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.
Some of the drawings do seem to show how different soils impact root growth. For example, see https://images.wur.nl/digital/collection/coll13/id/1288/rec/... Is there another explanation for the root structure in this drawing? It would have been nice to see this reflected in the metadata to make it more easily findable.
That's really cool. The tree sends out a root tendril in that location and when it encounters better conditions, that tendril becomes the main source of gathering and it expands and builds.
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.
It reminds me of the drawings by John E. Weaver from the thirties [1]. They were made by painstakingly digging a deep trench to study and sketch the roots. They did it multiple times for each crop to get a sense of how they develop in time.
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.
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!
The networks and growth processes can be wonderfully complex and even social among the root systems of neighboring trees — often mediated by extensive second-order fungal networks.
The trees support the fungi (sugars) and the fungi enable exchange of nutrients and tree-to-tree hormonal signaling of environmental health state. This is useful in enabling speedier responses to pathogens and insects infestation and sharing nutrients across trees (“altruism”). Usually this sharing and communication network is among members of the same species and often the same kinship. I do not know the primary literature on this area, but this is a good introduction:
