Natural Resource

Biodiesel has become more attractive recently because of its environmental bene®ts and the fact that it is made from renewable resources. The cost of biodiesel, however, is the main hurdle to commercialization of the product. The used cooking oils are used as raw material, adaption of continuous transesteri®cation process and recovery of high quality glycerol from biodiesel by-product (glycerol) are primary options to be considered to lower the cost of biodiesel. There are four primary ways to make biodiesel, direct use and blending, microemulsions, thermal cracking (pyrolysis) and transesteri®cation. The most commonly used method is transesteri®cation of vegetable oils and animal fats. The transesteri®cation reaction is aected by molar ratio of glycerides to alcohol, catalysts, reaction temperature, reaction time and free fatty acids and water content of oils or fats. The mechanism and kinetics of the transesteri®cation show how the reaction occurs and progresses. The processes of transesteri®cation and its downstream operations are also addressed. Ó : S 0 9 6 0 -8 5 2 4 ( 9 9 ) 0 0 0 2 5 -5

A serious threat to human beings and their environment is the continuous and accelerating overuse and destruction of natural resources. Bearing this in mind, it is unfortunate that e¡orts to permanently change people's environmentally destructive behaviour through interventions has typically not been met with success. A necessary condition may be an increase in environmental concern and knowledge about the e¡ects and consequences of the ongoing environmental deterioration for future generations. Studies are reviewed that have attempted to show (1) correlations between determinants, such as socio-demographic and/or psychological factors, and environmental concern, and (2) an impact of environmental concern on environmentally responsible behaviour. In general, correlations with background factors are weak. Factors a¡ecting behaviour appear to be knowledge, internal locus of control (positive control beliefs), personal responsibility, and perceived threats to personal health. The need for further research that attempts to specify the process leading to environmentally responsible behaviour is highlighted. A new framework is presented which integrates some of the previous research.

The building industry uses great quantities of raw materials that also involve high energy consumption. Choosing materials with high content in embodied energy entails an initial high level of energy consumption in the building production stage but also determines future energy consumption in order to fulfil heating, ventilation and air conditioning demands.

The accumulation of solid organic waste is thought to be reaching critical levels in almost all regions of the world. These organic wastes require to be managed in a sustainable way to avoid depletion of natural resources, minimize risk to human health, reduce environmental burdens and maintain an overall balance in the ecosystem. A number of methods are currently applied to the treatment and management of solid organic waste. This review focuses on the process of anaerobic digestion which is considered to be one of the most viable options for recycling the organic fraction of solid waste. This manuscript provides a broad overview of the digestibility and energy production (biogas) yield of a range of substrates and the digester configurations that achieve these yields. The involvement of a diverse array of microorganisms and effects of co-substrates and environmental factors on the efficiency of the process has been comprehensively addressed. The recent literature indicates that anaerobic digestion could be an appealing option for converting raw solid organic wastes into useful products such as biogas and other energy-rich compounds, which may play a critical role in meeting the world's ever-increasing energy requirements in the future.

Arturo Escobar examines the increasing number of conflicts over natural resources around the world in response to neo-liberal globalization. He argues that such escalating environmental conflicts can be conceptually understood through three inter-related rubrics: economic, ecological, and cultural. His interest is in the relationship between difference and equality of access in economic, ecological, and cultural distribution conflicts in order to

Payments for Ecosystem Services (PES) economically reward resource managers for the provision of ecosystem services and are thus characterised by (i) an ecological function subject to trade; (ii) the establishment of a standard unit of exchange; (iii) and supply, demand and intermediation flows between those who sell and buy ecosystem services. This paper departs from the term commodity fetishism, broadly understood as the masking of the social relationships underlying the process of production, to illuminate three invisibilities in the commodification of ecosystem services. Firstly, we argue that narrowing down the complexity of ecosystems to a single service has serious technical difficulties and ethical implications on the way we relate to and perceive nature. Secondly, the commodification of ecosystem services denies the multiplicity of values which can be attributed to these services, since it requires that a single exchange-value is adopted for trading. Finally, we suggest that the process of production, exchange and consumption of ecosystem services is characterised by power asymmetries which may contribute to reproducing rather than addressing existing inequalities in the access to natural resources and services.

