Promotion of Tree Health

Promotion of Tree Health, Soil Quality & Mulching

Regular application of quality mulch around individual trees and tree groups is of high importance to provide adequate moisture retention within the soil. As drought conditions become more prevalent, evaporation will intensify as hot dry winds increase in occurrence and duration.

Irrigation will also play a role in helping the tree population through times of drought, however if there is no mulch or old degenerated mulch has not been topped up then any supplementary irrigation will evaporate quickly, not allowing it to absorb into the soil profile for plants to utilise.

Mulch should be applied across the surface of garden beds to a depth of 75mm and consist of general arboricultural wood chip or similar in 50-150 mm chunks, with less than 5% fines (small particles). It should be applied to the biggest area reasonably practicable however a good general guide would be to the drip line (edge of the canopy) of the trees, and 200 mm away from the base of the tree - where possible.

Other benefits of mulching include;

Weed suppression – A layer of mulch inhibits sunlight that penetrates through to the ground below, therefore suppressing weed growth, which in turn reduces the need for the use of herbicide applications as well as reducing competition for water and nutrients.

Reduction of Soil Erosion – A heavy layer of mulch is an effective way to reduce erosion from rainfall and/or wind on slopes or banks.

Replenishment of Nutrients – Organic material breaks down over time and this process allows nutrients and minerals to become available for trees and plants. Nutrients and minerals are utilised to carry out necessary functions essential for tree health and growth.

Soil Texture – Mulch is highly beneficial for the improvement of soil texture. Space between soil particles improves gaseous exchange, water availability and uptake which are all essential functions which in turn improve tree health.

Reduces Mechanical Damage – Trees are often subject to mechanical damage from lawn mowing and whipper snipping around the base of trees when turf can grow right to the base of a tree. Mulching around trees even when they are standalone trees in a turfed area can reduce the need for this maintenance which will reduce the risk of mechanical damage occurring.

Hazard Reduction Strategy – A supplementary advantage of mulching is the ability for it to deter people from congregating under trees that may pose a hazard due to structural or health issues. Adding mulch around the base of trees will naturally deter people from sitting beneath them or walking under them reducing the likelihood of personal injury in the event of complete or partial tree failure.