Draft:Tree defects

A tree defect is any feature, condition, or deformity of a tree that indicates weak structure or instability that could contribute to tree failure.

Common types of tree defects
Codominant stems: two or more stems that grow upward from a single point of origin and compete with one another.


 * common with decurrent growth habits


 * occurs in excurrent trees only after the leader is killed and multiple leaders compete for dominance

Included bark: bark is incorporated in the joint between two limbs, creating a weak attachment.


 * occurs in branch unions with a high attachment angle (i.e. v-shaped unions)


 * common in many columnar/fastigiate growing deciduous trees

Dead, diseased, or broken branches: woundwood cannot grow over stubs or dead branches to seal off decay.


 * symptoms/signs of disease:

e.g. oozing through the bark, sunken areas in the bark, and bark with abnormal patterns or colours, stunted new growth, discolouration of the foliage

Cracks


 * longitudinal: decay, rips/tears


 * Seams – bark edges meet at a crack or wound
 * Ribs – bulges, indicating interior cracks


 * transversely: buckled wood

Cavity and hollows: sunken or open areas wherein a tree has suffered injury followed by decay


 * further indications: fungal fruiting structures, insect or animal nests

Lean: a lean of more than 40% from vertical presents a risk of tree failure

Taper: change in diameter over the length of trunks branches and roots

Epicormic branches (water sprouts in canopy or suckers from root system): often grow in response to major damage or excessive pruning

Roots:


 * girdling roots compress the trunk, leading to poor trunk taper, and restrict vascular flow


 * kinked roots provide poor structural support; the kink is a site of potential root failure


 * circling roots occurs when roots encounter obstructions/limitations such as a small tree well or being grown too long in a nursery pot; these cannot provide adequate structural support and are limited in accessing nutrients and water


 * Healthy soil texture and depth, drainage, water availability, makes for healthy roots