This is a great resource. The type of soil however impacts the root growth significantly, and unfortunately isn't mentioned in the drawings. Other than that this can be very helpful if you want incorporate root structure in the design of a polyculture system.
I wonder if we are missing half of the tree. Moles can probably tell one tree species from another clearly by their roots, and will be surprised to learn their surface halves are also different.
I keep seeing 'Tree of Life' designs at the local farmer's market, but every variation has even fewer roots than the classical celtic knot version, which is at least balanced top and bottom.<p>As these diagrams illustrate, a typical tree has roots reaching out at least 3x the radius of the 'root line' myth common among landscapers and construction workers. The truth seems to be more that any damage within that circle affects a pie slice of roots that are doing the real work. Cut a hole that's 18° wide and you can kill up to 5% of the roots.
Unfortunate that Joshua Tree (Yucca brevifolia) are not in there. I always thought they would have a pretty fascinating root structure because of how separated they grow. Makes sense that it’s not in a Dutch database though!