Quantify biomass on a grid pattern

We are running long term trials on various products’ influence on citrus tree growth. I took reference photos of each tree at the start of the trial (jpeg unfortunately). We would like to establish a number that represents the tree biomass on the photo in order to calculate a % growth over time for each treatment.

I could not find any thread that looked like it could provide an answer/ strategy.

I am an absolute imagej novice

There are several strategies to measure the tree growth or biomass non-destructive (Destructive: I used to scan all leaves of a special grass plant and then applied ImageJ particle analysis to measure all scanned leaves for the area, etc.).

If using ImageJ you can set the scale (from a known length in the vicinity of the tree - the illuminaton could be improved), threshold the image and measure the height and area (or tree crown) in several ways, e.g.:


Here you find a massive amount of tutorials and YouTube links, see:

https://imagej.net/User_Guides

Beside ImageJ:

However a 3d-scan of the tree would give you a even better measure of biomass.

Nowadays a very common and relatively cheap method is to use photogrammetry (beside more expensive laser scans, etc.):


Here an example with a drone:

Thanks Bio7 - I will spend some more time in the tutorials.

And finally an OpenSource solution:

Blender Plugin: