DBH (diameter at breast height measurement

[Lazurus]

Can someone explain DBH (diameter at breast height) measurement to me. or is it as simple as it sounds?

[LewisB]

Pretty much as simple as it sounds.

[Paul in the woods]

Can someone explain DBH (diameter at breast height) measurement to me. or is it as simple as it sounds?

 

It depends on your breast, or rather take care you measure the correct height from the ground. Forestry uses 1.3m but I thought other people use 1.4 or even 1.5?

 

It can get more complicated if you're on a slope, have multiple stems etc but this is an easy guide (for forestry): http://www.forestry.gov.uk/pdf/15-Diameter-DBH-Assessments-June-2014.pdf/$FILE/15-Diameter-DBH-Assessments-June-2014.pdf

Edited September 13, 2016 by Paul in the woods

[AA Teccie (Paul)]

DBH, strictly speaking, is a forestry mensuration term for measuring volumes of timber and is taken at 1.3m above ground level. This is often done using a specific DBH tape which has standard metric scale on one side, so you can measure 1.5 'agl' (above ground level) and then the other side looks like inches but is in effect 3.142 cm (Pi). Hence when you wrap it around the stem/truck you read off the diameter (be sure you know where to actually measure to on the tape as not always the end of it.)

 

In 'arb', and in particular trees in relation to construction context (BS5837 etc) we measure 'stem diameter' and at 1.5m rather than 1.3m (in nursery production I think they measure 'girth', not diameter, at 1.0m )

 

Lastly, "tip of the day", instead of having to measure 1.3 or 1.5m agl every time measure it on you and then simply hold the tape at that height (fro me its about the Adams Apple in my throat.)

 

Cheers..

Paul

[se7enthdevil]

i thought it was always 1.5m from ground level on a maiden?

 

some trees that are multi stemmed have other guidelines to follow.

 

either way get the circumference at the height you can and divide by pi...

[Lazurus]

Cool, more to it that it sounds then.....

[AA Teccie (Paul)]

Cool, more to it that it sounds then.....

 

In theory maybe, but not really in practice.

 

Cheers..

[Jon Heuch]

Can someone explain DBH (diameter at breast height) measurement to me. or is it as simple as it sounds?

 

It does of course depend on what you are measuring it for and whether an accurate measure is important - it can be simple, it can be quite complex. In detail, it can be important to use the right procedure for multi-stems, on slopes and other situations. Height of measurement is part of the procedure but by far from the only thing.

 

if you are measuring thousands of trees and putting a price on volume it is important to get an unbiased number i.e. get it accurate. For the most part in arboriculture, even BS5837 it's not that important but it's worth while if it's not too much effort to get it right. As for measuring it to the nearest mm, I find that's a bit of a joke.

 

Forestry on the whole deals with circular trees normally without too many branches so their protocols (which may use a "diameter" tape which actually measures girth and the UK tape rounds down) don't typically cover the more complex tree shapes found in arboriculture; arboriculture has not developed a full protocol but BS5837:2012 has Annex C which covers some of the more common problems encountered but doesn't cover eccentricity: I measured an avenue of oaks the other day - possibly about 5 years since establishment as heavy standards. I was amazed at how oval the stems were - something that a diameter tape would not pick up but calipers did.

 

As for the height of measurement, for a regular tree with little taper it makes little difference; for one with large whorls of branches on a slope it can make quite an impressive difference.

[Breezeblock]

what if you were a midget

[Arctostaphylos uva-ursi]

what if you were a midget

 

You would measure dbh at the same height as your Adam's apple.