One Ecosystem :
Review Article
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Corresponding author: C. Sylvie Campagne (sylviecampagne@gmail.com)
Academic editor: Sander Jacobs
Received: 13 Feb 2020 | Accepted: 28 Apr 2020 | Published: 30 Apr 2020
© 2020 C. Sylvie Campagne, Philip Roche, Felix Müller, Benjamin Burkhard
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Campagne CS, Roche P, Müller F, Burkhard B (2020) Ten years of ecosystem services matrix: Review of a (r)evolution. One Ecosystem 5: e51103. https://doi.org/10.3897/oneeco.5.e51103
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With the Ecosystem Service (ES) concept's popularisation, the need for robust and practical methodologies for ES assessments has increased. The ES matrix approach, linking ecosystem types or other geospatial units with ES in easy-to-apply lookup tables, was first developed ten years ago and, since then, has been broadly used. Whereas detailed methodological guidelines can be found in literature, the ES matrix approach seems to be often used in a quick (and maybe even "quick and dirty”) way. Based on a reviewa of scientific publications, in which the ES matrix approach was used, we present the diversity of application contexts, highlight trends of uses and propose future recommendations for improved applications of the ES matrix.
A total of 109 studies applying the ES matrix approach and one methodological study without concrete applications were considered for the review. Amongst the main patterns observed, the ES matrix approach allows the assessment of a higher number of ES than other ES assessment methods. ES can be jointly assessed with indicators for ecosystem condition and biodiversity in the ES matrix. Although the ES matrix allows us consider many data sources to achieve the assessment scores for the individual ES, in the reviewed studies, these were mainly used together with expert-based scoring (73%) and/or ES scores that were based on an already-published ES matrix or deduced by information found in related scientific publications (51%). We must acknowledge that 27% of the studies did not clearly explain their methodology. This points out a lack of method elucidation on how the data had been used and where the scores came from. Although some studies addressed the need to consider variabilities and uncertainties in ES assessments, only a minority of studies (15%) did so. Our review shows that, in 29% of the studies, an already-existing matrix was used as an initial matrix for the assessment (mainly the same matrix from one of the Burkhard et al. papers). In 16% of the reviewed studies, no other data were used for the matrix scores or no adaptation of the existing matrix used was made. However, the actual idea of the ES scores, included in the Burkhard et al.'s matrices published 10 years ago, was to provide some examples and give inspiration for one's own studies. Therefore, we recommend to use only scores assessed for a specific study or, if one wishes to use pre-existing scores from another study, to revise them in depth, taking into account the local context of the new assessment. We also recommend to systematically report and consider variabilities and uncertainties in each ES assessment. We emphasise the need for all scientific studies to describe clearly and extensively the whole methodology used to score or evaluate ES in order to be able to rate the quality of the scores obtained. In conclusion, the application of the ES matrix has to become more transparent and integrate more variability analyses. The increasing number of studies that use the ES matrix approach confirms its success, appropriability, flexibility and utility for decision-making, as well as its ability to increase awareness of ES.
capacity matrix; ecosystem services assessment; tiered approach; expert-based; look-up table
Since the Ecosystem Service (ES) concept was largely popularised by the
The ES matrix approach was originally published by
The ES matrix approach is based on the use of a lookup table consisting of geospatial units which, for instance, can be Ecosystem Types (ET), habitat types or other geospatial units, such as Land Use and Land Cover (LULC) types and sets of ES, which are to be assessed in a specific study area. Thus, the selection of the study area is the starting point of the ES matrix approach, followed by the selection of relevant ET or geospatial units and the selection of relevant ES to be in the lines and columns of the matrix (look-up) table. Then, suitable indicators for the ES quantification and appropriate ES quantification methods have to be defined. Based on that, a score for each of the ES considered is generated, referring to ES potential, ES supply, ES flow/use or demand for ES (see
We conducted a systematic review of published studies through Web of Science and Scopus (terms used for the review research in Suppl. material
In the following, the results of the review are presented, referring to analysed attributes including case study location, the matrix elements, the scoring system and the methods used.
