This section includes adapted excerpts from two NESP papers “Best Practices for Integrating Ecosystem Services into Federal Decision Making” and “Building Ecosystem Services Conceptual Models.”
Introduction to Conceptual Diagrams
In an ecosystem services assessment, conceptual diagrams provide a systematic approach to connect ecological conditions and societal benefits. An ecosystem services conceptual diagram—also known as a causal chain, conceptual model, logic model, path model, or means-ends diagram—links changes caused by an external stressor or intervention through the ecological system to socio-economic and human well-being outcomes (Figure 1). These diagrams can also include direct (not ecologically mediated) changes in human well-being.1 Conceptual diagrams can support widespread implementation, underpinning both simple and complex methods while helping to improve consistency and credibility.
Figure 1. Components of an ecosystem service conceptual diagram
Conceptual diagrams could be useful for applications like streamlining National Environmental Policy Act (NEPA)-related assessments and building common assessment templates for activities ranging from forest planning, to coastal restoration, to energy development siting, to incentivizing of native plantings in agricultural fields.2
Conceptual diagrams can be used to evaluate current conditions, desired conditions, and changes caused by a management alternative. When assessing current or desired conditions, these diagrams reveal the services provided and also help stakeholders and decision makers consider what services they may want to enhance or sustain when setting future objectives. When assessing alternatives, they assess how management options will change the biophysical landscape (and related human behaviors) and then relate those changes to both the provision of ecosystem services and ultimately societal benefits. These alternatives can include individual changes in conditions at one site, changes in conditions for multiple sites, or combinations of actions that make up a management scenario or management plan. They also reflect changes in human behavior that may be expected as part of these ecosystem changes, for example, increases in recreational visits (and hence benefits) that might be expected when relevant conditions improve at sites used for recreation. Conceptual diagrams can also be used to consider project options (e.g., funding wetlands restoration in Florida versus Minnesota) or policy choices, which are evaluated in terms of the actions they imply—for example, policies affecting incentive payments for protecting riparian zones would be evaluated in terms of the changes to those zones. Conceptual diagrams linked to alternatives will be the inputs for the analysis step.
Creating conceptual diagrams is one of many simultaneous and interactive scoping activities. Other activities are assessing current status and trends (both ecological and social) and identifying services, objectives, and alternatives (Figure 2). Stakeholders can be engaged in all of these activities. For example, by identifying services they care about, stakeholders can provide information directly relevant to the development of causal chains and conceptual diagrams. Conceptual diagrams can serve as communications tools. For example, resource managers often think about outcomes in terms of ecological conditions alone—healthy long-leaf pine forest, fire-resilient riparian ecosystems, or hydrologically functional wetlands. Unlike managers, stakeholders may be apt to think about changes to their surroundings in terms of concrete experiences and opportunities—areas available for fishing, trails open for hiking, water available for irrigation, risk of flood or fire to personal property. In other words, stakeholders think in terms of ecosystem services, though they may not use that term, whereas resource managers may think in terms of the conditions that lead to those services.
Figure 2. Simultaneous and interactive scoping activities initiate the decision process
Conceptual diagrams can be developed for any given site and intervention or created as reference models for a general type of intervention across sites. Given a constrained set of ways in which managers manipulate the natural environment and a fixed number of effects such management can have on the environment and people, it seems possible to establish a reference set of evidence-based conceptual diagrams that become a go-to resource that can provide efficiency and consistency in application.
Types of Conceptual Diagrams
Three variations of conceptual diagrams can be adapted and used for different aspects of and steps in decision making.
Exploratory conceptual diagrams are preliminary models that illustrate major relationships but are most often incomplete and unrefined. These preliminary models are often developed over the course of a few hours or a day with the input of experts, practitioners, and stakeholders that bring together a range of perspectives (e.g., cultures, roles, socio-economic status) and knowledge (e.g., ecology, economics, medicine, anthropology). These models help stakeholders and experts get on the same page and communicate priorities. However, they can be challenging to produce when teams are unfamiliar with ecosystem or human well-being aspects of a system. In these situations, general conceptual diagrams provide a starting point for exploration.
