When planning your tree planting you should give thought to how to keep mammals off your plants. They will eat them given a chance
Voles and mice will ring bark at ground level, rabbits will eat all the leaves, and deer will eat all of it! Have a good look around for evidence of footprints and droppings, and remember that all the above are most active at night so you might not see the animals themselves. Tree shelters not only protect against mammal damage but can act as a temporary greenhouse and some can act as spray guards. You can take the risk and not put shelters on to start with, but it is a bind having to come back to do it. There are a multitude of products available to protect from voles to red deer. I will happily talk you through the different ones or you can come and see them here or on one of my courses.
I stock spirals and canes, shelterguards and stakes.
Spirals and canes (photo)
Shelter guards and stakes (photo)