Thank you for contacting us regarding your concerns and your question.  Deer can cause damage to trees by eating the leave and/or branches and by the rub of the antlers on the trunks.  There is also damage from rabbits and voles.  Barriers include: tree shelters, wire mesh, drain tile, spiral wraps, paper tree wraps, snow fence, or tubes you can make. Browse may still happen if deer can reach the tender new growth out the top of shorter barriers.  Typically,  tube type barriers that are 5-6 feet tall allow the plant to grow past the reach of deer. 

Determining which type of protection will work best for your trees is the first step, and some can be purchased, others you create. For Deer, a rigid fence is usually best. Many of the items can be found at your local hardware or box stores.  I am including several links to help you with this.

Iowa State University - https://www.extension.iastate.edu/news/yard-and-garden-prevent-wildlife-damage-trees-and-shrubs

USDA Natural Resources Conservation Service - https://www.nrcs.usda.gov/Internet/FSE_DOCUMENTS/nrcs141p2_001562.pdf

Michigan State University - https://www.canr.msu.edu/news/smart_gardening_to_deter_deer