Recommendations and Outlook

First of all, the purpose of the investigation needs to be defined, and the concrete task definition clearly formulated. The question as to why the ES need to be evaluated in the first place should be answered, and also which advantages this would have in comparison with traditional approaches in the concrete case. Without a deeper purpose, it will in most cases hardly be possible to address the more high-effort tasks, particularly the quantitative evaluation of ES. The latter may for example be useful in protected areas, especially if these have a high socio-economic or a significant development potential, if a pollution or danger thereof due to inappropriate land-use practices exists, or if alternatives are sought or protective goals are to be formulated (especially with regard to land-use changes , e.g. forest restructuring; ▶ Sect. 6.​3). The calling of ES to attention is useful if stakeholders are to be won over to the protective effort, and if financial resources need to be secured. A clear setting of goals is also useful in order to find suitable indicators and to avoid mistaken interpretations with regard to ES as much as possible.

Ideally, we should start by obtaining an overview of the area under investigation: its size, for example in order to establish the suitable scale for the ascertainment; properties and natural capacity of important ecosystems, its dominant land uses and the overall socio-economic situation; known uses based on the ecosystem and the beneficiaries of those uses; existing conflicts, problems or pollution situations; expired or expected changes or trends , existing planning procedures, or pending decisions.

In order to develop a clear and comprehensible investigative approach, to correctly interpret and communicate the results, and to avoid having the experts from different disciplines and scientific schools, and the practitioners, talk past each other, a definition and explanation of the terminology to be used is indispensable (▶ Sect. 2.​1) . Otherwise, misunderstandings may arise, for to this day there is no system of terminology for the ES area which is clear in detail and generally accepted. That includes the term ES itself, and also the term ‘function,’ among others. Moreover, to date there is no consensus regarding the most useful classification of ES. It can therefore be noted as clearly as possible why a certain classification system has been decided upon. The corresponding proposals have been presented in ▶ Sect. 3.​2.

A representative selection should be made from the wide variety of possible ES. What are the most important ES upon which society depends and/or needs? Which ES are endangered, and which are subject to changes, or will be in the foreseeable future? If only for reasons of the work effort involved, it would appear to be hardly possible to process a very large number of ES, let alone the entire spectrum (see case studies, ▶ Chap. 6). However, the representative selection of ES should be considered important—and not only provisioning ES such as food and fibres should be represented, but also regulatory and socio-cultural ES, including those relevant for the preservation of biological diversity .

Functioning properly ecosystems often yield a whole bundle of different ES . Their shares vary from one ecosystem to the other, from place to place and from time to time. It is important to keep track of the totality of ES and their linkages, in order, e.g. to avoid establishing financial incentives for the benefit of a single ES at the expense of others, which are then damaged. This often occurs in the interaction between provisioning ES and regulatory ES, e.g. energy crop cultivation vs. biodiversity. The consideration of a broad spectrum of ES is also necessary in order to arrive at statements on sustainability.

When ascertaining or evaluating ES, the question frequently arises: What are the most appropriate procedures for the concrete situation? As explained in ▶ Sect. 4.​2, using the example of the travel cost method , the inappropriate application of a procedure may lead to nonsensical results.

ES evaluations should not ignore risks and uncertainties or knowledge gaps with regard to the effect of people on ecosystems and ES, and their significance for human well-being.

On the one hand, it is necessary to simplify, e.g. in order to communicate with political leaders or the broad public; on the other, misguided simple solutions to complex problems should be avoided, in order not to cause more harm than good, thus for example causing mistakes in the decision-making process . The most useful solution appears to be a medium level of complexity, or differentiation according to various levels of complexity (as in the model InVEST, ▶ Sect. 4.​4) .

The determination of suitable indicators (▶ Sect. 4.​1) has proven to be helpful. These should have a high level of explanatory potential for the problem to be solved, and also be politically rele­vant in order to be able to correctly interpret and apply the results of the investigations.

Every ES evaluation starts with a compilation of existing knowledge, the ascertainment/measurement needed to obtain the necessary basic data, and a qualitative evaluation which is generally, but not always followed by a quantification. Not all ES are easy to quantify. Also suitable are qualitative measures (see the example of the orchard meadows, ▶ Sect. 6.​5.​1). Where no direct measures are available, and/or possible, and where there are also no exact data, it may be necessary to work with estimated values. These steps do not however constituted evaluation in the strict sense .

The principle of the distinction between measurement and evaluation, or between the factual level (the structures and current processes existing within ecosystems), and the value level is often overlooked. Both descriptive and normative work steps are necessary in ES investigations, and must be embedded into a broader socio-ecological context.

The pyramid of ES valuation methods designed by ten Brink (2008) depicts the step-by-step narrowing down of the quantum of investigation from the qualitative overview to the monetary evaluation; the latter is a very high-effort procedure, and hence not always used (◉ Fig. 7.1).

The ecological ascertainment of ecosystem structures and processes, e.g. based on data, maps, fieldwork, experiments, measurements and modelling, is necessary in order to gain an understanding of how ES are generated, and in order to provide a scientifically based framework within which the actual valuation will take place.

The pros and cons of economic (monetary) valuation methods have already been addressed (▶ Sect. 4.​2). They require not only economic expertise, but are also usually very high-effort, and can be usefully applied only in certain situations. Economic valuations can however contribute to a greater consideration for ES in economic calculations, balancing of interests and planning processes, for instance in cost-benefit analyses, and also in the internalisation of environmental impacts.

Certain services attributed to ecosystems are not provided by them alone, but require human input. For example, the crops grown on farmland are the product of ES, dependent upon site conditions and potentials; they provide utility for people and contain value. They are planted, cared for, fertilised, irrigated, etc., in order to secure increased yields. If appropriate, reference should be made to such environmental services (▶ Sect. 2.​1, 4.​2, 6.​2.​4) .

In general, valuation methods–and not only economic ones—should be seen as part of a broad spectrum of diagnostic instruments and of institutional and policy mechanisms (including legal stipulations, participatory methods, and governance; ▶ Sect. 4.​3, 5.​1, 5.​4) which facilitate an understanding of complex socio-ecological systems and provide decision-makers with the necessary background knowledge. ES evaluations require a strong interdisciplinary perspective which integrates not only ecological and economic factors, but also a wide variety of natural, planning and social-scientific disciplines.

ES are the link between ecosystems/landscapes and the utility and/or values which they provide to people. It is important to understand whether a service is simply being ‘supplied’ by the ecosystem, or whether this service is actually being ‘demanded’ by people. In the former case, the service is a potential of the ecosystem and/or of the landscape (▶ Sect. 3.​1). Whether the utility corresponds to the potential, whether overuse exists which constitutes a burden on the ecosystem, or whether there is leeway for further-reaching utilisation is helpful for the evaluation and planning process.

The effect of ES on human well-being should be demonstrated: Is that well-being being affected by the increase or decrease in ES, and what policy abilities to ES provide to increase that well-being? How, for example, would an improvement of the percolation and water-retention capacity of soil in the watershed of a river increase the safety of the inhabitants by reducing the risk of flooding, or preventing it altogether?

Important questions in this context include:

For ES, there is a high level of relevance of scales