. Annual inventory report for Pennsylvania's forests [electronic resource] : results from the first three years. Forest surveys Pennsylvania Statistics; Forests and forestry Pennsylvania Statistics. 10 12 14 16 Diameter Class (inches) Figure 7.—Distribution of growing- stock trees ( inches and larger) per acre of timberland, Pennsylvania, 1965, 1978, 1989, and 2002. by a decrease in sapling-seedling stands and an increase in sawtimber stands. Stand-size classes are not strictly defined by age but do indicate broad stages of stand development (successional stage). Sapling-seedling stands are
. Annual inventory report for Pennsylvania's forests [electronic resource] : results from the first three years. Forest surveys Pennsylvania Statistics; Forests and forestry Pennsylvania Statistics. 10 12 14 16 Diameter Class (inches) Figure 7.—Distribution of growing- stock trees ( inches and larger) per acre of timberland, Pennsylvania, 1965, 1978, 1989, and 2002. by a decrease in sapling-seedling stands and an increase in sawtimber stands. Stand-size classes are not strictly defined by age but do indicate broad stages of stand development (successional stage). Sapling-seedling stands are young, early successional stands while sawtimber stands are older stands that are approaching financial maturity. The decrease in the sapling-seedling class is of concern because this is a long-term and negative trend. Since 1955, the area of sapling-seedling stands decreased by well over 50 percent. The situation bears close monitoring because of potential adverse impacts on a variety of wildlife species that depend on young successional stands. Less forest land is entering the poletimber class compared to land moving into the sawtimber class. Sawtimber stands have more than doubled in area since 1955. slower rate. The most recent changes suggest a gradual but steady shift toward larger sawtimber-size trees, particularly in the larger classes. These most recent changes also are reflected in Figure 8, which shows the distribution of all live trees down to the 2-inch diameter class. Note that the apparent increase in the number of trees in this class is not statistically significant. A closer examination of the results reveals that most of the prospective increases in 2-inch trees are heavily influenced by increases in 2-inch black birch trees (Fig. 9). Red maple, sugar maple, and eastern hemlock appear to be experiencing decreases in 2-inch trees. Numbers of 2-inch oaks showed little change. Stand Structure The distribution of live trees by various measures is a valuable ind
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