Contribution of Small-Scale Agroforestry Systems to Carbon Pools and Fluxes: A Case Study from Middle Hills of Nepal

In view of the heavy people’s dependence (80 %) on various forms of land-based resources, carbon sequestration should not only be targeted in forests, but also on private land agroforestry. A survey was conducted in 2011 to investigate the gap in contribution of agroforestry carbon to the household economy in the middle hills region of Rasuwa district of Nepal. A total of 120 households were randomly selected and surveyed, of which eight were further examined for detailed tree carbon measurement. It is estimated that a total of 48.60 ton C per hectare has been stocked in agroforestry sites in the middle hills region. Assuming a carbon price of $US12/ton, the total potential income from carbon sequestration per household would amount to NPR 45,490/ha in 20 years of agroforestry if a payment scheme were introduced. The income from carbon sequestration is quite low compared with other agroforestry income. Policy implications are thus oriented towards farmers reaping multiple benefits from the existing international mechanisms by having negotiations based on contribution of all agroforestry components (farm trees, crops and animals) rather than limited to forest carbon stock. To benefit from these multiple functions of farms and forests, the policy framework to address the climate-related affects and risks (e.g., of landslides, burst of Himalayan lakes) should be broad enough to produce potential synergy between the negative effect of climate change and agroforestry income.     

Soil Classification and Carbon Storage in Cacao Agroforestry Farming Systems of Bahia,Brazil

Information concerning the classification of soils and their properties under cacao agroforestry systems of the Atlantic rain forest biome region in the Southeast of Bahia, Brazil is largely unknown. Soil and climatic conditions in this region are favorable for high soil carbon storage. This study is aimed to classify soils under cacao agroforestry and further, to quantify carbon stocks in these soil profiles. Soil classification was performed, and the amount of C stored was estimated, based on the thickness of the soil horizons, their bulk density, and total organic carbon stored. In the sites studied under cacao, four general classes of soils were identified: Ultisols, Oxisols, Alfisols, and Inceptisols. Carbon stocks in these soil profiles showed wide variation, ranging from 719.24 to 2089.93 Mg ha^?1. Carbon stocks in soil surface and subsurface layers in different agroforestry systems with cacao (cacao cabruca, cacao?×?rubber tree, and cacao?×?erythrina) were comparable; however, total storage of organic C in these soils was higher than expected, compared to values reported for the International Soil Reference and Information Center (ISRIC), based on the FAO-UNESCO database, and were also higher than estimated regional soil data.     

豫东平原杨农复合系统物质生产与碳截存

农林复合系统由于林分、农作物和土壤之间的相互作用而对储藏和固定碳具有巨大的潜力.其已经成为减少大气CO2浓度、解决全球气候变暖问题的重要土地利用方式之一,将会对陆地生物圈中通量的输入和碳的长期贮藏产生重要的影响.对豫东平原农区5,9,11和13年4个不同林龄的杨农间作复合系统的生物量、生产力和碳截存量进行测定和研究,结果表明:豫东平原农区5,9,11和13年4个不同年龄段的杨农间作复合系统的总生物量分别为33.03,103.06,124.30和154.60 t·hm-2.4个年龄的杨农间作复合系统平均净生产力分别为19.95,29.30,33.24和56.94t·hm-2a-1.豫东平原农区5,9,11和13年4个年龄的杨农间作复合系统总碳截存量分别达到了19.86,52.42,62.45和76.44 t·hm-2.     

Carbon sequestration through agroforestry in indigenous communities of Chiapas, Mexico

