I saw the following diagram and wanted to give some feedback.
It's time we address the oversight in our #educational curriculum that often leaves out soil's crucial role in food webs. Soil is teeming with life and plays a vital part in sustaining all life on Earth. It's time for a new curriculum!https://t.co/z6MmqLXuw6#savesoil #food pic.twitter.com/PUm7HwXOTZ
— Conscious Planet #SaveSoil (@cpsavesoil) May 19, 2023
I agree with the spirit of the post that understanding food chains is improved in light of soil science. There are some concerns I have with both diagrams.
The left-hand diagram is a food web, which is a collection of food chains. Perhaps it is comprehensive enough as model in a particular project, but it seems quite incomplete. For some reason vertebrates take a strong majority of the diagram, ignoring almost all invertebrates. Likewise, there is no indication of microorganisms and only a single (polyphyletic) group of plants. This kind of comprehensiveness is not necessary for pedagogy, but it is a limitation of these sorts of diagrams. A bigger limitation of this sort of diagram is that it gives the impression that food webs are directed acyclic graphs when it has been well-established that cycles exist in food webs.
The second diagram removes the need to speak of specific species or clades by abstracting to a “food chain”. People can choose terminology as they like, but I would rather say that the second diagram shows a class of food chains. Often food chains are assumed to always ascend up a total order of trophic levels. This characterization is not entirely accurate of observed interactions, but it does communicate a tendency accurately. For modelling purposes it is productive to model the interactions as a stochastic directed graph, which would allow for violations in the typical partial orders but still be able to represent the order-like properties. Lastly, food chains are supposed to have classes of organisms as nodes. While some have claimed that “soil is an organism”, the arguments I have seen in its favour are subject to a fallacy of composition. In my opinion referring to decomposers, which often live in soil, would be more appropriate than simply “soil”.