And here is the Daily Mail with an article saying that we are destroying 15 billion trees a year.
And how does anyone know how many trees have grown since or before human civilization came about.
3 trillion divided by 15 billion = never run out as trees grow back.
“We’ve nearly halved the number of trees on the planet, and we’ve seen the impacts on climate and human health as a result,” Crowther said. “This study highlights how much more effort is needed if we are to restore healthy forests worldwide.”
http://phys.org/news/2015-09-trees-previously-believed.html
I think this is a SWAG (Scientific Wild-Ass Guess).