StressorsA brief introduction to a

revolutionary approach to impact management

In the beginning…

…We spoke of threats. Common threats included:

• Loss of resource quantity• Loss of resource quality• Disruption of a process

Loss of resource quantity:

• Habitat loss

• Reduced availability of a resource (i.e., resource depletion as opposed to removal)

• Barriers to movement/restricted access

Threats

Loss of resource quality:

• Habitat degradation• Fragmentation

Threats

Disruption of processes: Ecological: cyclical processes

disrupted (e.g., hydrologic cycles, fire regimes, natural succession)

Physiological: hibernation, estivation, metamorphosis processes disrupted

Biological: predation rates, competition rates

Threats

Problem: One has to know the species to comprehend a threat• Fragmentation• Habitat degradation• Loss of breeding habitat

The Problem

The Problem(s)

Population dynamics

Prey Base Dynamic

Inter-special Competition

Basic Habitat Need and Function

Predation Rates

Then came stressors…

Stressors

Increased predation rates

Or

Wildlife access to foodstuffs?

What would we tell a project proponent to avoid, minimize, and mitigate?

A stressor is a clear descriptor that needs little to no interpretation

Sedimentation Soil compaction Vegetation removal Floating debris Chemical contamination

Stressors

• Active agents– Vehicle strikes– Trampling– Ensnarement– Electrocution

• Physical agents– Chemical effluent– Sedimentation– Artificial light

Stressors

• Breeding• Feeding• Sheltering

Conservation Needs

Resource 1 R2 R3 R4

Stressor1 S2 S3 S4

Species

Need:Breeding

Species have three needs (i.e., breeding, feeding, sheltering).

A need has resources associated with it (e.g., Breeding need: forested wetlands to nest in, riparian areas to rear young in).

The resources have stressors impacting them.

• Individual• Habitat• Circumstance

Resources

Conservation Needs