A root protection area refers to a calculated area that is taken to avoid damaging a tree’s root system under and just beyond the crown. The importance of tree root protection areas are that by taking this measurement down, urban foresters ensure that any work on a site will not result in damage to pre-existing trees, thereby saving any potential cost of damages.
Essentially, this important step is a layout design tool which indicates the minimum area around a tree that has sufficient roots as well as rooting volume (which maintains a tree’s health and longevity). The tree’s soil structure as well as protection of the roots is the top priority.
How Are Root Protection Areas Calculated
Root protection areas are calculated using the BS5837 Standard, which is a standard guide that relates to design, demolition, and construction recommendations surrounding sites that contain trees. The BS5837 can be purchased or viewed in any local planning authority.
In the UK, all trees must be considered when any planning or construction work is being performed on a site. Local planning authorities, landscapers, urban foresters, anybody working in a site that contains trees must understand the impacts of any proposed development on the trees that are present in the site.
Root protection areas can vary, as the extent of root systems is different from tree to tree. Some root systems are known to extend as much as seven times the crown area or 2.5 times the crown radius.
Mostly, tree roots are within the top 30cms, this is because oxygen becomes more limiting further down the soil and roots need to respire. The root protection area does not usually consider the extent of the fungus-root, which refers to fungi directly associated with the fine roots.
Problems with Root Protection Area
As mentioned above, root protection areas do not usually consider the extent of the fungus root, which is a problem for ancient trees that have a crown radius higher than what the standard accounts for.
For some trees, having an RPA that is 15 times the diameter of the tree at breast height, or 2 metres beyond the crown (whichever is greater) would be necessary to ensure these trees’ roots are protected.
Why are Root Protection Areas Important?
The roots of trees not only provide stability to the overall tree but are crucial for the uptake of water and nutrients to the whole tree. If the roots are damaged, the effects of this may not be immediately obvious. It can result in a slow decline in the tree’s health over the years.
The point is that it can take years for tree decline to show up if the roots are damaged, which means that the importance of tree root protection areas are that they are vital to the longevity of a tree, and for eliminating any potential costs of removing and replacing an affected tree.
Root protection areas are a crucial way of ensuring the safety and longevity of a tree. It is important to use BS5837 for the appropriate guidelines on RPAs and to get them performed by a professional, licensed Arboriculturalist.
You can read more about the BS5837 Standard here.
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