Indicator Roll-up and Synthesis

Simulations can track numerous environmental and economic indicators, providing a diversity of response surfaces to evaluate the performance of land use scenarios. Communication of results to stakeholders and policy makers is problematic, however, because few are likely to be sufficiently familiar with the full suite of indicators to be able to readily interpret units of measurement that vary from habitat suitability to dollars. An additional challenge in communicating results is that the quantity of information can obscure key lessons conveyed by land use simulations. To overcome these challenges indicator results can be converted to a common scale and aggregated indicators into a small set of indices. The approach is based on strategies adopted by the Alberta Biodiversity Monitoring Institute (ABMI), modified to fit the needs of regional land use planning.

Using a common unit of measurement for indicator results

Indicator results can be converted to two common units of measurement, one for environmental indicators and the other for economic indicators. Common units of measurement readily convey the environmental and economic implications of simulation outcomes and permit comparison and aggregation of results across indicators. Indicator results can be presented as departure from reference conditions to achieve units of measurement relevant to management objectives and applicable to a wide range of indicators. The appropriate reference condition for environmental indicators is the estimated range of natural variation whereas for economic indicators the reference condition was today’s economic performance.

Using the range of natural variation as a reference condition is a well-accepted approach for interpreting the status of ecosystems that has been adopted by numerous initiatives including the Terrestrial Ecosystem Management Framework for the Regional Municipality of Wood Buffalo (CEMA 2008) and the ABMI. Risk to species and ecosystem services increases as environmental indicators depart from natural conditions. As such, natural conditions are a relevant benchmark for assessing the compatibility of land use strategies with the LUF’s outcome of “healthy ecosystems and environment”. Departure from natural conditions is not relevant, however, for assessing the performance of economic indicators relative to the Framework’s outcome of “healthy economy supported by our land and natural resources”. In the absence of industrial development, economic indicators such as energy production, royalties, and GDP are effectively 0. Instead, it is possible to adopt the percent departure from today’s economy as a measure for communicating the economic performance of land use strategies. Percent departure from today is consistent with percent growth, a concept often adopted when setting economic objectives.

For environmental indicators, percent departure from natural (%DN) in simulation year i was estimated as the absolute difference between the indicator’s status (yi) and the edge of the RNV (RNVedge), expressed as a proportion of RNVedge (equation 1).

%DN = | yi - RNVedge|/ RNVedge (equation 1)

The upper and lower RNV bounds estimated using ALCES® simulations of natural ecosystem dynamics can be used for RNVedge. If an indicator’s status (yi) exceeds the RNV, the upper bound of the estimated RNV is used for RNVedge whereas the lower bound of the estimated RNV is used when an indicator’s status was less than the RNV. Implied is that an indicator falling above or below the RNV implies a departure from natural conditions (i.e., %DN>0), and that an indicator falling within the RNV is equal to natural conditions (i.e., %DN=0). This approach incorporates indicators that are likely to increase in response to land use such as biota associated with humans and their footprints. %DN is similar to the intactness index developed by the ABMI to communicate monitoring results for species and habitats. The intactness index scales indicator results to between 0 and 100%, where 100% equals natural conditions. Indicator results can be expressed as % departure from natural to align with the concept of setting objectives for environmental attributes as percent acceptable departure from natural (e.g., CEMA 2008). %DN can be calculated for all environmental indicators tracked by ALCES® except for those within the air theme and the disturbed land theme. The concept of %DN is not applicable to these indicators either because coefficients are not available to estimate natural condition (air emission indicators) or because the natural condition equals zero (disturbed land sub-theme).

For economic indicators, percent departure from today (%DT) in simulation year i was estimated as the difference between the indicator’s status (yi) and today’s value of the indicator (y0) , expressed as a proportion of y0 (equation 2).

 %DT = (yi - y0)/ y0  (equation 2)

The status of economic indicators during the last year of the backcast simulation can be used to estimate y0. Unlike with %DN, %DT could have a negative value implying a contraction of the economy.

It should be noted that the concept of expressing environmental and economic status as percent departure from reference conditions is flexible with respect to what the reference conditions are. If guidance is provided with respect to alternative reference conditions, those conditions can be used instead of RNV and today’s economic performance. For example, it may be advantageous to present the status of environmental indicators relative to regulations (e.g., air emission guidelines).

