Keywords:

2

Emmental cheese ripening is based on different combinations of time and temperature, according to manufacturer's practices.

In France, the legal ripening time of Emmental cheese is a minimum of 6 weeks. But, it can be extended to months, like for example Emmental PDO cheese from Switzerland. → 76% of the production of cow milk hard-cooked cheeses → 37% of the total production of cheeses Consumption: 4 kg of Emmental cheese/person/year CONTEXT Emmental cheese ripening Ripening for 2-3 weeks at 10-14°C Ripening at 20-25°C (warm room) Long storage at 2-4°C (cold room) Cold adaptation of the cheese ripening bacterium Propionibacterium freudenreichii

Cultures in triplicate

The medium had a composition in complex nitrogen sources and carbon (lactate) close to Swiss cheese aqueous phase

RESULTS: Cell adaptation and survival in the cold

Cell wall

Cytosol

Ribosome

Protein

Outer medium

These results were also confirmed by proteomic data

  synthesis: down-regulation of genes coding for ribosomal proteins Outer medium RESULTS: General slowing down of cell machinery Cold adaptation of the cheese ripening bacterium Propionibacterium freudenreichii Drmetabolism: downregulation of genes coding for the electron transport chain and ATP synthases

ACKNOWLEDGMENTS

INRA-AGROCAMPUS OUEST (Rennes, France) FIL-IDF France

RESULTS: Production of aroma compounds

The production of methylbutanoic acids decreased by a factor of only 3 at 4°C


Keywords: Economic valuation, Ecosystem services, Payments for ecosystem services, Cost-benefit analysis, Ecological complexity

Current issues in ecosystem services valuation (ESV)

Introduction

While numerous approaches to valuation exist, economic valuation is focused on allocating scarce resources based on people preferences. Economic value of the environment at large is poorly, or not at all, expressed in the marketplace. Hence valuation techniques have been developed to make visible what is presumably not, with the purpose to inform public decision making. Scientific interest in valuing what was not yet named "ecosystem services" emerged in the late 1960's both as a concern for ecologists [START_REF] King | Wildlife and man[END_REF][START_REF] Helliwell | Valuation of wildlife resources[END_REF] and as a theoretical challenge for economists [START_REF] Krutilla | Conservation reconsidered[END_REF]. Soon thereafter interest was confirmed more broadly in the profession [START_REF] Westman | How much are nature's services worth[END_REF][START_REF] Ehrlich | Extinction: the causes and consequences of the disappearance of species[END_REF][START_REF] Ehrlich | Extinction, Substitution, and Ecosystem Services[END_REF] and several points were clarified (see [START_REF] Mooney | Ecosystem services: A fragmentary history[END_REF], [START_REF]Biodiversity and Ecosystem Functioning: Synthesis and Perspectives[END_REF], [START_REF] Gomez-Baggethun | The history of ecosystem services in economic theory and practice: from early notions to markets and payment schemes[END_REF] for detailed analysis). It is commonly admitted that, aside the seminal book edited by G.C.

Daily [START_REF] Daily | Nature's Services: Societal Dependence on Natural Ecosystems[END_REF], the publication in Nature of a tentative worldwide synthesis of the value of ecosystems services and natural capital by Costanza et al. [START_REF] Costanza | The value of the world's ecosystem services and natural capital[END_REF] acted as a launching declaration for the on-going ecosystem valuation research programme. This paper was so provocative that a few months later, Ecological Economics published a special section "Forum on the valuation of ecosystem services", offering room to thirteen papers that covered "a range of perspectives, from those who basically agree that this work is important but raise other important issues, to those who question the wisdom of the exercise of valuing ecosystem services itself, to those who question the validity of the methods used" [START_REF] Costanza | The value of ecosystem services: putting the issues in perspective[END_REF]. Some critics of [START_REF] Costanza | The value of the world's ecosystem services and natural capital[END_REF] have been particularly severe [START_REF] Norgaard | Next, the value of God, and other reactions[END_REF], not only about the utilitarian philosophy underlying economic evaluation, or about methods but, more fundamentally, because of the risk that science is manipulated to attract media attention.

Fifteen years later, this programme is flourishing yet many questions remain unanswered. Fisher et al. [START_REF] Fisher | Defining and classifying ecosystem services for decision making[END_REF] identified more than 1000 papers related to ESV since a clear definition of the concept was given [START_REF] Ehrlich | Extinction, Substitution, and Ecosystem Services[END_REF]. In a recent survey of influential articles in environmental and ecological economics in the 21 st century [START_REF] Hoepner | Environmental and ecological economics in the 21st century: An age adjusted citation analysis of the influential articles, journals, authors and institutions[END_REF], a ranking -unavoidably questionable -placed seven papers related to ecosystem services in the top ten papers (but only twelve among the top fifty, and seven in the following fifty).

Whereas the survey covers the 2000-2009 period, most "influential papers" related to ecosystem services have been published since 2007, as if the lessons from the Millennium Ecosystem Assessment [START_REF]Millennium Ecosystem Assessment. Ecosystems and Human Well-being: A Framework for Assessment[END_REF][START_REF]Millennium Ecosystem Assessment. Ecosystems and Human Wellbeing: Synthesis[END_REF] had needed some time for maturation and assimilation by the valuation scientific community. This literature review aims to present some of the issues that frame the scientific debate. The choice of problems to be reviewed is based on: i) the selection previously made for a French report on an economic approach to biodiversity and ecosystem services for public decision-making [START_REF] Chevassus-Au-Louis | Approche économique de la biodiversité et des services liés aux écosystèmes[END_REF], especially the sixth chapter that, building on interdisciplinary knowledge presented in previous chapters, suggests research priorities, ii) the TEEB "Foundations" report [START_REF] Kumar | The economics of ecosystems and biodiversity: ecologic and economic foundations, An output of TEEB[END_REF], specifically chapter 5 [START_REF] Pascual | The economics of valuing ecosystem services and biodiversity[END_REF] and the requirement of "best practices" for the evaluation, ii) and finally our arbitrary and, no doubt, our ignorance. Clearly, we have excluded important issues, for reasons that we may sometimes explain but remain more or less arbitrary anyway. Two examples: 1) we do not expose the discussion of methods of evaluation, because mostly they are not specific to the topic and ecosystem services and because the reader can find excellent reviews elsewhere (see for instance [START_REF] Pascual | The economics of valuing ecosystem services and biodiversity[END_REF]) , 2) the issue of false or distorted perception that agents may have about the impact of ecosystem services is undoubtedly very important, but we also set it aside because it seems that no robust and consensual knowledge has emerged yet . We will successively discuss the following six issues: 1) the inherent complexity of ESV, 2) its links with payment mechanisms, 3) the challenge of a meaningful and operational classification of ecosystems services, 4) the link between economic valuation and values, 5) the incommensurability debate and 6) the limits of cost benefit analyses when applied to ecosystem valuation. Then we will give a few examples of valuations of particular ecosystem services before turning to the conclusion.

