Best trees for steep slope clay

Greetings!

I'm about to laser level a swale onto a steep slope as part of our food forest. The trees don't necessarily have to be fruit/nut producing...just excellent at preventing erosion.

I'm in SE Iowa (Zone 5b) with HEAVY clay soil. We can always amend the soil around what we plant though. Access to good compost.

Thanks in advance!

do you use deep rooting cover crops such as alfalfa to break up the soil to prep it?
-meg from iowa city