Root Protection Area Calculation Origin

[Sam Archer]

I am looking for information, preferably research or scientific papers which relate to the origin of the Root Protection Area calculation (DBHx12=RPA) used in BS5837. I have been told that the mathematical equation is based purely on a 'guess', this may be the case, however, for reference purposes, I'd appreciate it if some could help me out with a source.

 

Cheers

Edited November 13, 2019 by Sam Archer

[daltontrees]

This has been discussed many times, especially on UKTC, and the consensus is that there is no proof that it is right, or wrong. If anything, it is believed that as a simple rule of thumb for people working near trees in the USA decades ago the idea was to measure stem diameter in inches, and that gave a RPA radius in feet. It's a bit like the NJUG rule of thumb, girth x 4 = standoff radius. Which works out at 12.5 times diameter.

During all the discussion I've read and heard about it, no-one has come up with a more appropriate number. That's not to say it shouldn't be modified, with justification, for shallower or deeper soils, veteran or ancient trees or other relevant circumstances.

[trotter251]

Pretty sure there’s some research on  RPA’s in the latest arb journal ? I haven’t read it but briefly saw the contents earlier and I think there was something relevant in there