It may not be appropriate to propose a maximum percent departure from natural conditions that could form a management objective for environmental indicators. Incomplete knowledge and stochastic ecosystem dynamics generally do not permit the identification of empirical thresholds for environmental indicators beyond which species and ecosystem services are lost. Rather, the maximum permissible departure from natural conditions is a societal choice regarding the acceptable level of risk to ecosystem goods and services. It may also not be appropriate to propose guidelines for minimum acceptable growth in economic performance. Rather, the maximum permissible departure from natural conditions and the minimum acceptable increase in the economy is a societal choice regarding the appropriate trade-off between risk to ecosystem goods and services and economic growth. Examples of relevant objectives include the following:

• CEMA (2008) recommends that, at a regional scale, environmental indicators be maintained within 10% of the range of natural variation. This objective was set to allow for “some regional scale loss of ecological value resulting from the region’s important economic development, while maintaining ecological risk at acceptable levels”;
• Schieck (2009) suggests that a LARP biodiversity indicator that exceeds 90% of its range of natural variation is probably of concern and should trigger corrective action.

Summary indices

To summarize indicator outcomes, similar indicators can be aggregated to form indices. The approach for aggregating indicators follows the information pyramid approach used by the ABMI to communicate indicator results. Detailed results from the base of an information pyramid and the results are aggregated into summary indices at successively higher levels of the pyramid until, at the peak, a single index is produced. The information pyramid concept is advantageous as it provides a transparent and hierarchical structure for synthesizing results. The pyramid describes how results are aggregated and moving up and down the hierarchy provides summary and detailed information depending on the user’s need.

The primary use of information pyramids within ABMI is to aggregate species results into broader indices based on guilds and taxonomic groups. Here we use information pyramids to synthesize simulation results within environmental and economic indicator categories. The common units of measurement (% departure from natural or % departure from today) are used when aggregating results into indices. Indices from the environmental perspective are referred to as “risk” indices to convey the concept that risk to environmental attributes increases as departure from natural condition increases.

The structure of the information pyramids is flexible. There can be three information pyramids, one for each of three perspectives: economic, environmental, and social. Forming the base of each pyramid are results for individual indicators within a perspective. Sub-theme indices are calculated by averaging results across indicators falling within each sub-theme. Occasionally sub-themes contain numerous indicators, some of which are closely related. When this is the case, indicator results are first averaged by indicator group prior to averaging by sub-theme so that sub-theme indices are not overly influence by similar sets of indicators.

Sub-theme indices are then averaged to calculate theme indices and a single index for a perspective is calculated by averaging theme indices. Calculating an index by averaging the status of its component parts is consistent with the approach adopted by ABMI. Alternatively, indices could be calculated as weighted averages. Often there is no a priori rationale for emphasizing any indicator or group of indicators above others.

The primary benefit of indices is capacity to succinctly compare scenarios in terms of their relative balance between managing environmental risk and supporting economic growth. Environmental and economic outcomes of scenarios can be compared using trade-off graphs. A trade-off graph plots economic performance on the x-axis and environmental risk on the y-axis using high-level indices from the information pyramids.

Although indices are useful for summarizing results, they should not be considered meaningful entities to manage for. Averaging results across indicators has the potential to gloss over declines in species or ecosystem services, and % departure from natural may be an inappropriate measure for some indicators. An example is woodland caribou finite rate of increase for which even small but persistent departures from RNV can cause extirpation of the species. It is also important to realize that indices can not necessarily be interpreted as comprehensive assessments of perspectives, themes, sub-themes, or indicator groups. Rather, the indices summarize the performance of indicators within each category that is tracked during ALCES® simulations. For example, the landscape nutrient runoff loading sub-theme only includes indicators related to nutrification and sedimentation and therefore cannot be interpreted as a comprehensive assessment of water quality that considers attributes such as pollutants and physical characteristics. Due to the inherent loss of information associated with summary indices, managers should drill down into the lower levels of information pyramids (i.e., indicators) when setting management objectives and prioritizing management action towards those indicators at greatest ecological risk.