Two tools that can facilitate side-by-side comparison of management, project, or policy alternatives are alternatives matrices and maps. Alternatives matrices can incorporate information about estimated ecological changes and their effect on the provision of services, uncertainty about these changes, and the social importance of every service for each alternative. Maps can visually display changes in the provision of services by each alternative.
Measures of benefit relevant indicators (BRIs), relative value (dollars or utils), or both can be organized by ecosystem service and management alternative and incorporated into alternatives or decision matrices. The columns of the table list management alternatives (do this, do that, or continue business as usual), and the rows list ecosystem services affected by these alternatives (Table 1). The matrices can be populated with ecological information (in which case they might also be referred to as performance matrices or alternatives/attributes matrices), or they can include information on stakeholder preferences for different levels of performance for each service.
Table 1. An example of an alternatives matrix for three management alternatives affecting four services.
|Status Quo/BAU||Alternative A||Alternative B|
Alternatives matrices can distill results from much of the assessment process documented in this guidebook, summarizing the state of knowledge for a management decision: what is known about how the ecosystem of interest will respond to management, stakeholders’ preferences for the changes resulting from management, and confidence in that information. The measures and units that populate the matrix will vary (dollar value, percent change, or BRI), depending on the methods used for the assessment. Consequently, these matrices can be a powerful communications tool for managers and stakeholders. Ideally, they will be accompanied by a description of assumptions and discarded options.
In principle, alternatives matrices should include measures of all the important services significantly affected by management actions, even services about which there are uncertainties. Explicit recognition of uncertainties can point to needed research or collaboration. It also can suggest a conservative approach to decision making until knowledge gaps are filled.
Spatial variability in management and in the provision of services can often be visualized by complementing the alternatives matrix with spatially explicit maps of service provision. Geospatial tools can estimate the production and value of services for in a spatially explicit manner (e.g., InVEST , ARIES).1 Maps are most often used to show the supply(location and amount) of a service, but as described in this guidebook’s discussion of benefit-relevant indicators (BRIs), that information alone is insufficient for analysts to determine whether the service provides a benefit to people (meets demand). In the case of a use service, the service (e.g., water yield)needs to reach the user, the user needs to be able to access the service (e.g., by boat), and the service needs to be sufficient for use (e.g., meet water quality thresholds necessary for swimming). In the case of a preventative service, the service needs to reduce risk to the user (e.g., the flood plain or coastal barrier system needs to be in the right place to provide protection).2 Thus it is critical to have information about the supply of services (location and amount), the beneficiaries of services (location and amount of demand), and the characteristics of possible losses along the way.Mapping the flow of some services to beneficiaries (e.g., water-based services within watersheds) is straightforward, and mapping the flow of some other services (e.g., mapping the existence value of biodiversity) can be challenging.
When supply and demand information is integrated into an ecosystem services assessment through valuation methods, the resulting measure of ecosystem services benefits can be shown on a map, allowing analysts to explore spatial variability in services values. Figure 1 shows use of the InVEST model to estimate the dollar values of services affected by land use change scenarios. In this example, as in many such examples, the map depicts the value of services at the location of production (the source), not at the location of the actual beneficiaries (though in this case the value is estimated from the beneficiaries’ perspective).
Figure 1. InVEST model estimations of the values of services affected by land use change scenarios.
Source: K.Kovacs, S. Polasky, E. Nelson, B.L. Keeler, and D. Pennington, “Evaluating the Return in Ecosystem Services from Investment in Public Land Acquisitions,” PLoS ONE 8(6)(2013): e62202, doi:10.1371/journal.pone.0062202.