Although squirrels can usually find the acorns they have buried, some escape. Deer eat acorns directly from the ground or trees, without burying them. How might succession in a forest that had deer, but no squirrels, differ from one that had squirrels, but no deer
Squirrels leaves the nuts which go into the ground that plant new trees making it so that squirrels are needed for forestation, but deers eat the acorns from the ground which in turn don't do much.