Plant communities come about through a process of natural selection. Many species within a community will eventually create conditions unsuitable for their further growth, which results in the appearance of a new species which can take advantage of the new conditions. Thus the community changes until it ultimately may reach a climax stage--where the plants do not create conditions unfavorable to themselves. Most of the Sunken Forest has reached a climax stage characterized by American holly and sassafras. Remnants of an earlier community of oak, pitch pine and red cedar are scattered here and there, but are mostly on the way out.
The lack of dead holly trees suggests that the large ones are the first generation rather than replacements of earlier trees. The sassafras is a somewhat shorter-lived species and many of the older trees have died over the past few years. This process of succession leading to a climax stage can take thousands of years, but most likely took around 300 years in the Sunken Forest. Barring a large natural disturbance--such as a fire, hurricane, or human interference--the climax forest should persist for many years.