There are various options for deer exclusion fencing styles, and we don't have research trials evaluating if any one of them is more reliable or cost-effective than another. (Nor do we collect information on what is on the market in terms of recommending particular brands or sources.) Fence layout options include two low fences that the deer cannot jump over (where the space between them isn't enough to land in and recoup for the second jump, and they can't clear both fences in a single leap), one high fence around eight feet tall, a solid fence just high enough that they can't see over (they don't like to jump blindly into an unknown area), or a minimalist fence that is electrified and possibly baited at first (so they run into it to learn it's not pleasant to touch). Fence materials are usually metal, though metal posts with netting (nylon or similar) strung taut between them can be used; however, netting of that type could risk ensnaring birds and snakes.

Since fencing-in large areas can be quite costly, you could encircle individual trees instead. Small trees used in reforestation plantings tend to be just enclosed in "tree tubes", though that won't be practical if the saplings are already well-branched, since they won't fit. Slightly larger cylinders of wire mesh (such as hardware cloth) can protect the trunk and short branches. Even larger cylinders can encircle the entire sapling just past the canopy spread, which will require more stakes to stabilize it. A sample photo of a redbud tree (older than the plants you'll be installing) surrounded by deer exclusion fencing is attached.

As trees grow and branches develop higher off the ground, browsing risk will decrease but the risk of "buck rub" (antler rubbing to remove velvet each autumn) will remain. Antler damage to trunks can be serious, untreatable, and potentially fatal for a young tree. In that case, trunk protection is important, but the rest of the canopy should be fine unprotected once the majority of it is above browsing height. Trees can afford to lose some foliage each year to browsing or other causes (insect damage, leaf spot diseases, storm damage, etc.), so some minor deer damage to the outer edges of a canopy won't be concerning as long as the tree trunks are protected. We don't know at what age trees are less appealing to bucks, but generally they target young saplings whose trunks are either a bit flexible or slender enough to fit between antler points. Make sure any material used to shield a trunk from buck rub still allows the bark to get good air circulation and doesn't risk "strangling" the trunk as it expands with maturity. You'd also need to be careful anchoring it into the ground, since close to the trunk those stakes would be at risk of injuring major roots or impacting their growth by being in the way of expansion.

For the long term, fortunately pawpaw foliage is not very palatable to deer, and river birch grows pretty quickly, so it will rise above browsing height in just a few years. Sassafras can be slower-paced, but sucker growth (stems arising from the trunk base or root system) can be quick. Plus, as a pioneer tree in the wild (one which readily colonizes disturbed areas like clearings and beneath power lines with little shade), it might grow quickly for a few years before slowing down.

Miri