The importance of agroforestry systems as carbon sinks has recently been recognized due to the need of climate change mitigation. The objective of this study was to compare the carbon content in living biomass, soil (0–10, 10–20, 20–30 cm in depth), dead organic matter between a set of non-agroforestry and agroforestry prototypes in Chiapas, Mexico where the carbon sequestration programme called Scolel’te has been carried out. The prototypes compared were: traditional maize (rotational prototype with pioneer native trees evaluated in the crop period), Taungya (maize with timber trees), improved fallow, traditional fallow (the last three rotational prototypes in the crop-free period), Inga-shade-organic coffee, polyculture-shade organic coffee, polyculture-non-organic coffee, pasture without trees, pasture with live fences, and pasture with scattered trees. Taungya and improved fallow were designed agroforestry prototypes, while the others were reproduced traditional systems. Seventy-nine plots were selected in three agro-climatic zones. Carbon in living biomass, dead biomass, and soil organic matter was measured in each plot. Results showed that carbon in living biomass and dead organic matter were different according to prototype; while soil organic carbon and total carbon were influenced mostly by the agro-climatic zone (P < 0.01). Carbon density in the high tropical agro-climatic zone (1,000 m) was higher compared to the intermediate and low tropical agro-climatic zones (600 and 200 m, respectively, P < 0.01). All the systems contained more carbon than traditional maize and pastures without trees. Silvopastoral systems, improved fallow, Taungya and coffee systems (especially polyculture-shade coffee and organic coffee) have the potential to sequester carbon via growing trees. Agroforestry systems could also contribute to carbon sequestration and reducing emissions when burning is avoided. The potential of organic coffee to maintain carbon in soil and to reduce emissions from deforestation and ecosystem degradation (REDD) is discussed.     

Temporal changes in soil carbon and nitrogen in west African multistrata agroforestry systems: a chronosequence of pools and fluxes

The conversion of forests to agroecosystems or agroforests comes with many changes in biological and chemical processes. Agroforestry, a tree based agroecosystem, has shown promise with respect to enhanced system nutrient accumulation after land conversion as compared to sole cropping systems. Previous research on tropical agroforestry systems has revealed increases in soil organic matter and total organic nitrogen in the short term. However, research is lacking on long-term system level sustainability of nutrient cycles and storage, specifically in traditional multi-strata agroforestry systems, as data on both the scope and duration of nutrient instability are inconclusive and often conflicting. This study, conducted in Ghana, West Africa, focused on carbon and nitrogen dynamics in a twenty-five year chronosequence of cacao (Theobroma cacao Linn.) plantations. Three treatments were selected as on-farm research sites: 2, 15 and 25-year-old plantations. Soil carbon (C, to a depth of 15 cm) varied between treatments (2 years: 22.6 Mg C ha⁻¹; 15 years: 17.6 Mg C ha⁻¹; 25 years: 18.2 Mg C ha⁻¹) with a significant difference between the 2- and 15- and the 2- and 25-year-old treatments (p < 0.05). Total soil nitrogen in the top 15 cm varied between 1.09 and 1.25 Mg N ha⁻¹ but no significant differences were noted between treatments. Soil nitrification rates and litter fall increased significantly with treatment age. However, photosynthetically active radiation (PAR) and soil temperature showed a significant decrease with age. No difference was found between decay rates of litter at each treatment age. By 25 years, system carbon sequestration rates were 3 Mg C ha⁻¹ y⁻¹, although results suggest that even by 15 years, system-level attributes were progressing towards those of a natural system.     

Effects of agroforestry-pasture associations on groundwater level and salinity

Stream and land salinisation brought about by rising groundwater levels due to the clearing of native forest for agricultural development is a major environmental and resource problem in Western Australia and several other semi-arid regions of the world. One potential approach to reclamation with simultaneous economic benefits is agroforestry. To determine the effects of agroforestry on groundwater level and salinity, two experiments were carried out in Western Australia. In Experiment I a pinius-pasture agroforestry covering 58% of the cleared area with final stem densities of 75–225 stems ha⁻¹ was successful in lowering a saline groundwater table. Over the period 1979–1989, groundwater levels decliend by 1.0 m relative to groundwater levels beneath a nearby pasture site. In Experiment II the eucalyptus-pasture agroforestry covering 57% of farmland at a final density of 150–625 stems ha⁻¹ was found to successfully lower the yearly minimum groundwater level by 2.0 m relative to a pasture site over seven years. The salinity of the groundwater beneath agroforestry decreased by 9% and 6% for Experiments I and II respectively, which was contrary to some early expectations. The design of agroforestry for controlling saline groundwater tables needs further evaluation with respect to species, stem densities and proportion of cleared area planted.     

