. Our evidence for Shandong province shows that agroforestry activities rapidly produced approximately ten percent increases in agricultural productivity — and their contribution probably has not reached its limit. The relevance of this finding goes beyond China's agriculture to the broader question of how world agricultural production can be sustained in the long-run — after the possible exhaustion of the contributions of current institutions and farming systems. If the opportunities for expanding the agricultural land base and for multiple cropping are small, and if ever more labor must be squeezed into the agricultural sector, then what can contribute to agricultural growth? One answer must lie in improvements to the agricultural environment, and trees may be a part of this improvement.     

The Effects of Household Asset Endowments on Agricultural Diversity among Frontier Colonists in the Amazon

This paper focuses on agricultural diversity, a key property of agroforestry systems, and examines the influences of household asset endowments. The analysis addresses a debate between ‘differential motivation’ and ‘ differential capacity’ arguments concerning the importance of asset inequality for agricultural diversification among rural households in developing regions. I draw on data from a survey of small farm colonists in the Brazilian Amazon to assess components and measures of agricultural diversity, and to model those diversity measures using indicators of household asset endowments. The results indicate that agricultural diversification is modest in the study site, but varies among households, as do asset endowments. Models of agricultural production and income diversity indicate that agricultural diversity primarily reflects labor endowments, though certain types of capital are also important. These findings bear implications for research on agricultural diversity in other contexts, and for policies aiming to promote ‘productive conservation’ by compatibilizing poverty reduction, economic development and environmental sustainability.     

Agroforestry and land-use change in industrialized nations: a case study from northeastern Germany

The paper describes the changes in agricultural structure and land use in northeastern Germany that were triggered by reunification. It projects possible effects of the recent EU-agricultural policy reform with the help of a simulation model. It is concluded that a considerable part of land (especially permanent grassland) might not have a productive use in the mediumrun. Agroforestry systems relevant for Central Europe are discussed and problems identified. Agroforestry systems are evaluated as one land-use option among others (afforestation, natural succession, new agricultural systems) and their possible impact is assessed.     

Agroforestry in Europe: a review of the disappearance of traditional systems and development of modern agroforestry practices, with emphasis on experiences in Germany

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.     

河北省农业自然灾害发生的特点、成因及对策研究

根据河北省近十几年的统计数据和相关专业部门的调查数据,分析出河北省农业自然灾害发生的特点。其成因是农业生态失衡,投入不足造成基础设施薄弱,防灾、抗灾服务体系不健全,农业保险业务空白。提出抗御农业自然灾害的对策是:加强农业自然灾害的学科研究建设,加强农业基础设施建设,树立新的节水理念,充分利用好自然降水,加强抗灾服务体系,完善灾害防御体系,加快发展农业保险事业。     

The potential of intercropping as an alternative land use system in temperate North America

The success of many intercropping systems in North America is attributable to the generation of a short term return from an agricultural crop during the early, unprofitable years of a longer term crop that is fruit, nuts or wood. This highly-efficient use of land and related profitability are important not only in the development of intercropping systems per se, but also in other applications which have tremendous potential independent of profitability. For example, intercropping can be effectively used during the establishment phases of hardwood plantations where it is essential to have a high level of weed control, the costs of which are often recovered with the agricultural production. Intercropping can also be used to grow trees rapidly and with a form that can be easily integrated into recreational or park situations, or urban fringe areas. In an urban context, intercropping can be used to grow trees in agricultural areas that are likely to be developed where traditional forestry options are not appropriate and the value of younger, thrifty trees may enhance property values far in excess of the cash value of the wood.     

From Farmers to Loggers: The Role of Shifting Cultivation Landscapes in Timber Production in Cameroon

This article focuses on timber sourced from the agricultural areas in the shifting cultivation landscapes of the Central Region of Cameroon. Data about volumes marketed in urban centres, harvesting operations and on-farm timber management are used to discuss the ecological impact of small-scale logging and its sustainability in the long term. An opportunistic association exists between small-scale logging and agricultural land uses, determined mostly by the abundance of valuable species in fallows and on cocoa farms, their easy accessibility and the low price of farmland timber. Farmers apply various strategies to the management of tree resources in fallows and cocoa agroforests, with most felling authorized in fallows and most trees preserved on the cocoa farms. With current agricultural expansion and intensification trends associated with small-scale logging, timber resources on rural land are at risk of depletion with direct consequences for domestic timber supply and the thousands of livelihoods it sustains. Marketing and regulatory changes are needed to encourage the integration of timber production in agricultural management systems.     

谈我国农区“经济林”发展战略

我国的经济林已有较大的发展,但各地区的发展还很不平衡。作者通过调查研究,总结出当前农区经济林发展的几个特点。讨论了农区经济林发展战略的现实意义;强调了发展经济林要用“系统论”的观点和方法搞好规划,加强宏观调控的重要性。作者呼吁：应把在农区发展经济林作为农区经济发展的一项战略任务来抓。     

Tree Culture of Smallholder Farmers Practicing Agroforestry in Gunung Salak Valley,West Java,Indonesia

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.     

