I've worked with the Beacon Food Forest team, and they've done
dozens of charrettes with huge sheets of paper, with one team collating
design ideas on a giant white board. I don't think digital technologies are good enough at public engagement to be used for participatory landscape design.
In terms of mapping the development of the forest,
Ecosynth might be useful for watching canopy cover develop. I think p
ole mapping is also a useful thing in confined areas. You might consider public engagement with a
Picture Post as well.
over the long-term, the biggest issue is flagging what can be eaten, and when. That is a sticky issue.