Ah but you need to think when the house was there. Nature and man change things. That area could have been dry as a bone when the house was there.
Somebody might have dammed up a stream or creek or old mother nature changed the route of such, and what was once dry is now wet, or visa versa.
Something else, other then the one large tree in the background, most of the ones in the picture are not that large.
Those trees aren't that old as compared to the big one. So they are a more recent part of the event of change.
Need to look at the big picture to see the details sometimes. If you are in PA, that could have easily been strip mined for coal, I've got spots on mine where such was done when I was a wee lad, and the trees there are similar in size to those in the picture.
Funny there is/was a bit of an apple orchard by the spring at my place. The one tree closest to the spring is nearly 4 feet in diameter. It's been there a long long time. The other trees of different species farther away barely are a foot across.
Maybe take a look at the Penn Pilots site, lot of nice aerial maps of Pa, going back to the 1930's.
Might give you a look see into the past, and you may see a lot more info of the area.
http://www.pennpilot.psu.edu/