There are a lot more pine trees on the slopes of the Sierra Nevada range in California than a 100 or even 150 years ago. This fact has been discovered by comparing old photos to the same scenes today.
Same here in the Black Hills. A local photographer has painstakingly found the identical spots & camera angles that Custer's 1874 expedidition photographer used thoughout the Hills, then printed a book of side by side photos, just to show this.
It is amazing how many of the old trees (or their remains) are still standing; as well as how many times more tree cover exists now than back then. It was really sparse in 1874.