Although the above ground visible parts of a tree tend to get most of the glory, it’s the tree’s roots that are the key to its survival.
The horizontal distance that roots extend underground is called root spread and is usually a distance of about 1.5 to 1.5 times that of the crown (the branches and leaves). This means that although we tend to think of a tree as the bit we see, around one third of its total volume is underground.
However, all roots are not the same. Water and nutrients, essential for growth and survival, are absorbed from the ground through fine, thin roots which carry them through woody, coarse roots to the stem.
These coarse roots also anchor the tree in the ground, counteracting the effects of high winds on the crown which may increase the risk of the tree toppling.
Actually, trees are supported by a system of between 3 and 11 large structural roots and the more evenly they develop, the more secure the tree will be as these lateral roots thicken over time – creating a mature tree’s framework roots system.
And surprisingly, over 90% of a tree’s roots, and certainly most of the large structural roots, develop in the first 60cm of soil beneath the surface and most of them go no deeper than 2metres.
Obviously, a tree’s route system will vary depending on the species of the tree, the structure and type of soil, temperature, and water content so there needs to be enough space for its roots to thrive and grow.
Certainly, in an urban environment, the use of salt for de-icing pavements over winter or chemicals used in the treatment of weeds can cause problems for trees, as can construction or civils projects in which tree roots may be physically damaged from the equipment used during pipe laying or groundworks.
By calculating a root protection area around a tree, tree surgeons can calculate how much space is needed to contain enough roots to ensure its survival.
Professional tree surgeons are fully aware of the risks of damage to tree roots and are properly trained to mitigate risk and keep trees healthy and thriving.
