Species Analysis
Understanding the trees in our hazard management program
The Trees of Lake Connor Park
Our forest is predominantly composed of native Pacific Northwest conifers, with Western Hemlock making up the vast majority of our hazard tree inventory. This isn’t surprising – Hemlocks are susceptible to several root diseases and are a natural part of our forest succession story.
Species Distribution
Western Hemlock
Tsuga heterophylla – The dominant species in our program. Hemlocks are particularly susceptible to Annosus root rot and Armillaria, which can weaken root systems and lead to windthrow. Our mature hemlocks range from 100-200 feet tall with diameters up to 42 inches.
Western Redcedar
Thuja plicata – These iconic Pacific Northwest trees are generally more disease-resistant but can develop heart rot over time. Many of our redcedars require monitoring for structural integrity issues and crown dieback.
Douglas-fir
Pseudotsuga menziesii – Our Douglas-firs are some of the tallest and most impressive trees in the park. They’re susceptible to laminated root rot and were significantly impacted during the November 2024 storm event.
Bigleaf Maple
Acer macrophyllum – These deciduous hardwoods add seasonal color to our forest. Issues often involve branch failure potential and root crown damage.
Red Alder
Alnus rubra – Fast-growing pioneer species that naturally have shorter lifespans. We monitor older alders for decay and structural issues.
Other Species
Including Sitka Spruce, Cherry, Black Cottonwood, Balsam Fir, and River Birch. These species add biodiversity to our forest ecosystem.
Why Are Hemlocks So Prominent?
You might wonder why Western Hemlock makes up 73% of our hazard tree inventory. There are several reasons:
- Natural abundance: Hemlock is the climax species in Pacific Northwest forests, meaning it naturally dominates mature forest ecosystems like ours.
- Disease susceptibility: Hemlocks are particularly vulnerable to Annosus and Armillaria root rots, which are endemic to our region.
- Shallow root systems: Compared to Douglas-fir, Hemlocks have shallower roots, making them more prone to windthrow when root systems are compromised.
- Age of forest: Many of our Hemlocks are mature trees entering their later life stages where disease susceptibility increases.