Monday, May 23, 2011

Tree Problem 8: Sweet Gum with double leader

Site: Street tree on S side of my street. (NE Portland)
+ Tall tree providing much appreciated summer shade.
- The fruit are a pain for roller skating or skate boarding.

Tree Characteristics
A female Sweet Gum (Liquidambar styraciflua) a young-mature tree with a single trunk DBH 27". Live crown ratio is around 40%.

Tree Health
New foliage looks healthy. No significant signs of decay.

Site Conditions
Street tree with good southern exposure. Level ground, no direct irrigation except in adjacent lawn.

House, cars, power lines.

Tree Defects
Co-dominant leaders from the lowest scaffold branch, possibility of included bark (needs closer inspection). Some exposed roots and sidewalk lifting.

Hazard Rating
Part most likely to fail: branch failure. Moderate failure potential on moderate parts with significant targets for a hazard rating of 2+2+3 = 7.

Hazard Abatement
Inspect for included bark. Prune to subordinate one leader and reduce end weight. Might be a good candidate for cabling to reduce the risk of slitting. Rationale: If this tree fails it could well split in half. Cabling might be a good idea since the leaders are so nearly equal in size, it might be difficult to get one subordinated to the other and it would unbalance the tree to remove a leader.

Other Recommendations
Keep an eye on this one since the risks will only increase with time.

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