How to calculate the size of the tree?

Different standards, different measurement methods.

Crown width: the diameter of the vertical projection of the crown on the ground.

Ground diameter: the diameter of the trunk at a distance of 0.20 meters from the ground, often represented by "D".

DBH: The diameter of the trunk at a distance of 1.30 meters from the ground, often expressed as "φ".

Meter diameter: the diameter of a tree one meter from the ground. Usually used to indicate the specifications of trees (seedlings). Represented by the symbol φ.

Crown width, also called crown diameter, refers to the word "crown diameter" when a single tree is big.

When the section is deformed, a set of vertically intersecting data should be measured, and the average of the maximum and minimum values should be taken.