Sustainability in Supply Chain Management: Aggregate Planning from Sustainability Perspective

Supply chain management that considers the flow of raw materials, products and information has become a focal issue in modern manufacturing and service systems. Supply chain management requires effective use of assets and information that has far reaching implications beyond satisfaction of customer demand, flow of goods, services or capital. Aggregate planning, a fundamental decision model in supply chain management, refers to the determination of production, inventory, capacity and labor usage levels in the medium term. Traditionally standard mathematical programming formulation is used to devise the aggregate plan so as to minimize the total cost of operations. However, this formulation is purely an economic model that does not include sustainability considerations. In this study, we revise the standard aggregate planning formulation to account for additional environmental and social criteria to incorporate triple bottom line consideration of sustainability. We show how these additional criteria can be appended to traditional cost accounting in order to address sustainability in aggregate planning. We analyze the revised models and interpret the results on a case study from real life that would be insightful for decision makers.     

Enabling Future Sustainability Transitions

This synthesis article presents an overview of an urban metabolism (UM) approach using mixed methods and multiple sources of data for Los Angeles, California. We examine electric energy use in buildings and greenhouse gas emissions from electricity, and calculate embedded infrastructure life cycle effects, water use and solid waste streams in an attempt to better understand the urban flows and sinks in the Los Angeles region (city and county). This quantification is being conducted to help policy‐makers better target energy conservation and efficiency programs, pinpoint best locations for distributed solar generation, and support the development of policies for greater environmental sustainability. It provides a framework to which many more UM flows can be added to create greater understanding of the study area's resource dependencies. Going forward, together with policy analysis, UM can help untangle the complex intertwined resource dependencies that cities must address as they attempt to increase their environmental sustainability.     

Sustainability in a nutshell

Sustainable exploitation is widely advocated as a strategy for reconciling economic pressures upon natural habitats with nature conservation. Two recent papers examine different aspects of the sustainability of the nut harvest on wild populations of Brazil nut trees Bertholletia excelsa in Amazonia. Peres et al. find that many populations of the Brazil nut tree lack juvenile trees and are not regenerating. In a socioeconomic study, Escobal and Aldana find that nut-gathering provides insufficient income on its own to support nut-gatherers and that their other income-raising activities damage the forest. The existence of a market for rainforest products is, therefore, not sufficient on its own to prevent habitat destruction or the overexploitation of the resource and a more sophisticated approach to sustainability is required. Development of a market in ethically traded Brazil nuts might be one solution.     

Life Cycle Sustainability Dashboard

One method to assess the sustainability performance of products is life cycle sustainability assessment (LCSA), which assesses product performance considering the environmental, economic, and social dimensions of the life cycle. The results of LCSA can be used to compare different products or to support decision making toward sustainable production and consumption. In both cases, LCSA results could be too disaggregated and consequently too difficult to understand and interpret by decision makers. As non‐experts are usually the target audience of experts and scientists, and are also involved in decision‐making processes, the necessity for a straightforward but comprehensive presentation of LCSA results is becoming strategically important. The implementation of the dashboard of sustainability proposed in this article offers a possible solution. An outstanding characteristic of the dashboard of sustainability is the communicability of the results by means of a graphical representation (a cartogram), characterized by a suitable chromatic scale and ranking score. The integration of LCSA and the dashboard of sustainability into a so‐called Life Cycle Sustainability Dashboard (LCSD) is described here. The first application of LCSD to a group of hard floor coverings is presented to show the applicability and limitations of the methodology.     

Assessing Sustainability of Nontimber Forest Product Extractions: How Fire Affects Sustainability

