Damage to this area for the palm can have dire consequences for long term health and stability.

Trimming the lower trunk to provide clearance will damage the epidermis (outer sheath) and the peripheral ring of lignified fibres that lay below which in turn may compromise the structural stability of the plant and could result in pathogens such as Thielaviopsis, Ganoderma and Fusarium getting a foot hold in the plant as palms do not create secondary growth and cannot repair injuries to their stem.

Furthermore, damage to this area of the trunk which is part of the root initiation zone could also affect future root initiation limiting available water and nutrient required to sustain plant health and to maintain the plant in an upright position.

Hope this helps

regards

David Balsamo

regards

David Balsamo

Any advice would be welcomed.

Thanks
Alison

The heaving around the trunk is no more than two feet so taking this into account
it seems like permeable paving no closer than three feet to the trunk will be fine.

I am unclear as to the detail of the proposed landscape design around your palm as you mention paving and a retaining wall.

Several considerations you need to be aware of when installing paving around you palm.

Excavation associated with the installation of light infrastructure such as pedestrian paving, if kept to a depth of say no greater than 150mm below existing grade will generally not affect the health of the palm despite the loss of some root mass (Do compensate with additional irrigation during the first spring, summer autumn period post construction).

However, installing an impervious pavement over the root zone can reduce soil moisture levels, which in turn can have a negative effect on palm health if the soil beneath dries out. Water pervious paving would be preferable.

Furthermore, the provision of a 3 ft / 1m clearance around the trunk may lead to future lifting of the pavement by the force of root growth beneath. I imagine the palm, if it is 150 years old and if no previous level changes have occurred around the base will exhibit an area of heaved soil surrounding the base of the palm, the result of root massing in this area. Such heave usually dissipates within a couple of meters from the trunk. This area of heave provides a useful guide for paving clearances around palms to minimize paving distress.

With regard to raising soil levels, roots are sensitive to changes in their growing environment and raising soil levels around your palm can have a deleterious impact on the health of your palm. Minor level change may be tolerated; the fundamental consideration is to maintain soil properties conducive to healthy root growth (adequate water infiltration and gaseous exchange between the soil and the atmosphere). I recommend site and design specific advice be sought from a suitably qualified arborist if you are considering raising soil levels.

Capping or increasing soil profiles over the root zone of your palm could have a detrimental effect on plant health by limiting the exchange of gas from the soil and the percolation of water. You may want to consider installing a permeable pavement at existing site grade to limit impact.

Palm root morphology is different to that of broad leaf trees. New roots are produced every 12 to 24 months from the root initiation zone located at the base of the palm and that is why palms will transplant with relatively small root balls. Roots can be severed close to the base of the palm with minimal impact on plant health although supplemental irrigation will be required.

I hope this advice has been helpful

regards

David