The environmental services that agroforestry practices can provide, and especially their potential contribution to the conservation of biodiversity, have only recently attracted wider attention among agroforestry and conservation scientists. This new view is consistent with the ecosystem approach to natural resource management advocated by the Convention on Biological Diversity. This collection of six papers, which is based on a Workshop held in June-July 2004, brings together studies of biodiversity impacts of traditional agroforestry practices from Central and South America, Africa and Asia. The contributions highlight the considerable potential of traditional agroforestry practices to support biodiversity conservation, but also show their limits. These include the importance of sufficient areas of natural habitat and of appropriate hunting regulations for maintaining high levels of biodiversity in agroforestry land use mosaics, as well as the critical role of markets for tree products and of a favourable policy environment for agroforestry land uses. In combination the case studies suggest that maintaining diversity in approaches to management of agroforestry systems, along with a pragmatic, undogmatic view on natural resource management, will provide the widest range of options for adapting to changing land use conditions.

Meta-governance -or governance of governance -is a concept that raises questions regarding how values, norms and principles underpin governance systems and governing approaches. Values, norms and principles pertain both to substantive governance issues, for instance, related to sustainable resource use, and to governance system issues in themselves, for instance, regarding their institutional design. This article deals primarily with the latter. Thus the interactive perspective serves as basis for developing a coherent set of meta-governance principles. We argue that an explicit, deliberated and decided upon set of meta-governance principles as an integral part of governance can help in making hard substantive governance choices easier. Interactive learning plays a key role in governance processes when public and private governing actors have to make such hard choices. In the article, examples from natural resource governance will serve as illustrations for the more conceptual argumentation and reasoning.

Due to the existence of multiple stakeholders with conflicting goals and policies, alterations to the existing Internet are now limited to simple incremental updates; deployment of any new, radically different technology is next to impossible. To fend off this ossification once and for all, network virtualization has been propounded as a diversifying attribute of the future inter-networking paradigm. By allowing multiple heterogeneous network architectures to cohabit on a shared physical substrate, network virtualization provides flexibility, promotes diversity, and promises security and increased manageability. In this paper, we present a network virtualization model with a set of quintessential design goals, survey the past and the state-of-the-art of network virtualization, and discuss the future challenges that must be addressed to realize a viable network virtualization model.

Currently, the use of synthetic chemicals to control insects and arthropods raises several concerns related to environment and human health. An alternative is to use natural products that possess good efficacy and are environmentally friendly. Among those chemicals, essential oils from plants belonging to several species have been extensively tested to assess their repellent properties as a valuable natural resource. The essential oils whose repellent activities have been demonstrated, as well as the importance of the synergistic effects among their components are the main focus of this review. Essential oils are volatile mixtures of hydrocarbons with a diversity of functional groups, and their repellent activity has been linked to the presence of monoterpenes and sesquiterpenes. However, in some cases, these chemicals can work synergistically, improving their effectiveness. In addition, the use of other natural products in the mixture, such as vanillin, could increase the protection time, potentiating the repellent effect of some essential oils. Among the plant families with promising essential oils used as repellents, Cymbopogon spp., Ocimum spp. and Eucalyptus spp. are the most cited. Individual compounds present in these mixtures with high repellent activity include a-pinene, limonene, citronellol, citronellal, camphor and thymol. Finally, although from an economical point of view synthetic chemicals are still more frequently used as repellents than essential oils, these natural products have the potential to provide efficient, and safer repellents for humans and the environment.