Sustainable use of nontimber forest products (NTFPs) can be affected by levels of extractions as well as by other anthropogenic influences such as fire and grazing. We examined the effects of fire on the demography of Phyllanthus emblica, an important NTFP in the forests of Biligiri Rangan Hills, India. We then assessed demographic responses to the combined effects of fire and current fruit harvesting patterns. Fruits of Phyllanthus are commercially harvested by an indigenous forest dwelling people. Using matrix population models, we compared demographic indices across a chronosequence of time since last fire. Population growth rates (λ) ranged from 0.7692 to 1.1443 across the five times since last fire. λ was the lowest at times since last fire of 2 and 3 yr. Frequent fires increased time to maturity by altering growth and survival rates, thereby causing a demographic shift from growth to regressions or negative growth. Elasticity analysis revealed that stasis of adults makes the biggest contribution to λ. Simulations of periodic and stochastic fire regimes suggest that higher λ and population persistence can be achieved at fire-return intervals of ≥7 and ≥9 yr, respectively. These fire-return intervals became longer when the simulations included harvesting and fire. Extinction probabilities under the current fire regimes (every 2–3 yr) suggest that populations will decline to lower densities. Our findings provide critical information for developing guidelines for sustainable use and management of NTFPs in Biligiri Rangan Hills, and demonstrate the need to incorporate various human-generated physical regimes in assessing sustainability of NTFPs.     

Sustainability indices with multiple objectives

One of the many debates about sustainability centers on how a natural resource stock (e.g. a forest) generates flows of desired human services (such as lumber and recreation). Should resources be sustained as they currently exist or should the services that they provide be sustained? This is a difficult question to address since there is very little quantitative information available. The purpose of this study was to address this question by using information from an empirical study that was able to look at sustainability when there is one output and extend that framework to a multiobjective setting. We then discuss the framework by using a multiobjective resource, the Neuse River in North Carolina.We identified several concepts from the single objective study, including that there are at least three important types of resource stocks, two types of goals, substitutes for natural resources, and a need to consider uncertainty and reversibility. An index of resource quality was used in a production model, which also allowed substitution of manufactured inputs to achieve the sustainability objective over long periods of time. The relationship between resource quality, manufactured inputs and output over time proved critical to meeting sustainability definitions and varied from one resource to another. When we expanded the framework, we found that constructing indices for one resource output might reveal that it is positively or negatively correlated to another output. For example, an index for drinking water might be made better through an indicator that is a positive, or negative, input into another index such as fishability.Sustainability should consider what is being sustained — i.e. stock, flow or something else, and be inclusive enough to account for multiple services, lest governments will under fund conservation (when services are positively correlated) or waste money by competing one objective against another (when they are negatively correlated) — addressing one objective through some policy requires more money in another government program to fix a problem that the first program caused. It should also be dynamic to allow for changes in relationships over time.     

Sustainability indices for exploited populations

Evaluating the sustainability of hunting is key to the conservation of species exploited for bushmeat. Researchers are often hampered by a lack of basic biological data, the usual response to which is to develop sustainability indices based on highly simplified population models. However, the standard indices in the bushmeat literature do not perform well under realistic conditions of uncertainty, bias in parameter estimation, and habitat loss. Another possible approach to estimating the sustainability of hunting under uncertainty is to use Bayesian statistics, but this is mathematically demanding. Red listing of threatened species has to be carried out in extremely data-poor situations: uncertainty has been incorporated into this process in a relatively simple and intuitive way using fuzzy numbers. The current methods for estimating sustainability of bushmeat hunting also do not incorporate spatial heterogeneity. No-take areas are one management tool that can address uncertainty in a spatially explicit way.     

Absolute versus Relative Environmental Sustainability

The cradle‐to‐cradle (C2C) concept has emerged as an alternative to the more established eco‐efficiency concept based on life cycle assessment (LCA). The two concepts differ fundamentally in that eco‐efficiency aims to reduce the negative environmental footprint of human activities while C2C attempts to increase the positive footprint. This article discusses the strengths and weaknesses of each concept and suggests how they may learn from each other. The eco‐efficiency concept involves no long‐term vision or strategy, the links between resource consumption and waste emissions are not well related to the sustainability state, and increases in eco‐efficiency may lead to increases in consumption levels and hence overall impact. The C2C concept's disregard for energy efficiency means that many current C2C products will likely not perform well in an LCA. Inherent drawbacks are restrictions on the development of new materials posed by the ambition of continuous loop recycling, the perception that human interactions with nature can benefit all parts of all ecosystems, and the hinted compatibility with continued economic growth. Practitioners of eco‐efficiency can benefit from the visions of C2C to avoid a narrow‐minded focus on the eco‐efficiency of products that are inherently unsustainable. Moreover, resource efficiency and positive environmental effects could be included more strongly in LCA. Practitioners of C2C on the other hand should recognize the value of LCA in addressing trade‐offs between resource conservation and energy use. Also, when designing a “healthy emission” it should be recognized that it will often have an adverse effect on parts of the exposed ecosystem.     