The complexity of the ecosystem services concept

Ecosystem services are defined as the benefits human populations derive, directly or indirectly, from ecosystem functions [START_REF] Costanza | The value of the world's ecosystem services and natural capital[END_REF] or ''the benefits people obtain from ecosystems'' [START_REF]Millennium Ecosystem Assessment. Ecosystems and Human Wellbeing: Synthesis[END_REF]. R. Costanza [START_REF] Costanza | Ecosystem services: Multiple classification systems are needed[END_REF] considers that "this is a good, appropriately broad and appropriately vague definition" that allows people to communicate or, at least, to have the feeling to understand each other when analyzing the way our societies take advantages from well-functioning ecosystems. Working with not yet quite a clear definition can be a limit for developing formal analysis, but it can be useful to let a variety of research develop, especially of controversial issues such as the actual dependence of human wellbeing on these services or their potential substitutability, and identifying what is really at stake in decisions and policies. However, such a defense is problematic. For instance, it has been shown, e.g. for semi-natural grasslands [START_REF] Lamarque | The diversity of the ecosystem services concept and its implications for their assessment and management[END_REF], that this vagueness and some lexical ambiguity could lead to very different assessments of quality, quantity and location of ecosystem services. This objection can be elaborated further with related arguments. The concept of ecosystem services has garnered widespread appeal partly because it has been interpreted in terms of economic production and how human wellbeing depends on services provided by human actions and organisations. From an economic perspective, considering the functioning of ecosystems in the same way as the activity of economic agents was rather a comfortable and useful representation that helped integrating this supply in standard valuation analysis. But the analysis of ES has to cope with the evidence that, on the contrary to activities of firms, the services provided by ecosystem are unintentional [START_REF] Salles | Valuing biodiversity and ecosystem services: Why put economic values on Nature?[END_REF]. Instead of direct or indirect voluntary contributions of ecosystems to human well-being [24], it would be more appropriate to consider them as what human societies are obtaining or taking from ecosystems. And despite the statement of a potential for "capturing the value of ecosystem services" in real markets [START_REF] Heal | Nature and the Marketplace -Capturing the Value of Ecosystem Services[END_REF], most ES are commons, and the values of nature are not thoroughly visible in the functioning of advanced market economies [START_REF] Mccauley | Selling out on nature[END_REF]. In fact, it has been argued that ecosystem diversity may not always be a source of benefits and can constitute a dis-service. This possibility has been studied in the case of agricultural production [START_REF] Zhang | Ecosystem services and dis-services to agriculture[END_REF] and, to a lesser extent, wetlands restoration [START_REF] Holmquist Westerberg | To restore or not? A valuation of social and ecological functions of the Marais des Baux wetland in Southern France[END_REF].

More generally, several works have shown that focusing on services could result in not guaranteeing sufficient interest to the complexity of ecosystems [29, [START_REF] Ghazoul | Recognizing the complexities of ecosystem management and the ecosystem service concept[END_REF][START_REF] Jones-Walters | Valuing nature: The economics of biodiversity[END_REF] and the incomplete knowledge we have on their functioning and interdependence [32,[START_REF] Carpenter | Science for Managing Ecosystem Services: Beyond the Millennium Ecosystem Assessment[END_REF][START_REF] Peterson | Obscuring ecosystem function with application of the ecosystem services concept[END_REF]. Also, since biodiversity does not necessarily identify with ecosystem services, it must be understood that enhancing human welfare and preserving biodiversity may be conflicting objectives [START_REF] Groot | Integrating the ecological and economic dimensions in biodiversity and ecosystem service valuation[END_REF][START_REF] Maltby | Functional assessment of wetlands. Towards evaluation of ecosystem services[END_REF][START_REF] Haines-Young | The links between biodiversity, ecosystem services and human well-being[END_REF]. Should we prioritize welfare over any other social goals? Many analysts have emphasized the large variety of reasons to protect nature [START_REF] Balmford | Economic reasons for conserving wild nature[END_REF]. Clearly, the concept of ecosystem services plays an integrative role in many papers in ecological economics and conservation sciences. But, despite evidence of the positive aspect of species richness on primary biological production [START_REF] Costanza | Biodiversity and ecosystem services: A multi-scale empirical study of the relationship between species richness and net primary production[END_REF], a larger provision of service is not necessarily associated with a wider diversity or a deeper wilderness of ecosystems, especially for provisioning services and cultural services related to recreation and tourism [START_REF] Braat | The Cost of Policy Inaction (COPI) -The Case of not Meeting the 2010 Biodiversity Target[END_REF]. The extent to which we can rely solely on these services to value biodiversity remains questioned [41, 42, 43, 44, 45, and 46]. So, are we so focused on the concept of ES that we can't see the forest for the trees? The lesson that can be drawn is certainly that ecosystem services and biodiversity are different things, thought interacting, that can be jointly preserved by appropriate human actions [START_REF] Benayas | Enhancement of Biodiversity and Ecosystem Services by Ecological Restoration: A Meta-Analysis[END_REF][START_REF] Bullock | Restoration of ecosystem services and biodiversity: conflicts and opportunities[END_REF]. Therefore they must be thought in terms of arbitrage, trade-off and "hard choices" [START_REF] Mcshane | Hard choices: Making tradeoffs between biodiversity conservation and human well-being[END_REF], i.e. decision-making regarding ecosystem services is to some extent amenable to economic analysis.

Are payment mechanisms the sole purpose of the valuation of ecosystem services?

PES are often vaguely defined as monetary incentives offered to farmers or landowners in exchange for managing their land to provide some ecological service. There is evidence that, after empirical beginnings, related to various policy and institutional contexts, PES have become a generic term to describe a heterogeneous set of incentives to manage ecosystems [50, 51, 52, 53, 54, and 55].

PES are definitely a relevant framework for thinking the main issues related to ecosystem conservation and management and a large body of literature has been devoted to two of them : how the practical efficiency of these mechanisms relies on appropriate institutional arrangements; how PES can contribute to development and poverty alleviation. Actually, two opposing views are advocated between analysts that study primarily contracting and informational issues [START_REF] Depres | Contracting for environmental property rights: The case of Vittel[END_REF][START_REF] Ferraro | Asymmetric information and contract design for payments for environmental services[END_REF][START_REF] Ferraro | Asymmetric information and contract design for payments for environmental services[END_REF] and those who consider larger institutional issues and suggest alternatives analysis of what is really at stake in the implementation of PES, especially equity and poverty reduction [59, 60, 61, 62, 63, and 64], institutional or property rights issues [START_REF] Pascual | Exploring the links between equity and efficiency in payments for environmental services: a conceptual approach[END_REF][START_REF] Sommerville | The role of fairness and benefit distribution in community-based Payment for Environmental Services interventions: A case study from Menabe, Madagascar[END_REF][START_REF] Engel | Payments for environmental services as an alternative to logging under weak property rights: The case of Indonesia[END_REF], and sometimes more fundamental critics [68, 69, 70, and 71].

Finally, the relation between valuation and PES is not obvious. In a recent analysis of the history of ecosystem services in economic theory and practice [START_REF] Gomez-Baggethun | The history of ecosystem services in economic theory and practice: from early notions to markets and payment schemes[END_REF], the payments for ecosystem services (PES) appear as the natural aim of economic valuation, as mechanisms that would translate non market values for the environment into real financial incentives for local agents. But, as Heal [START_REF] Heal | Valuing ecosystem services[END_REF] puts it: "valuation is neither necessary nor sufficient for conservation. We conserve much that we do not value, and do not conserve much that we value". The devil is in the details: valuation is not necessary to establish incentives in a cost-efficiency perspective (to reach a given objective at the least cost); it would be useful to define the appropriate incentive to reach an optimal level of conservation. But this level is usually not considered as being practically knowable nor reachable, and the PES are calibrated on the base of the opportunity costs borne by the agents that hold control on the service and are to be compensated for their effort [START_REF] Engel | Designing payments for environmental services in theory and practice: An overview of the issues[END_REF][START_REF] Kumar | Payment for ecosystem services[END_REF]. The main evaluation issue associated with PES and related to institutional arrangements is eventually the need and opportunity of a systematic assessment of their scope, limitations, and practical effects [START_REF] Daily | Ecosystem services: From theory to implementation[END_REF][START_REF] Kinzig | Paying for Ecosystem Services. Promise and Peril[END_REF].

The classification of ecosystem services unfinished business?

Unlike the classification of firm activities which has been built for statistical purpose related to national accounts, there exists no comprehensive taxonomy of the services delivered by Nature.

Several tentative typologies have provided more or less comprehensive canvas [11, 14, 17, 21, 35, 75, 76, 77, 78, and 79]. For instance the MA initiative distinguishes four core kinds of ecosystem services: provisioning, supporting, regulating, cultural. Table 1 below gives more details about this classification and a few existing others that aimed at: i) integrating ecosystems in national accounts, and ii) improving cost-benefit analysis for decision-making.