The accumulation of solid organic waste is thought to be reaching critical levels in almost all regions of the world. These organic wastes require to be managed in a sustainable way to avoid depletion of natural resources, minimize risk to human health, reduce environmental burdens and maintain an overall balance in the ecosystem. A number of methods are currently applied to the treatment and management of solid organic waste. This review focuses on the process of anaerobic digestion which is considered to be one of the most viable options for recycling the organic fraction of solid waste. This manuscript provides a broad overview of the digestibility and energy production (biogas) yield of a range of substrates and the digester configurations that achieve these yields. The involvement of a diverse array of microorganisms and effects of co-substrates and environmental factors on the efficiency of the process has been comprehensively addressed. The recent literature indicates that anaerobic digestion could be an appealing option for converting raw solid organic wastes into useful products such as biogas and other energy-rich compounds, which may play a critical role in meeting the world's ever-increasing energy requirements in the future.

Waste is an unavoidable by product of human activities. Economic development, urbanization and improving living standards in cities, have led to an increase in the quantity and complexity of generated waste. Rapid growth of population and industrialization degrades the urban environment and places serious stress on natural resources, which undermines equitable and sustainable development. Inefficient management and disposal of solid waste is an obvious cause of degradation of the environment in most cities of the developing world. Municipal corporations of the developing countries are not able to handle increasing quantities of waste, which results in uncollected waste on roads and in other public places. There is a need to work towards a sustainable waste management system, which requires environmental, institutional, financial, economic and social sustainability.This study explores alternative approaches to municipal solid waste (MSW) management and estimates the cost of waste management in Mumbai, India. Two alternatives considered in the paper are community participation and public private partnership in waste management. Data for the present study are from various non-governmental organizations (NGOs) and from the private sector involved in waste management in Mumbai. Mathematical models are used to estimate the cost per ton of waste management for both of the alternatives, which are compared with the cost of waste management by Municipal Corporation of Greater Mumbai (MCGM). It is found that the cost per ton of waste management is Rs. 1518 (US$35) with community participation; Rs. 1797 (US$41) with public private partnership (PPP); and Rs. 1908 (US$44) when only MCGM handles the waste. Hence, community participation in waste management is the least cost option and there is a strong case for comprehensively involving community participation in waste management.

JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org. This paper studies the evolution of sectoral concentration in relation to the level of per capita income. We show that various measures of sectoral concentration follow a U-shaped pattern across a wide variety of data sources: countries first diversify, in the sense that economic activity is spread more equally across sectors, but there exists, relatively late in the development process, a point at which they start specializing again. We discuss this finding in light of existing theories of trade and growth, which generally predict a monotonic relationship between income and diversification. (JEL F43, F15, 040) This paper characterizes the pattern of sectoral diversification along the development path. Using data on sector-level employment and value added, covering a wide cross section of countries at various levels of disaggregation, we provide new and robust evidence that economies grow through two stages of diversification. At first, sectoral diversification increases, but there exists a level of per capita income beyond which the sectoral distribution of economic activity starts concentrating again. In other words, sectoral concentration follows a U-shaped pattern in relation to per capita income.

From the perspective of sustainable development, some principles have been emerging concerning work in territorial regulation as a basic strategy to obtain an adequate physical and spatial planning. The goal of those principles has been to supervise the good use of natural resources, to appropriately locate productive activities, and to increase infrastructural and urban facilities for a more equitable regional development, as well as a more successful fight against poverty and marginalization. This paper describes some of the frameworks currently in use in support of that perspective and it argues that researchers must resort to multiple analysis techniques from the social sciences, such as interviews with development actors, as well as to new quantitative tools such as SIG and SPSS.

Africa is not poor, it is poorly led. – Omoruyi Aigbe

ABSTRACT

Africa's colonial legacy has been blamed for the socioeconomic, security, political challenges, the tension and hostility among the many ethnic groups, especially in sub-Saharan Africa. Political historians have traced security challenge, conflict and instability in most Africa nations, especially in Burundi, Democratic Republic of Congo (DRC), Central African Republic (CAR), Nigeria, Rwanda, Sudan, and elsewhere to colonial programs of division, discrimination, collective exclusion, and manipulation of ethnic identity envisioned to ensure power and control over vast natural resources.

