Christmas trees don’t just look pretty, they give out lovely life-giving oxygen. an acre of christmas trees will provide oxygen for how many people?

The answer would be about  18.

Christmas trees give, in fact, a lot of oxygen and in return they consume a lot of carbon dioxide.
The oxygen produced by each tree depends on several factors, but there is a estimative. In about 1 acre of land, there are enough trees to produce the oxygen necessary for 18 people to breath during a whole year!