Over the last 10 years, the number of published studies increased progressively, especially during the last five years (Fig.
The flow of ES from nature to society is not always as straightforward as one could perhaps expect. Instead, it includes several components, including the ecosystem-based supply of ES and the societal demand for ES. In literature, many different terms are used, depending on the different ES frameworks, the perception of the authors and the individual applications. In the reviewed studies, we also found a diversity of ES components that were assessed through the ES matrix approach: ES capacity (e.g.
The ES matrix approach has been applied mainly in Europe in 73 analysed studies with a concentration of studies in Germany and neighbouring countries (Fig.
The ES matrix approach has been applied for a large diversity of purposes. While each study presents its own context and objectives, we can observe a broad pattern of application types (using illustrative examples):
The ES matrix approach has been used to assess an average of 15.6 different ES per matrix, whereof 7.0 (on average) were regulating ES, 6.7 provisioning ES and 3.8 cultural ES (Fig.
Mean number of assessed ES and Ecosystem Disservices (EDS) and mean number of ecological condition and biodiversity components used in the published matrix studies (bars) with 95% error bars. Number of analysed studies assessing ES, ecological condition, ecosystem disservices and biodiversity (orange diamond). The error interval was not computed for the ecosystem disservices since only 2 studies evaluated them.
Ecosystem disservices (ES with a negative impact on human well-being; for further definition, see
Biodiversity was added in addition to ES in 16 studies mainly through one indicator - called "Biodiversity" (e.g.
The geospatial units, that were mainly used in the different ES matrices, were related to LULC types and many studies used the European CORINE Land Cover typology or a related typology (
Furthermore, the ES matrix approach has been adapted in a “species matrix”, which linked different species types to ES supply, as in
Precise elaborations of the stepwise ES matrix application can been found in literature (
Several methodological steps are common in all applications of the ES matrix and we propose to look closer at the data and approaches used in and with the matrix, the scoring systems and the scoring process used, as well as the confidence and realiability analyses done in the analysed papers.
The ES matrix approach involves a scoring process to assess ES (supply, flow/use, demand) in ecosystem types or other explicit geospatial units. These scores can be based on or can integrate data from diverse sources of varying quantity and quality (
For the ES scoring process, expert scoring was the dominant data source, as it was used in 82 of the reviewed studies. When the scoring was expert-based, the number of experts involved in the scoring exercises varied between 2 and 170 with a mean of 31 experts. Nevertheless, the number of involved experts was not specified in 32 studies out of 82. Expert consultation was undertaken through workshops in 34 studies, interviews were conducted in 15 studies and specific surveys were carried out in 9 studies.
The second dominant data source was literature data transfer, which is when ES scores are based on an already-published ES matrix or deduced by information found in related scientific publications. This was used in 57 studies, more than half of the studies. Other data or approaches, such as statistical data (13 studies, e.g. national statistics of yield production), models (12 studies), remote sensing data (6 studies) and field data (6 studies) were used less in the analyses studies (Fig.
Several types of data or approaches were used in 57 studies, of which 29 only combined two types of data or approaches: literature data transfer and expert scoring.
One main characteristic of the ES matrix approach is to express ES provision with an ordinal scale and so allows the comparison of different ES. Several ranking scales were used to fill in the matrix. However, a numeric score ranging from 0 (no [relevant] supply) to 5 (very high [maximum] supply), as originally proposed by
Several other scoring scales were used with 2, 3, 4, 5 or 7 levels in 33 studies (e.g. “0 to 1” in
In two studies, the scoring system used non-numeric values (+) to (+++) (
A first step for implementing a matrix-based ES evaluation is to define the initial matrix that is to be used (
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After the definition of the initial matrix, the scoring process can be carried out with diverse sources of data. In the 32 studies that used an existing ES matrix as an initial matrix, 18 studies used no additional data to define the matrix scores and, therefore, made no adaptation of the values provided in the existing matrix (Fig.
Finally, the methodology to define the final scores, using all kind of data and approaches presented in Fig.