The idea to integrate environmental aspects into national accounts emerged in the 1970's as a central issue. The presentation of the economic value of ecosystem services and natural capital in an input/output (ecosystems/services) table [START_REF] Costanza | The value of the world's ecosystem services and natural capital[END_REF] follows a comparable rationale to the formalization of national accounts. Reference to national accounts or GDP is explicit in several papers that suggest disentangling the imprecise idea of ecosystem services as an economically rooted concept of "final ecosystem service units" [START_REF] Boyd | What are ecosystem services? The need for standardized environmental accounting units[END_REF] but recognize the practical difficulty not to mix means (the processes underlying the services) and ends (the services themselves) within the classification categories [START_REF] Kinzig | Paying for Ecosystem Services. Promise and Peril[END_REF]. A distinction would nevertheless be useful between intermediate services, final services and benefits in order to operationalize tradeoffs in natural resource management [START_REF] Fisher | Ecosystem services: Classification for valuation[END_REF].

A central motive for including ecosystem services into national accounts is to build a systematic monitoring of their contribution to the wealth of nations which allows comparability with the definition of conventional goods and services found in GDP and the other national accounts. An appropriate monitoring would imply not only to measure total values (as it is usually the case with contingent valuation of non-markets goods and services), but to follow quantities and prices separately in order to "track the evolution of ES, compute indices of them, and enter them into National Income accounts, all of which are important goals" [START_REF] Heal | Environmental accounting for ecosystems[END_REF].

The importance of ecosystem services and natural capital of soils, though more and more recognized, remains poorly understood and informed [START_REF] Turner | The ecosystem services framework and natural capital conservation[END_REF]. A recent study [START_REF] Dominati | A framework for classifying and quantifying the natural capital and ecosystem services of soils[END_REF] mobilizes recent scientific knowledge on soil formation, functioning and classification, and current thinking on ecosystem services to develop a framework to classify and quantify soil natural capital and ecosystem services, including cultural services, and identify human needs fulfilled by soil ecosystem services.

As a matter of fact, the System of Environmental and Economic Accounting (SEEA) is to be revised in 2012 in order to allow to better taking into account ecosystems and their diversity. Aside of the Central Framework completed in 2011 and adopted by the United Nations Statistical Commission in 2012, as the first international standard for environmental-economic accounting, an additional Experimental Ecosystem Accounts is expected to be completed before the 44th Session of the Statistical Commission in February 2013. But the concern for resilience remains unsolved: "while the SEEA is an important advance in national accounting it remains deficient in a number of ways in regard to natural resources. The dynamic and interactive nature of ecosystems means that any linear, compartmentalized system of accounting will miss significant changes that influence human wellbeing. In particular, losses in resilience of critical capital stocks (through changes in underlying ecosystem variables that do not contribute directly to valued flows, and are therefore not included in the accounts) means that the accounts will not recognize that such stocks are becoming riskier, likely to collapse, and are therefore over-valued" [START_REF] Walker | A resilience perspective of the SEEA[END_REF].

Integrating ecosystem services in decision-making also faces informational issues [START_REF] Bingham | Issues in ecosystem valuation: improving information for decision making[END_REF][START_REF]Valuing ecosystem services: toward better environmental decision making[END_REF][START_REF] Daily | Natural capital: Theory and practice of mapping ecosystem services[END_REF]. There is of course the hurdle of clarifying ambiguities in the definitions of key terms, such as ecosystem processes, functions and services [START_REF] Johnston | An operational structure for clarity in ecosystem service values[END_REF]. However, those informational issues also raise somewhat distinct challenges, since the valuation must be explicitly related to the impact of the decision as described in appropriate scenarios and the list and hierarchy of the values at stake must be related to the context [START_REF] Toman | Why not to calculate the value of the World's ecosystem services and natural capital[END_REF]. Making the concept of ecosystem services useful for conservation policy requires clear definition and placement into a framework so that it is usable for the societal decision-making [START_REF] Wallace | Classification of ecosystem services: Problems and solutions[END_REF]. attempt to impose unrealistic order and consistency" [START_REF] Costanza | Ecosystem services: Multiple classification systems are needed[END_REF]. The conclusion is unavoidable: multiple classification systems are needed, according to the variety of situations and the diversity of decisionmaking perspectives. "There are many contexts in which ecosystem services can be used and the context should help to determine which classification scheme is the most appropriate for decision making." [START_REF] Fisher | Defining and classifying ecosystem services for decision making[END_REF].

It would understandably be more appealing to build an integrated view of ES typologies and values that make both a bridge between natural capital and the diversity of the decision contexts and with national accounts, but despite undeniable progress, scientific understanding remains a limiting factor [START_REF] Carpenter | Science for Managing Ecosystem Services: Beyond the Millennium Ecosystem Assessment[END_REF][START_REF] Daily | Ecosystem services: From theory to implementation[END_REF][START_REF] Kremen | Managing ecosystem services: What do we need to know about their ecology?[END_REF][START_REF] Daily | Ecosystem services in decision-making: time to deliver[END_REF] and the possibility to use the category of ecosystem service to improve resource management decision in practice is still questioned [START_REF] Wainger | Can the concept of ecosystem services be practically applied to improve natural resource management decisions?[END_REF].

Quantification and valuation

"What are birds worth-what is their actual dollar value to human society? To most of us in the ornithological community, birds are invaluable. But in these times we need more specific rationales to convince policy makers and business leaders to include bird conservation in land-use and development decisions." [START_REF] Wenny | The need to quantify ecosystem services provided by birds The[END_REF] This recent statement expresses, among many others, the perception by experts from various fields of conservation science of the usefulness of quantifying and valuing ES.

Quantification and valuation are directly related since values allow the aggregation, in a broad sense, of services of heterogeneous nature. But, beyond this technical aspect, valuation raises many issues that have been clearly addressed by leading authors in the field [START_REF] Costanza | Introduction to the special issue on the dynamics and value of ecosystem services: integrating economic and ecological perspectives[END_REF]:

"Economic, or monetary, measures of value are only one type of measure that can be useful in managing human activities. But they are particularly useful because most societies have some intuitive notion of economic value, and the sources of human impacts on natural systems are frequently economic, such as the construction of a dam or harvesting timber. They are also especially useful insofar as they can be used to provide signals to regulate human activity, as in the case of environmental taxes and adjustments to national income accounts. However, like any signal in complex systems, they can also provide false or misleading information".

Since a large majority of ES lack market prices [START_REF] Heal | Valuing ecosystem services[END_REF][START_REF] Daily | The value of nature and the nature of value[END_REF][START_REF] Naidoo | Mapping the economic costs and benefits of conservation[END_REF], valuations are ad hoc, motivated by policy purposes which must be explicit about whose value has to be accounted for [START_REF] Opschoor | The value of ecosystem services: whose values?[END_REF]. Economic values, though numerous, diverse and sometimes complex [START_REF] Balmford | Economic reasons for conserving wild nature[END_REF], obviously do not cover all the reasons that may justify social choices and actions [START_REF] Turner | Valuing nature: lessons learned and future research directions[END_REF].

The Millennium Ecosystem Assessment [START_REF]Millennium Ecosystem Assessment. Ecosystems and Human Well-being: A Framework for Assessment[END_REF] provided a simple general framework for ESV which, starting from the identification of ecosystems structures and functions, switches to the characterization of ES and results in their evaluation in terms of human well-being. This scheme has recently been clarified [START_REF] Haines-Young | The links between biodiversity, ecosystem services and human well-being[END_REF]24] by distinguishing between "services" that describe what human societies can obtain from ecosystems in biophysical terms, "benefits", defined as positive change in well-being from the fulfillment of needs and wants, and "values" which are related to the goals and objectives of the societies (at least as they are perceived by the analyst who must also pay attention to possible substitutes that may allow the society to reach this objective).

The debate on incommensurability

Different assets are said commensurable if it is possible to align them on a common cardinal scale of value. Should the values of any asset or choice to which humans attach importance be made commensurable? This question is in fact at the root of the opposition between environmental economics and ecological economics [START_REF] Martinez-Alier | Weak comparability of values as a foundation for ecological economics[END_REF][START_REF] Patterson | Commensuration and theories of value in ecological economics[END_REF]; it is also the cornerstone between strong and weak conceptions of sustainability [100, 101]. When applied to the value of ecosystems, the idea is that their contribution to human well-being is multidimensional, related both to satisfaction of short view preferences and to the cognitive and emotional traits of human life Is monetary valuation a problem by itself? The use of money as unit is perceived, namely by ecologists [106] as puzzling, since real markets are not always very convincing of their ability to converge toward efficient equilibriums. As noted by several authors, the numeraire matters in economic analysis: since money is the most commonly used interchangeable commodity, valuation in monetary terms may send the message that a service is more easily substitutable by human manufactured providers than it actually is [100, 107]. The final words might be given by the ironic statement that monetary valuation would be "precisely incorrect" [108].

