What Are Old-Growth Forests and Where Can They Be Found?

There’s a lot of talk in the news and in conservation about mature and old-growth forests. You’ll sometimes see them abbreviated as MOG(F). But what exactly is old-growth forest, and do we really have any around here?

Old-growth forests are some of the most valuable ecosystems on the planet. They give a wide range of benefits to both the environment and local communities. Destroying old-growth can have devastating consequences. Let’s explore why old-growth forests are so important, and what we can do to help.

What Are Old-Growth Forests?

An old-growth forest is a forest that has reached its later stages of stand development. These forests tend to have:

  • large or older (80+ year old) trees
  • many different plant and animal species
  • multilayered canopies: lots of different tree heights and leaves
  • deep organic layers in the soil

Old-growth forests are habitat for many wildlife species. Therefore, they support high levels of biodiversity. Mature and older forests types have had time to go through ecological processes. These processes include floods, fires, strong winds, and even ice in the winter. These events are also known as “natural disturbances”. These events help to create “canopy gaps”. They weed out weaker or unlucky trees. Ultimately, they create the old-growth characteristics that we’re looking for.


Old-Growth Forests vs. Young Forests

This is in contrast to younger forests. Younger forests may have younger trees, poor quality soil, and not as many species. Large trees are few and far between. The canopy (the top of the forest) looks even and simple with lots of canopy gaps.

Unfortunately, there may be a lot of evidence of human disturbance in both young and old forests. Human disturbance can be remnants of housing or fences, trash and litter, or even damage to the trees.

Old-Growth Forests Vs. Virgin Forests

You might see some folks refer to “virgin” forests when talking about old-growth. A virgin forest is defined as one that humans have never disturbed. Virgin forests are so rare in the US that they’re practically nonexistent.

Unfortunately, the logging industry argues that old-growth forests and virgin forests are the same thing. They go on to say that there’s no “true” old-growth left. And therefore, every forest can and should be logged. This dangerous argument causes logging in vulnerable habitats across the country.

Why are old-growth forests rare in the United States?

From 1850 to about 1920, we deforested two-thirds of the Eastern US. This massive loss of forests means that many of our forests are a maximum of a hundred years old. That means that many forest types could just now be maturing into old-growth.

area of "virgin" forest in the US through time

Unfortunately, much of the country has been repeatedly logged. This is especially true in the US South. Even so-called “responsible” forest management can leave behind ugly clearcuts. Clearcuts have dead, dry soil and total loss of animal life.

Examples of Old-Growth Forests in the Southeast

There are well-known old-growth forests in the Eastern US. You can find most of them in a national park. The Great Smoky Mountains National Park, for example, has quite a bit of old-growth. Many protected forests in and near North Carolina do, too, including:

  • Pisgah National Forest (North Carolina)
  • Nantahala National Forest (North Carolina)
  • Chatahoochee-Oconee National Forests (Georgia)
  • The Great Smoky Mountains National Park (Tennessee and North Carolina)

In addition to these well known forests, there are many others. Strongholds of old-growth forest still exist anywhere it’s challenging to clearcut. If we couldn’t get to it easily, it had a much better chance of developing old-growth conditions. Many hardwood forests occur on ancient mountains (near the Appalachian Trail, for example). These difficult landscapes contain potential or confirmed old-growth forests. But a mountain range isn’t the only safe harbor for old-growth.

Old-Growth in the Eastern United States

Other places can and do have old-growth forests, including:

  • the Green Swamp (North Carolina)
  • Congaree National Park (South Carolina)
  • Minnesota (largest contiguous tract of old-growth forests in the Eastern US)
  • the Adirondacks (world-renowned large tract of old-growth in Northern New York)
  • many different wildlife reserves and game lands across the Eastern US

You can find undiscovered old-growth at higher elevations, in the middle of swamps, and far from roads. Old-growth can be found in the hills and the valleys, at low and high elevation. An old tree can be found just about anywhere. But finding a whole old-growth ecosystem can be challenging, especially in the US South.

