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。     

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.     

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...     

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.     

A Community Forestry Model Linking Research,Management, Education,and Stakeholder Engagement: Case Study Results from the Town of Weston,Massachusetts, USA

Forested land in the eastern United States is owned by a complex mix of public and private owners, often with highly varied objectives and uses. There is an increasing trend at local scales of community forestry programs that use community-based decision making to determine what type of management will occur on town-owned forests. Within the suburban town of Weston, Massachusetts, this type of coordinated approach has been ongoing for nearly 4 decades. This article describes the integration of forest ecology and management research, including a forest inventory and long-term monitoring program, to educate townspeople about their forests, engage students in ecological research, and provide data that the town can use to make informed management decisions. This article presents a novel model for a research-based community forestry program, results from the first inventory and plot measurement period, and describes how other towns can use this type of program to supplement existing active forest management, or provide a baseline for future management. Results are applicable to municipalities that own forest land, as well as land trusts or other private entities that wish to manage their forests using a community based forestry model.     

Sugar palm (Arenga pinnata (Wurmb) Merr.) for livelihoods and biodiversity conservation in the orangutan habitat of Batang Toru, North Sumatra, Indonesia: mixed prospects for domestication

Domestication of desirable forest resources in agroforestry is expected to contribute to community based forest conservation efforts, but there may be an optimum level of domestication in this respect. Aren or sugar palm (Arenga pinnata (Wurmb) Merr.) is a multipurpose tree that provides livelihoods for local people and food for other biota in the landscape. However, its domestication is still limited in many places, such as in Batang Toru Forest Block, an area of high conservation value, including habitat for the Sumatran orangutan (Pongo abelii). Options for aren management were prioritized as part of a landscape-scale conservation study by comparing domestication levels in the area. Data on economic indicators and ecological knowledge were gathered through interviews with key farmers, focus groups and transect walks. Four representative villages were selected for the study, that is, (i) two villages with no domestication of aren; and (ii) two villages with aren cultivation in rubber-based land-use systems. Costbenefit analyses suggested that in a rich biodiversity area, such as Batang Toru, although aren was one of the sources of local livelihoods, additional investment for domestication beyond cultivation was not an option considered by farmers. Farmers still perceived wildlife as an efficient mode of aren regeneration, supported by the coexistence of people and other biota in the area. It appears the value of aren for local people’s livelihoods and conservation can be enhanced by increasing its stocking density. There is also scope for improving market access and share of end-user value received by farmers.     

Forest biomass estimated from MODIS and FIA data in the Lake States: MN, WI and MI, USA

This study linked the Moderate Resolution Imaging Spectrometerand USDA Forest Service, Forest Inventory and Analysis (FIA)data through empirical models established using high-resolutionLandsat Enhanced Thematic Mapper Plus observations to estimateaboveground biomass (AGB) in three Lake States in the north-centralUSA. While means obtained from larger sample sizes in FIA datasetscan be used as reference numbers over large scales, remote sensing(RS)-based observations have the ability to reflect spatialvariation of properties of interest within a given area. Thus,combining two national on-going datasets may improve our abilityto accurately estimate ecological properties across large scales.Using standard and consistent data sources can reduce uncertaintyand provide more comparable results at both temporal and spatialdimensions. We estimated total forest AGB in the region was1479 T_g (10¹² g, dry weight) in 2001 with mean AGB value of95 mg ha^–1 ranging from 4 to 411 mg ha^–1 (within95 per cent percentiles). Mixed forests featured 66 per centof the total AGB while deciduous and evergreen forests contained32 and 2 per cent of the total AGB, respectively, at 1-km pixelresolution. Spatially, AGB values increased from north-westto south-east in general. The RS-based estimates indicated agreater range in AGB variations than the FIA data. Deciduousforests were more variable (both in absolute and relative terms)than evergreen forests. The standard deviation of AGB for deciduousforests was 137 mg ha^–1, or a coefficient of variationof 92 per cent, that for evergreen forests was 24 mg ha^–1,or a coefficient of variation of 37 per cent.     

Transaction costs and the organization of CFEs: Experiences from ejidos in Quintana Roo,Mexico

Forest areas owned by indigenous people, families, and communities are increasingly linking to markets and attempting to harness the benefits of timber commercialization by setting up community forestry enterprises (CFEs). The interaction between markets and commonly owned forests is only until now enjoying greater attention from researchers. Common property scholarship has normally been used to study community natural resource management but currently it is deemed insufficient for understanding market interactions. This paper adds to this growing area of scholarship through the application of transaction costs economics (TCE) to the organization of community forest enterprises. TCE proposes that under certain circumstances and depending on the nature of the production process and context of exchange, different forms of organization play a role in reducing transaction costs in market exchange. Through fieldwork carried out in the state of Quintana Roo, Mexico, this paper finds that hierarchical, collective organization is not the only way to reduce transaction costs for CFEs. Although market transactions can expose communities to opportunistic behaviour and hazards in many jurisdictions, capacity-building and skilling will decrease information costs and asymmetries for CFEs of organizational forms that rely on market contracting for production. Additionally, this research found that CFEs and their business partners value relationships that reduce the range of transaction costs even if this represents trade-offs in prices and making concessions such as informal loans. We recommend that policy should not focus on driving specific organizational forms in communities that attempt to eliminate intermediaries, contractors and service providers. Efforts should concentrate primarily on creating enabling environments by reducing transaction costs, particularly information costs and asymmetries that hinder productive relations between CFEs and their exchange partners. Better commercial relationships, social innovation and entrepreneurship can develop in conditions in which both CFEs and trading partners stand on even footing. Transaction cost theory should further investigate the role of learning in reducing transaction costs and its effect on organizational choice. It should consider that transaction costs may be experienced differently by individuals with different skills and abilities.     

Investigation and Analysis of the Lending Needs of Forestry Households in China: Based on Data from Zhejiang,Fujian, Guangxi,and Jiangxi Provinces

As the collective forestry property system in China has developed in recent years, the difficulty faced by forestry households (the main managers of Chinese forests) in securing loans has received extensive attention. To address this problem, we should follow the bottom-up principle and undertake effective measures based on a clear understanding of forestry financing. Based on the results of a questionnaire, this article investigates and analyzes the credit demand in forestry households, lending channels, scaling, time limits, loan usage, and cost structures. Studies have shown that funding deficits contribute to the intense demand for loans. The salient characteristics of foresters’ credit demand indicate that such demand is typically large-scale and of long duration—particularly when compared with the credit demand of common farmers. Loans to foresters are used for production purposes and mainly come from formal financing. The structural dislocation of current forestry loan products has resulted in a demand for forestry farming credit that is difficult to satisfy. Therefore, improving the quality of credit services and optimizing loan product structures would help foresters and the Chinese forestry industry.