The limits of CBA when applied to ES

Cost-benefit analysis (CBA) is the general framework for the economic valuation of ES. It consists of comparing alternative policy options, including laisser-faire, by quantifying their impact on ecosystem services in monetary units. The net present value (NPV) resulting from the difference between positive and negative impacts (benefits and costs) of each option allows to rank them according to their contribution to social well-being [START_REF] Patterson | Commensuration and theories of value in ecological economics[END_REF]. If the goal of maximizing well-being is considered unreachable because the informational basis on preferences is too hard to elicit or the decision maker is unable to take into account the full range of services and their values, the analysis can focus on the cost-efficiency goal of maintaining the ecological potential [109] or any other objective such as the "no net losses" of the UN Decade on Biodiversity.

The definition of ES includes the benefits people perceive, and many that they do not. The conventional economic approach to ''benefits'' appears too restrictive, in this regard, since it tends to limit the benefits to those that people perceive and are ''willing to pay'' for. Since people's information about ecosystem services is rather limited, it can be expected that many ecosystem services will only be noticed by most when they are destroyed or degraded. The contrast here is to be made with private goods and services provided on the marketplace. We benefit from consuming those items and we are fully aware of the utility they bring to us, .even when they have not disappeared.

In recent decades, several approaches have been proposed to measure empirically the values of ES, based either on revealed or stated preferences, or on observable costs for restoration, replacement, and supply of the service or through productivity effects. The chapter 5 of the "Foundations" book of TEEB study offers an outstanding review of the existing literature published or in press up to 2009 [START_REF] Pascual | The economics of valuing ecosystem services and biodiversity[END_REF]. The key messages insist on: the importance of uncertainty about ecosystems functioning and the double value of ecosystems as output providers and as insurance mechanisms (whose importance in captured in option values when they can be estimated); the limits of methods and the interest on hybridizing methods (e.g. stated preference and deliberative approaches); the influence of social, cultural and economic contexts; the practical, swift and cheap potential of benefit transfers;

the importance of being realistic and honest with the limitations of valuation techniques; considering the possibility of irreversible and heavy costly changes when approaching thresholds, ecosystem management should be based on "safe-minimum-standards" and "precautionary approaches".

The year after the publication of the TEEB "foundations" book [START_REF] Pascual | The economics of valuing ecosystem services and biodiversity[END_REF], one of the lead authors published with a colleague [110] a multidisciplinary critique of the use of CBA in the context of ecosystem services. They particularly stress the difficulties raised by the articulation and aggregation of individual well-beings into a measure of social well-being related by welfare economics and alternative theories of value when applied to ES; the bias that spatial and temporal frame can introduce in valuation; and explain the persistence of CBA "despite its own predicament" with four rationales: expediency, democracy, value neutrality, and the inescapability of trade-offs. They pragmatically conclude on the coming pluralistic framework for ecosystem services decision making.

Temporal inconsistency, that is to say the fact that a chronicle of decisions may not remain optimal once reconsidered at a later date, is a complex issue on its own [111]. One important feature was the emphasis put, in the context of climate change, on the dynamics of relative prices as a pragmatic but sounded solution to the apparent paradox of discounting [112]: when some asset becomes endangered on a large scale one must anticipate that its price, or implicit price if there is no market for it, will increase dramatically and overcome any reasonable discount rate.

Time to deliver: some examples of ESV

Applied (and less applied) economists involved in ESV have recently attempted building analytical frameworks that overcome several critics [START_REF] Kumar | The economics of ecosystems and biodiversity: ecologic and economic foundations, An output of TEEB[END_REF]. They insist on the necessity of ESV to serve an explicit purpose (CBA, Accounting, Payment, Evaluation of action/inaction, etc.), which is not to demonstrate the importance of ES or biodiversity to society but to help decision makers facing tradeoffs, choices between competing resources and conflicting goals. ESV has to be context specific, ecosystem specific, and guided by the perception of beneficiaries. The spatial and temporal scale must be defined and clear linkages with biophysical change scenario would not only facilitate the valuation exercise but will improve its credibility for public policies. Since uncertainty is a real issue that can undermine the credibility of the results, sensitivity analysis would be appreciated by the decision makers.

In

Conclusion/Summary

In a posthumous published paper, David Pearce wondered "Do we really care about biodiversity?"

[146], and responded dubiously. In a policy oriented paper related to the objectives to be reached during the 2011-2020 Decade on Biodiversity [147], four research directions were prioritized:

Functional diversity; Environmental uncertainty and target adjustment; Interactions between targets;

Trade-offs between targets. Ecosystem services valuation does not appear at that level of generality, but the ideas of a better understanding of the hierarchies, the uncertainties and the trade-offs are at the core of this roadmap, and valuation is implicitly the intellectual framework that underlies these issues.

The two objectives of the quantification and valuation of ecosystem services are not independent.

The construction of aggregate accounts, for example at the national level, likely requires of a mapping of ecosystems and their conservation state. Specialists, while stressing the importance of accounting in physical terms, are aimed at moving to monetary values so as to link them with the national accounts. On the other hand, the integration of ecosystems and biodiversity in the economic analysis of choices or policy instruments does really matter for choice with a strong spatial dimension (development of transport infrastructure, urban expansion, agricultural policies, etc.).

The central issue in the valuation of biodiversity and ecosystem services certainly lies in the fact that, to a large extent, these services are merit goods or credence goods whose utility for growing fractions of the population, and especially urban population, does not result from direct conscious experience but from mediatized information relayed by various more or less truthful means. Since it is considered that significant parts of their total economic value are non-use values, their elicitation has to rely on stated preferences methods. And the general opinion of a lack of reliability of these methods has led scholars to seek to improve the robustness of the results by combining these techniques with deliberative approaches [148, 149, 150, 151, 152, and 153] to enable the construction of rational preferences among respondents.

The last word has to open on a rather stringent question: is ecosystem service valuation really useful? Twelve years ago Geoffrey Heal [START_REF] Heal | Valuing ecosystem services[END_REF] wrote: "Valuation is neither necessary nor sufficient for conservation. We conserve much that we do not value, and do not conserve much that we value."

Valuing ecosystem services and biodiversity is in no way an end by itself, but a means to improve the choices our societies and the public bodies that design and implement conservation policies make to frame our relation to nature. In recent decades many analysts, conservationists and economists, have stated that valuation was a way to enlighten the importance of well-functioning ecosystem for our societies [16, 24, and 154]. In the economists' view, ecosystem services would then be considered as "Veblen goods", i.e. goods for which individual demands increase when the prices increase, since higher price (whereas there are in most case no "market price" for ecosystem services) confers higher status. But other analysts argue instead that linking economic values to ecosystems might be interpreted as an encouragement to drop deontological principles or "moral sentiments" [155] in choices that involve their conservation, resulting in lesser precautionary attitudes (this is the so-called crowding-out effect). Whatever views prevail in the coming decades, the valuation of ecosystem services will likely remain a central tool for clarifying choices involving ecosystems; and it seems likely that an increasing number of hard decisions will have to be made and more importantly concrete choices to be implemented. Any tool that will help to clarify the issues and legitimize the choices will be useful and have to be upgraded.

