The height of trees is an interesting topic. Both areas were heavy duty mainlines and both areas saw extensive use of helpers in the steam era. If you look at pictures of the Curve in the 50's and early 60's, the hillsides are almost devoid of vegetation. I assume that this was due to the cinders coming from the steam plumes.
Much like the part of PA. I/my family is from. But not so much caused by just the locomotives themselves...
Logging-by the 1940's,most of the state had been cut "bare" of anything big enough for a "2X4". Takes a long time to grow back...
Pulp and chemical,& to a lesser extent fire-wood cutting-that got most of the stuff not big enough for the loggers to take...
Coke ovens-the smoke and fumes from these played hell on the vegetation and killed a lot of regrowth before it really got started.
Looking up into the curve, you see a valley on the left;there's a road goes under the curve there now,and long ago a rail spurr went up it.
The valley was lined with coke ovens;the ruins are still there.(or were last time I visited some years ago. So much for the greenery "back in the day", and all together it slowed recovery for a long time to come...
Man, that is some layout! I live just across the border near Niagara Falls now;I'd love to see it some day!