Analysis of existing agroforestry practices in Madhupur Sal forest: an assessment based on ecological and economic perspectives

A study was conducted in Madhupur sal forest of Tangail, Bangladesh to identify the suitable agroforestry practices of the area. Considering the ecological aspects of different agroforestry practices 10 sample plots (10 m × 10 m) from each land uses were taken, including natural forest to get a comparative scenario. The study showed that among the different agroforestry practices, Margalef and Shannon-Weiner index values are the maximum for pineapple agroforestry and lower for banana agroforestry, and Evenness index value is the maximum for lemon agroforestry. Determination of tree biomass in different land uses revealed that it is highest (3 078.6 kg/100 m²) in natural forest followed by pineapple agroforestry, lemon agroforestry and banana agroforestry. Soil pH, moisture content, organic matter, organic carbon, phosphorus and total nitrogen showed statistically significant variation while bulk density, particle density, sulphur and potassium did not show any statistically significant variation among the land uses. Soil fertility status showed that pineapple agroforestry is more fertile than rest of other land uses. The Net Present Value (NPV) indicated that banana agroforestry is financially more profitable than other two systems, while the Benefit-Cost ratio (BCR) is higher in pineapple agroforestry (4.21 in participatory agroforestry and 3.35 in privately managed land). Even though banana agroforestry gives higher NPV, capital required for this practice is much higher. The findings suggest that pineapple agroforestry has a tendency towards becoming ecologically and economically more sound than other two practices as it has better ecological attributes and required comparatively low investment.     

Carbon storage benefits of agroforestry systems

The process of land degradation is a local phenomenon that occurs field by field. Because of the extent at which it is occurring, however, it also has a global dimension. Agroforestry represents a link between the local and global scales. From the farmer's perspective, agroforestry can be a way to increase crop yields and the diversity of products grown. An additional benefit is the creation of a carbon sink that removes carbon dioxide from the atmosphere. Successful agroforestry systems will also reduce land clearing and maintain carbon in existing vegetation. An extensive literature survey was conducted to evaluate the carbon dynamics of agroforestry practices and to assess their potential to store carbon. Data on tree growth and wood production were converted to estimates of carbon storage. Surveyed literature showed that median carbon storage by agroforestry practices was 9 tC/ha in semi-arid, 21 tC/ha in sub-humid, 50 tC/ha in humid, and 63 tC/ha in temperate ecozones. The limited survey information available substantiated the concept that implementing agroforestry practices can help reduce deforestation.The research described in this article has been funded by the US Environmental Protection Agency. This document has been prepared at the EPA Environmental Research Laboratory in Corvallis, Oregon, through contract number 68-C8-0006 to ManTech Environmental Technology, Inc. It has been subjected to the Agency's peer and administrative review and approved for publication. Mention of trade names or commercial products does not constitute endorsement or recommendation for use.     

Transformation of jackfruit (<Emphasis Type="Italic">Artocarpus heterophyllus</Emphasis> Lam.) orchard into multistory agroforestry increases system productivity

A number of traditional and modern agroforestry systems are common in the agricultural landscape of Bangladesh. Jackfruit (Artocarpus heterophyllus Lam.) based agroforestry is one of them and predominantly found in terrace ecosystems. There is an enormous opportunity to improve the system through utilizing available space by growing compatible associated crops. For this, a jackfruit orchard was transformed into a multistoried agroforestry system during the period from 2012 to 2013, where jackfruit trees were kept as overstory, and associated crops, such as papaya and eggplant were grown as middle and lower story crops, respectively. In the improved system, jackfruit yield increased by 32.7% due to fertilizers and irrigation applied for the middle and lower-storied crops. Yields of papaya and eggplant were reduced by 22.8 and 17.4%, respectively, because of competition for both belowground and aboveground resources. For example, light interception by the middle and lower story crops were 55.5 and 30.8%, respectively. However, the total production per unit area (by combining the yields of jackfruit, papaya, and eggplant) in the multistoried agroforestry system was remarkably higher than the monoculture system for the same area due to intensive land use. The benefit–cost ratio and land equivalent ratio for the studied multistoried agroforestry systems were 5.47 and 2.59, respectively. These results suggest that the traditional jackfruit orchard could be transformed to multistoried agroforestry systems for its higher system productivity including higher yield, and increased income that ultimately will improve the livelihood of the farming community.     