We considered a total of 109 studies over a period of 10 years that have applied the ES matrix approach. Those studies were mainly carried out in Europe, but an increasing number of applications outside Europe can be noted, particularly in Asia. Applications mostly focused on ES supply assessments, whereas ES demand and ES flow/use assessments remain a minority.
Our review shows a mean of 15.6 ± 1.9 different ES were assessed through the matrix approach in 109 studies, whereby a mean of 7.9 ± 4.7 was found in the review by
The flexibility of the ES matrix approach was illustrated through the diversity of the applied scoring systems, data sources, matrix elements and the different purposes of applications. Nevertheless, the scoring system that was mostly used was the original “0 to 5” range, based on expert opinions, harnessing existing matrices or scores defined by authors, based on published results.
Our review highlights several major limitations or even mistakes in existing ES matrix approach applications.
The review shows that 29% of the studies used an existing matrix as an initial matrix, 16% of the studies used no other data in the matrix scores and made no adaptation of the existing matrix values. As for other value-transfer methods, the lack of adaptation bears the risk that incorrect or, for the specific case study, unsuitable values are used. A critical evaluation of the validity of the scores in the matrix should therefore be mandatory. A total of 21 studies specified that the scores came from one of the Burkhard et al. published matrices (matrices in
In 27% of the reviewed studies, it is not clear how the data has been used and where the final scores came from. This leads to a deficit in the scientific robustness and replicability of the studies, as well as a lack of proper consideration of the importance of the data acquisition protocol by the reviewers. It is important to be precise and explicitly transparent about the methods that were used in order to allow the end-user to be aware of uncertainties inherent in the assessment. A categorisation of the used data and approaches used according to the "tiered approach" (see "Methodologies used in the studies" Section above) can help to understand the type and complexity of the applied approaches.
The limits and uncertainties of the ES matrix approach have been listed, for instance in
A regular critique of the ES matrix approach is that it is too subjective, particularly when based on expert scoring alone. One way to tackle such remarks is to benchmark the ES expert scores against "more quantitative" estimates. However, up to today, only a few studies have dealt with the topic of comparing ES matrix experts-based scores with quantitative estimates.
Basically, the ES matrix approach is based on spatial units as LULC categories, although LULC categories can be considered as important proxies for many ES. Nevertheless, LULC alone lacks information regarding important components of ecosystem conditions that support ES capacities, such as soil type and quality, water availability, geomorphology or overall ecosystem integrity. These components also vary in space and time within and between LULC categories. One approach is to consider that the generality of LULC, especially when using broad categories, can be associated with high confidence of ES scores and is, in itself, a strength and the main interest of the ES approach - applicability and genericity. Another approach is to complement the LULC categories based ES scoring with other sources of informations that can be used to tune the matrix ES scores, based on local ecosystem condition and thus improve local validity of scores. As a consequence, this reduces the manageability of the comparably simple look-up-table approach.
Despite these limitations, the ES matrix approach has proven its usefulness. The advantages of the approach were listed, amongst others, in
The ES matrix approach is widely applied in a high diversity of contexts and with various data and quantification approaches. Based on our analysis on ES matrix applications and methodologies within a ten year period, our key recommendations for future improvements include:
We also take the opportunity to provide the recommendations for improved applications of the ES matrix beyond the results achieved from the review (based on
The simplicity of the method has been acknowledged, on the one hand, as the main strength of the method. On the other hand, this is also considered its key weakness. The success of the method is also linked to its feasibility and its easy comprehensibility that can promote the use and ability to increase awareness of ES for decision-making (
Nevertheless, the application of the ES matrix approach has to become more transparent and integrate more confidence analysis. It remains an important task to elaborate which are the most appropriate ES assessment methods for each individual ES or group of ES in different human-environmental system settings and for the different assessment purposes.
We would like to thank Candice Christin and Emily Bank for their contributions to the literature review and the database construction, Bastian Steinhoff-Knopp for an informal review and Angie Faust for a language check before submission. Additionally, we would like to thank the reviewers for their constructive comments and suggestions which helped to improved the text. The publication of this article was funded by the Open Access Fund of the Leibniz Universität Hannover.