Northern spotted owl (Strix occidentalis caurina) recovery strategy: chapter 27

Wetter ecosystems: Maritime Coastal Western Hemlock and Mountain Hemlock Biogeoclimatic Zones

Natural Disturbances: Rare to infrequent stand-initiating events.

• Three or more canopy layers, multi-species canopy dominated by large (>75 cm dbh) overstorey trees (typically 37–185 stems/ha)
• Moderate to high (60–80%) canopy closure.
• Five or more large (>50 cm dbh) trees/ha with various deformities (e.g., large cavities, broken tops, dwarf mistletoe infections).
• Five or more large (>75 cm dbh) snags/ha.
• Accumulations (>268 m³/ha) of fallen trees and other coarse woody debris on the ground.

• Two or more canopy layers, multi-species canopy dominated by large (>50 cm dbh) overstorey trees (typically 247–457 stems/ha, although densities as low as 86 stems/ha are possible where large diameter trees are present).
• Moderate to high (60–80%) canopy closure.
• Five or more large trees/ha (>50 cm dbh) with various deformities (e.g., large cavities, broken tops, dwarf mistletoe infections).
• Five or more large (>50 cm dbh) snags/ha.
• Accumulations (>100 m³/ha) of fallen trees and other coarse woody debris on the ground.

Dryer ecosystems: Sub-maritime Coastal Western Hemlock and Mountain Hemlock, and Interior Douglas-fir and Engelmann Spruce–Sub–Alpine Fir Biogeoclimatic Zone

Natural Disturbances: Infrequent stand-initiating events to frequent stand-maintaining fires; however, fire suppression has increased the frequency of stand-initiating events.

• Three or more canopy layers, multi-species canopy dominated by large (>50 cm dbh) overstorey trees (typically 173–247 stems/ha, although densities as low as 86 stems/ha are possible where large diameter trees are present).
• Moderate to high (60–85%) canopy closure.
• Five or more large trees/ha (>30 cm dbh) with various deformities (e.g., large cavities, broken tops, dwarf mistletoe infections).
• Seven or more large (>50 cm dbh) snags/ha.
• Accumulations (>268 m³/ha) of fallen trees and other coarse woody debris on the ground.

• Two or more canopy layers, multi-species canopy dominated by large (>30 cm dbh) overstorey trees (typically >247 stems/ha).
• Stands must contain 20% Fd and/or Hw in the overstorey.
• Greater than 50% canopy closure.
• Five or more large trees/ha (>30 cm dbh) with various deformities (e.g., large cavities, broken tops, dwarf mistletoe infections).
• Five or more large (>30 cm dbh) snags/ha.
• Accumulations (>100 m³/ha) of fallen trees and other coarse woody debris on the ground.