Economic potential of agroforestry for public recreational parks

The availability of public recreational facilities is being threatened by growing demands, limited supplies, and declining government funding. In response to these pressures, the economic potential of agroforestry for supplementing operating budgets of public recreational parks is examined in a case study park consisting of 324 hectares. Agroforestry enterprises native to the area were selected for development on 70 hectares of the site. Linear programming was used to determine the optimum combinations of 23 agroforestry regimes composed of the following activities: 1) conventional forestry planting, tree density of 1682 trees/hectare, 2) the selected agroforestry planting with hay, tree density of 1495 trees/hectare, 3) the selected agroforestry planting with grazing, 4) hay production, and 5) rental of pasture for grazing. The objective function of the study was to maximize the net present value of the study site subject to land, labor, capital, and minimum annual income constraints. The preferred optimal regime generated $1782 per hectare from an agroforestry planting configuration of 1495 trees/hectare with 75 percent hay, 25 percent grazing, and no annual income requirements. Minimum annual income requirements of $2400 and $4800 were feasible but suboptimal from a net present value criteria. The study found that agroforestry could be used to privatize selective activities of public recreational parks and thus enable public agencies to provide these facilities more effectively.     

Acacia nilotica trees in rice fields: A traditional agroforestry system in central India

Time-tested, indigenous land-use systems can provide valuable information for the design of ecologically sustainable and socially acceptable agroforestry systems. One such traditional system is the growing of Acacia nilotica (L.) Willd. Ex Delile trees, locally known as babul, in rice fields of smallholder farmers in Madhya Pradesh State of Central India, an area with subhumid monsoon climate and hot summer. The functional characteristics of the system were collected through participatory rural appraisal involving intensive interactions with farmers in the region during six years, and through a structured-questionnaire survey in 25 villages, involving a total of 200 farm families. The farms had an average of 20 babul trees, ranging in age from <1 to 12 years, per hectare in upland rice fields, the tree-stand density being greater on smaller than on larger farms (>8 ha). Over a ten year rotation period, the trees provide a variety of products such as fuelwood (30 kg/tree), brushwood for fencing (4 kg/tree), small timber for farm implements and furniture (0.2 cu.m), and non-timber products such as gum and seeds. The babul + rice system was estimated to have a benefit/cost (B/C) ratio of 1.47 and an internal rate of return (IRR) of 33% at 12% annual discount rate during a ten-year period, though at a low level of income. Babul trees account for nearly 10% of the annual farm income of smallholder farmers (<2 ha). By practising the agroforestry (rice + babul) system, farmers get higher cash returns on a short-term (10-year) harvest cycle of trees, and the labour input (both family- and hired) on farms was distributed more uniformly throughout the year than in rice monoculture. Purchased inputs are seldom used in the system. The ease of management of the system, the self-generating and robust nature of the tree and the multiple products and services it provides, and easy marketability of the products are the major factors that encourage farmers to adopt the system. Furthermore, the farmers have secure ownership rights to their land, so that they are interested in long-term measures such as tree plantings on their farms. In spite of its long history and tradition as a sustainable approach to land use, the system has not attracted the attention of development agencies. More detailed investigations on its social, economic, and cultural attributes are warranted to not only improve this system, but provide insights into farmer adoption of agroforestry innovations.This revised version was published online in November 2005 with corrections to the Cover Date.     

