The climax forest of the park is beech/maple northern hardwood forest. The park probably is the best representation of this forest within the National Park system except for Great Smokey Mountains National Park. The composition of the forest also includes hemlock, basswood, black cherry, and white pine. This forest has reached its climax in the better soil areas of the park in the absence of fire and because of the maritime climate and longer growing season influenced by Lake Michigan.
On South Manitou Island there is a small stand of very large, pre-Columbian northern white cedar. This 40-acre grove has some cedars that are 100 feet tall with 60-inch diameter trunks. The grove appears to have been larger but is being gradually succeeded by hardwoods.
Other forest stages of the park are the sub-climax forests of oak and pine in the sandier soils nearer the shoreline and dunes, and black ash swamps nearer streams and wetlands. Foredunes are found behind the beaches with shrub growth of juniper, buffalo berry and jack pine. This is an area of some of Michigan’s best habitat for the threatened prairie warbler. Behind the dunes, sheltered by the forest, lush growths of yew can be found.