General conceptual diagrams are completed and refined models that capture the cascade of changes through the system and that fully articulate, in generalized categories, the benefits for and impacts on human well-being. These diagrams are designed to be the parent model for a type of intervention (e.g., salt marsh restoration, utility-scale solar development) that can be adapted to different contexts. The models can be developed by aggregating common elements across site-specific conceptual diagrams for a given intervention or by directly creating a generalized diagram, which will require expert knowledge and evidence review. In addition to helping stakeholders and experts get on the same page, these general diagrams are particularly useful for providing consistency in application/implementation and, often, a key set of services and indicators to include. They also provide a user-friendly starting point for those not knowledgeable about ecosystem services, and they can increase efficiency of implementation. Therefore, their use could be incorporated into agency directives, manuals, handbooks, or other resources provided to managers. General conceptual diagrams made accessible through a library-type resource can ensure teams have access to the best available science and can reduce duplication of effort.
Specified conceptual diagrams are complete and refined versions of either exploratory or general diagrams that are adapted and specified for a particular place and decision context. These diagrams are more likely to follow best practices and to include measurable indicators. These are the diagrams that will most often be used in decision making because they’ll have stakeholder and expert buy in and will be targeted to the relevant decision context. Adapting a general diagram to a local context should require comparatively less time and effort and less expertise in ecosystem services than starting from scratch. It can also provide a common level of underlying knowledge (best available science) and offer consistency in application. Specified conceptual diagrams can be the foundation for further assessment of evidence for a particular site or context, construction of a predictive model, or monetary or non-monetary valuation.
Building Conceptual Diagrams
Answering the following questions sequentially will help assessors build conceptual diagrams for decision making (Figure 3):
- How does a policy, management decision, or program action affect biophysical and ecological conditions (e.g., infrastructure, ecosystem structure and function)?
- How do the changes in biophysical and ecological conditions lead to changes in the delivery of goods and services, including ecosystem services to the specific people who are using them, affected by them, or appreciating them (e.g., availability of irrigation water for farmers, sustainability of a rare bird population)?
- How do those changes in the delivery of goods and services affect benefits or costs to individuals or groups (e.g., time spent in traffic, cost of hospital visits, additional fish caught, value of property)?
- How does the policy, management decision, or program directly affect people (e.g., job creation, access to resources, capacity building)?
- Have all services that people care about been included in the diagram (even if they will not all be included in the final analysis)?
Using Conceptual Diagrams
Agencies and experts that have worked with the (NESP) over the years have identified conceptual diagrams as a useful tool for streamlining environmental impacts statements, engaging stakeholders, encouraging a common understanding among experts, and improving project planning and alternatives assessments. Non-federal land managers like The Nature Conservancy use similar methods.3 Conceptual diagrams can also be useful for prioritization by allowing better comparisons of projects, selection of key indicators, visioning efforts, and identification of knowledge gaps and research priorities.4 These diagrams can facilitate incorporation of ecosystem services into decision making by helping to
- Get stakeholders and experts on the same page.
- Provide an intuitive entry point for those new to considering ecosystem services because no particular expertise in ecosystem services is needed to understand these chains.
- Capture priorities and link them to interventions in a transparent and systematic way.
- Make sure there are no critical outcomes/impacts that are missing from consideration to help identify unintended effects both positive and negative.
- Provide an evidence-based qualitative assessment of ecosystem services implications of potential interventions/alternatives/scenarios that indicates the expected magnitude and direction of change.
- Provide a common foundation of best available science to reduce time and expertise needed for use and to reduce duplication of effort.
- Identify critical information or research gaps that generate significant uncertainty for decision makers.
- Identify a subset of socio-economic metrics that best capture important endpoints.
- Provide consistency in services assessed, evidence considered, and metrics selected.
- Provide a consistent and credible foundation for qualitative assessments, quantitative assessments, or monetary or non-monetary valuation where such methods are desired.
Conceptual Diagrams in Ecosystem Services Assessments
An ecosystem services assessment must consider how and which changes in the environment affect benefits to people. When causal connections to people are not made explicit, it is unclear whether and how each ecological change will result in changes to social benefits, and important changes to societal benefits may be left out of the analysis.