  [102], to physiological and mental health, or even to what constitutes the identity of the subjects [103]. More generally the complexity of ecological and social systems make valuation of ecosystems services with non-linear properties based on short term human preferences poorly reliable and their main purpose might be to identify potential catastrophes rather than to inform some fine tuning in resource allocation [104]. Some critics are even mobilizing an Hayekian perspective on markets as gathering mechanisms of dispersed and heterogeneous information, which is contrasted with the collective and centralized knowledge characteristic of science, and argues that "the conceptual distance between market-based and science-based methods of assembling information and applying knowledge defeats efforts to determine the "value" of ecosystem services in any integrated sense" [105].

  recent years, a growing body of work on the valuation of a range of ES have been published: ecosystem services in a river basin[113], services to agriculture[START_REF] Zhang | Ecosystem services and dis-services to agriculture[END_REF] or from agriculture[114, 115], provision of productive inputs[116], protection against hurricane [117], pollination[118], services derived from forests [119, 120], the assessment of conservation policies [121], the service loss related to invasive species [122] or the ambiguous effects of restoring ecological function[START_REF] Holmquist Westerberg | To restore or not? A valuation of social and ecological functions of the Marais des Baux wetland in Southern France[END_REF],constructed wetland [123], etc.1 . The most impressive recent accomplishment might be the valuation of the change in the ecosystem services which should result from the whole UK Biodiversity Action Plan (UK BAP) undertaken on the initiative of the DEFRA. The valuation of such a bundle of services related to a large set of changes of heterogeneous ecosystems was made possible by combining a large public survey (a "choice experiment" that aimed at determining the values people place on these ES changes) with an innovative Ecological Weighting Matrix that pooled "experts' judgments and an assessment of the ecosystem services provided by a broad range of habitats"[126]. Though implemented by recognized experts of contingent valuation, this study relies on a stated preference approach that was argued to be unsuitable for extracting appropriate information from such surveys [127].1 We do not take in consideration in this paper other works related to the value of nature or biodiversity like the value of endangered species [124] or genetic resources[125].

Table 1 . Different classifications for ecosystem services (from [88])

 1

	Source	Daily (1997)	MA (2005)	Boyd and Banzhaf (2007)	Wallace (2007)	Fisher et al. (2009)	UK NEA (2011)
	ES definition	The conditions and processes through which natural ecosystems… sustain and fulfil human life	Benefits people obtain from ecosystems	Components of nature directly enjoyed, consumed, or used to yield being human well-	Benefits people obtain from ecosystems	Aspects of well-being ecosystems utilised (actively or passively) to produce human	The benefits people obtain from ecosystems
	Classifications and ES value a	Production inputs Sustenance of plant and animal life Provision of existence and option values	Cultural Provisioning Regulating Supporting	Intermediate components Services Benefits	Processes Ecosystem services Benefits	Abiotic inputs Intermediate services Final services Benefits	Ecosystem process/interm ediate services Final ES Goods Well-being value b
	Economic values	Use and non-use values	Use and non-use values	Use values	Use and non-use values	Use values	Use and non-use values
	Nature of the ES	Ecological and anthropogenic	Ecological and anthropogenic	Ecological functions	Ecological and anthropogenic	Ecological functions	Ecological and anthropogenic
	ecosystem services are in fact means to the end of human well-being, ecosystem processes can also
	be services (they are not mutually exclusive categories), and the same services can be both
	intermediate and final. The real world is complex and messy and our systems of classification and
	definition of ecosystem services should recognize that and work with it, not ignore it in a misguided

a. The category in which economic valuation is performed under each classification is highlighted in bold. b. UK NEA also uses the MA classification but establishes the links between processes, services and goods, which are valued.

Of course, no framework can accommodate the multiplicity of situations. "Ecosystems are complex, dynamic, adaptive systems with non-linear feedbacks, thresholds, hysteresis effects, etc. (…) all

Table 2 : Headline results on the value of the UK BAP by ecosystem service

 2 Recently under the understanding that decision and policy-making generally impact large territories, the mapping of ecosystem services and values have become an intense research field. Since the first large scale studies[START_REF] Daily | Nature's Services: Societal Dependence on Natural Ecosystems[END_REF][START_REF] Costanza | The value of the world's ecosystem services and natural capital[END_REF] the project of mapping ES values was implicit, including by using satellite imagery[128]. But linking GIS and value transfers remains a central challenge[129]. An alternative recognizes that resources for conservation are scarce and the policies have to be spatially explicit in order to improve the efficiency of each unit of expenditure. A first demonstration of the importance of these choices has been made from five ecosystem services related to Atlantic Forests in Paraguay[START_REF] Naidoo | Mapping the economic costs and benefits of conservation[END_REF] 2 . Analyzing changes in the delivery of ES related to land cover and land use change was made (food production) has been considered critical for human well-being; technology and social innovation have decoupled human well-being from ecosystem degradation; and there is a time lag between ecosystem service degradation and impacts to human well-being. None of these fully explains the Environmentalist paradox, but these theories, which arise from different academic disciplines, are interacting in complex dynamics. Available data show the existence of local declines in populations' well-being but no evidence of a global decline. They conclude that we have a better understanding of the human impact on ecosystems, than of the ways the evolution of ecosystems impacts human well-being, and draw a research avenue toward ES synergies and trade-offs, technology enhancing ES, and ES forecasting. These are positive contributions toward a better understanding of the condition to maintain a "safe operating space for humanity" [145].

	(from [126])

3

The InVEST model (Integrated Valuation of Ecosystem Services and Tradeoffs) is developed since 2009 at the Stanford University within the "Natural Capital Project", in partnership with "the Nature Conservancy" and WWF. It builds from scenarios of land use changes and landscape management

[133]

, as a support to decisionmaking

[134]

. services


M E Abdelmohsin'

A E Eijack

M T Yousif'

E A Ahmed

M Pitrat

Inheritance of andromonoecy in Tibish

Keywords: Melon, sex expression, Cucumis melo, genetic control, monoecy

ln melon, the presence of stamens in female flowers is controlled by the recessive allele a, while the absence of stamens in the female flowers is controlled by the alle1e a+ (or A). Tibisli group of melon is characterized by small, ovoid fruits which are harvested before maturity and consumed raw in salad, like cucumber. The plants have male and perfect flowers, characteristics of andromonoecy. The F1 progenies between Tibish and monoecious cultivars belonging to the jlexuosus group were andromonoecious. ln F 2 and backcross progenies between Tibish and 'V édrantais' (andromonoecious cultivar belonging to the cantalupensis group), monoecious plants were observed indicating that a genomic region independent from the locus ala: was involved. The segregations observed in F 2 progenies between tibisn and 3 cultivars belonging to the jlexuosus group could be explained by two linked loci. The symbols A-2 and A-3 are proposed.

INTRODUCTION

Melon (Cucumis melo) is cultivated throughout the world for different kind of fruits. Two main groups correspond to the non-sweet types (for instance conomon, chate,jlexuosus, acidulus) and the sweet types (for instance cantalupensis, inodorus, ameri). On a typical melon plants, there are more than 20 female flowers which will give only 4 or 5 mature fruits due to a very strong competition between fruits. ln cultigroups with non-sweet fruits, the fruits are harvested before maturity and the competition between fruits is less severe. By increasing the female flower number it could be possible to increase the total yield. Breeding hermaphrodite cultivars, with perfect flowers at each no de On the main stem and the lateral branches, belonging to cultigroups where fruits are harvested before maturity, as inflexuosus or tibisn groups, could be a possibility to increase earliness and yield.

Cucurbitaceae 2012, Proceedings of the X" EUCARPIAmeeting on genetics and breeding of Cucurbitaceae (eds. Sari, Solmaz and Aras) Antalya (Turkey), October 15-18 ' '', 2012 Melon cultivar 'Vedrantais' (Cucumis melo L. var. cantalupensis) is a typical climacteric fruit and the ripening phenomena dramatically proceed within two to three days after initiation of ripening. Ethylene has critical roles in ripening of climacteric fruit and ethylene receptor is an important factor located front line of the signal transduction pathway. It is known that ethylene receptor genes construct multigene family. Three ethylene receptor genes, CmETRl, CmETR2 and CmERS 1 have been identified in melon. However their molecular characterization during fruit development is still unclear.

Characterization of gene expression and protein accumulation in melon ethylene receptors

We analyzed melon ethylene receptors (CmETRl, CmETR2, CmERSl) for pattern of gene expression and protein accumulation of various tissues, fruit enlargement and ripening stages of the climacteric 'Vedrantais' melon. Additionally, the connection with ethylene was studied with I-methylcyclopropen, a gaseous ethylene action inhibitor.

ln this study, we suggest that ripening initiation is involved in the change of expression levels of each ethylene receptor before or after ripening ethylene production on the basis of gene expression analysis and that the expression levels of ethylene receptors are adjusted by both ethylene dependent and independent systems.

