FWIW, yes, semantics (what things mean) and ontology (what things exist and how they’re related) are important, and there has been a lot of work done on this, e.g. http://www.ontobee.org/ontology/RO?iri=http://purl.obolibrary.org/obo/RO_0002574, sometimes including/inspired by iNat discussions. GLoBI does try to stick to established ontologies, but one problem with the obs field approach is that iNat users aren’t necessarily aware of the implied semantics, e.g. we all need constant reminders of what the difference between “eating” and “preys on” might be. Something we will need to keep in mind if we ever get to this feature.
Also, my personal opinion is that iNat should only focus on interactions that can be verified in a photo, so a photo of a birch in a hemlock forest doesn’t prove an interaction. The co-occurrence is interesting, but that could be derived from existence of an observation of a birch and an obs of a hemlock at the same time and place. Same thing with pollination: a bee covered with pollen on a flower doesn’t demonstrate that pollination is happening, though it is highly suggestive.