Africa's natural resource wealth, which ought to be a blessing, is arguably a curse, natural resource in Africa has become a source of tremendous suffering, which Collier, (2007) referred to natural resource trap. There is a strong correlation between natural resource, conflict and security challenge in Africa, the ongoing conflict, which is arguably a civil war in the world’s newest country, South Sudan demonstrates the effect of natural resource made conflict.

Conflicts involving the ownership, management and control of natural resources have engaged attention about Africa in the last decade. To date, there has been limited empirical study, which examines the effect of natural resource and leadership on conflict and poverty. However, there is a handful of research which analyses the relationship between conflict and poverty. While this paper also seeks to look at conflict and poverty in Africa, it is interested in exploring the role of natural resource and leadership.

Transparency is increasingly viewed as central to curbing corruption and other dysfunctions of resource-rich developing countries. The international development community has pushed transparency in resource revenues through such initiatives as the Extractive Industries Transparency Initiative (EITI). Despite the popularity of the transparency concept, its role in reducing corruption and averting the resource curse is poorly understood. This paper reviews the main mechanisms through which transparency can reduce corruption. It argues that transparency is insufficient in itself, and needs to be complemented by other types of policies. Transparency reform should focus on the areas most important to alleviating the resource curse. In view of the resource curse literature, the emphasis of the EITI on revenues rather than on expenditures appears misplaced.

Land use planning and necessary supporting data are crucial to developing countries that are usually under severe environmental and demographic strains. Approaches and methods to map the variability of natural resources are important tools to properly guide spatial planning. In this paper, we describe a method to quickly map terrain at reconnaissance Ž . Ž . 1:250,000 and semi-detailed 1:50,000 levels. This method can be utilized as a basis for further land evaluation and land use planning in large territories. The approach was tested in the state of Michoacan, central-western Mexico, currently undergoing rapid deforestation and subsequent land degradation.

The present work provides an integrated view of rural entrepreneurship and sets the agenda for future research in the area. Rurality defines a territorially specific entrepreneurial milieu with distinct physical, social and economic characteristics. Location, natural resources and the landscape, social capital, rural governance, business and social networks, as well as information and communication technologies, exert dynamic and complex influences on entrepreneurial activity in rural areas. Rurality is viewed as a dynamic entrepreneurial resource that shapes both opportunities and constraints. Rural entrepreneurship is depicted as a three-stage sequential process highly influenced by specific territorial characteristics. The proposed research agenda addresses issues related to theoretical studies concerning entrepreneurial processes in rural areas and more applied issues concerning the formulation of integrated and competent policies supporting entrepreneurship in such areas.

This article lays out six propositions centering on a relationship between peopleplace connections and strategic behavior in natural resource politics. The first two propositions suggest a strong and direct connection between self-identity, place, and how individuals perceive and value the environment. The third, fourth, and fifth propositions tie together social group identity and place, particularly emphasizing the influence of social group identity on strategic behavior in natural resource politics. The sixth proposition relates to the geographic scale of place as a strategic choice in natural resource decision making. Taken together, the propositions suggest that natural resource politics is as much a contest over place meanings as it is a competition among interest groups over scarce resources. The place perspective suggests an expanded role for natural resource social scientists as giving voice to meanings and values that may not otherwise be expressed in natural resource decision-making processes.

The structure of lignin has remained one of the most difficult biopolymers to characterize, however recent advances in analytical chemistry and spectroscopy have dramatically improved our knowledge of this natural resource. This paper highlights our current understanding of lignin structure and examines the process chemistry surrounding kraft pulping. The application of this knowledge, with respect to converting lignin into novel biomaterials, biocomposites, and biofuels is examined briefly.