This work was supported by JSPS KAKENHI Grand Number 23-40033.

Cucurbitaceae 2012, Proceedings of the X" EUCARPIAmeeting on genetics and breeding of Cucurbitaceae (eds. Sari, Solmaz and Aras) Antalya (Turkey), October 15-18 t \ 2012

Wild melons are monoecious and many modern cultivars are andromonoecious. A few accessions from China are hermaphrodite. From these last accessions, breeders have been able to develop gynoecious lines. Two main genes are involved in the genetic control of these phenotypes: locus a controls the presence (allele a) or absence (allele a+ or A) of stamens in female flowers [START_REF] Rosa | The inheritance of flower types in Cucumis and Citrullus[END_REF]) and locus g controls the presence of one type (allele g) or two types of flowers (allele g+ or G) on one plant (Poole and GrimballI939).The combinations ofthese two independent loci generate four phenotypes: monoecious (zz"-g+g+), andromonoecious (aa g+-), gynoecious (a+a+gg) and hermaphrodite (aa gg).

Four types of melons are cultivated in Sudan: sweet melons, snake melon (C melo var.jlexuosus), a salad melon known locally as 'Tibish' (C. melo var. tibish), and a melon type used for its edible seeds known locally as 'Seinat'. True wild melons known locally as 'Humaid' are present in central, northern and western parts of Sudan. The tibisb type is characterized by small (300-500 g), ovoid smooth fruits, light green with dark green stripes, five placentas, white finn flesh, non sweet at maturity. It is andromonoecious.

To breed hermaphrodite jlexuosus and tibish lines an hermaphrodite accession from China was crossed with cultivars belonging to both types. The observed segregations with tibish did not fit the expected ones. It prompted the study of the inheritance of sex expression in tibish.

MATERIALS AND METHODS

Plant material

Two accessions of tibish are used, namely lebel Kordofan 4 and Khurtagat 15. Both were collected from Kordofan area in 2006 and were andromonoecious. They were crossed with three monoecious accessions ofjlexuosus melon, namely 'Alimin' and 'Silka', which are commercial cultivars of snakemelon in Sudan, and PI 222187 from the Afghanistan and with 'Védrantais', an andromonoecious Charentais line (obt. Vilmorin).

Sex expression

Opening flowers were examined daily to observe the presence of pistillate flowers, with only female organs like stigma, or perfect flowers with both female organs and stamens. Segregation ratios in F 2 and BC populations were tested for goodness offit to theoretical ratio with Chi square test.

RESULTS

Allelism of andromonoecy

The FI progeny of the cross between tibish Khurtagat 15 and 'Védrantais', both andromonoecious, was andromonoecious as expected (Table 1). Monoecious plants were observed in the F 2 and BC progenies indicating that andromonoecy in tibish was not controlled by the locus a/a+ and that Khurtagat 15 had the allele «:

Inheritance of andromonoecy in tibisb

The FI progenies of the five crossés between both andromonoecious tibish accessions and the three monoecious flexuosus accessions were clearly andromonoecious (Table 1) indicating that andromonoecy is dominant. ln the F2 progenies, more andromonoecious plants were observed than monoecious in opposition with the dominance of monoecy controlled by the a+ allele.

Taking in account that Khurtagat 15 had the allele a", different hypothesis were tested, with the symbols A-2 and A-3 for the dominant alleles in tibish: Hl = One dominant gene for andromonoecy in tibish independent from the locus a and epistatic on a+ i.

e. tibish [a+/a+A-2/A-2] andflexuosus [a+/a+A-J+/A-J+].

The observed segregation on the pooled F 2 (380 andromonoecious versus 199 monoecious) did not fit the expected 3 andromonoecious vers us 1 monoecious (X 2 = 27.11, Prob <0.001). H2 = Two independent dominant genes, each sufficient for andromonoecy, in tibish independent from the locus a and epistatic on a+ i.e. tibish [a+/a+A-2/A-2

A-3/A-3] andflexuosus [a+/a+A-2+/A-2+ A-3+/A-3+].

The observed segregations did not fit the expected 15 andromonoecious vers us 1 monoecious (X2 = 781.35, Prob <0.001). H3 = Two independent dominant genes, both necessary for andromonoecy, in tibish independent from the locus a and epistatic on a". The observed segregations did not fit the expected 9 andromonoecious versus 7 monoecious (X2 = 20.703, Prob <0.001). H4 = Two linked dominant genes, both necessary for andromonoecy, in tibish independent from the locus a and epistatic on a". The recombination frequency between the two lociA-2 andA-3 was estimated by the maximum likelihoodmethod and varied between 0.12 and 0.44 on the five F 2 and was estimated at 0.21 on the pooled F 2 . With this last value, the observed segregations of the five F 2 between tibish andflexuosus and also of the F 2 and BC between tibish and 'Védrantais' fitted the expected segregations.

DISCUSSION AND CONCLUSIONS

Monoecy in C. melo has always been considered under a monogenic dominant control [START_REF] Rosa | The inheritance of flower types in Cucumis and Citrullus[END_REF]Poole and Grimball1939;[START_REF] Kubicki | Sex determination in muskmelon (Cueumis melo L.)[END_REF][START_REF] Kenigsbuch | The inheritance of gynoecy in muskmelon[END_REF] with the recessive allele a for andromonoecy. This is the first work to study inheritance of andromonoecy using tibish genotypes. Andromonoecy is clearly dominant to monoecy and another genomic region than the locus a is involved. It seems that two linked dominant genes are necessary for this phenotype. We propose the names Andromonoecy-2 (symbol A-2) and Andromonoecy-3 (symbol A-3) for these genes. The genotypes of the lines studied here could be 'Védrantais'

[aa A-2+A-2+ A-3+A-3+],jlexuosus [a+a+A-2+A-2+ A-3+A-3+], tibish. [a+a+A-2A-2 A-3A-3].
Gene a corresponds to anACC synthase (CmACS-7) inactive for the alle1e a and active for the allele a+ [START_REF] Boualem | A conserved mutation in an ethylene biosynthesis enzyme leads to andromonoecy in melons[END_REF]). Further study is needed to know if the dominant genes correspond also to enzymes involved in the ethylene pathway.

ACKNOLEDGEMENTS

This work was partly supported by a grant from the French Embassy in Khartoum (Sudan) z Observed number of andromonoecious and monoecious plants in different progenies YVarious hypothesis for the genetic control of andromonoecy in tibish. Hl = one dominant gene; H2 = two independent dominant genes, each sufficient; H3 = two independent dominant genes, both necessary; H4 = two linked dominant genes, both necessary.

x Expected ratio of segregation according to the hypothesis Hl to H3. wProbability of the X 2 for the expected ratio v Recombination fraction estimated by the maximum likelihood method.

K. Hiwasa-Tanase, C. Shibata, T. Ariizumi and H. Ezura

	Graduate School of Life and Environmental Sciences, University ofTsukuba, Tsukuba
	305-8572, Japan

Table 1 .

 1 Phenotypes observed for sex expression (monoecy or andromonoecy) in melon in crosses between tibisb (Khurtagat 15 or Kordofan 4) and monoecious accessions ofjlexuosus melon, namely 'Alimin' and 'Silka', which are corrimercial cultivar of snakemelon in Sudan, and PI 222187 from the Afghanistan and with 'Védrantais', an andromonoecious Charentais line (obt. Vilmorin).