For example, Figure 3a compares an ecological assessment with ecological indicators that are not explicitly linked to things people value, to an ecosystem services assessment using benefit-relevant indicators (BRIs). In this example, resource managers are assessing mechanical thinning of forests to reduce the intensity of fire. An ecological assessment of this option might consider changes in the fuel load, which affects fire intensity, along with a variety of other biophysical implications. An ecosystem services assessment, in contrast, would extend these conceptual diagrams to specific benefits to people that would result from mechanical thinning and the consequent management of fire risk (Figure 3b). There are many ways that people might be influenced by this action. For example, by reducing fire intensity, the management action would reduce the incidence of smoke and the extent of poor air quality and exposure, reducing adverse health impacts from fire for nearby residents (e.g., as hospital visits, missed work days, or actual health care costs).5 These considerations extend the ecological assessment to an ecosystem services assessment by including the interaction of people with the ecology (Figure 3b). Best practice for ecosystem services assessment will focus on estimation of changes in ecosystem service values or preferences (blue text in Figure 3), but when time or resources are limiting, the minimum standard for assessment is to focus on BRIs (red text in Figure 3).
Figure 3. Differences between ecological and ecosystem services assessments and indicators
Note: Causal chains consider expected outcomes from forest fire management activities like mechanical thinning. Black text indicates an ecological assessment and indicators; red text indicates extension of an ecosystem services assessment; indicators within ovals illustrate BRIs; and blue text indicates measures of social benefit and value. The demarcation among ecology, ecosystem services, and social benefits is not absolute (the lines between categories are drawn differently by different people), as represented by the tri-colored arrow.
Adding these details (and subsequent quantification) requires expertise. Practitioners should engage experts from all relevant fields to ensure that the diagrams are as complete and accurate as possible. This group may include (but is not limited to) physical and biological scientists (hydrologists, wildlife biologists, botanists, ecologists, fisheries managers, ecological modeling experts, and foresters), social scientists, and economists as well as experts in public health and community development.
Developing conceptual diagrams is a critical step to ensure that ecosystem services assessments are relevant, comprehensive, and transparent. All possible impacts to valued services should be included in the diagram, even those likely difficult to measure or model or likely to have only minor effects on people (Figure 4). This transparency enables practitioners to explain to stakeholders why only select services are carried forward in further analysis and hopefully reduces accusations of forgetting or ignoring services. Because all impacts are included, this process will likely identify too many services to be meaningfully quantified in any ecosystem services assessment. Those effects likely to be most important to the decision—often those expected to have the largest impacts on human welfare—can be targeted for quantitative analysis (see “Selecting Ecosystem Services”). However, by identifying the full range of pathways through which actions can influence people regardless of jurisdiction, these diagrams can often provide important insights for decision making and present opportunities to identify necessary partners and stakeholders.
Figure 4. Conceptual diagram with causal chains for an ecosystem services assessment of a forest management alternative
Note: This conceptual map of simplified causal chains shows possible outcomes from forest fire management activities like mechanical thinning. Black text indicates an ecological assessment and indicators; red text indicates extension to an ecosystem services assessment; and blue text indicates measures of social benefit and value.
Another reason that conceptual diagrams are useful is that they can help to avoid double counting. Double counting occurs when an estimate of a value for an output (something further to the right on a causal chain) is added to the estimated value of an input along the same chain or pathway in these diagrams (something further to the left on the causal chain). A comprehensive value estimate for any element on a chain will capture some of the values associated with all of the elements to the right of it on the same chain—even if one ecological outcome leads to multiple social benefits. In principle, a conceptual diagram helps identify the logical endpoints of how the system responds to management, with each endpoint (on the right side of the diagram) representing a single service or benefit that is meaningful to an identified beneficiary or stakeholder population. If a single indicator is selected to capture each meaningful endpoint to each affected beneficiary group, double counting is less likely to occur. Hence, a properly constructed conceptual diagram can be used to minimize double counting in an ecosystem services assessment because it clearly illustrates these input-output relationships.6 However, no diagram can eliminate all possibility of double counting. Hence, if the analysis is to proceed to values assessment, it would be important to involve experts in monetary or non-monetary valuation to ensure that double counting is eliminated or minimized and that all major sources of value are considered (i.e., to avoid under counting as well as double counting).
