Agroforestry: a profitable land use. An overview of the 12th North American Agroforestry Conference

This special issue features papers contributed by presenters at the 12th North American Agroforestry Conference held June 4–9, 2011 in Athens, Georgia, USA. The conference brought together agroforestry researchers, educators, practitioners, and students to highlight agroforestry research, implementation, policy, education, and entrepreneurial opportunities across North America. Eight papers cover topics ranging from adoption of silvopastoral systems across eco-regions and countries; economics of pine straw production; and timber and alley crop production in the Southeastern U.S.; reduction of sublimation of snow with shelterbelts in Canada, carbon offset incentives for agroforestry practices; consumer and market dynamics for chestnut and elderberry specialty crops; and web-based graduate degree and certificate programs in agroforestry.     

Agroforestry performance on small farms in Amazonia: Findings from the Rondonia Agroforestry Pilot Project

Experiences from not only ‘success stories’ but also ‘failed’ agroforestry projects provide potentially useful lessons for future agroforestry-project designers. Experimental one-hectare agroforestry plots were established on 50 small-scale farms in the western Brazilian Amazon State of Rondonia from 1993 to 1995. Drawing from a menu of 25 different species (10 tropical hardwoods and softwoods and 15 fruits and palms), this species trial shows encouraging survival and growth performance for most species under wide ranging plot management regimes. Tropical hardwood survival rates (after 18 months) ranged from 65% for Cerejeira (Torresea acreana) to 88% for mahogany (Swietenia macrophylla). Survival rates for commercial fruit and palm species were even higher. A comparison of attributes of two sub-groups (successful and unsuccessful planters) suggests that previous experience with perennial monocultural cropping, greater social participation, land use history, and soil chemistry are positively associated with successful agroforestry species performance, while no significant differences exist between successful and unsuccessful planters in household size, area deforested, area in pasture, and land tenure security. A closer analysis of ‘failed’ agroforestry plots indicates the primary importance of social factors originating at the household-level (e.g. inadequate plot maintenance, improper planting techniques, illness, etc.). Twelve different causes of plot failure were cited, falling into three classes. Of the total number of reasons given for plot failure, household level factors represented 54% of all causes cited. Project design and implementation factors (inappropriate plot design, defective planting material, etc.) were cited 25% of the times and environmental factors (soil fertility constraints and pasture grass invasion) were cited 21% of the times. This revised version was published online in June 2006 with corrections to the Cover Date.     

The North American long-term soil productivity experiment: Findings from the first decade of research

First decade findings on the impacts of organic matter removal and soil compaction are reported for the 26 oldest installations in the nation-wide network of long-term soil productivity sites. Complete removal of surface organic matter led to declines in soil C concentration to 20 cm depth and to reduced nutrient availability. The effect is attributed mainly to the loss of the forest floor. Soil C storage seemed undiminished, but could be explained by bulk density changes following disturbance and to decomposition inputs of organic C from roots remaining from the harvested forest. Biomass removal during harvesting had no influence on forest growth through 10 years. Soil compaction effects depended upon initial bulk density. Soils with densities greater than 1.4 Mg m⁻³ resisted compaction. Density recovery was slow, particularly on soils with frigid temperature regimes. Forest productivity response to soil compaction depended both on soil texture and the degree of understory competition. Production declined on compacted clay soils, increased on sands, and generally was unaffected if an understory was absent.     

4个北美树种在辽西地区的引种试验研究

为了丰富本地区的树种资源,满足园林绿化对树种多样性的需求,从物候期、生长节律及光合特性等几个方面对美洲朴、毛核木、银水牛果、西部沙樱这4个北美树种在辽西地区的引种适应性进行了研究。结果表明,4个树种的萌芽、展叶期均较北京地区有所延后,花期则提前;美洲朴未见开花坐果,银水牛果秋季叶片不变色;4个树种株高、地径、枝条的快速生长期为5—7月份,美洲朴和毛核木具有明显的越冬枯梢现象,翌年生长多以萌蘖条为主;西部沙樱和银水牛果具有较强的光合作用和较高的水分利用效率,是辽西地区园林绿化可尝试引入的优良观赏树种。     

北美结构板产业发展及市场问题的研究

北美结构板产业由于技术革新的推动,长期保持着增长势头。本文对其发展特征、增长原因、主要细分市场、市场策略以及影响结构板需求等问题进行了分析,以供我国探讨定向刨花板的导入问题和制定人造板产业政策时借鉴。     

Sweet trees, sour circumstances: the long search for sustainability in the North American maple products industry

Maple sugar and maple syrup have long been important non-timber forest products in North America. We examined the historical and the scientific literature to determine the long-term sustainability of the industry in an economic, an ecological, and a cultural context. During the 18th and 19th centuries, maple sugar was an inexpensive substitute for cane sugar and a cash crop that fit into the work schedule of the northern farmer. Maple syrup replaced maple sugar as the mainstay of the industry at the end of the 19th century as increasingly cheaper cane sugar and other sweeteners undercut the sugar market. Active government intervention and support have made Quebec the major bulk supplier of maple syrup today. Quebec alone produces approximately 80% of the world’s supply of maple products. A series of good sap years and production in excess of demand, however, has recently reduced the price of bulk syrup and the profit of producers in Quebec. Producers in the United States have focused on the more lucrative and price stable retail syrup market.