	Literature cited


est destinée au dépôt

Biohydrogen production by dark fermentation : Current trends and main scientific challenges

Eric Trably

To cite this version: INRA, UR050, Laboratoire de Biotechnologie de l'Environnement, Avenue des Etangs, F-11100 Narbonne, France. eric.trably@supagro.inra.fr

The degradation of our natural environment and energy crisis are two vital issues for sustainable development worldwide. In this context, the production of bioenergy from lignocellulosic biomass or urban residues is receiving ever-increasing interest. Among the different processes, biohydrogen production by dark fermentation presents considerable advantages since bioH2 is renewable, carbon free and environmental friendly. An overview of the literature shows a worldwide interest of the scientific community to propose new ways of carbon-free biological processes having a low energy demand. In particular, biohydrogen production from agricultural waste is very advantageous since agri-wastes are abundant, cheap, renewable and highly biodegradable. However, biological conversion to biohydrogen is often limited by the accessibility of readily degradable sugars that are embedded in the lignin network. Considering that such wastes are complex substrates and can be degraded biologically by complex microbial ecosystems, the current trends and recent findings in biotechnological development are here presented, with a special focus on the key operational parameters such as pH, partial pressure, temperature and microbial actors. Finally, the main scientific challenges are exposed and discussed to facilitate further research in this domain.

KEYWORDS:

Biohydrogen, dark fermentation, biogas, hydrogen, methane, physicochemical treatment, operational parameters

Biohydrogen

  Eric Trably. Biohydrogen production by dark fermentation : Current trends and main scientific challenges. ICABB 2013 -International Conference on Advances Biotechnology and Bioinformatics, Dr. D. Y. Patil Biotechnology and Bioinformatics Institute. IND., Nov 2013, Pune, India. hal-01189752


Emmanuelle Garrigues
email: emmanuellegarrigues@hotmail.com

Michael S Corson

Christian Walter

Denis A Angers

Hayo Van Der Werf

AND SOIL QUALITY 8

Keywords: soil quality, life cycle assessment, indicators, site dependence

Impacts on soil quality should be included in life cycle assessments because of the essential role that soils play in ecosystem functioning. We propose a method that integrates impacts on quality of agricultural soils (erosion, soil organic matter, and compaction) of each stage of an agricultural product as a function of the soil and climate contexts of its agricultural processes. Input data must be as site-specific and accurate as possible, but if measured data are missing, the method has a standardised framework of rules and re commendations for estimating or finding them. We present a case study focused on the soil-quality impacts of producing pig feed in Brittany, France. The framework allows for incremental improvement of the method through the inclusion of new soil-quality impacts.

Introduction

Soils are an essential resource in both managed and natural systems, and maintaining soil quality is critical to the sustainable development of human activities, in particular agriculture. The difficulty in representing impacts on soil quality remains an unresolved problem in Life Cycle Assessment (LCA) because of soil's spatial and temporal variability and the complex interactions among soil properties. Current status of soil quality in LCA in presented in [START_REF] Garrigues | Soil quality in Life Cycle Assessment: Towards development of an indicator[END_REF]. It is crucial to consider soil quality in the environmental assessment of products, especially those with a majority of their life cycle in bio-based processes (such as agriculture and forestry).

Soil is defined herein as naturally occurring, unconsolidated mineral or organic material at least 10 cm thick that occurs at the earth's surface and is capable of supporting plant growth. In this definition "naturally occurring" excludes displaced materials such as gravel dumps and mine spoils, but "unconsolidated material" includes that compacted or cemented by soil-forming processes. Soil quality can be defined by its capacity to function [START_REF] Karlen | Soil quality: a concept, definition, and framework for evaluation[END_REF] and/or its fitness for use [START_REF] Larson | The dynamics of soil quality as a measure of sustainable management. Defining soil quality for a sustainable environment[END_REF][START_REF] Letey | Deficiencies in the soil quality concept and its application[END_REF].

The objective of this study was to establish a framework for quantifying indicator(s) of impact on soil quality in a life cycle perspective, valid for all soil and climate conditions, and considering both on-site and off-site agricultural soils. The method developed answers needs identified by [START_REF] Garrigues | Soil quality in Life Cycle Assessment: Towards development of an indicator[END_REF] for LCA indicators of impacts on soil quality. It includes the impact categories erosion, soil organic matter (SOM) and compaction. Erosion and SOM impacts already exist in LCA approaches [START_REF] Milà I Canals | Method for assessing impacts on life support functions (LSF) related to the use of 'fertile land' in Life Cycle Assessment (LCA)[END_REF][START_REF] Nuñez | Assessing potential desertification environme ntal impact in life cycle assessment[END_REF], but compaction impacts have yet to be quantified in detail in LCA. [START_REF] Cowell | A methodology for assessing soil quantity and quality in life cycle assessment[END_REF] provided some ideas but excluded soil compactibility of their indicator. We applied the method to a case study of soil-quality impacts of producing pig feed in Brittany, France.

Method Presentation

General framework

Integrating soil-quality impacts throughout the life cycle of an agricultural product requires a global approach to assess impacts on soil quality that can be adapted to individual soil and climate contexts. Input data must be as site-specific and accurate as possible, but if measured data are missing, the method has a standardised framework of rules and recommendations for estimating or finding them.

Soil-quality impact assessment within LCA is quantified with midpoint indicators describing processes that can degrade or improve the soil. Soil physical, chemical and biological properties and function are excluded as indicators because of the difficulty in determining how they influence the system functions reflected in the functional units. Pathways were selected to link elementary flows of the inventory (LCI) to the midpoint impact indicators, which result from the combination of soil, climate, and management characteristics (Fig. 1).

Figure 1. Steps for assessing impacts on soil quality (outlined) (adapted from [START_REF] Garrigues | Soil quality in Life Cycle Assessment: Towards development of an indicator[END_REF].

The LCI and impact assessment (LCIA) are based on simulation modelling, using models simple enough for use by non-experts, general enough to parameterise with available data at a global scale, and already validated: RUSLE2 for erosion [START_REF] Renard | RUSLE model description and database sensitivity[END_REF]; RothC for SOM [START_REF] Coleman | Simulating trends in soil organic carbon in long-term experiments using RothC-26.3[END_REF][START_REF] Coleman | ROTHC-26.3 A model for the turnover of carbon in soil. Model description and windows users guide[END_REF], and COMPSOIL for compaction [START_REF] O'sullivan | A simplified method for estimating soil compaction[END_REF]. Most of the input data necessary for establishing the LCI are common to the three midpoint indicators. For each indicator, total impact is estimated by summing the impacts from individual upstream agricultural sites together. Thus, the method currently has no regionalised characterisation factors for LCIA, assuming that a given erosion, SOM, or compaction impact has equal impact regardless of location.

Inventoryinput data requirements 2.2.1 Soil data

Soil characteristics such as texture, C content, bulk density, and slope are required. If necessary, national or international databases, such as the Harmonized World Soil Database [START_REF] Fao | Harmonized World Soil Database (version 1.1). FAO[END_REF], can provide the required data. In the future, the Global Soil Map project (http://www.globalsoilmap.net) will provide data at a finer resolution. Users can assume that agricultural processes in a region occur on its dominant soil type, a compromise between data precision and availability.

Agricultural-practice data

Crop data (e.g., yield, residues), management data, and vehicle characteristics (e.g., type and weight of vehicle, tyre size) are necessary.

Climate data

Monthly (erosion and SOM) and daily (compaction) temperature, precipitation, and potential evapotranspiration (PET) data are necessary. For SOM predictions, a time series up to 20 years is preferable. We used the TURC method [START_REF] Federer | Intercomparison of methods calculating potential evaporation in regional and global water balance models[END_REF] to estimate PET: PET=0.313 T m (R s + 2.1)/(T m + 15) with PET=0 when T m <0

(1) where T m is mean daily air temperature (°C) and R s is daily solar radiation (MJ/m²). If climate data are not found from national sources, international climate databases exist (NASA, 2012).

Simulation models used 2.3.1 Erosion: RUSLE2

The RUSLE2 (Revised Universal Soil Loss Equation) model [START_REF] Renard | RUSLE model description and database sensitivity[END_REF] improves upon the original USLE model. The fundamental equation is:

A = R × K × LS × C × P (2)
where A is the computed annual soil loss, R is the rainfall-runoff erosivity factor, K is the soil erodibility factor, LS is a topographic factor combining slope length (L) and steepness (S), C is a cover-management factor, and P is a supporting-practice factor. Three input databases are required that describe climate, crops and field operations.

