Wife's sister has owned a canal lot for over 30 years on the Tx gulf coast very near the La line and the high tide is about the same level it's allways been. More to that haveing to move story is my point.
Was listening to a seminar several years back put on by Tx Forestry Service and they say there are more trees in North America today than when the Pilgrams landed. Maybe just in the wrong place ?
Don't know anything about sea levels but used to know more about trees.
Much of the nation was forested when the pilgrims landed. Of course, exceptions come to mind, like the Prairies or marshlands. I'm sure there were others.
As the states were colonized, we were primarily agrarian. Farmers cleared fields and pastures. Put drainage in wetlands to make them productive. A lot of timber was cut and sawn to build houses, barns, etc.
In the 18th, 19th and early 20th Centuries, I think New York State was <20%+/- forested. Today that is more like 60-65%.
"Old growth" is rare anywhere as everything was cut-over at some point, probably from coast-to-coast.
As many of those small family-sustaining farms were lost, the woodlands were restored.
Native tree species have natural regeneration process. Often there are "pioneer" species that populate an inactive pasture or field. Later, more long-lived species will populate the area until a "climax" forest is restored.
People think of NYS as New York City, but we have some very rural parts in NYS.
My county is 900 square miles (600k+ acres), 47k people, and almost 100k acres are State lands. Much of the State Lands are former farmlands. Now many are softwood (spruce, pine) tree plantations planted by the Civilian Conservation Corps (CCC) during the Great Depression of the 1930's.
All that said, I can certainly see Texas as being an exception to the rule. I don't know that much about Texas or the Prairies/ grasslands of our early days. I can envision plantations, and other stuff done by people that could potentially increase forestation percentages over time. Further east, there were many 1,000's of acres of short-rotation plantations managed for the pulp/paper industry.