Sustainability of culture-driven population dynamics

We consider models of the interactions between human population dynamics and cultural evolution, asking whether they predict sustainable or unsustainable patterns of growth. Phenomenological models predict either unsustainable population growth or stabilization in the near future. The latter prediction, however, is based on extrapolation of current demographic trends and does not take into account causal processes of demographic and cultural dynamics. Most existing causal models assume (or derive from simplified models of the economy) a positive feedback between cultural evolution and demographic growth, and predict unlimited growth in both culture and population. We augment these models taking into account that: (1) cultural transmission is not perfect, i.e., culture can be lost; (2) culture does not always promote population growth. We show that taking these factors into account can cause radically different model behavior, such as population extinction rather than stability, and extinction rather than growth. We conclude that all models agree that a population capable of maintaining a large amount of culture, including a powerful technology, runs a high risk of being unsustainable. We suggest that future work must address more explicitly both the dynamics of resource consumption and the cultural evolution of beliefs implicated in reproductive behavior (e.g., ideas about the preferred family size) and in resource use (e.g., environmentalist stances).     

Sustainability in single-species population models

In this paper, we review the concept of sustainability with regard to a single-species, age-structured fish population with density dependence at some stage of its life history. We trace the development of the view of sustainability through four periods.The classical view of sustainability, prevalent in the 1970s and earlier, developed from deterministic production models, in which equilibrium abundance or biomass is derived as a function of fishing mortality. When there is no fishing mortality, the population equilibrates about its carrying capacity. We show that carrying capacity is the result of reproductive and mortality processes and is not a fixed constant unless these processes are constant. There is usually a fishing mortality, F(MSY), which results in MSY, and a higher value, F(ext), for which the population is eventually driven to extinction. For each F between 0 and F(ext), there is a corresponding sustainable population. From this viewpoint, the primary tool for achieving sustainability is the control of fishing mortality.The neoclassical view of sustainability, developed in the 1980s, involved population models with depensation and stochasticity. This view point is in accord with the perception that a population at a low level is susceptible to collapse or to a lack of rebuilding regardless of fishing. Sustainability occurs in a more restricted range from that in the classical view and includes an abundance threshold. A variety of studies has suggested that fishing mortality should not let a population drop below a threshold at 10-20% of carrying capacity.The modern view of sustainability in the 1990s moves further in the direction of precaution. The fishing mortality limit is the former target of F(MSY) (or some proxy), and the target fishing mortality is set lower. This viewpoint further reduces the range of permissible fishing mortalities and resultant desired population sizes. The objective has shifted from optimizing long-term catch to preserving spawning biomass and egg production for the future. The use of discount rates in objective functions involving catch is not a suitable alternative to protecting reproductive value.As we move into the post-modern time period, new definitions of sustainability will attempt to incorporate he economic and social aspects of fisheries and/or ecosystem and habitat requirements. These definitions now involve "warm and fuzzy" notions (healthy ecosystems and fishing communities, the needs of future generations, diverse fish communities) and value judgements of desired outcomes. Additional work is needed to make these definitions operational and to specify quantitative objectives to be achieved. In addition, multiple objectives may be incompatible, so trade-offs in what constitutes sustainability must be made. The advances made under the single-species approach should not be abandoned in the post-modern era, but rather enhanced and combined with new approaches in the multi-species and economic realms.     

农业生态系统的持续性及其评价指标

持续发展已成为当今全球关注的热点 ,从学术界、企业界、经济界及政府报告中 ,都在讨论与强调持续发展问题 ,持续发展已得到社会各界的共识。农业生态系统具有四大特性[3] 。一是生产力 ;二是稳定性 ;三是持续性 ;四是公平性。作为四大特性之一的持续性 ,越来越受到农业生态学界的重视。但是关于持续性的定义及评价指标 ,到目前为止还没有一个统一的、公认的定义 ,因此 ,有关持续性的定义及评价指标是近来学术界经常探讨的问题 ,发表了不少有关该问题的学术论文。1　持续性的定义由于环境的退化 ,不可再生资源的浪费 ,可再生资源的过度开发…