Red Alder
Alnus rubra
Pioneer species found throughout the Tri-Cities, especially near creeks and in recovering forest areas. Common along the Traboulay PoCo Trail.
Identification
15-25m (50-80ft)
Up to 0.5m diameter with thin, smooth, light grey bark often covered with lichens
Oval leaves (7-15cm) with doubly-serrated edges and pointed tips, edges slightly rolled under
Small woody cones (1-2cm) that persist on the tree year-round
Key Identifying Features
- Smooth, pale grey bark with white patches
- Leaves with rolled-under edges
- Persistent small woody cones
- Inner bark turns orange when scratched
- Often grows in dense stands
Identification Photos
Click any photo to enlarge. Photos help with identification but may vary by age, season, and location.
Tree Care
Watering
Prefers moist conditions, naturally found near streams. Relatively drought-tolerant once established.
Pruning
Generally not pruned as an ornamental. Remove hazardous deadwood as needed.
Best time: Late fall to winter when dormant
Common Issues
- Short-lived (40-60 years typical lifespan)
- Tent caterpillars
- Alder flea beetle
- Phytophthora root rot in wet conditions
Maintenance Notes
Low maintenance but short-lived. Plan for replacement as trees age. Nitrogen-fixing roots benefit nearby plants.
Root System
Shallow, spreading root system with nitrogen-fixing nodules
Moderate spread, typically matching canopy width
Potential Concerns
- Nitrogen-fixing roots actually improve soil for other plants
- Shallow roots mean lower stability than conifers
- Less likely to damage infrastructure than maples
- Roots may sucker after removal
Hazard Assessment
Common Failure Modes
- Whole-tree windthrow in storms
- Trunk failure in older trees
- Branch failures from decay
- Root failure in saturated soil
Warning Signs to Watch For
- Bracket fungi on trunk
- Significant lean
- Sparse foliage in crown
- Bark falling off in patches
- Multiple dead branches
Removal Considerations
Key Considerations
- Relatively soft wood, easy to cut
- Often grows in clusters requiring multiple tree removal
- Smaller size makes access easier
- Wood decays quickly if left on site
- Often protected near streams and wetlands
Permit Notes
May be protected if within riparian zones. Check for stream setback requirements. Often less restricted than conifers.
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