Conceptual diagrams and decision support tools
Conceptual diagrams can be built on to develop more detailed decision support tools. Evidence libraries can be constructed to assess and document what is generally known about the relationships in the diagram and to provide an initial assessment of magnitude and direction of changes. Assessments of the evidence that document confidence in the evidence for each relationship in the diagram can be used to develop strength of evidence maps, provide an assessment of knowledge gaps, and indicate critical research or monitoring needs. Given that conceptual diagrams end with a series of benefit-relevant outcomes, they provide an ideal starting place for the development of benefit–relevant or socio-economic indicators that can be used to track progress and performance in measures that are meaningful to decision makers and the public. With sufficient resources, these conceptual diagrams can also be the foundation for quantitative predictive models.7
Limitations of Conceptual Diagrams
Ecosystem service diagrams are conceptual schematics to help users think through the logic of changes in a system, but they do not depict all important aspects of these changes. They can sometimes include a simplified indication of the temporal dimensions of changes, such as temporary changes versus persistent changes, but often the temporal dimension is missing. Ecosystem service conceptual diagrams do not explicitly show the spatial dimensions of system dynamics, but they can help identify where spatial dynamics will be critical—for example, where distance to a resource or exposure can affect human use or impact—and therefore should be considered in the assessment. We recognize that spatial context plays an important role in many natural resource decision processes, and because the delivery of ecosystem services is not uniform across the landscape, complementary spatial analysis is likely needed.
Olander, Lydia, Sara Mason, Katie Warnell, and Heather Tallis. 2018. Building Ecosystem Services Conceptual Models. National Ecosystem Services Partnership Conceptual Model Series No. 1. Durham, NC: Duke University, Nicholas Institute for Environmental Policy Solutions. https://nicholasinstitute.duke.edu/conceptual-model-series.
This report facilitates development and use of evidence-based ecosystem services conceptual models in federal decision making by presenting a “how-to” guide and illustrative examples.
Olander, Lydia, Robert J. Johnston, Heather Tallis, Jimmy Kagan, Lynn Maguire, Steve Polasky, Dean Urban, James Boyd, Lisa Wainger, and Margaret Palmer. 2015. “Best Practices for Integrating Ecosystem Services into Federal Decision Making.” Durham: National Ecosystem Services Partnership, Duke University. https://nicholasinstitute.duke.edu/ecosystem/publications/best-practices-integrating-ecosystem-services-federal-decision-making.
This paper sets best practice standards for implementation of ecosystem services to assist federal agencies. Its recommendations include details on use of ecosystem services causal chains.
Olander, Lydia P., Dean Urban, Robert J. Johnston, George Van Houtven, and James Kagan. 2016. “Proposal for Increasing Consistency When Incorporating Ecosystem Services into Decision Making.” National Ecosystem Services Partnership Policy Brief 16-01. Durham, NC: Duke University. https://nicholasinstitute.duke.edu/publications/proposal-increasing-consistency-when-incorporating-ecosystem-services-decision-making.
This policy brief illustrates the use of ecosystem service conceptual diagrams as a tool for supporting consistency—that is, use of one set of services and metrics—across the varied actions and geographies relevant to a decision maker.
Qui, Jiangxiao, Edward T. Game, Heather Tallis, Lydia Olander, Louise Glew, James, S. Kagan, Elizabeth L. Kalies, Drew Michanowicz, Jennifer Phelan, Stephen Polasky, James Reed, Erin O. Sills, Dean Urban, and Sarah Kate Weaver. 2018. “Evidence-Based Causal Chains for Linking Health, Development, and Conservation Actions.” Bioscience 68 (3): 182–193. https://academic.oup.com/bioscience/article/68/3/182/4850537.
This journal article discusses how causal chains can help link across disciplinary expertise and perspectives.
Tallis, H., K. Kreis, L. Olander, C. Ringler, et al. 2017. Bridge Collaborative Practitioner’s Guide: Principles and Guidance for Cross-sector Action Planning and Evidence Evaluation. Washington, D.C.: The Nature Conservancy. http://bridgecollaborativeglobal.org/wp-content/uploads/2017/10/Bridge-Collaborative-Principles-and-Guidance-2017.pdf.
This report provides guidance on developing robust results chains for analyzing interventions and linking them to evidence.
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