|Pumpkin Ash (Fraxinus profunda) is named for the fact that the base of the trunk swells up like a pumpkin when grown in wet places.|
Pumpkin Ash is one of the few species of trees that can grow in standing water. Bald Cypress is another as are Swamp Tupelo and Silver Maple. That makes Pumpkin Ash an strong candidate for "special teams".
Extremely rare species can run into inbreeding depression or genetic bottlenecking. This is a problem with Cheetahs in the wild and is probably an issue with Black Gum and Pumpkin Ash in Michigan.
Species that are extremely dispersed result in the only pollen sources being parents or siblings. Think of the Romanov family here.
A more robust configuration would be to have a small, dense planting with materials from Ohio, Indiana and Illinois planted upwind of prime Pumpkin Ash habitat. Nine trees would be plenty, three from each donor site.
The project could be jump-started by grafting scion wood from those locations onto suckers from existing ash trees.
I don't know if any readers have a Pumpkin Ash growing out in their swamp, but I would like to give grafting Pumpkin Ash a whirl.