Malaysia is blessed with abundant natural resources and bears a favorable climate for commercial cultivation of crops such as oil palm. In Malaysia the total plantation area of oil palm was 4,487,957 ha in 2008. It has been reported that in 2005 there was a total of 423 palm oil mills having production capacity of approximately 89 million tonnes of fresh fruit bunch (FFB) per year. Waste from the oil palm mill process include palm oil mill effluent (POME), generated mainly from oil extraction, washing and cleaning up processes. POME contains cellulosic material, fat, oil, and grease. Discharging untreated effluent into water streams may cause considerable environmental problems. The solid wastes generated are mainly decanter cake, empty fruit bunches, seed shells and fibre from the mesocarp. POME as well as the solid wastes may rapidly deteriorate the surrounding environment if not dealt with properly. Hence there is an urgent need for a sustainable waste management system to tackle these wastes. As these wastes are organic in origin, they are rich in plant nutrients. Composting of waste generated from palm oil mills can be good practice as it will be helpful in recycling useful plant nutrients. This review deals with various aspects of waste management practices in palm oil mills and the possibility of composting the wastes.

This paper examines local responses to potential ecotourism development in the Tawushan Nature Reserve located in southeastern Taiwan. Community attitude and intention toward four dimensions of ecotourism, including conservation of natural resources, preservation of cultural tradition, sustainable community development, and participation in ecotourism planning and management, were measured. Furthermore, the paper examines whether or not there is congruence between community attitude and intention toward ecotourism development. Analysis is based on data collected using face-to-face questionnaire interviews in two indigenous communities consisting primarily of the Paiwan ethnic group. The study findings show that local people hold generally positive views of the measures necessary to achieve ecotourism; however, their intentions to engage in behaviors to support these measures do not entirely match with their positive views. This suggests that while local residents may support ecotourism development based on international guidelines, their intentions to act will depend on local environmental, social, and politico-economic conditions. It is suggested that issues related to community empowerment, relationship between government and communities, value conflicts introduced by ecotourism development, and the dynamics among and between various community groups will need to be addressed if positive community intention to participate in ecotourism is to be encouraged.

Companies in the natural resources industry (e.g., mining, timber, farming and fishery) face the dilemma of whether to focus upstream or downstream in the value chain. The literature provides arguments and empirical evidence for either position. This paper presents an analytical framework based on the neoclassical theory of the firm, for which the best competitive advantage is the one that maximizes production efficiency. It serves to formulate an optimization model for the sawmill industry, and draws the data from the largest sawmilling company in the southern hemisphere. Although one conclusion is that the company should concentrate on the upstream activities, such conclusion is not applicable to other firms, since the analysis of the upstream-downstream dilemma must focus on the individual capabilities of each firm.

Urban sprawl refers to the extent of urbanisation, which is a global phenomenon mainly driven by population growth and large scale migration. In developing countries like India, where the population is over one billion, one-sixth of the world's population, urban sprawl is taking its toll on the natural resources at an alarming pace. Urban planners require information related to the rate of growth, pattern and extent of sprawl to provide basic amenities such as water, sanitation, electricity, etc. In the absence of such information, most of the sprawl areas lack basic infrastructure facilities. Pattern and extent of sprawl could be modelled with the help of spatial and temporal data. GIS and remote sensing data along with collateral data help in analysing the growth, pattern and extent of sprawl. With the spatial and temporal analyses along with modelling it was possible to identify the pattern of sprawl and subsequently predict the nature of future sprawl. This paper brings out the extent of sprawl taking place over a period of nearly three decades using GIS and Remote Sensing. The study also attempts to describe some of the landscape metrics required for quantifying sprawl. For understanding and modelling this dynamic phenomenon, prominent causative factors are considered.

Natural resource-dependent societies in developing countries are facing increased pressures linked to global climate change. While social-ecological systems evolve to accommodate variability, there is growing evidence that changes in drought, storm and flood extremes are increasing exposure of currently vulnerable populations. In many countries in Africa, these pressures are compounded by disruption to institutions and variability in livelihoods and income. The interactions of both rapid and slow onset livelihood disturbance contribute to enduring poverty and slow processes of rural livelihood renewal across a complex landscape. We explore cross-scale dynamics in coping and adaptation response, drawing on qualitative data from a case study in Mozambique. The research characterises the engagements across multiple institutional scales and the types of agents involved, providing insight into emergent conditions for adaptation to climate change in rural economies. The analysis explores local responses to climate shocks, food security and poverty reduction, through informal institutions, forms of livelihood diversification and collective land-use systems that allow reciprocity, flexibility and the ability to buffer shocks. However, the analysis shows that agricultural initiatives have helped to facilitate effective livelihood renewal, through the reorganisation of social institutions and opportunities for communication, innovation and micro-credit. Although there are challenges to mainstreaming adaptation at different scales, this research shows why it is critical to assess how policies can protect conditions for emergence of livelihood transformation.

