Ecological Restoration Guidlines for British Columbia

Concepts of Scale in Ecological Restoration

Ecosystems function at multiple spatial and temporal scales (Holt 2000), and so does ecosystem restoration. Table 2 provides examples of scales of restoration. Generally, examining ecosystem restoration needs at the scale of ecological processes is the most effective and appropriate way of addressing ecosystem damage, as it is ecological processes that regulate the condition of ecosystems. Natural disturbances and natural disturbance patterns are prime ecological processes that pertain to ecological restoration. It is implicit in process-based restoration that if the processes that were affected are restored, then other ecosystem components should also recover. This is sometimes referred to as the coarse filter approach. However, specific habitat needs or components within these ecosystems are often a crucial component of a restoration program. For example, wildlife trees are a critical habitat component for cavity nesters. The smallest scale of restoration is at the level of the individual species. While it isn't generally efficient to focus on one species, as opposed to a whole ecosystem, there are sometimes compelling reasons to do so. Restoration at the scale of habitat and species is sometimes referred to as the fine filter approach.

Dave Polster
Scales of Restoration. This photograph illustrates natural river morphology and the after-effects of fire, both prime examples of ecological processes. The process of succession will eventually regenerate a forest on the burn site. The small wetland at the top of the photo shows a habitat scale element. The standing snags are habitat features, and can provide critical habitat for specific species.

Jim Gilliam
Burning (coarse filter) restoration projects like this one near Squamish take into account fine-filter concerns, like preservation of important veteran trees and snags, and control of invasive weeds.

Table 2: Potential Scales of Restoration (adapted from Holt 2000)

Restoration Scale	Examples
Restoration of processes	Re-introduction of natural disturbances: Setting ground fires in the Ponderosa Pine, Bunch Grass and Interior Douglas Fir zones Restoring unregulated flooding in formerly dammed or dyked river channels Restoring the former hydrologic regime post-logging or post-mining Reintroduction of patterns related to natural disturbance: Increasing the area of grasslands in the landscape Initiating or speeding up succession, to restore seral stage distributions across the landscape (e.g. restoring for old forests) Restoring former abundance of hardwood and mixed forest stands
Restoration of Habitat (ecosystem components)	Restoration of specific structures/features within ecosystems: Restoring large woody debris in streams Restoring large-sized trees to managed forests Restoring large-sized standing dead trees (wildlife trees), and fallen trees (coarse woody debris) to managed forests Restoration of soil in industrial areas, and in ecologically sensitive areas Restoration of wildlife habitat features, i.e. known critical or rare habitat such as: coarse woody debris in appropriate salamander sites tree cavities for cavity nesters lichen populations for caribou browse
Restoration of Species	Re-introduction of extirpated species (e.g., burrowing owl) Stabilization of decreasing populations (e.g., mountain caribou) Removal/management of invasive exotic species (e.g. Scotch broom/knapweed) Restoring keystone species (e.g. salmon, major tree species), and rare and endangered species, Restoring habitat for umbrella species (e.g. grizzly bear, caribou)

Coarse and Fine-Filter Restoration

The coarse filter concept is an ecosystem-based approach that assumes most species will have their needs met by restoring or protecting the fundamental structure of an ecosystem. For example, restoring natural flows to a degraded wetland can provide conditions suitable for the re-establishment of most wetland species. Fire-based restoration is another coarse-filter process, where it is assumed that the opening of forests or grasslands by fire will meet the needs of species dependant on these habitats. However, the fine filter approach should always be used in tandem with the more generic coarse filter approach. While it is impossible to manage for all the different species or attributes in an ecosystem, there are always some that will require individual attention. In the example of fire restoration, specific habitat features, including wildlife trees or coarse woody debris, may need to be preserved or created, weedy invasive species may need monitoring and control, and the timing or location of burning may need to take into account the nesting season of certain birds.