Adoption potential of fruit-tree-based agroforestry on small farms in the subtropical highlands

Worldwide, fruit-tree-based agroforestry systems have been only modestly studied, although they are common on smallholder farms. Such systems based on apple (Malus spp.), peach (Prunus spp.), and pear (Pyrus spp.) are common in northwest Guatemala as low intensity homegardens and are known to increase total farm productivity in communities where farm size is a limiting factor. This study investigated the potential for adoption of fruit-tree-based agroforestry by resource-limited farmers using ethnographic investigation and linear programming simulations of farm activities at the household level. Two communities with differing demographics, infrastructure, and access to regional markets were selected based on the presence of extensive fruit-tree-based agroforestry. The influences of family size, land holdings, and tree and crop yields on the optimal adoption levels of fruit trees were evaluated through a comparative study of the varying social and physical infrastructure present in the two communities. Fruit-tree-based agroforestry was potentially more attractive to relatively prosperous families or those with larger land holdings. Improvements in fruit-tree productivity and interspecies competition were of greater importance where family land holdings were smaller. The inability of families to produce sufficient food to meet annual needs, poor fruit quality, and lack of market infrastructure were identified as constraints that limit adoption. The complementarity of production with the dominant maize (Zea mays) crop, home consumption of fruit, and the potential to generate additional cash on limited land holdings were identified as factors promoting adoption of fruit-tree-based agroforestry.     

Floristic structure and sequestration potential of cashew agroecosystems in Africa: A case study from Cameroon

Agroecosystems are not only recognized by their high capacity of carbon storage and sequestration, they could also offer an opportunity of financial benefits in the event of payment for environmental services. The present study aimed to evaluate the carbon storage and describe the structure of cashew nut plantation. Three types of cashew stand were selected according to the age of plantations; we also used savannah as a treatment witness. Carbon stocks varied according to the age of plantations; 14.51 ± 0.306 t C/ha for plantations aged 0–10 yr; 34.78 ± 0.331 t C/ha for plantations aged 10–20 yr, and 40.02 ± 0.381 t C/ha for plantations aged over 20 yr. In the witness, we found 13.05 ± 0.177 t C/ha. These values were significantly different between the studied sites (p < 0.05). The mean values of the service of carbon sequestration also varied with the age of stands; $53.5/ha/yr (0–10 yr); $63.35/ha/yr (10–20 yr); $73.95/ha/yr (over 20 yr). In regard to carbon storage, $3279 are stored in these stands. These agroecosystems are also true carbon sinks. A development plan of such agroecosystems should be considered for the conservation of the species already endangered by anthropogenic activities on natural ecosystems.     

贵州岩溶峡谷区石漠化对土壤碳库的影响

研究以喀斯特典型区贵州省关岭布依族苗族自治县花江峡谷区为例,对未石漠化土地和不同程度石漠化土地中的土壤有机碳和无机碳进行了测定,并计量分析了石漠化治理对土壤碳库的影响。结果表明:(1)未石漠化土地的土壤平均碳库总量比石漠化土地的高,石漠化土地的土壤平均碳库总量主要受植被类型和土层深度的影响,其影响程度大于石漠化程度的影响;(2)土地平均碳密度则与石漠化影响程度呈显著的负相关关系,即呈非石漠化土地潜在石漠化土地石漠化土地,轻度石漠化土地中度石漠化土地重度石漠化土地极重度石漠化土地的变化规律;(3)通过石漠化综合治理工程,关岭县未石漠化土地和不同程度石漠化土地的面积发生了明显变化,对治理工程的碳汇效益计量分析表明,碳库增加量为724.00 t·km-2,仅增加的有机碳价值可达51.36万元·km-2,治理效果显著。     

Land suitability evaluation for multiple crop agroforestry planning using GIS and multi-criteria decision analysis: A case study in Fiji

