This photograph shows an Allegheny Plateau forest stand. Allegheny Plateau forests are largely second-growth forests that -originated after extensive turn-of-the-century harvests. These forests contain tree species of widely different growth rates and tolerance of shade. As a result, the tree species are often stratified within forest stands in predictable positions. The fastest growing, shade intolerant species, like black cherry or yellow-poplar, survive only in the dominant, tallest, positions in the upper crown. Their diameters are often larger than those of other trees in the stand. Species of intermediate tolerance for shade, and intermediate growth rates, such as red maple, black and yellow birch, are often found in intermediate positions in the crown and in the diamter distribution. Slow growing, shade tolerant species, like sugar maple and American beech, persist near the bottoms of the crown canopy and at the small end of the diameter distribution.

These characteristics of mixed species Allegheny Plateau forests can create confusion. Stands often have a wide range of diameters, because of these differences in growth rates and shade tolerance. Thus, people often confuse even-aged with uneven-aged stands, and sometimes, people believe that they can harvest the largest trees because the smaller trees are younger. See the page about long-term studies to watch the size differences develop over a 60-year period in an Allegheny hardwood stand.