The Formation and Conservation of Old Growth Forests
There is a common myth that all forests, prior to the arrival of humans, were in their 'old growth' state. This, however, is not accurate. Old growth forests did exist, but they were found in small and non-contiguous stands, and their presence varied by forest type and local climate. The amount of old growth in the United States, using scientifically accepted definitions, never exceeded 50%, regardless of the forest type.
Understanding Old Growth Forests
The term 'old growth' refers to forests that have not been disturbed by logging or other major developments for a certain period. In professionally accepted science-based definitions, old growth is defined as one that has not undergone significant human intervention for a period of time. These forests contain trees of significant size and age, and they feature multiple age classes, which represent the various stages of forest development over time.
Fires, Insects, and Storms
Forests have naturally gone through cycles of growth and disturbance. Fires, insects, diseases, and storms have all caused large-scale forest mortality, creating significant openings. These natural disasters play a crucial role in the ecological processes that shape our landscapes, leading to the formation of new growth forests.
Fire Exclusion and Old Growth
Fire exclusion, a policy of preventing and suppressing fires, played a significant role in the creation and preservation of old growth forests. In many locations in the western United States, such as the Lake Tahoe Basin, the amount of old growth forest has increased despite significant human activities. This is because areas were allowed to regrow naturally, and the suppression of diseases and fires, coupled with limited harvesting, allowed these forests to mature into old growth.
The Paradox of Modern Forestry
Yes, old growth forests were, indeed, primarily "chopped down." This process was driven by the clearing of land for agricultural use and pasture, along with the use of wood for fuel and construction. By the early 1800s, nearly 80% of the land in New England had been cleared for these purposes. Small patches of forest were left and managed as sources of fuel and timber. As people moved further west, more land was cleared for agriculture, and trees were cut for lumber, with much of this timber being shipped back east.
In New England, a second phase of intensive lumber cutting occurred in the early to mid-20th century. The trees that had replaced the original old growth forests had matured, making them suitable for timber harvesting. Additionally, forests in Maine have been repeatedly cut and replanted for pulpwood destined for paper mills. Less than 0.1% of the approximately 18 million acres of forest in Maine have never been cut. This gives a clear indication of the intensity and scale of the lumbering activity.
Modeling and Projection
Modeling efforts have shown that under current and projected conditions, the old growth forest cover in the Sierra Nevada mountains will not exceed 30%, compared to the current 17%. This indicates that the natural recovery and regeneration of old growth forests are limited by existing conditions and future projections.
Misconceptions and Reality
What we often refer to as 'old growth' is, in fact, 'second growth' forests. The remaining old growth forests are either protected from human intervention or located in areas where they were less economically viable to harvest. Many of the areas with remaining old growth forests were protected due to their inaccessibility or the high cost of harvesting.
Understanding the history of these forests and the processes that form old growth is critical. It underscores the importance of sustainable forest management and conservation efforts to protect and restore these valuable ecosystems.