May 18 2021

What is a Root Protection Area and what does it mean?

Healthy and adequate rooting space is essential for trees to thrive. A root protection area is usually a calculated area of ground that lies immediately under a tree and just beyond the extent of its crown. It is intended to help avoid damage to the tree’s rooting system. But how is that area worked out, who needs to use it and why is protecting roots so important?


Root protection areas need to be bigger


We believe RPAs should be greater for ancient trees and veteran trees.


Along with the Ancient Tree Forum, we propose an area greater than the existing standard RPA for these trees. We suggest it should be whichever is greater of:


  • an area with a radius which is 15 times the diameter of the tree, with no cap
  • 5m beyond the crown.


In England, our recommendations are supported in guidance for making decisions on planning applications. Standing advice from Government suggests a ‘buffer zone’ around ancient or veteran trees of at least 15 times the tree’s diameter, or 5m from the edge of the tree’s canopy if that area is larger.


An example


According to the British Standard, the RPA for the Westonbirt veteran oak in Gloucestershire would have been up to 15m away from the tree. But in 2018, new radar technology which can detect woody roots from above ground found large roots – over 2cm thick – up to 23m away from the tree. The fine roots and wider mycorrhizal networks stretch even further, so in this case, an RPA of 15m – or even 23m – would not safeguard the whole root system.


Over time, this radar technology will help to improve our understanding of rooting environments and our recommendations.


Read more on this subject on the main Woodland Trust website here

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