Tree Assessment: Case Study 4

Assignment:

The tree pictured above has shed multiple limbs during wind events but has caused little or no damage or disruption. The tree is heavily managed due to the large volume of visible decay at its base, throughout the trunk and in the upper crown. Previous actions have included air-knifing of the trunk flare to inspect root quality and reduction pruning to mitigate against future limb failures.

Target and Site:

Both low and high voltage electrical infrastructure as well as a low use road are within the target zone of the tree. Soil had previously become heavily compacted on the road side due to drivers pulling off the road to exploit the shade provided by the tree (bollards have since been erected to stop this from occurring). However, a large residential block on the opposite side of the tree provides large volumes of exploitable soil.

Tree Condition:

The crown density and foliage colour of the tree would suggest that it is in good health. However, as mentioned above, there is a large amount of visible decay throughout the tree (see image 2 & 3). Additionally, the most recent inspection identified two hazard beam cracks in separate limbs (see image 4 & 5)

Analysis:

The extent of decay present in the tree is clearly identifiable and requires no further enquiry. More import is the stability of the trees root plate and the condition of the remaining sound wood in the trunk and upper canopy. The multiple limb shedding events would suggest that the tree is in senescence but should be retained for as long as possible due to its high wildlife value.  

Recommendations:

1. Electrical resistance tomography to measure sound wood quality and tilt sensors to measure root plate stability are a priority for this tree so that a long or short term management plan for the tree can be established.
2. Further retrenchment pruning of over reaching and highly decayed scaffold branches should be considered in an attempt to mitigate against further limb failures. The hazard beam crack limbs should be trimmed out of the canopy immediately.