The dual objective of sustainable aquaculture, i.e., to produce food while sustaining natural resources is achieved only when production systems with a minimum ecological impact are used. Recirculating aquaculture systems (RASs) provide opportunities to reduce water usage and to improve waste management and nutrient recycling. RAS makes intensive fish production compatible with environmental sustainability. This review aims to summarize the most recent developments within RAS that have contributed to the environmental sustainability of the European aquaculture sector. The review first shows the ongoing expansion of RAS production by species and country in Europe. Life cycle analysis showed that feed, fish production and waste and energy are the principal components explaining the ecological impact of RAS. Ongoing developments in RAS show two trends focusing on: (1) technical improvements within the recirculation loop and (2) recycling of nutrients through integrated farming. Both trends contributed to improvements in the environmental sustainability of RAS. Developments within the recirculation loop that are reviewed are the introduction of denitrification reactors, sludge thickening technologies and the use of ozone. New approached towards integrated systems include the incorporation of wetlands and algal controlled systems in RAS. Finally, the review identifies the key research priorities that will contribute to the future reduction of the ecological impact of RAS. Possible future breakthroughs in the fields of waste production and removal might further enhance the sustainabilty of fish production in RAS.

El desarrollo sustentable está referido a la administración eficiente y racional de nuestros recursos naturales, con el objetivo de mejorar el bienestar de la población actual sin comprometer la calidad de vida de las generaciones futuras. La protección del ambiente y el desarrollo humano sustentable van de la mano y es necesario ampliar las investigaciones sobre la utilización de métodos biológicos para la protección de los cultivos; debido a que estos son atacados por insectos y enfermedades que reducen significativamente la producción. A nivel mundial, se han contrarestado estos daños a través del uso de agroquímicos lo que ha traído como consecuencia la contaminación del medio ambiente y ha contribuido a aumentar los problemas de plagas y enfermedades, al desarrollo de resistencia y a la destrucción de enemigos naturales. Así mismo, el uso de los recursos del medio es sostenible cuando se realiza por debajo de su capacidad de renovación o sustitución, cuando lo trasladamos a la agricultura, describe sistemas de cultivo capaces de "mantener indefinidamente su productividad y utilidad para la sociedad. El objetivo de este trabajo es conocer la importancia del control biológico como un componente vital de la agricultura sustentable y sostenible que preserve los recursos naturales y el ambiente mediante la utilización de microorganismos seleccionados por su alta eficiencia e inocuidad.

The concept of sustainable development is focused on the improvement of the quality of life, avoiding the unbalanced utilisation of natural resources. Several concepts have recently been developed to evaluate the use of resources and the environmental management from an individual to a global scope. One of them, Life Cycle Assessment, has been considered for the environmental analysis of a product of consumption: beer. The results of this study show that whereas beer production itself has been found to be accountable for a small portion of the environmental performance of the life cycle of beer, production and the manufacture of the packaging elements as well as the harvesting and transport of cereals are responsible for the largest percentage. Consequently, improvements have to be made regarding these aspects to achieve more respectful behaviour towards the environment.