Farming practices in the late 18th and early 19th centuries tended to clear away sugar maple on the more fertile, level sites and preserve sugar maple as a source of fuel wood, sugar and syrup on the less accessible, marginal sites. The crude tapping procedures employed at the same time often killed the trees. Widespread grazing in the 20th century and more recently diameter-limit cutting of even-aged stands have hindered the regeneration of the sugarbush. An emphasis on monocultures and global warming currently threatens the sustainability of the sugarbush. On the whole, however, the maple products industry has probably increased sugar maple’s representation in the forest. From a cultural standpoint, the industry represents a positive work experience that unites families, connects one to the land, and provides a sense of continuity with the past.     

Bringing Agroforestry Technology to Farmers in Leyte, the Philippines: A Comparison of Two Extension Assistance Regimes

The response of farmers to personalised forestry and agroforestry extension assistance has not been well documented in the Philippines, thus providing the impetus for this research in which the effectiveness of extended on-farm assistance was compared with more limited assistance. In four municipalities in Leyte Island, farmers responded positively to an extended program which helped them overcome problems in germinating and growing seedlings and establishing trees on their land. A limited assistance program which sought to make use of farmers’ familiarity with growing and raising plants was relatively unsuccessful, with less preparation of tree planting sites and a higher rate of abandonment. Allowing farmers freedom to select planting sites and aspects of technical advice which suited their personal circumstances, encouraged a high degree of cooperation between extension staff and farmers, but 38% of farmers neglected post-planting weed control and 35% of sites were inappropriate for growing trees. Destruction of sites by flooding and grazing also caused farmers to blame extension staff even though these risks had been discussed with them beforehand. This suggested that a more interventionist approach would be appropriate for site selection although it may reduce recruitment. The number of farmers recruited through local government staff was low, but attendance by neighbours at locally held demonstrations was high, suggesting an avenue for further recruitment. Overall, the program was successful in shifting the initiative for further planting from extension staff to those farmers who received extended extension assistance.     

Agroforestry policy issues and research directions in the US and less developed countries: insights and challenges from recent experience

Efforts to improve the performance of agroforestry systems, and to expand the land area and number of people able to benefit from this integrative approach to agriculture and natural resource management, are constrained throughout the world by non-supportive land use policies. A growing sense of urgency that policy change is needed to enable agroforestry to flourish has contributed during the past two years to an unprecedented level of agroforestry policy assessment and planning activity.In the US, agroforestry has emerged from academia, where it has incubated since the mid-1980s, into the professional resource management arena. A multi-organizational agroforestry evaluation process has driven national policy and program formation to the forefront of the agenda of the agroforestry community, as it seeks to influence the 1995 Farm Bill. Internationally, the Consultative Group on International Agricultural Research and collaborators fostered a sequence of policy issue identification activities as a basis for setting strategic research priorities for forestry and agroforestry.Following a brief review of forces driving agroforestry development in industrialized and less developed countries, the paper highlights recent policy assessment initiatives in each sphere. Observations on the issues driving and the priorities emerging from these processes are offered, to lend perspective to the critical challenges facing the agroforestry policy research community. An explanation for pervasive constraints and inconsistencies in policy effectiveness is then explored, from which a promising approach to research intervention is forwarded.It is argued that social scientists might influence agroforestry policy most favorably at this critical juncture, as perceptions of inter-dependence increase among different stakeholders in the policy system, by employing interventionist, actor-oriented perspectives and participatory methods to facilitate policy innovation and evaluation. The approach is consistent with participatory technology design processes that earlier helped to establish agroforestry as a prototype for sustainable development.     

河南博爱南竹北移的实践与思考

河南省博爱县的竹林拥有2 000多年的历史,是我国黄河以北纬度最高、面积最大、历史最久、品种最多的规模产业化竹林。近年来,北方地区如山东肥城和聊城、河南洛宁等地把培育竹资源、发展竹产业作为当地一项重要的生态建设任务。总结博爱县南竹北竹实践经验,对于进一步推动北方地区竹产业发展具有一定的现实意义。文章介绍了河南博爱县南竹北移的历史和应用情况,提出笋用、景观、材用是北方竹产业发展的3大方向。     

Ecology of tree intercropping systems in the North temperate region: Experiences from southern Ontario,Canada

Agroforestry Systems - Agroforestry practices in northern latitudes, although less diverse than those in warmer regions, have unique advantages over conventional land-use systems in the region in...     

世界若干地区的小型林业

通过概述东亚、北美和西欧林地所有制构成来展现小型林业的现状。勾勒出小型林业的几个主要特点。讨论了小林主所面临的重要挑战,并总结了一些国家针对现存问题而采取的经济措施,对今后小型林业研究方向提出几点看法。     

Natural enemies of the South American moth, Tuta absoluta, in Europe, North Africa and Middle East, and their potential use in pest control strategies

The South American tomato leafminer, Tuta absoluta Meyrick (Lepidoptera: Gelechiidae), is an invasive Neotropical pest. After its first detection in Europe, it rapidly invaded more than 30 Western Palaearctic countries becoming a serious agricultural threat to tomato production in both protected and open-field crops. Among the pest control tactics against exotic pests, biological control using indigenous natural enemies is one of the most promising. Here, available data on the Afro-Eurasian natural enemies of T. absoluta are compiled. Then, their potential for inclusion in sustainable pest control packages is discussed providing relevant examples. Collections were conducted in 12 countries, both in open-field and protected susceptible crops, as well as in wild flora and/or using infested sentinel plants. More than 70 arthropod species, 20 % predators and 80 % parasitoids, were recorded attacking the new pest so far. Among the recovered indigenous natural enemies, only few parasitoid species, namely, some eulophid and braconid wasps, and especially mirid predators, have promising potential to be included in effective and environmentally friendly management strategies for the pest in the newly invaded areas. Finally, a brief outlook of the future research and applications of indigenous T. absoluta biological control agents are provided.     

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.