AGE CLASS ACREAGE BY FOREST TYPE

TABLE 9. AGE CLASS ACREAGE BY FOREST TYPE FOR TIMBERLAND, RESERVED, AND OTHER FOREST, (1977 - 2005)

Below are links to tables and graphs that illustrate the amount of timberland area by age for each forest type across the four inventory periods.

Several of the trends in the previous tables are depicted in these tables; specifically, the decline in balsam fir forest type area and subsequent increase in hardwood forest type area. Further, by breaking area estimates into age classes, it is possible to speculate on the future extent of some forest types. To maintain constant area of a forest type at a certain age, it is necessary to maintain at least that amount of the target area across the younger age classes. For instance, looking at the area by age class distribution of the aspen forest type, it is very likely that the amount of aspen forest type will remain relatively stable over the next several decades. In contrast, the bell shaped distribution of oak-hickory and some of the other hardwood forest types, suggests that the area of these forest types, in any age class, will show considerable fluctuation over the next several decades.

Note: 1977 and 1990 inventories did not separate out the forest type groups: exotic hardwoods, exotic softwoods, eastern red cedar and oak-pine. As a result, the tables for these forest type groups listed below will have zero values for 1977 and 1990 inventories. To group current types in a manner comparable to 1977 and 1990, we suggest combining types as follows:

Exotic softwood --> red pine
Eastern red cedar --> oak-hickory
Oak-pine --> oak hickory
Exotic hardwoods --> elm, ash and cottonwood

Jack pine
Red pine
White pine
Black spruce
Balsam fir
Northern white cedar
Tamarack
White spruce
Eastern red cedar
Exotic softwoods
Oak-pine
Oak-hickory
Elm, ash, and cottonwood
Sugar maple, beech, and yellow birch
Aspen
Paper birch
Balsam poplar
Exotic hardwoods
Non-stocked

We urge you to use Table 4 to appreciate the amount of confidence that might be placed in area or volume estimate of forest types. We have a reasonable level of confidence in forest type area estimates for the aspen, black spruce, and other major hardwood types. We have very little confidence in estimates made for forest types such as white pine and white spruce. Further, it is difficult to generate reliable estimates on an area within age classes by forest type, except on a statewide.