This paper discusses the impact of local and national policies in the Philippines on the participation of indigenous peoples in relation to fisheries management. Specifically, this research focuses on the Tagbanua, an indigenous group in Coron Island, Palawan, on the western side of the Philippines. The struggle of the Tagbanua in reclaiming their ancestral title to the land and sea reflects broader moves toward self-determination, which is critical not only to their ancestral lands and waters, but also to their survival. Indigenous rights are essential in addressing social justice and in giving a greater voice that encourages indigenous peoples towards self-governing institutions and common management of resources. Significantly, the fundamental development of indigenous peoples lies in the recognition of their rights in their ancestral domain and the preservation of their culture, tradition, system, practices and their natural resources. This paper examines the Tagbanua experience, through a critical exploration of institutions and property rights, with attention to corresponding effects in reducing conflict with other stakeholders in the area, and in affecting the sustainability of fishery resources.

Throughout the 1990s, many armed groups have relied on revenues from natural resources such as oil, timber, or gems to substitute for dwindling Cold War sponsorship. Resources not only financed, but in some cases motivated conflicts, and shaped strategies of power based on the commercialisation of armed conflict and the territorialisation of sovereignty around valuable resource areas and trading networks. As such, armed conflict in the post-Cold War period is increasingly characterised by a specific political ecology closely linked to the geography and political economy of natural resources. This paper examines theories of relationships between resources and armed conflicts and the historical processes in which they are embedded. It stresses the vulnerability resulting from resource dependence, rather than conventional notions of scarcity or abundance, the risks of violence linked to the conflictuality of natural resource political economies, and the opportunities for armed insurgents resulting from the lootability of resources. Violence is expressed in the subjugation of the rights of people to determine the use of their environment and the brutal patterns of resource extraction and predation. Beyond demonstrating the economic agendas of belligerents, an analysis of the linkages between natural resources and armed conflicts suggests that the criminal character of their inclusion in international primary commodity markets responds to an exclusionary form of globalisation; with major implications for the promotion of peace. 

Although the development of animal drawn tillage tools in the world has been on the agenda for thousands of years, there is still room for their improvement. The present study attempts to give an overview of previous works toward development of animal drawn tillage tools and to identify the areas having most potential for future improvement. The socio-economy, natural resource situation, historic perspective of animal traction in eastern and southern Africa and more specifically the ard plough history in Ethiopia are presented. The design, construction, performance and attempts done since 1939 for the improvement of the ard plough in Ethiopia are also presented. Moreover, trials towards the development of appropriate farm implements for Vertisols management, i.e. the broad bed maker (BBM) were also surveyed. From the review, it can be concluded that previous developments in animal traction tillage implements relied on cultural, trial and human experience. With the recent development in farm technologies and mathematical modelling techniques supported by computer-based simulations, new methodologies in research are available to improve animal traction tillage implements. When adopted, these methodologies could significantly assist in optimising the implement designs and operational conditions aiming at minimum draught requirement and best soil manipulation performance. #

This article contributes to understanding about the potential and limitations of social learning for collaborative natural resource management. Participants in a deliberative planning process involving a state agency and local communities developed common purpose and collaborative relationships, two requisites of comanagement. Eight process characteristics fostered social learning: open communication, diverse participation, unrestrained thinking, constructive conflict, democratic structure, multiple sources of knowledge, extended engagement, and facilitation. Social learning is necessary but not sufficient for collaborative management. Other requisites for comanagement, including capacity, appropriate processes, appropriate structures, and supportive policies, are necessary to sustain joint action.

Purpose -In the context of increased interest in the sustainability of food supply chains, this paper aims to assess perceptions of the relative importance of economic, social and environmental factors as they influence decision making by growers, merchants and retailers, using fresh potatoes in Britain as a case study. Design/methodology/approach -Following exploratory interviews with key informants, a two-staged survey of 240 potato growers, 17 potato merchants, and four retailers was carried out to assess perceptions of sustainability. Data analysis used a range of non-parametric statistical methods. Findings -Economic and related market factors associated with staying in business and maintaining competitive advantage were the dominant concern for all supply chain participants. Greater importance, however, is now given to social and environmental factors both as influences on decision making and as indicators of business performance. The social capital of the supply chain, as it describes relationships amongst participants, is an important moderator of business uncertainty. Environmental performance, measured in terms of the use of natural resources and the risk of pollution, is driven by a mix of compliance requirements and perceived market drivers.