Soil organic matter change: RothC

RothC (version 26.3) simulates the dynamics of organic carbon (C) in soil [START_REF] Coleman | ROTHC-26.3 A model for the turnover of carbon in soil. Model description and windows users guide[END_REF]. The effects of soil type, temperature, moisture content and plant cover are considered in the turnover process. It uses a monthly time-step to calculate total organic carbon (TOC, t/ha) and microbial biomass carbon (t/ha) over one to hundreds of years. The method simulates 20 years of the same management practice and divides the total change in SOM by 20 to provide the rate over one year.

Compaction: COMPSOIL

COMPSOIL (O' Sullivan et al., 1999) predicts the effect of an agricultural machine on soil bulk density using readily available machine and tyre data. Topsoil and subsoil compaction are reported both separately (0-30 and 30-50 cm, respectively) and together. Initial dry bulk density comes from the SOTWIS database (ISRIC, 2012) from which soil texture is divided into five classes (coarse to very fine, according to the FAO texture triangle), each associated with an initial bulk density. Soil water content, a required input, is predicted from soil and precipitation data with the two-reservoir BILHY model [START_REF] Jacquart | Un modèle de bilan hydrique simplifié à deux réservoirs utilisable en agrométéorologie[END_REF]. The method assumes uniform initial bulk density and water content profiles.

Indicators of impact on soil quality

The erosion indicator represents a loss of soil (t), while the SOM indicator represents an increase or decrease in the stock of soil C (t C). The compaction indicator represents a loss of soil porosity (m 3 /ha) and distinguishes topsoil from subsoil compaction because the former is more easily reversible. Estimates of these soil processes in an inventory level are already informative enough to serve as indicators impact without requiring characterisation factors. A single indicator of impact on soil quality has not yet been developed because of the difficulty in aggregating diverse impacts into a single measure.

Case study

The case study was selected to illustrate impacts of a composite product formed from crop-based ingredients produced with widely differing soils, climates, and crop-management practices. It focused on the global soil-quality impacts of producing pig feed in Brittany, France, with ingredients coming from Brittany, Brazil, and Pakistan (Table 1). The system boundary for crop products used as feed ingredients was set at the farm gate, while that for feed ingredients was set at the factory gate. For each crop, the temporal boundary included the inter-crop period (if any) that occurs just before the crop. Impacts were predicted per ha of each crop and then converted to impact per tonne of feed ingredient based on crop yields and economic allocation for rapeseed cake, cane molasses and soya oil and cake. Impacts per tonne of ingredient in pig feed were added together to calculate total impact per tonne of pig feed produced in Brittany.

Results and discussion

Table 2 shows predicted erosion, SOM change, and compaction impacts per t of feed; note that SOM change is the only indicator that can have a negative value. For erosion, despite constituting only 9% (by mass) of pig feed (Fig. 2 left), soya-based ingredients (cake + oil) contributed 69% of the impact (Fig. 2 right). Agriculture-related erosion in Brazil tends to be higher than in Europe, especially in the location where we assumed soya to originate: Santa Catarina state, where precipitation and mean slopes are high. The erosion model used, RUSLE2, represents well the high sensitivity of erosion to precipitation and mean slope. For SOM change, rapeseed cake and pea contributed most to the net negative impact (Fig. 3). In Brittany pea is mostly cultivated with only mineral fertilisation and has few residues left on field. The C dynamics simulate by Roth C is sensitive to manure and plant-residues supplies. Furthermore, the soil of Brittany has a high C content (2.5% TOC), which requires high C input over the 20 years of simulation of pea cultivation to be able to maintain it.

For compaction, as crops grown in Brittany require similar agricultural practices, the relative impact of each ingredient is similar to its relative mass in the feed (Fig. 4). The impact of wheat is relatively higher because of the highest number of passes in field than the others crops. In Brazil, machines are heavy, but reduced-tillage practices result in fewer passes than in Brittany. Furthermore, Brazilian soils have high clay contents, which decrease their sensitivity to compaction (unlike the loamy soils of Brittany). These soil-quality impact indicators can be used in LCAs of bio-based materials (e.g., plants, wood, food, industrial bio-based materials) for cultivation processes or for waste-management processes if considering composting. Although, the impact of non-cultivation processes on soil quality could be included, many of them, such as soil sealing with concrete, transform soil into nonsoil, which has zero soil quality. Thus, we believe that non-cultivation processes are better included with impacts of land use and land-use change.

In a life cycle perspective, soil-quality impact indicators can interact with other impact categories, such as climate change, in which SOM changes influence net C emissions into the atmosphere. Also, soil-quality impact indicators complement other impact categories, providing increased ability to identify "impact swapping" or trade-offs between transport distance and agricultural soil quality.

All the input data necessary for establishing the LCI (approximately 30 parameters) will be presented in the project report in late 2012 and can be found in the international databases cited. Most input data are common to the three indicators. As the framework allows for incremental improvement, the inclusion of new soil-quality impact indicators (such as salinisation) will increase input-data requirements little. A forthcoming users' guide will describe each step of the method.

Conclusion

Impacts on soil quality should be taken into account into a life cycle perspective because of the essential role of soils in ecosystem functioning. We have developed a framework for quantifying indicators of impact on soil quality, valid for all soil and climate conditions, and considering both on-site and off-site agricultural soils. These indicators can be used in LCAs of bio-based materials or the waste-management stage when considering composting.

The first indicators developed represent the most prevalent threats on soil: erosion, SOM change and compaction. Overall impact estimates result from the combination of soil, climate, and management characteristics. Results to date can begin to fill a database of soil-quality impact indicators for crops and crop-based products from a several regions. Most of the input data necessary for establishing the LCI are common to the three midpoint indicators and can be found in existing databases.

The framework allows for incremental improvement of the method through the inclusion of new soilquality impacts. Improvement efforts will focus first on developing robust impact indicators for individual soil processes before considering whether to aggregate them into a single indicator. Nonetheless, a variety of aggregation approaches can be explored [START_REF] Garrigues | Soil quality in Life Cycle Assessment: Towards development of an indicator[END_REF].

Figure 2 .

 2 Figure2. Left: Ingredient composition by mass of representative pig feed produced in Brittany. Right: Contribution of crop-based ingredients to erosion impact per tonne of pig feed in Brittany (total soil loss: 0.177 t soil/t feed).

Figure 3 .

 3 Figure 3. Contribution of crop-based ingredients to impact of change in soil organic matter (SOM) per tonne of pig feed in Brittany (net SOM change: -0.026 t C/t feed).

Figure 4 .

 4 Figure 4. Left: Ingredient composition by mass of representative pig feed produced in Brittany. Right: Contribution of crop-based ingredients to compaction impact in the upper 50 cm of soil (topsoil + subsoil) per tonne of pig feed in Brittany (loss of porosity: 23.5 m 3 /t feed). The subsoil compaction is irreversible.

Table 1 .

 1 Ingredient composition (by mass) and sources of representative pig feed produced in Brittany.

	Ingredient	Maize	Wheat	Triticale	Barley	Pea	Rapeseed cake	Soya cake	Soya oil	Molasses
	Soil type	Loam	Loam	Loam	Loam (Brittany)	France (Brittany)	France (Brittany)	Brazil (Santa Catarina)	Pakistan
	Source crop	Maize	Winter wheat	Triticale	Barley	Pea	Rapeseed	Soya		Sugar-cane
	Yield (t DM/ha)	9.0	7.0	7.0	6.5	4.2	3.3	2.8		35.0
	Pig feed in-gredient (%)	3.1	34.5	14.6	4.3	16.3	8.8	1.1	7.8	3.6
	Economic allocation (%)	100	100	100	100	100	23.8	65.4	34.6	18.1

Table 2 .

 2 Erosion, change in soil organic matter (SOM), and compaction impacts per tonne of pig feed in Brittany.

	EROSION	SOM CHANGE	COMPACTION
			Topsoil: 17.6 m 3 /t feed
	0.177 t soil/t feed	-0.026 t C/t feed	Subsoil: 5.9 m 3 /t feed
			Total: 23.5 m 3 /t feed

th Int. Conference on LCA in the Agri-Food Sector, 1-4 Oct 2012