You can see from aerial photos of oak island over the years that the forest boundaries really ebb and flow.
And let's not forget tree canopies prevent sunlight from reaching the ground, which is essential for saplings to grow.
Now we need a tree guy to weigh in. The question is how long does a clearing stay a clearing?
Depends!
Natives used to burn low cover. As did later arrivals. Or at least some of them..
An high cycle population of mice and or voles can be hard on a year class of sprouted acorns. Or on the more delicate bark of younger seedlings or even saplings.
A failed mast (acorn) crop for a year or multiple years could see more young trees girdled and dead over the course of a winter or subsequent winters. Inner bark can keep some rodents alive when nothing else exists to eat. Rodents and other causes of mortality decline , trees can see a surge of a seedling year class flush. With note of your canopy factor applying of course.
Storms, floods, droughts, lightning, humans. An old oak is a survivor.
Soil type matters. Highly mineralized low organic material soil scars remain near sterile (as far as life)for a long time. The "sand blows" of exhausted prior good soils are evident in places.
In other areas that were glacial scoured there are varied deposits , and areas of sand that just don't have enough in them to sustain life in multiple season climes. Note dunes and their histories.
Something you might look for in history specific to Oak Island is if it had any oak savannas on it.
They would make your opening span question even more interesting.
Not sure why I've envisioned the trio of youths oak as being near shoreline. Very near.
The specific clearing you're inquiring of can be unique to the islands clearings for all I know.
Humans were altering the islands flora and plant /tree succession prior and during. As was nature.
An isolated incident and presto, your clearing is unique.
