section2-03b

Measure

Standards

Land Species

Diversity
Ecosystems with more species are flexible in responding to change and generally operate more efficiently than ecosystems with fewer species. Parks Canada maintains lists of the species present in each park rated according to abundance. The expected number of species in a park is determined based on an analysis of the average species numbers found within a given zone across North America. Not surprisingly, more species are expected in hotter areas.

Green: the number of species is close to or greater than what is expected for the climate (i.e., within one standard deviation¹ of the expected number).
Yellow: the number of species is between one and two standard deviations lower than the expected number.
Red: the number of species is more than two standard deviations lower than expected for the climate.

Predator and Prey
In healthy ecosystems, the populations of predators and their prey maintain a rough balance over time. Loss of a key predator or a large change in abundance (either up or down) can lead to large-scale ecosystem impacts (e.g., lack of a predator can lead to overgrazing by its usual prey with impacts on vegetation, soil erosion and loss of nutrient cycling). Scientists in Parks Canada determine whether characteristic predators and prey are present in a park in sufficient number, and the extent to which loss of characteristic predators and/or prey is having larger impacts on the ecosystem.

Green: all native large predators and prey are present in numbers consistent with historical variability.
Yellow: the abundance of at least one native large predator or prey is outside levels of historical variability, but no secondary impacts on the ecosystem are presently known.
Red: the abundance of at least onenative large predator or prey is outside the range of historical variability and there is evidence of significant secondary ecosystem impacts.

Species Loss
In a healthy ecosystem, viable populations of breeding native species are maintained over time. Parks Canada tracks the number of breeding species within a park in its species database. A determination of whether a species has been lost reflects the consensus of our scientists who study species at risk. How many species an ecosystem can afford to lose is a matter of judgement. Generally, the loss of one or two species in a park would reduce the number of species by less than one per cent; a loss of several species would reduce the numbers by less than 15 per cent. Greater loss implies more ecosystem change.

Green: less than 1% of native, breeding species lost.
Yellow: between 1% and 1.5% of species are lost, suggesting concern that all aspects of the ecosystem are not working properly.
Red: more than 15% of species are lost, indicating possible loss of whole groups of organisms and definite ecosystem change.

Land Processes

Plant Growth
An important question to ask about an ecosystem is whether the rate of plant growth is consistent over time. A strong increase in plant growth creates the potential for native species to be replaced, while a steep decline in plant growth leads to a weak response to other changes.

An indirect measure of plant growth is the amount of light absorbed each year by plants and soils. Satellite photography – the same images used for daily weather reports can measure light absorption quite precisely over large areas. This information was used to study whether plant growth in national parks was increasing or declining over the 1993-2001 period. Northern parks, including Wood Buffalo, were updated for the 1998-2006 period.

Green: no identifiable trend in plant growth.
Yellow: a slight change up or down (a slope² between two and four standard errors³ from zero) in plant growth.

Forest Fires
Over time, fire changes and rearranges the age and composition of vegetation within national parks and contributes to the existence of healthy ecosystems with greater biodiversity. The historic average number of hectares burned per year has been determined for twenty-four national parks based on fire history studies (e.g., a combination of physical fire evidence, historical accounts and vegetation age stand analysis).

Green: annual average area burned is 20% or more of the area burned historically.
Yellow: average 5% to 20% of the area burned historically.
Red: annual average of area burned is 5% or less of the area burned historically.

Land Stressors

Developed Area
Developed areas in and around parks can disrupt native species and natural ecological processes. An indirect measure of the extent of human development is the percentage of the greater park ecosystem that contains outdoor light in excess of specific levels. Parks Canada is able to calculate this percentage using U.S. Defence Department satellite images of Earth at night (2000). Studies have suggested thresholds for the percentage of a given area in which development (as indicated by light levels) is likely to have disruptive effects on native species.

Green: 3% or less development.
Yellow: 3% to 41% of the greater park ecosystem developed.
Red: 41% or more development.

Population Density
Another indication of stress on ecosystems is density of human population. A recent study of U.S. national parks shows that human population density is correlated with the rate of species loss. Parks Canada calculates human population density in greater park ecosystems by matching population density values from Statistics Canada’s 2001 census tracks to the greater park ecosystem and computing the average number of persons in a square kilometre.

Green: less than one person per square kilometre.
Yellow: one to 100 people per square kilometre.
Red: more than 100 people per square kilometre.

Internal Road Densities
Roads are a dominant type of human infrastructure in national parks. Roads contribute to landscape fragmentation, reduced habitat range, higher levels of invasive species and increased species mortality. The density of roads within national parks is measured from national topographical series maps produced by Natural Resources Canada (e.g., the number of metres of road per square kilometre of national park area). Reviews of scientific literature on road density have suggested that densities beyond certain critical values have negative effects on large mammal species.

Green: Density 200 metres or less of road per square kilometre.
Yellow: Density of 200-600 metres of road per square kilometre.
Red: Density of more than 600 metres of road per square kilometre.

Water Stressors

Water Quality
Water quality is the most commonly measured aspect of ecological integrity. Water pollution can make aquatic habitats unsuitable for fish, insects or plankton. The Canadian Environmental Sustainability Indicators report includes a water quality index that considers the effects of up to ten of the most threatening pollutants in streams and lakes across Canada. Where pollution effects are infrequent or minor, the index shows good water quality.

Green: 80 to 100 on the water quality index (rarely or never exceeds water quality guidelines)
Yellow:   45 to 79.5 on the water quality index (often or sometimes exceed water quality guidelines)
Red: 0 to 44.9 on the water quality index (usually exceeds water quality guidelines by a considerable margin).

1. Standard deviation is a statistic that describes how ordinary a value is. At one standard deviation from the average a value is slightly odd, while two standard deviations from the average is quite unusual.
2. Slope describes how rapidly a relationship changes (in this case, with each successive year).
3. A standard error is a standard deviation corrected for the number of observations made.