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Southwide Growth-to-Removals Ratios

The ratio of growing stock removed annually to the amount of growth is a subject of great interest. A growth-to-removals (GR) ratio greater than one signifies that growth is exceeding removals. Conversely, a ratio of less than one denotes more volume is being removed than is being replaced by growth. For the past three survey cycles, GR ratios for both softwoods and hardwoods have decreased (fig. 16.33). In 1982, the GR ratios for both total growing stock and hardwood growing stock exceeded 1.5. The softwood GR ratio was at 1.4. By 1999, the GR ratio for all species was 1.05, indicating that growth and removals were virtually equal. Average annual growing-stock removals of softwoods exceeded growth in 1999. However, this is the first time that average annual softwood removals exceeded average annual growth. The implications of this information are widely debated. Many view removals exceeding growth as over-exploitation of the resource. Others think of this as a temporary fluctuation, as we are approaching a GR ratio of one, which represents stability between growth and removals.

It is important to remember that the growth and removals estimates in this chapter are based on growing-stock trees. Any trees not meeting the minimum size requirement (5.0 inches d.b.h.) are excluded. Therefore, any interpretation of GR ratios should consider nonmerchantable trees and stands, and their impacts on future growth. In 1999, 14 percent of the South’s timberland was in stands 0 to 7 years old (table 16.10). Most of these stands are composed of submerchantable-sized trees. An additional 9 percent of the South’s stands are 8 to 12 years age old. Many of these stands also have yet to reach merchantable status. Planted stands 0 to 12 years old account for 9 percent of the timber base. These stands have the potential to greatly affect future standing volume and average annual growth. These stands will contribute to future growth as the trees in these stands reach 5 inches d.b.h.