We present novel methods that use geographic information systems (GIS) and multi-criteria decision analysis (MCDA) to evaluate land suitability for a set of seven agroforestry crops, with the aim to differentiate relative land suitability and its potential to achieve different benefit goals for the Sigatoka Valley, Fiji. Our first model (Land Suitability) identifies optimal areas for each crop based on readily available edaphic and environmental cultivation criteria and common GIS datasets. The second model (Weighted Maximum) uses objective approaches for weighting the relative importance of target crops to derive a multi-crop suitability map. We use the analytical hierarchy process (AHP) technique (a form of MCDA) to identify the relative importance of five benefit types (i.e. agroforestry initiative goals/AHP Objectives). AHP criterion weights were used to map the most important crops for different agroforestry goals. Our methods are unique among GIS-MCDA applications of land suitability analysis in that our aim was to investigate and spatially evaluate land use suitability for multiple crops on a per-crop basis, whereas the aim of most GIS-MCDA land suitability analyses is to evaluate relative suitability (e.g. low, medium, high), evaluate potential for different land uses (e.g. production, intensive, or multifunctional) or land suitability for a single crop. We conclude that the methods described can be adapted to agroforestry initiatives and other similar land use suitability applications in the Pacific region and other geographical settings.

     

Solving the problem of carbon dioxide emissions

More than just an environmental challenge, the problem of carbon dioxide emissions is a basic human rights issue. This paper proposes a solution to the problem based on the proposition of Green Human Right that all men are created equal and thus entitled to equal carbon dioxide emissions per person. Countries with per capita carbon dioxide emissions above that of the global average must pay for the privilege to pollute. Conversely, countries with that below the global average are entitled to compensations.To determine the excess or slack carbon dioxide emissions of individual countries, the total carbon dioxide emissions of every country are adjusted for international trade to account for carbon dioxide out-sourcing and carbon sequestration by forests and forest products to arrive at their net carbon dioxide emissions. Countries with above the global average in net per capita carbon dioxide emissions have excess emissions. Those with below the global average have slack emissions. Total excess or slack carbon dioxide emissions are determined by multiplying the per capita excess or slack per capita emissions by its population. They then pay into or get compensated from the Green Climate Fund based on their respective excess or slack carbon dioxide emissions.Based on the total excess carbon dioxide emission figures from 2009 and $10 per ton of carbon dioxide emissions, major excess emission countries and the amount of money they would pay into the Green Climate Fund are the U.S. $40.8 billion, Japan $7.8 billion, U.K. $5.1 billion, Canada $4.7 billion, Germany $4.6 billion, and Russia $4.2 billion. China, for the first time, also would become an excess emission country and would pay $446 million, thus obliterating the artificial separation between developed and developing countries and removing a major stumbling block in climate change negotiations. Major slack emission countries and the amount of money they would earn from the Green Climate Fund are India $3.7 billion, Pakistan $645 million, Bangladesh $626 million, Nigeria $433 million, Ethiopia $358 million, the Philippines $351 million and Vietnam $333 million.The incentives created by the proposed solution would propel all countries to focus on controlling or lowering their total global carbon dioxide emissions. Excess emission countries have incentives to reduce their carbon dioxide emissions to lower their payments. Slack countries also have incentives to lower or limit their emissions, if they want to keep earning money over time. When the price of carbon dioxide emissions is high enough, its impact on the global carbon dioxide emissions would be significant. Furthermore, as a dynamic system, every year the price set for carbon dioxide emissions would depend on how quickly the total global carbon dioxide emissions are being reduced through conservation efforts and technical innovations. Once the price is set, there is total transparency. Every country will know exactly how much it would either pay into or earn from the Green Climate Fund, sparing rich countries from haggling over how much each will pay and poor countries over how much each will earn.     

A general classification of agroforestry practice

Present classification schemes confuse agroforestry practices, where trees are intimately associated with agricultural components at a field scale, with the whole farm and forest systems of which they form a part. In fact, it is common for farming systems to involve the integration of several reasonably discrete agroforestry practices, on different types of land. The purpose of a general classification is to identify different types of agroforestry and to group those that are similar, thereby facilitating communication and the organized storage of information. A new scheme is proposed that uses the ‘practice’ rather than the ‘system’ as the unit of classification. This allows an efficient grouping of practices that have a similar underlying ecology and prospects for management. A two stage definition of agroforestry is proposed that distinguishes an interdisciplinary approach to land use from a set of integrated land use practices. Four levels of organization are recognized through analysis of the role of trees in agricultural landscapes: the land use system, categories of land use within systems, discrete groups of components (trees, crops, animals) managed together, and functionally connected groups of such discrete practices in time and space. Precedents for this form of analysis are found in the literature and it conforms with generally accepted methods of systems analysis. Classification of major types of agroforestry practice proceeds primarily according to the components involved and the predominant usage of land. A secondary scheme further classifies these in terms of the arrangement, density and diversity of the tree components involved. This revised version was published online in June 2006 with corrections to the Cover Date.     

