Hello, at least in Germany a tree with a bifurcation below the breast height is measured as if this would be two trees, so you get two data for one tree.

David Schlauß Hello, Thank you. Can you please share any literature or any reference of the same .

There are several ways to handle tree forms that have this bifurcation pattern. One way is to measure the cross-sectional areas of each stem at 4.5 feet and back in the diameter (or circumference) that would give the same total cross-sectional area as the sum of the individual areas. The following formula implements this concept where Di represents the diameter of an individual stem and D is the equivalent diameter for the combination of the stems. D = π*sqrt(∑Di^2). If you choose to use circumference, the formula is just C = sqrt(∑Ci^2).

A second solution is the take the narrowest circumference between the point of bifurcation and the ground. For tree forms such as Virginia Live Oak in the United States commonly take, this solution is common.

If it is clear at ground level that there are two distinct trunks, just pressed to gather with some bark inoscuation, then you can treat the form as separate trees.

Hope this helps.

Robert Leverett Thank you. yes this circumference formula will definitely work in my case. Rather i would request you to please share any published literature, manual or book stating this circumference formulae so that i can use it and cite it in my work.

Sk Imran, there are two sources that you might quote. The first is the Native Tree Society BBS. It is www.ents-bbs.org. If you select Measurement & Dendromorphometry and scan down to the 25th topic, you'll see functional circumference discussed.

There are many email discussions about the concept with the organization American Forests. As soon as we update the national champion tree program website at the University of Tennessee School of Natural Resources being devoted to the champion tree program (formerly with American Forests), you'll have a second convenient source. There is a third possibility. Dr. Robert Van Pelt at the University of Washington employs this concept for tree-measuring and probably has described it in some of his publications.

While the functional circumference concept is old and based in forestry, its use in the field is not widespread. One reason is that there are usually several opinions on what constitutes a single tree versus several trees growing together. There are the species that freely stump sprout after cutting or damage to the main stem. However, the origin of all goes back to a single root system.

If the objective is the amount of basal area for a tree form, functional circumference handle the problem nicely and keeps the standard height of 4.5 feet as the place to take circumference or diameter.

Sk Imran

Hello, this is described for example in the instructions for the national forest inventory for germany: https://bwi.info/Download/de/Methodik/Aufnahmeanweisung_BWI3.pdf In chapter 5.5.8 on page 44 the second sentence says "Unter Brusthöhe (1,30 m) gezwieselte Bäume werden wie zwei verschiedene Bäume erfasst." which means that such trees are handled as two separate trees. There are also illustrations to such measurement problems.