Influences of trees on abundance of natural enemies of insect pests: a review

In this article we review the use of natural enemies in crop pest management and describe research needed to better meet information needs for practical applications. Endemic natural enemies (predators and parasites) offer a potential but understudied approach to controlling insect pests in agricultural systems. With the current high interest in environmental stewardship, such an approach has special appeal as a method to reduce the need for pesticides while maintaining agricultural profitability. Habitat for sustaining populations of natural enemies occurs primarily at field edges where crops and edge vegetation meet. Conservation and enhancement of natural enemies might include manipulation of plant species and plant arrangement, particularly at these edges; and consideration of optimum field sizes, number of edges, and management practices in and near edges. Blending the benefits of agricultural and forestry (windbreak) systems is one promising approach to field edge management that has additional benefits of wind protection and conservation of desirable wildlife species.Journal series 10549 of the Agriculture Research Division, University of Nebraska-Lincoln. This material was prepared with the support of USDA Agreement 91-COOP-1-6592 for the USDA/EPA Program, Agriculture in Concert with the Environment. Any opinions, findings, conclusions or recommendations expressed herein do not necessarily reflect the views of the US Department of Agriculture or the US Environmental Protection Agency.     

Ecological benefits provided by alley cropping systems for production of woody biomass in the temperate region: a review

In temperate Europe alley cropping systems which integrate strips of short rotation coppices into conventional agricultural fields (ACS) are receiving increasing attention. These systems can be used for crops and woody biomass production at the same time, enabling farmers to diversify the provision of market goods. Adding trees into the agricultural land creates various additional benefits for the farmer and society, also known as ecosystem services. However, tree-crop interactions in the temperate region have not been adequately substantiated which is identified as a drawback to the practical implementation of such systems. In order to bridge this gap, the current paper aims to present a comprehensive overview of selected ecosystem services provided by agroforestry with focus on ACS in the temperate region. The literature indicates that compared with conventional agriculture ACS have the potential to increase carbon sequestration, improve soil fertility and generally optimize the utilization of resources. Furthermore, due to their structural flexibility, ACS may help to regulate water quality, enhance biodiversity, and increase the overall productivity. ACS are shown as suitable land use systems especially for marginal sites. Based on the available data collected, we conclude that ACS are advantageous compared to conventional agriculture in many aspects, and therefore suggest that they should be implemented at a larger scale in temperate regions.     

The persistence of secondary forests on colonist farms in the BrazilianAmazon

While slash-and burn farmers convert forest to agriculture, they also regenerate significant areas of secondary fallow forests on their farms. Under what conditions does secondary forest cover persist on slash-and-burn farms? Survey data from Pará, Brazil show that secondary forests occupy 20% of farm area even after a century of settlement. In addition to restoring soil fertility, secondary forests contribute over 20% of farmers' income through products such as charcoal, fruit, game animals and firewood for on-farm processing. Econometric analysis shows that slow rates of population growth and increases in agricultural incomes through on-farm processing of agricultural products enable farmers to maintain long fallows and result in diversified systems compatible with secondary forest cover in the study area. On the other hand, declining agricultural productivity, subsidized credit, declines in the growth rate of secondary forests and policies favoring speculative land acquisition threaten secondary forest persistence. In older settlement areas, secondary forests are often the only forest resource available to the rural poor. Fallow areas should therefore be managed not only for agricultural productivity, but also for conserving forest resources.     

Integrating belowground carbon dynamics into Yield-SAFE,a parameter sparse agroforestry model

Agroforestry combines perennial woody elements (e.g. trees) with an agricultural understory (e.g. wheat, pasture) which can also potentially be used by a livestock component. In recent decades, modern agroforestry systems have been proposed at European level as land use alternatives for conventional agricultural systems. The potential range of benefits that modern agroforestry systems can provide includes farm product diversification (food and timber), soil and biodiversity conservation and carbon sequestration, both in woody biomass and the soil. Whilst typically these include benefits such as food and timber provision, potentially, there are benefits in the form of carbon sequestration, both in woody biomass and in the soil. Quantifying the effect of agroforestry systems on soil carbon is important because it is one means by which atmospheric carbon can be sequestered in order to reduce global warming. However, experimental systems that can combine the different alternative features of agroforestry systems are difficult to implement and long-term. For this reason, models are needed to explore these alternatives, in order to determine what benefits different combinations of trees and understory might provide in agroforestry systems. This paper describes the integration of the widely used soil carbon model RothC, a model simulating soil organic carbon turnover, into Yield-SAFE, a parameter sparse model to estimate aboveground biomass in agroforestry systems. The improvement of the Yield-SAFE model focused on the estimation of input plant material into soil (i.e. leaf fall and root mortality) while maintaining the original aspiration for a simple conceptualization of agroforestry modeling, but allowing to feed inputs to a soil carbon module based on RothC. Validation simulations show that the combined model gives predictions consistent with observed data for both SOC dynamics and tree leaf fall. Two case study systems are examined: a cork oak system in South Portugal and a poplar system in the UK, in current and future climate.