Benefits of Old-Growth Forests

Old-growth forests offer many benefits to both the environment and local communities. Perhaps what they’re best known for are carbon storage and wildlife habitat.

Old trees are world-renowned for carbon storage. Every living tree in old-growth forests is busy storing carbon year round. Every ton of carbon stored in a forest is one less in the atmosphere. (Side note: natural forests are among the best solutions to climate change.)

Old-growth forests are also great for wildlife habitat. Old-growth tends to have a lot of “microclimates.” These are little patches where the weather is cooler or warmer depending on the trees above. Microclimates support a wide range of plant and animal life. From shade-tolerant species to rare birds, old-growth is where it’s at.

Other old-growth benefits include:

  • providing clean air and water through natural filtration systems
  • reducing soil erosion by stabilizing slopes with root systems
  • creating recreational opportunities for people to hike, birdwatch, and more
  • supporting Indigenous cultures through traditional foods and medicines
  • providing unusual homes (like dead trees) for plant and animal life

There are so many benefits to old-growth forests, and we’re discovering more and more every year.

Effects of Destroying Old-Growth Forests

Destroying old-growth forests hurts everyone. It can:

  • have devastating effects on both the environment and local communities
  • lead to increased soil erosion that can contaminate waterways
  • remove habitat for wildlife species
  • reduce access to traditional foods and medicines
  • disrupt spiritual sites used for ceremonies
  • decrease recreational opportunities
  • contribute to climate change by releasing stored carbon into the atmosphere

Old-growth is an untapped resource

The old-growth characteristics that protect these forests can also have a downside. For example, old-growth tends to be challenging to access (like on ancient mountains). Therefore, scientists can’t properly study the plant and animal life within. There may be undiscovered species lurking in old-growth that we just don’t know about. Many people believe that these forests are reservoirs for biological diversity. Our next cure for cancer could be in some moss, bacteria, or fungi only found in old-growth forests.

Conservation and Stewardship Efforts

There are many conservation efforts to protect old-growth forests from destruction. Organizations like The Old-Growth Forest Network (OGFN) identify areas where old-growth still exists. Then, they work to protect these places from logging that could damage the special environments.

Unfortunately, in the US, this is challenging. Many people believe the lie that there are no old-growth forests in the Eastern United States. Or, they think that the only old-growth that we have left is confined to protected areas like the Great Smoky Mountains National Park.

But National Parks are just the start of the old-growth story in the United States. Remember, old-growth forests can be cultivated through time. And many of our forests are almost at the old-growth threshold! There are some ways that we can support the growth of mature and older forests in the US.

Proforestation as a way to increase old-growth

Proforestation is the act of allowing forests to grow to maturity. Proforestation is a term that Dr. Bill Moomaw and colleagues coined in 2019. It’s a climate mitigation strategy that supports forests by leaving them alone. Radical, yet cost effective. We’ve written about proforestation a few times, and we’re behind it 100%. Proforestation is critical to ensuring a safe climate future.

Political focus on mature and old-growth forests

President Biden has signed several executive orders about mature forests. One executive order focused on the value of old-growth. The other demanded that our natural resource agencies actually document where old-growth forests are located.

It’s a great start, but it’s not nearly enough. We need action to protect mature and old-growth forests now. Not decades from now. Here’s how you can help:

Act Now: Forest Defense is Climate Defense!

We all have a responsibility to protect our planet’s precious old-growth forests!

Take action today to tell your elected officials about the importance of mature forests.

2 Responses to “What Are Old-Growth Forests and Where Can They Be Found?”

  1. Thanks for this great article! I’m the executive director of the 500-Year Forest Foundation in Virginia. Please check out our website. Thanks, Mary

  2. Maureen Daigle

    I live in Smokie mountains.. specifically in a small community that I believe has OLD Growth and the want to stop logging and any more building on my spot on my mountain! Please help , any advice is welcome


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