There’s a lot of talk in the environmental world about cumulative effects these days. But what are they, exactly? And why are they so important to Interface and the work we do?
Cumulative effects are the combined impacts of all disturbance – big or small, natural or human-caused – on the land in a particular region or study area. Instead of zooming in on a single project, cumulative effects analyses take a broader approach: what is the state of the landscape if we account for all industrial projects, roads, trails, municipalities, forest harvest, forest fires, and insect outbreaks in our study area? A small development may seem insignificant on its own, but when combined with other industrial projects, urban development, roads, seismic lines, cutblocks, and natural disturbance, things can add up quickly.
How are cumulative effects assessed?
First, we compile the best available spatial data to help us tell the story of what is happening on the land. Spatial data can be put on a map: points, lines or polygons, each with unique information attached. We gather both static variables — features that stay the same or change very little over time, such as elevation, soils, and waterbodies — and dynamic variables, which change over time, like roads, forest age, development, and wildfire. We put it all together and ask, how much disturbance, and what kind of disturbance is happening here? And how is it changing?
Next, we look at how these patterns of disturbance affect specific wildlife species or ecosystems. Caribou, moose, elk, aquatic ecosystems, and grizzly bears are but a few of the ecological values, or performance measures, we assess. Each ecological value has unique habitat needs and sensitivities to disturbance, and is assessed using indicators tailored specifically to it. For example, aquatic ecosystems are sensitive to road disturbance. As road density increases, so too does the amount of exposed surface material, which can facilitate easier movement of sediment into waterways. Consequently, watersheds with a road density above 1.2 km/km2 are considered high risk for aquatic ecosystems.
So what can we actually do with cumulative effects, and how does it all come together?
Something truly exciting in the cumulative effects world is the ability to assess landscape change through time. In our work, we develop temporal scenarios. What might the landscape have looked like prior to major human disturbance? This is our reference, or baseline. It gives us an idea of the land’s ability to support each ecological value under optimal conditions. Next, we assess the landscape under current conditions using the most up-to-date data available to us. What has changed, and how? Finally, we look to the future. How might the land be impacted if we continue to develop at the current rate? What if we introduce restoration or other beneficial landscape management into the mix? Here, we can play with hypotheticals and make them more concrete.
And when it all comes together, we work with web developers to present our cumulative effects assessments in a user-friendly way. An online platform that is used by scientists, land managers, and community members alike, providing the ability to assess landscape change through space and time for species and ecosystems of interest. Cumulative effects assessments show which parts of the study area remain relatively intact and are better able to support wildlife and healthy ecosystems, and which areas are more heavily disturbed and less able to support them. This information helps guide restoration, conservation, and other land-use decisions.
With this work, we support informed decision-making and sustainable land management practices that capture the entire story, not just bits and pieces.