森林生态系统碳储量估测方法及其研究进展

森林生态系统作为陆地生态系统最大的碳库, 其碳交换对全球碳平衡有着重要影响, 研究其碳储量具有重要的科研和社会意义。文中阐述了森林生态系统碳储量研究进展及估测方法, 并展望了未来森林生态系统碳研究的主要方面。     

Financial returns, stability and risk of cacao-plantain-timber agroforestry systems in Central America

Diversification of agroecosystems has long been recognized as a sound strategy to cope with price and crop yield variability, thus increasing farm income stability and lowering financial risk. In this study, the financial returns, stability and risk of six cacao (Theobroma cacao L.) – laurel (Cordia alliodora (R&P) Oken) – plantain (Musa AAB) agroforestry systems, and the corresponding monocultures, were compared. Production and cost data were obtained from an on-going eight-year old experiment. The agroforestry systems included a traditional system and a replacement series between cacao (278, 370, 556, 741 and 833 plants ha^–1) and plantain (833, 741, 556, 370 and 278 plants ha^–1) with a constant laurel population (timber tree; 69 trees ha^–1). An ex-post analysis was conducted using experimental and secondary data to build a simulation model over a 12-year period under different price assumptions. The probability distribution functions for the three commodity prices were modeled and simulated through time, accounting for their possible autocorrelation and non-normality. The expected net incomes from the agroforestry systems were considerably higher than from monocultures. The agroforestry systems were also less risky. Agroforestry systems with proportionally more cacao than plantain were less risky, but also less stable. The timber component (C. alliodora) was a key factor in reducing farmer's financial risks. Methodologically, the study illustrates a technique to evaluate both expected returns and the corresponding financial risks to obtain a complete, comparable profile of alternative systems. It shows the need to allow for the possibility of non-normality in the statistical distributions of the variables entering a financial risk and return analysis.     

Agroforestry systems in the rural landscape – a case study in Garhwal Himalaya, India

A mid altitude (700–1200 m amsl.) village in Garhwal Himalaya was analysed in terms of energy and economic efficiency of different land use-land cover types constituting the landscape. Simultaneous agroforestry, sequential agroforestry, home garden and community forests accounted for 27.47%, 27.47%, 1.1% and 43.96% of the total geographical area of the village. Simultaneous agroforestry is the traditional land use involving substantial input of manure derived from forest litter and animal excreta and was practised on terraced slopes in private ownership. Tree cover in this system was represented by nine species with total average density of 390 trees ha⁻¹, Grewia optiva and Boehmeria rugulosa being the most dominant. Sequential agroforestry system involving slash-burn practice and cultivation on unterraced slopes without tillage and manuring was an illicit land use on community lands where forestry land use is desirable as per the government policy. Per ha annual energy input in simultaneous agroforestry system was 305267 MJ compared to 279 MJ in sequential agroforestry and 27047 MJ in home garden. In monetary terms, highest per ha annual output was obtained from simultaneous agroforestry (Rs 25370, Rs 35 = US$1) followed by home garden (Rs 18200) and sequential agroforestry (Rs 9426). Local food, fodder and fuelwood production was in excess of the local consumption. While most of the surplus food was stored, surplus fodder and fuelwood were sold for cash. Production in simultaneous agroforestry system in private lands was sustained with substantial biomass and nutrient inputs from the community and government forests. Land use-land cover changes in the region are driven by the interaction of ecological, policy and human factors. It is concluded that present policy of treating forests and agriculture as closed and independent ecological or production systems needs to be replaced by an integrated land use policy. This revised version was published online in August 2006 with corrections to the Cover Date.