Burnwood Trail Stop 2: Defining Old-Growth

A large fallen tree in the Burnwood forest.

Thomas Saladyga

Quick Facts

Location:

38.07647, -81.07530

Significance:

Old-Growth Forest Network

Old-Growth Forest Hike Stop 2 - Defining Old-Growth

What determines if a forest is old-growth? Generally, old-growth forests are forests that existed prior to the prevalent industrial land clearing of the 19^th century. Natural processes have been the major force shaping an old-growth forest ecosystem. A defining feature people use to determine if a forest is old-growth is that it hasn’t had any human disturbance throughout its history. This type of forest is also called a primary forest. A forest that has experienced major human clearing in the past is referred to as a secondary forest, highlighting that the second forest has grown to replace the original that was cleared. A forest could have been cleared by humans 200 years ago and enough time has passed to where old-growth features are coming back, but this wouldn’t be considered a primary forest due to the history of human clearing.

The forest type and ecosystem are also important in determining what is considered old-growth. A 200-year-old forest in the eastern United States could be considered old-growth since most overstory tree species reach a maximum life of 300-400 years. However, a 200-year-old forest may not classify as old-growth in the Pacific Northwest where trees can live for over 1,000 years. Some forests and ecosystems don’t reach old-growth age status naturally due to large, frequent disturbances. In the New River Gorge, riverscour prairies naturally experience frequent flooding that keeps vegetation from reaching old age because of the scouring of the riverbank by water. A riverscour prairie could theoretically be a primary ecosystem that humans haven’t disturbed, but it isn’t considered old-growth since flooding naturally keeps most of the plants from achieving old age.

Despite some subjectivity surrounding the definition of old-growth, there are many characteristics that are unique to old-growth deciduous forests that can be scientifically measured and classified.